[CSSPGO] Pseudo probe encoding and emission.

[hoy]

Summary

This change implements pseudo probe encoding and emission for CSSPGO. Please see RFC here for more context: https://groups.google.com/g/llvm-dev/c/1p1rdYbL93s

Pseudo probes are in the form of intrinsic calls on IR/MIR but they do not turn into any machine instructions. Instead they are emitted into the binary as a piece of data in standalone sections. The probe-specific sections are not needed to be loaded into memory at execution time, thus they do not incur a runtime overhead. 

ELF object emission

The binary data to emit are organized as two ELF sections, i.e, the .pseudo_probe_desc section and the .pseudo_probe section. The .pseudo_probe_desc section stores a function descriptor for each function and the .pseudo_probe section stores the actual probes, each fo which corresponds to an IR basic block or an IR function callsite. A function descriptor is stored as a module-level metadata during the compilation and is serialized into the object file during object emission.

Both the probe descriptors and pseudo probes can be emitted into a separate ELF section per function to leverage the linker for deduplication. A .pseudo_probe section shares the same COMDAT group with the function code so that when the function is dead, the probes are dead and disposed too. On the contrary, a .pseudo_probe_desc section has its own COMDAT group. This is because even if a function is dead, its probes may be inlined into other functions and its descriptor is still needed by the profile generation tool.

The format of .pseudo_probe_desc section looks like:

.section   .pseudo_probe_desc,"",@progbits
.quad   6309742469962978389  // Func GUID
.quad   4294967295           // Func Hash
.byte   9                    // Length of func name
.ascii  "_Z5funcAi"          // Func name
.quad   7102633082150537521
.quad   138828622701
.byte   12
.ascii  "_Z8funcLeafi"
.quad   446061515086924981
.quad   4294967295
.byte   9
.ascii  "_Z5funcBi"
.quad   -2016976694713209516
.quad   72617220756
.byte   7
.ascii  "_Z3fibi"

For each .pseudoprobe section, the encoded binary data consists of a single function record corresponding to an outlined function (i.e, a function with a code entry in the .text section). A function record has the following format :

FUNCTION BODY (one for each outlined function present in the text section)
    GUID (uint64)
        GUID of the function
    NPROBES (ULEB128)
        Number of probes originating from this function.
    NUM_INLINED_FUNCTIONS (ULEB128)
        Number of callees inlined into this function, aka number of
        first-level inlinees
    PROBE RECORDS
        A list of NPROBES entries. Each entry contains:
          INDEX (ULEB128)
          TYPE (uint4)
            0 - block probe, 1 - indirect call, 2 - direct call
          ATTRIBUTE (uint3)
            reserved
          ADDRESS_TYPE (uint1)
            0 - code address, 1 - address delta
          CODE_ADDRESS (uint64 or ULEB128)
            code address or address delta, depending on ADDRESS_TYPE
    INLINED FUNCTION RECORDS
        A list of NUM_INLINED_FUNCTIONS entries describing each of the inlined
        callees.  Each record contains:
          INLINE SITE
            GUID of the inlinee (uint64)
            ID of the callsite probe (ULEB128)
          FUNCTION BODY
            A FUNCTION BODY entry describing the inlined function.

To support building a context-sensitive profile, probes from inlinees are grouped by their inline contexts. An inline context is logically a call path through which a callee function lands in a caller function. The probe emitter builds an inline tree based on the debug metadata for each outlined function in the form of a trie tree. A tree root is the outlined function. Each tree edge stands for a callsite where inlining happens. Pseudo probes originating from an inlinee function are stored in a tree node and the tree path starting from the root all the way down to the tree node is the inline context of the probes. The emission happens on the whole tree top-down recursively. Probes of a tree node will be emitted altogether with their direct parent edge. Since a pseudo probe corresponds to a real code address, for size savings, the address is encoded as a delta from the previous probe except for the first probe. Variant-sized integer encoding, aka LEB128, is used for address delta and probe index.

Assembling

Pseudo probes can be printed as assembly directives alternatively. This allows for good assembly code readability and also provides a view of how optimizations and pseudo probes affect each other, especially helpful for diff time assembly analysis.

A pseudo probe directive has the following operands in order: function GUID, probe index, probe type, probe attributes and inline context. The directive is generated by the compiler and can be parsed by the assembler to form an encoded .pseudoprobe section in the object file.

A example assembly looks like:

foo2: # @foo2
# %bb.0: # %bb0
pushq %rax
testl %edi, %edi
.pseudoprobe 837061429793323041 1 0 0
je .LBB1_1
# %bb.2: # %bb2
.pseudoprobe 837061429793323041 6 2 0
callq foo
.pseudoprobe 837061429793323041 3 0 0
.pseudoprobe 837061429793323041 4 0 0
popq %rax
retq
.LBB1_1: # %bb1
.pseudoprobe 837061429793323041 5 1 0
callq *%rsi
.pseudoprobe 837061429793323041 2 0 0
.pseudoprobe 837061429793323041 4 0 0
popq %rax
retq
# -- End function
.section .pseudo_probe_desc,"",@progbits
.quad 6699318081062747564
.quad 72617220756
.byte 3
.ascii "foo"
.quad 837061429793323041
.quad 281547593931412
.byte 4
.ascii "foo2"

With inlining turned on, the assembly may look different around %bb2 with an inlined probe:

# %bb.2:                                # %bb2
.pseudoprobe    837061429793323041 3 0
.pseudoprobe    6699318081062747564 1 0 @ 837061429793323041:6
.pseudoprobe    837061429793323041 4 0
popq    %rax
retq

Disassembling

We have a disassembling tool (llvm-profgen) that can display disassembly alongside with pseudo probes. So far it only supports ELF executable file.

An example disassembly looks like:

00000000002011a0 <foo2>:
  2011a0: 50                    push   rax
  2011a1: 85 ff                 test   edi,edi
  [Probe]:  FUNC: foo2  Index: 1  Type: Block
  2011a3: 74 02                 je     2011a7 <foo2+0x7>
  [Probe]:  FUNC: foo2  Index: 3  Type: Block
  [Probe]:  FUNC: foo2  Index: 4  Type: Block
  [Probe]:  FUNC: foo   Index: 1  Type: Block  Inlined: @ foo2:6
  2011a5: 58                    pop    rax
  2011a6: c3                    ret
  [Probe]:  FUNC: foo2  Index: 2  Type: Block
  2011a7: bf 01 00 00 00        mov    edi,0x1
  [Probe]:  FUNC: foo2  Index: 5  Type: IndirectCall
  2011ac: ff d6                 call   rsi
  [Probe]:  FUNC: foo2  Index: 4  Type: Block
  2011ae: 58                    pop    rax
  2011af: c3                    ret

[wmi]

Sorry for the delay in review. Some general questions.

I remember Wenlei mentioned in the RFC discussion that the overall binary size increase from pseudo probe is ~12% if CFG encoding is added. Is the size increase for object file from pseudo probe about the same as binary? I am asking because the total size of linker input matters for us. Previously we may use fission to separate the debug information from object file so it won't be accounted as linker input.

According to the description, The address range will be split into multiple ranges by the address of pseudo probe. If some BB somehow doesn't have block type pseudo probe, the addresses in the BB will be mistakenly associated with the pseudo probe located before it in the binary. I don't know whether you saw cases like that. A random thought is we may generate some fake pseudo probes for the BBs which don't have them, as a mark of the BB boundary.

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp

52

Is the comment up-to-date? Looks like the InlineStack only contains guid and probeid?

llvm/lib/MC/MCAsmStreamer.cpp

2135–2136

It is a reverse of sequence as the context string in the profile. Is it intentional?

2137

Is it unnecessary?

llvm/lib/MC/MCPseudoProbe.cpp

93–96

I think inline stack only contains guids and pseudo probe ids but here the example mentions line numbers in the stack. I understand probe id is extracted from the discriminator in the debug Location but it will be confusing if people don't know about it.

[hoy]

In D91878#2440875, @wmi wrote:

Sorry for the delay in review. Some general questions.

I remember Wenlei mentioned in the RFC discussion that the overall binary size increase from pseudo probe is ~12% if CFG encoding is added. Is the size increase for object file from pseudo probe about the same as binary? I am asking because the total size of linker input matters for us. Previously we may use fission to separate the debug information from object file so it won't be accounted as linker input.

According to the description, The address range will be split into multiple ranges by the address of pseudo probe. If some BB somehow doesn't have block type pseudo probe, the addresses in the BB will be mistakenly associated with the pseudo probe located before it in the binary. I don't know whether you saw cases like that. A random thought is we may generate some fake pseudo probes for the BBs which don't have them, as a mark of the BB boundary.

Thanks for reviewing this patch!

Regarding the binary size, an object file will likely have the same size inflation with an executable since the size of the pseudo probe sections are propositional to the text section. If that is an issue to the linker, we can also perform fission to the pseudo probe data. Pseudo probe encoding is currently done on function (comdat) level (see MCPseudoProbeSection::Emit in MCPseudoProbe.cpp`), which means a function always gets a separate real absolute probe encoded in the first place followed by relative address delta encoded for subsequent probes. Therefore fission on function level should be fine. Fission on block level won't work, as you pointed out. Would function-level fission work for you?

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp

52

Good catch. The numbers should refer to probe id.

llvm/lib/MC/MCAsmStreamer.cpp

2135–2136

Yes, it's intentional. We feel that it's easier to read when the inline context gets long. The decoding tool (https://reviews.llvm.org/D92334) also prints in the reverse order. What do you think? Would you perfer the profile context order?

2137

Good catch. Will remove it.

llvm/lib/MC/MCPseudoProbe.cpp

93–96

Right, the comment is out-dated. Will replace line numbers with probe ids.

[hoy]

Addressing Wei's feedbacks.

[hoy]

Fixing one more outdated comment.

[wmi]

In D91878#2441363, @hoy wrote:

In D91878#2440875, @wmi wrote:

Sorry for the delay in review. Some general questions.

I remember Wenlei mentioned in the RFC discussion that the overall binary size increase from pseudo probe is ~12% if CFG encoding is added. Is the size increase for object file from pseudo probe about the same as binary? I am asking because the total size of linker input matters for us. Previously we may use fission to separate the debug information from object file so it won't be accounted as linker input.

According to the description, The address range will be split into multiple ranges by the address of pseudo probe. If some BB somehow doesn't have block type pseudo probe, the addresses in the BB will be mistakenly associated with the pseudo probe located before it in the binary. I don't know whether you saw cases like that. A random thought is we may generate some fake pseudo probes for the BBs which don't have them, as a mark of the BB boundary.

Thanks for reviewing this patch!

Regarding the binary size, an object file will likely have the same size inflation with an executable since the size of the pseudo probe sections are propositional to the text section. If that is an issue to the linker, we can also perform fission to the pseudo probe data. Pseudo probe encoding is currently done on function (comdat) level (see MCPseudoProbeSection::Emit in MCPseudoProbe.cpp`), which means a function always gets a separate real absolute probe encoded in the first place followed by relative address delta encoded for subsequent probes. Therefore fission on function level should be fine. Fission on block level won't work, as you pointed out. Would function-level fission work for you?

Yes, function-level fission works for us. Adding that support later will be helpful.

[hoy]

In D91878#2441512, @wmi wrote:

In D91878#2441363, @hoy wrote:

In D91878#2440875, @wmi wrote:

Sorry for the delay in review. Some general questions.

I remember Wenlei mentioned in the RFC discussion that the overall binary size increase from pseudo probe is ~12% if CFG encoding is added. Is the size increase for object file from pseudo probe about the same as binary? I am asking because the total size of linker input matters for us. Previously we may use fission to separate the debug information from object file so it won't be accounted as linker input.

According to the description, The address range will be split into multiple ranges by the address of pseudo probe. If some BB somehow doesn't have block type pseudo probe, the addresses in the BB will be mistakenly associated with the pseudo probe located before it in the binary. I don't know whether you saw cases like that. A random thought is we may generate some fake pseudo probes for the BBs which don't have them, as a mark of the BB boundary.

Thanks for reviewing this patch!

Regarding the binary size, an object file will likely have the same size inflation with an executable since the size of the pseudo probe sections are propositional to the text section. If that is an issue to the linker, we can also perform fission to the pseudo probe data. Pseudo probe encoding is currently done on function (comdat) level (see MCPseudoProbeSection::Emit in MCPseudoProbe.cpp`), which means a function always gets a separate real absolute probe encoded in the first place followed by relative address delta encoded for subsequent probes. Therefore fission on function level should be fine. Fission on block level won't work, as you pointed out. Would function-level fission work for you?

Yes, function-level fission works for us. Adding that support later will be helpful.

Cool. It might already be there depending on how fission will be done. The current implementation always emit a relocation from a function's pseudo probe section to the function's text section. The rest of the function's probe will be encoded as a delta from that relocation. We will add more support if this is not sufficient.

[hoy]

llvm/lib/MC/MCAsmStreamer.cpp

2135–2136

I might be wrong. The decoding tool prints in the profile context (caller-callee) order. We should do the same here.

[hoy]

Print inline context in caller-callee order during asm printing

[wmi]

Please add a message for all the assertions. Other than that, LGTM.

[hoy]

Adding messages for assertions.

[mehdi_amini]

This breaks the build with gcc5:

llvm/lib/MC/MCParser/AsmParser.cpp:5836:49: error: converting to 'llvm::InlineSite {aka std::tuple<long unsigned int, unsigned int>}' from initializer list would use explicit constructor 'constexpr std::tuple<_T1, _T2>::tuple(_U1&&, _U2&&) [with _U1 = long int&; _U2 = long int&; <template-parameter-2-3> = void; _T1 = long unsigned int; _T2 = unsigned int]'
     InlineSite Site = {CallerGuid, CallerProbeId};

[hoy]

In D91878#2446515, @mehdi_amini wrote:

This breaks the build with gcc5:

llvm/lib/MC/MCParser/AsmParser.cpp:5836:49: error: converting to 'llvm::InlineSite {aka std::tuple<long unsigned int, unsigned int>}' from initializer list would use explicit constructor 'constexpr std::tuple<_T1, _T2>::tuple(_U1&&, _U2&&) [with _U1 = long int&; _U2 = long int&; <template-parameter-2-3> = void; _T1 = long unsigned int; _T2 = unsigned int]'
     InlineSite Site = {CallerGuid, CallerProbeId};

Thanks for reporting the issue. I will change to use an explicit constructor.

[hoy]

In D91878#2446557, @hoy wrote:

In D91878#2446515, @mehdi_amini wrote:

This breaks the build with gcc5:

llvm/lib/MC/MCParser/AsmParser.cpp:5836:49: error: converting to 'llvm::InlineSite {aka std::tuple<long unsigned int, unsigned int>}' from initializer list would use explicit constructor 'constexpr std::tuple<_T1, _T2>::tuple(_U1&&, _U2&&) [with _U1 = long int&; _U2 = long int&; <template-parameter-2-3> = void; _T1 = long unsigned int; _T2 = unsigned int]'
     InlineSite Site = {CallerGuid, CallerProbeId};

Thanks for reporting the issue. I will change to use an explicit constructor.

Fixed by changing to InlineSite Site(CallerGuid, CallerProbeId);

[craig.topper]

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp

66

This line doesn't compile with gcc 5.4

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp:65:62: error: converting to ‘std::tuple<long unsigned int, unsigned int>’ from initializer list would use explicit constructor ‘constexpr std::tuple<_T1, _T2>::tuple(_U1&&, _U2&&) [with _U1 = long unsigned int&; _U2 = long unsigned int&; <template-parameter-2-3> = void; _T1 = long unsigned int; _T2 = unsigned int]’
     ReversedInlineStack.push_back({CallerGuid, CallerProbeId})

Changing it to emplace_back and dropping the curly braces seemed to work.

[hoy]

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp

66

Thanks for the suggestion! Fix pushed in just now.

[hoy]

@hctim Can you please let me know why this is reverted? Is it breaking any build? Thanks.

[hctim]

Hi - yep, sorry for taking a sec to comment here. It broke the sanitizer buildbots here: http://lab.llvm.org:8011/#/builders/5/builds/2269

You can learn more about how to repro the exact bot here: https://github.com/google/sanitizers/wiki/SanitizerBotReproduceBuild

I've copied the ASan errors below just for your convenience :)

FAIL: LLVM :: Transforms/SampleProfile/pseudo-probe-emit-inline.ll (65962 of 72157)
******************** TEST 'LLVM :: Transforms/SampleProfile/pseudo-probe-emit-inline.ll' FAILED ********************
Script:
--
: 'RUN: at line 2';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/opt < /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll -passes='pseudo-probe,cgscc(inline)' -function-sections -mtriple=x86_64-unknown-linux-gnu -S -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp
: 'RUN: at line 3';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp --check-prefix=CHECK-IL
: 'RUN: at line 4';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc -pseudo-probe-for-profiling -function-sections </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp -filetype=asm -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1
: 'RUN: at line 5';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1 --check-prefix=CHECK-ASM
: 'RUN: at line 6';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc -pseudo-probe-for-profiling -function-sections </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp -filetype=obj -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp2
: 'RUN: at line 7';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp2 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll --check-prefix=CHECK-OBJ
: 'RUN: at line 8';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-mc -filetype=asm </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1 -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp3
: 'RUN: at line 9';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp3 --check-prefix=CHECK-ASM
: 'RUN: at line 10';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-mc -filetype=obj </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1 -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp4
: 'RUN: at line 11';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp4 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll --check-prefix=CHECK-OBJ
--
Exit Code: 1
Command Output (stderr):
--
=================================================================
==13817==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x8727eac in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:10
    #2 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #3 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #4 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #5 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #6 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #7 0x7fa76d5fa09a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
Indirect leak of 1536 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x88de0b6 in allocateBuckets /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:871:9
    #2 0x88de0b6 in llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::grow(unsigned int) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:805:5
    #3 0x88ddea4 in grow /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:536:36
    #4 0x88ddea4 in llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>* llvm::DenseMapBase<llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >, llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::InsertIntoBucketImpl<llvm::StringRef>(llvm::StringRef const&, llvm::StringRef const&, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:580:13
    #5 0x88dbb41 in InsertIntoBucket<const llvm::StringRef &> /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:546:17
    #6 0x88dbb41 in FindAndConstruct /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:325:13
    #7 0x88dbb41 in operator[] /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:329:12
    #8 0x88dbb41 in llvm::PseudoProbeHandler::PseudoProbeHandler(llvm::AsmPrinter*, llvm::Module*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp:40:5
    #9 0x8727ec1 in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:14
    #10 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #11 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #12 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #13 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #14 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #15 0x7fa76d5fa09a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
SUMMARY: AddressSanitizer: 1576 byte(s) leaked in 2 allocation(s).
--
********************
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 
FAIL: LLVM :: Transforms/SampleProfile/pseudo-probe-emit.ll (66047 of 72157)
******************** TEST 'LLVM :: Transforms/SampleProfile/pseudo-probe-emit.ll' FAILED ********************
Script:
--
: 'RUN: at line 2';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/opt < /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll -passes=pseudo-probe -function-sections -S -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp
: 'RUN: at line 3';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp --check-prefix=CHECK-IL
: 'RUN: at line 4';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp -pseudo-probe-for-profiling -stop-after=pseudo-probe-inserter -o - | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll --check-prefix=CHECK-MIR
: 'RUN: at line 5';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp -pseudo-probe-for-profiling -function-sections -filetype=asm -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp1
: 'RUN: at line 6';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp1 --check-prefix=CHECK-ASM
: 'RUN: at line 7';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp -pseudo-probe-for-profiling -function-sections -filetype=obj -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp2
: 'RUN: at line 8';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp2 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll --check-prefix=CHECK-OBJ
: 'RUN: at line 9';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-mc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp1 -filetype=obj -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp3
: 'RUN: at line 10';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp3 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll --check-prefix=CHECK-OBJ
--
Exit Code: 1
Command Output (stderr):
--
=================================================================
==15119==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x8727eac in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:10
    #2 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #3 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #4 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #5 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #6 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #7 0x7f642eb0909a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
Indirect leak of 1536 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x88de0b6 in allocateBuckets /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:871:9
    #2 0x88de0b6 in llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::grow(unsigned int) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:805:5
    #3 0x88ddea4 in grow /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:536:36
    #4 0x88ddea4 in llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>* llvm::DenseMapBase<llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >, llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::InsertIntoBucketImpl<llvm::StringRef>(llvm::StringRef const&, llvm::StringRef const&, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:580:13
    #5 0x88dbb41 in InsertIntoBucket<const llvm::StringRef &> /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:546:17
    #6 0x88dbb41 in FindAndConstruct /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:325:13
    #7 0x88dbb41 in operator[] /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:329:12
    #8 0x88dbb41 in llvm::PseudoProbeHandler::PseudoProbeHandler(llvm::AsmPrinter*, llvm::Module*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp:40:5
    #9 0x8727ec1 in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:14
    #10 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #11 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #12 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #13 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #14 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #15 0x7f642eb0909a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
SUMMARY: AddressSanitizer: 1576 byte(s) leaked in 2 allocation(s).
--
********************
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90.. 
********************
Failed Tests (2):
  LLVM :: Transforms/SampleProfile/pseudo-probe-emit-inline.ll
  LLVM :: Transforms/SampleProfile/pseudo-probe-emit.ll

[hoy]

In D91878#2447498, @hctim wrote:

Hi - yep, sorry for taking a sec to comment here. It broke the sanitizer buildbots here: http://lab.llvm.org:8011/#/builders/5/builds/2269

You can learn more about how to repro the exact bot here: https://github.com/google/sanitizers/wiki/SanitizerBotReproduceBuild

I've copied the ASan errors below just for your convenience :)

FAIL: LLVM :: Transforms/SampleProfile/pseudo-probe-emit-inline.ll (65962 of 72157)
******************** TEST 'LLVM :: Transforms/SampleProfile/pseudo-probe-emit-inline.ll' FAILED ********************
Script:
--
: 'RUN: at line 2';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/opt < /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll -passes='pseudo-probe,cgscc(inline)' -function-sections -mtriple=x86_64-unknown-linux-gnu -S -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp
: 'RUN: at line 3';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp --check-prefix=CHECK-IL
: 'RUN: at line 4';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc -pseudo-probe-for-profiling -function-sections </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp -filetype=asm -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1
: 'RUN: at line 5';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1 --check-prefix=CHECK-ASM
: 'RUN: at line 6';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc -pseudo-probe-for-profiling -function-sections </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp -filetype=obj -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp2
: 'RUN: at line 7';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp2 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll --check-prefix=CHECK-OBJ
: 'RUN: at line 8';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-mc -filetype=asm </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1 -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp3
: 'RUN: at line 9';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp3 --check-prefix=CHECK-ASM
: 'RUN: at line 10';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-mc -filetype=obj </b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp1 -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp4
: 'RUN: at line 11';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit-inline.ll.tmp4 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll --check-prefix=CHECK-OBJ
--
Exit Code: 1
Command Output (stderr):
--
=================================================================
==13817==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x8727eac in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:10
    #2 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #3 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #4 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #5 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #6 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #7 0x7fa76d5fa09a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
Indirect leak of 1536 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x88de0b6 in allocateBuckets /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:871:9
    #2 0x88de0b6 in llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::grow(unsigned int) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:805:5
    #3 0x88ddea4 in grow /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:536:36
    #4 0x88ddea4 in llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>* llvm::DenseMapBase<llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >, llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::InsertIntoBucketImpl<llvm::StringRef>(llvm::StringRef const&, llvm::StringRef const&, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:580:13
    #5 0x88dbb41 in InsertIntoBucket<const llvm::StringRef &> /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:546:17
    #6 0x88dbb41 in FindAndConstruct /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:325:13
    #7 0x88dbb41 in operator[] /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:329:12
    #8 0x88dbb41 in llvm::PseudoProbeHandler::PseudoProbeHandler(llvm::AsmPrinter*, llvm::Module*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp:40:5
    #9 0x8727ec1 in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:14
    #10 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #11 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #12 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #13 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #14 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #15 0x7fa76d5fa09a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
SUMMARY: AddressSanitizer: 1576 byte(s) leaked in 2 allocation(s).
--
********************
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 
FAIL: LLVM :: Transforms/SampleProfile/pseudo-probe-emit.ll (66047 of 72157)
******************** TEST 'LLVM :: Transforms/SampleProfile/pseudo-probe-emit.ll' FAILED ********************
Script:
--
: 'RUN: at line 2';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/opt < /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll -passes=pseudo-probe -function-sections -S -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp
: 'RUN: at line 3';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp --check-prefix=CHECK-IL
: 'RUN: at line 4';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp -pseudo-probe-for-profiling -stop-after=pseudo-probe-inserter -o - | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll --check-prefix=CHECK-MIR
: 'RUN: at line 5';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp -pseudo-probe-for-profiling -function-sections -filetype=asm -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp1
: 'RUN: at line 6';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll < /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp1 --check-prefix=CHECK-ASM
: 'RUN: at line 7';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp -pseudo-probe-for-profiling -function-sections -filetype=obj -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp2
: 'RUN: at line 8';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp2 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll --check-prefix=CHECK-OBJ
: 'RUN: at line 9';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-mc /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp1 -filetype=obj -o /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp3
: 'RUN: at line 10';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llvm-objdump --section-headers  /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/test/Transforms/SampleProfile/Output/pseudo-probe-emit.ll.tmp3 | /b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/FileCheck --allow-unused-prefixes=false /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll --check-prefix=CHECK-OBJ
--
Exit Code: 1
Command Output (stderr):
--
=================================================================
==15119==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x8727eac in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:10
    #2 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #3 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #4 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #5 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #6 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #7 0x7f642eb0909a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
Indirect leak of 1536 byte(s) in 1 object(s) allocated from:
    #0 0x462a9cd in operator new(unsigned long) /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x88de0b6 in allocateBuckets /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:871:9
    #2 0x88de0b6 in llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::grow(unsigned int) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:805:5
    #3 0x88ddea4 in grow /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:536:36
    #4 0x88ddea4 in llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>* llvm::DenseMapBase<llvm::DenseMap<llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >, llvm::StringRef, unsigned long, llvm::DenseMapInfo<llvm::StringRef>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long> >::InsertIntoBucketImpl<llvm::StringRef>(llvm::StringRef const&, llvm::StringRef const&, llvm::detail::DenseMapPair<llvm::StringRef, unsigned long>*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:580:13
    #5 0x88dbb41 in InsertIntoBucket<const llvm::StringRef &> /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:546:17
    #6 0x88dbb41 in FindAndConstruct /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:325:13
    #7 0x88dbb41 in operator[] /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/DenseMap.h:329:12
    #8 0x88dbb41 in llvm::PseudoProbeHandler::PseudoProbeHandler(llvm::AsmPrinter*, llvm::Module*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp:40:5
    #9 0x8727ec1 in llvm::AsmPrinter::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:339:14
    #10 0x9b380d5 in llvm::FPPassManager::doInitialization(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1495:41
    #11 0x9b222a8 in runOnModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1529:41
    #12 0x9b222a8 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:542:44
    #13 0x463416f in compileModule /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:658:8
    #14 0x463416f in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:363:22
    #15 0x7f642eb0909a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
SUMMARY: AddressSanitizer: 1576 byte(s) leaked in 2 allocation(s).
--
********************
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90.. 
********************
Failed Tests (2):
  LLVM :: Transforms/SampleProfile/pseudo-probe-emit-inline.ll
  LLVM :: Transforms/SampleProfile/pseudo-probe-emit.ll

Thanks for the pointers! I have reproduced and fixed the failure. Will re-push the patch in.

llvm/include/llvm/CodeGen/AsmPrinter.h

 class MCInst;
 class MCSection;
 class MCStreamer;
 class MCSubtargetInfo;
 class MCSymbol;
 class MCTargetOptions;
 class MDNode;
 class Module;
+class PseudoProbeHandler;
 class raw_ostream;
 class StackMaps;
 class StringRef;
 class TargetLoweringObjectFile;
 class TargetMachine;
 class Twine;
 
 namespace remarks {
private:
 
   /// Structure for generating diagnostics for inline assembly. Only initialised
   /// when necessary.
   mutable std::unique_ptr<SrcMgrDiagInfo> DiagInfo;
 
   /// If the target supports dwarf debug info, this pointer is non-null.
   DwarfDebug *DD = nullptr;
 
+  /// A handler that supports pseudo probe emission with embedded inline
+  /// context.
+  PseudoProbeHandler *PP = nullptr;
+
   /// If the current module uses dwarf CFI annotations strictly for debugging.
   bool isCFIMoveForDebugging = false;
 
 protected:
   explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
 
 public:
   ~AsmPrinter() override;
public:
   void emitCFIInstruction(const MachineInstr &MI);
 
   void emitFrameAlloc(const MachineInstr &MI);
 
   void emitStackSizeSection(const MachineFunction &MF);
 
   void emitBBAddrMapSection(const MachineFunction &MF);
 
+  void emitPseudoProbe(const MachineInstr &MI);
+
   void emitRemarksSection(remarks::RemarkStreamer &RS);
 
   enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
   CFIMoveType needsCFIMoves() const;
 
   /// Returns false if needsCFIMoves() == CFI_M_EH for any function
   /// in the module.
   bool needsOnlyDebugCFIMoves() const { return isCFIMoveForDebugging; }

llvm/include/llvm/IR/MDBuilder.h

public:
   /// GUIDs stored in \p Imports that need to be imported for sample PGO, to
   /// enable the same inlines as the profiled optimized binary
   MDNode *createFunctionEntryCount(uint64_t Count, bool Synthetic,
                                    const DenseSet<GlobalValue::GUID> *Imports);
 
   /// Return metadata containing the section prefix for a function.
   MDNode *createFunctionSectionPrefix(StringRef Prefix);
 
+  /// Return metadata containing the pseudo probe descriptor for a function.
+  MDNode *createPseudoProbeDesc(uint64_t GUID, uint64_t Hash, Function *F);
+
   //===------------------------------------------------------------------===//
   // Range metadata.
   //===------------------------------------------------------------------===//
 
   /// Return metadata describing the range [Lo, Hi).
   MDNode *createRange(const APInt &Lo, const APInt &Hi);
 
   /// Return metadata describing the range [Lo, Hi).

llvm/include/llvm/IR/PseudoProbe.h

 #ifndef LLVM_IR_PSEUDOPROBE_H
 #define LLVM_IR_PSEUDOPROBE_H
 
 #include <cassert>
 #include <cstdint>
 
 namespace llvm {
 
+constexpr const char *PseudoProbeDescMetadataName = "llvm.pseudo_probe_desc";
+
 enum class PseudoProbeType { Block = 0, IndirectCall, DirectCall };
 
 struct PseudoProbeDwarfDiscriminator {
   // The following APIs encodes/decodes per-probe information to/from a
   // 32-bit integer which is organized as:
   //  [2:0] - 0x7, this is reserved for regular discriminator,
   //          see DWARF discriminator encoding rule
   //  [18:3] - probe id

llvm/include/llvm/MC/MCAssembler.h

private:
   bool relaxLEB(MCAsmLayout &Layout, MCLEBFragment &IF);
   bool relaxBoundaryAlign(MCAsmLayout &Layout, MCBoundaryAlignFragment &BF);
   bool relaxDwarfLineAddr(MCAsmLayout &Layout, MCDwarfLineAddrFragment &DF);
   bool relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
                                    MCDwarfCallFrameFragment &DF);
   bool relaxCVInlineLineTable(MCAsmLayout &Layout,
                               MCCVInlineLineTableFragment &DF);
   bool relaxCVDefRange(MCAsmLayout &Layout, MCCVDefRangeFragment &DF);
+  bool relaxPseudoProbeAddr(MCAsmLayout &Layout, MCPseudoProbeAddrFragment &DF);
 
   /// finishLayout - Finalize a layout, including fragment lowering.
   void finishLayout(MCAsmLayout &Layout);
 
   std::tuple<MCValue, uint64_t, bool>
   handleFixup(const MCAsmLayout &Layout, MCFragment &F, const MCFixup &Fixup);
 
 public:

llvm/include/llvm/MC/MCContext.h

 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/BinaryFormat/XCOFF.h"
 #include "llvm/MC/MCAsmMacro.h"
 #include "llvm/MC/MCDwarf.h"
+#include "llvm/MC/MCPseudoProbe.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCTargetOptions.h"
 #include "llvm/MC/SectionKind.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/raw_ostream.h"
private:
     /// differences between temporary and non-temporary labels (primarily on
     /// Darwin).
     bool AllowTemporaryLabels = true;
     bool UseNamesOnTempLabels = false;
 
     /// The Compile Unit ID that we are currently processing.
     unsigned DwarfCompileUnitID = 0;
 
+    /// A collection of MCPseudoProbe in the current module
+    MCPseudoProbeTable PseudoProbeTable;
+
     // Sections are differentiated by the quadruple (section_name, group_name,
     // unique_id, link_to_symbol_name). Sections sharing the same quadruple are
     // combined into one section.
     struct ELFSectionKey {
       std::string SectionName;
       StringRef GroupName;
       StringRef LinkedToName;
       unsigned UniqueID;
const MCAsmMacro *lookupMacro(StringRef Name) {
       return (I == MacroMap.end()) ? nullptr : &I->getValue();
     }
 
     void defineMacro(StringRef Name, MCAsmMacro Macro) {
       MacroMap.insert(std::make_pair(Name, std::move(Macro)));
     }
 
     void undefineMacro(StringRef Name) { MacroMap.erase(Name); }
+
+    MCPseudoProbeTable &getMCPseudoProbeTable() { return PseudoProbeTable; }
   };
 
 } // end namespace llvm
 
 // operator new and delete aren't allowed inside namespaces.
 // The throw specifications are mandated by the standard.
 /// Placement new for using the MCContext's allocator.
 ///

llvm/include/llvm/MC/MCFragment.h

enum FragmentType : uint8_t {
     FT_Org,
     FT_Dwarf,
     FT_DwarfFrame,
     FT_LEB,
     FT_BoundaryAlign,
     FT_SymbolId,
     FT_CVInlineLines,
     FT_CVDefRange,
+    FT_PseudoProbe,
     FT_Dummy
   };
 
 private:
   /// The data for the section this fragment is in.
   MCSection *Parent;
 
   /// The atom this fragment is in, as represented by its defining symbol.
static bool classof(const MCFragment *F) {
     switch (Kind) {
     default:
       return false;
     case MCFragment::FT_Relaxable:
     case MCFragment::FT_CompactEncodedInst:
     case MCFragment::FT_Data:
     case MCFragment::FT_Dwarf:
     case MCFragment::FT_DwarfFrame:
+    case MCFragment::FT_PseudoProbe:
       return true;
     }
   }
 
   /// Should this fragment be placed at the end of an aligned bundle?
   bool alignToBundleEnd() const { return AlignToBundleEnd; }
   void setAlignToBundleEnd(bool V) { AlignToBundleEnd = V; }
 
void setLastFragment(const MCFragment *F) {
     assert(!F || getParent() == F->getParent());
     LastFragment = F;
   }
 
   static bool classof(const MCFragment *F) {
     return F->getKind() == MCFragment::FT_BoundaryAlign;
   }
 };
+
+class MCPseudoProbeAddrFragment : public MCEncodedFragmentWithFixups<8, 1> {
+  /// The expression for the difference of the two symbols that
+  /// make up the address delta between two .pseudoprobe directives.
+  const MCExpr *AddrDelta;
+
+public:
+  MCPseudoProbeAddrFragment(const MCExpr *AddrDelta, MCSection *Sec = nullptr)
+      : MCEncodedFragmentWithFixups<8, 1>(FT_PseudoProbe, false, Sec),
+        AddrDelta(AddrDelta) {}
+
+  const MCExpr &getAddrDelta() const { return *AddrDelta; }
+
+  static bool classof(const MCFragment *F) {
+    return F->getKind() == MCFragment::FT_PseudoProbe;
+  }
+};
 } // end namespace llvm
 
 #endif // LLVM_MC_MCFRAGMENT_H

llvm/include/llvm/MC/MCObjectFileInfo.h

protected:
   /// EH frame section.
   ///
   /// It is initialized on demand so it can be overwritten (with uniquing).
   MCSection *EHFrameSection = nullptr;
 
   /// Section containing metadata on function stack sizes.
   MCSection *StackSizesSection = nullptr;
 
+  /// Section for pseudo probe information used by AutoFDO
+  MCSection *PseudoProbeSection = nullptr;
+  MCSection *PseudoProbeDescSection = nullptr;
+
   // ELF specific sections.
   MCSection *DataRelROSection = nullptr;
   MCSection *MergeableConst4Section = nullptr;
   MCSection *MergeableConst8Section = nullptr;
   MCSection *MergeableConst16Section = nullptr;
   MCSection *MergeableConst32Section = nullptr;
 
   // MachO specific sections.
public:
   MCSection *getStackMapSection() const { return StackMapSection; }
   MCSection *getFaultMapSection() const { return FaultMapSection; }
   MCSection *getRemarksSection() const { return RemarksSection; }
 
   MCSection *getStackSizesSection(const MCSection &TextSec) const;
 
   MCSection *getBBAddrMapSection(const MCSection &TextSec) const;
 
+  MCSection *getPseudoProbeSection(const MCSection *TextSec) const;
+
+  MCSection *getPseudoProbeDescSection(StringRef FuncName) const;
+
   // ELF specific sections.
   MCSection *getDataRelROSection() const { return DataRelROSection; }
   const MCSection *getMergeableConst4Section() const {
     return MergeableConst4Section;
   }
   const MCSection *getMergeableConst8Section() const {
     return MergeableConst8Section;
   }

llvm/include/llvm/MC/MCPseudoProbe.h

+//===- MCPseudoProbe.h - Pseudo probe encoding support ---------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the declaration of the MCPseudoProbe to support the pseudo
+// probe encoding for AutoFDO. Pseudo probes together with their inline context
+// are encoded in a DFS recursive way in the .pseudoprobe sections. For each
+// .pseudoprobe section, the encoded binary data consist of a single or mutiple
+// function records each for one outlined function. A function record has the
+// following format :
+//
+// FUNCTION BODY (one for each outlined function present in the text section)
+//    GUID (uint64)
+//        GUID of the function
+//    NPROBES (ULEB128)
+//        Number of probes originating from this function.
+//    NUM_INLINED_FUNCTIONS (ULEB128)
+//        Number of callees inlined into this function, aka number of
+//        first-level inlinees
+//    PROBE RECORDS
+//        A list of NPROBES entries. Each entry contains:
+//          INDEX (ULEB128)
+//          TYPE (uint4)
+//            0 - block probe, 1 - indirect call, 2 - direct call
+//          ATTRIBUTE (uint3)
+//            reserved
+//          ADDRESS_TYPE (uint1)
+//            0 - code address, 1 - address delta
+//          CODE_ADDRESS (uint64 or ULEB128)
+//            code address or address delta, depending on ADDRESS_TYPE
+//    INLINED FUNCTION RECORDS
+//        A list of NUM_INLINED_FUNCTIONS entries describing each of the inlined
+//        callees.  Each record contains:
+//          INLINE SITE
+//            GUID of the inlinee (uint64)
+//            ID of the callsite probe (ULEB128)
+//          FUNCTION BODY
+//            A FUNCTION BODY entry describing the inlined function.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCPSEUDOPROBE_H
+#define LLVM_MC_MCPSEUDOPROBE_H
+
+#include "llvm/ADT/MapVector.h"
+#include "llvm/MC/MCSection.h"
+#include <functional>
+#include <map>
+#include <vector>
+
+namespace llvm {
+
+class MCStreamer;
+class MCSymbol;
+class MCObjectStreamer;
+
+enum class MCPseudoProbeFlag {
+  // If set, indicates that the probe is encoded as an address delta
+  // instead of a real code address.
+  AddressDelta = 0x1,
+};
+
+/// Instances of this class represent a pseudo probe instance for a pseudo probe
+/// table entry, which is created during a machine instruction is assembled and
+/// uses an address from a temporary label created at the current address in the
+/// current section.
+class MCPseudoProbe {
+  MCSymbol *Label;
+  uint64_t Guid;
+  uint64_t Index;
+  uint8_t Type;
+  uint8_t Attributes;
+
+public:
+  MCPseudoProbe(MCSymbol *Label, uint64_t Guid, uint64_t Index, uint64_t Type,
+                uint64_t Attributes)
+      : Label(Label), Guid(Guid), Index(Index), Type(Type),
+        Attributes(Attributes) {
+    assert(Type < 0xFF && Attributes < 0xFF);
+  }
+
+  MCSymbol *getLabel() const { return Label; }
+
+  uint64_t getGuid() const { return Guid; }
+
+  uint64_t getIndex() const { return Index; }
+
+  uint8_t getType() const { return Type; }
+
+  uint8_t getAttributes() const { return Attributes; }
+
+  void emit(MCObjectStreamer *MCOS, const MCPseudoProbe *LastProbe) const;
+};
+
+// An inline frame has the form <Guid, ProbeID>
+using InlineSite = std::tuple<uint64_t, uint32_t>;
+using MCPseudoProbeInlineStack = SmallVector<InlineSite, 8>;
+
+// A Tri-tree based data structure to group probes by inline stack.
+// A tree is allocated for a standalone .text section. A fake
+// instance is created as the root of a tree.
+// A real instance of this class is created for each function, either an
+// unlined function that has code in .text section or an inlined function.
+class MCPseudoProbeInlineTree {
+  uint64_t Guid;
+  // Set of probes that come with the function.
+  std::vector<MCPseudoProbe> Probes;
+  // Use std::map for a deterministic output.
+  std::map<InlineSite, MCPseudoProbeInlineTree *> Inlinees;
+
+  // Root node has a GUID 0.
+  bool isRoot() { return Guid == 0; }
+  MCPseudoProbeInlineTree *getOrAddNode(InlineSite Site);
+
+public:
+  MCPseudoProbeInlineTree() = default;
+  MCPseudoProbeInlineTree(uint64_t Guid) : Guid(Guid) {}
+  ~MCPseudoProbeInlineTree();
+  void addPseudoProbe(const MCPseudoProbe &Probe,
+                      const MCPseudoProbeInlineStack &InlineStack);
+  void emit(MCObjectStreamer *MCOS, const MCPseudoProbe *&LastProbe);
+};
+
+/// Instances of this class represent the pseudo probes inserted into a compile
+/// unit.
+class MCPseudoProbeSection {
+public:
+  void addPseudoProbe(MCSection *Sec, const MCPseudoProbe &Probe,
+                      const MCPseudoProbeInlineStack &InlineStack) {
+    MCProbeDivisions[Sec].addPseudoProbe(Probe, InlineStack);
+  }
+
+  // TODO: Sort by getOrdinal to ensure a determinstic section order
+  using MCProbeDivisionMap = std::map<MCSection *, MCPseudoProbeInlineTree>;
+
+private:
+  // A collection of MCPseudoProbe for each text section. The MCPseudoProbes
+  // are grouped by GUID of the functions where they are from and will be
+  // encoded by groups. In the comdat scenario where a text section really only
+  // contains the code of a function solely, the probes associated with a comdat
+  // function are still grouped by GUIDs due to inlining that can bring probes
+  // from different functions into one function.
+  MCProbeDivisionMap MCProbeDivisions;
+
+public:
+  const MCProbeDivisionMap &getMCProbes() const { return MCProbeDivisions; }
+
+  bool empty() const { return MCProbeDivisions.empty(); }
+
+  void emit(MCObjectStreamer *MCOS);
+};
+
+class MCPseudoProbeTable {
+  // A collection of MCPseudoProbe in the current module grouped by text
+  // sections. MCPseudoProbes will be encoded into a corresponding
+  // .pseudoprobe section. With functions emitted as separate comdats,
+  // a text section really only contains the code of a function solely, and the
+  // probes associated with the text section will be emitted into a standalone
+  // .pseudoprobe section that shares the same comdat group with the function.
+  MCPseudoProbeSection MCProbeSections;
+
+public:
+  static void emit(MCObjectStreamer *MCOS);
+
+  MCPseudoProbeSection &getProbeSections() { return MCProbeSections; }
+
+#ifndef NDEBUG
+  static int DdgPrintIndent;
+#endif
+};
+} // end namespace llvm
+
+#endif // LLVM_MC_MCPSEUDOPROBE_H

llvm/include/llvm/MC/MCStreamer.h

 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/MC/MCDirectives.h"
 #include "llvm/MC/MCLinkerOptimizationHint.h"
+#include "llvm/MC/MCPseudoProbe.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCWinEH.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/SMLoc.h"
 #include "llvm/Support/TargetParser.h"
 #include "llvm/Support/VersionTuple.h"
 #include <cassert>
public:
   }
 
   virtual void emitAddrsig() {}
   virtual void emitAddrsigSym(const MCSymbol *Sym) {}
 
   /// Emit the given \p Instruction into the current section.
   virtual void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI);
 
+  /// Emit the a pseudo probe into the current section.
+  virtual void emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
+                               uint64_t Attr,
+                               const MCPseudoProbeInlineStack &InlineStack);
+
   /// Set the bundle alignment mode from now on in the section.
   /// The argument is the power of 2 to which the alignment is set. The
   /// value 0 means turn the bundle alignment off.
   virtual void emitBundleAlignMode(unsigned AlignPow2);
 
   /// The following instructions are a bundle-locked group.
   ///
   /// \param AlignToEnd - If true, the bundle-locked group will be aligned to

llvm/include/llvm/Passes/PassBuilder.h

PGOOptions(std::string ProfileFile = "", std::string CSProfileGenFile = "",
     // a profile.
     assert(this->CSAction != CSIRUse || this->Action == IRUse);
 
     // If neither Action nor CSAction, DebugInfoForProfiling or
     // PseudoProbeForProfiling needs to be true.
     assert(this->Action != NoAction || this->CSAction != NoCSAction ||
            this->DebugInfoForProfiling || this->PseudoProbeForProfiling);
 
-    // Pseudo probe emission does work with -fdebug-info-for-profiling since
+    // Pseudo probe emission does not work with -fdebug-info-for-profiling since
     // they both use the discriminator field of debug lines but for different
     // purposes.
     if (this->DebugInfoForProfiling && this->PseudoProbeForProfiling) {
       report_fatal_error(
           "Pseudo probes cannot be used with -debug-info-for-profiling", false);
     }
   }
   std::string ProfileFile;

llvm/include/llvm/Transforms/IPO/SampleProfileProbe.h

 
 
 /// Sample profile pseudo prober.
 ///
 /// Insert pseudo probes for block sampling and value sampling.
 class SampleProfileProber {
 public:
   // Give an empty module id when the prober is not used for instrumentation.
-  SampleProfileProber(Function &F);
+  SampleProfileProber(Function &F, const std::string &CurModuleUniqueId);
   void instrumentOneFunc(Function &F, TargetMachine *TM);
 
 private:
   Function *getFunction() const { return F; }
+  uint64_t getFunctionHash() const { return FunctionHash; }
   uint32_t getBlockId(const BasicBlock *BB) const;
   uint32_t getCallsiteId(const Instruction *Call) const;
+  void computeCFGHash();
   void computeProbeIdForBlocks();
   void computeProbeIdForCallsites();
 
   Function *F;
 
+  /// The current module ID that is used to name a static object as a comdat
+  /// group.
+  std::string CurModuleUniqueId;
+
+  /// A CFG hash code used to identify a function code changes.
+  uint64_t FunctionHash;
+
   /// Map basic blocks to the their pseudo probe ids.
   BlockIdMap BlockProbeIds;
 
   /// Map indirect calls to the their pseudo probe ids.
   InstructionIdMap CallProbeIds;
 
   /// The ID of the last probe, Can be used to number a new probe.
   uint32_t LastProbeId;

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

 //===- AsmPrinter.cpp - Common AsmPrinter code ----------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the AsmPrinter class.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "CodeViewDebug.h"
 #include "DwarfDebug.h"
 #include "DwarfException.h"
+#include "PseudoProbePrinter.h"
 #include "WasmException.h"
 #include "WinCFGuard.h"
 #include "WinException.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"

 #include "llvm/IR/GlobalObject.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Mangler.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/IR/PseudoProbe.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCDirectives.h"
 #include "llvm/MC/MCDwarf.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
if (!EmitCodeView || M.getDwarfVersion()) {
         DD = new DwarfDebug(this);
         Handlers.emplace_back(std::unique_ptr<DwarfDebug>(DD), DbgTimerName,
                               DbgTimerDescription, DWARFGroupName,
                               DWARFGroupDescription);
       }
     }
   }
 
+  if (M.getNamedMetadata(PseudoProbeDescMetadataName))
+    PP = new PseudoProbeHandler(this, &M);
+
   switch (MAI->getExceptionHandlingType()) {
   case ExceptionHandling::SjLj:
   case ExceptionHandling::DwarfCFI:
   case ExceptionHandling::ARM:
     isCFIMoveForDebugging = true;
     if (MAI->getExceptionHandlingType() != ExceptionHandling::DwarfCFI)
       break;
     for (auto &F: M.getFunctionList()) {
for (const MachineBasicBlock &MBB : MF) {
     // Emit the basic block size. When BBs have alignments, their size cannot
     // always be computed from their offsets.
     emitLabelDifferenceAsULEB128(MBB.getEndSymbol(), MBBSymbol);
     OutStreamer->emitULEB128IntValue(getBBAddrMapMetadata(MBB));
   }
   OutStreamer->PopSection();
 }
 
+void AsmPrinter::emitPseudoProbe(const MachineInstr &MI) {
+  auto GUID = MI.getOperand(0).getImm();
+  auto Index = MI.getOperand(1).getImm();
+  auto Type = MI.getOperand(2).getImm();
+  auto Attr = MI.getOperand(3).getImm();
+  DILocation *DebugLoc = MI.getDebugLoc();
+  PP->emitPseudoProbe(GUID, Index, Type, Attr, DebugLoc);
+}
+
 void AsmPrinter::emitStackSizeSection(const MachineFunction &MF) {
   if (!MF.getTarget().Options.EmitStackSizeSection)
     return;
 
   MCSection *StackSizeSection =
       getObjFileLowering().getStackSizesSection(*getCurrentSection());
   if (!StackSizeSection)
     return;
for (auto &MI : MBB) {
         }
         break;
       case TargetOpcode::IMPLICIT_DEF:
         if (isVerbose()) emitImplicitDef(&MI);
         break;
       case TargetOpcode::KILL:
         if (isVerbose()) emitKill(&MI, *this);
         break;
+      case TargetOpcode::PSEUDO_PROBE:
+        emitPseudoProbe(MI);
+        break;
       default:
         emitInstruction(&MI);
         if (CanDoExtraAnalysis) {
           MCInst MCI;
           MCI.setOpcode(MI.getOpcode());
           auto Name = OutStreamer->getMnemonic(MCI);
           auto I = MnemonicCounts.insert({Name, 0u});
           I.first->second++;

llvm/lib/CodeGen/AsmPrinter/CMakeLists.txt

add_llvm_component_library(LLVMAsmPrinter
   DwarfDebug.cpp
   DwarfExpression.cpp
   DwarfFile.cpp
   DwarfStringPool.cpp
   DwarfUnit.cpp
   EHStreamer.cpp
   ErlangGCPrinter.cpp
   OcamlGCPrinter.cpp
+  PseudoProbePrinter.cpp
   WinCFGuard.cpp
   WinException.cpp
   CodeViewDebug.cpp
   WasmException.cpp
 
   DEPENDS
   intrinsics_gen
 

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.h

+//===- PseudoProbePrinter.h - Pseudo probe encoding support -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing pseudo probe info into asm files.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_PSEUDOPROBEPRINTER_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_PSEUDOPROBEPRINTER_H
+
+#include "llvm/ADT/DenseMap.h"
+
+namespace llvm {
+
+class AsmPrinter;
+class MCStreamer;
+class Module;
+class DILocation;
+
+class PseudoProbeHandler {
+  // Target of pseudo probe emission.
+  AsmPrinter *Asm;
+  // Name to GUID map
+  DenseMap<StringRef, uint64_t> Names;
+
+public:
+  PseudoProbeHandler(AsmPrinter *A, Module *M);
+  void emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
+                       uint64_t Attr, const DILocation *DebugLoc);
+#ifndef NDEBUG
+  void dump() const;
+#endif
+};
+
+} // namespace llvm
+#endif // LLVM_LIB_CODEGEN_ASMPRINTER_PSEUDOPROBEPRINTER_H

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp

+//===- llvm/CodeGen/PseudoProbePrinter.cpp - Pseudo Probe Emission -------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing pseudo probe info into asm files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PseudoProbePrinter.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PseudoProbe.h"
+#include "llvm/MC/MCPseudoProbe.h"
+#include "llvm/MC/MCStreamer.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "pseudoprobe"
+
+PseudoProbeHandler::PseudoProbeHandler(AsmPrinter *A, Module *M) : Asm(A) {
+  NamedMDNode *FuncInfo = M->getNamedMetadata(PseudoProbeDescMetadataName);
+  assert(FuncInfo);
+  for (const auto *Operand : FuncInfo->operands()) {
+    const auto *MD = cast<MDNode>(Operand);
+    auto GUID =
+        mdconst::dyn_extract<ConstantInt>(MD->getOperand(0))->getZExtValue();
+    auto Name = cast<MDString>(MD->getOperand(2))->getString();
+    // We may see pairs with same name but different GUIDs here in LTO mode, due
+    // to static same-named functions inlined from other modules into this
+    // module. Function profiles with the same name will be merged no matter
+    // whether they are collected on the same function. Therefore we just pick
+    // up the last <Name, GUID> pair here to represent the same-named function
+    // collection and all probes from the collection will be merged into a
+    // single profile eventually.
+    Names[Name] = GUID;
+  }
+
+  LLVM_DEBUG(dump());
+}
+
+void PseudoProbeHandler::emitPseudoProbe(uint64_t Guid, uint64_t Index,
+                                         uint64_t Type, uint64_t Attr,
+                                         const DILocation *DebugLoc) {
+  // Gather all the inlined-at nodes.
+  // When it's done ReversedInlineStack looks like ([66, B], [88, A])
+  // which means, Function A inlines function B at calliste with a probe id 88,
+  // and B inlines C at probe 66 where C is represented by Guid.
+  SmallVector<InlineSite, 8> ReversedInlineStack;
+  auto *InlinedAt = DebugLoc ? DebugLoc->getInlinedAt() : nullptr;
+  while (InlinedAt) {
+    const DISubprogram *SP = InlinedAt->getScope()->getSubprogram();
+    // Use linkage name for C++ if possible.
+    auto Name = SP->getLinkageName();
+    if (Name.empty())
+      Name = SP->getName();
+    assert(Names.count(Name));
+    uint64_t CallerGuid = Names[Name];
+    uint64_t CallerProbeId = PseudoProbeDwarfDiscriminator::extractProbeIndex(
+        InlinedAt->getDiscriminator());
+    ReversedInlineStack.push_back({CallerGuid, CallerProbeId});
+    InlinedAt = InlinedAt->getInlinedAt();
+  }
+
+  SmallVector<InlineSite, 8> InlineStack(ReversedInlineStack.rbegin(),
+                                         ReversedInlineStack.rend());
+  Asm->OutStreamer->emitPseudoProbe(Guid, Index, Type, Attr, InlineStack);
+}
+
+#ifndef NDEBUG
+void PseudoProbeHandler::dump() const {
+  dbgs() << "\n=============================\n";
+  dbgs() << "\nFunction Name to GUID map:\n";
+  dbgs() << "\n=============================\n";
+  for (const auto &Item : Names)
+    dbgs() << "Func: " << Item.first << "   GUID: " << Item.second << "\n";
+}
+#endif

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalAlias.h"
 #include "llvm/IR/GlobalObject.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Mangler.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/PseudoProbe.h"
 #include "llvm/IR/Type.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCSectionCOFF.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCSectionWasm.h"
if (NamedMDNode *DependentLibraries = M.getNamedMetadata("llvm.dependent-libraries")) {
 
     for (const auto *Operand : DependentLibraries->operands()) {
       Streamer.emitBytes(
           cast<MDString>(cast<MDNode>(Operand)->getOperand(0))->getString());
       Streamer.emitInt8(0);
     }
   }
 
+  if (NamedMDNode *FuncInfo = M.getNamedMetadata(PseudoProbeDescMetadataName)) {
+    // Emit a descriptor for every function including functions that have an
+    // available external linkage. We may not want this for imported functions
+    // that has code in another thinLTO module but we don't have a good way to
+    // tell them apart from inline functions defined in header files. Therefore
+    // we put each descriptor in a separate comdat section and rely on the
+    // linker to deduplicate.
+    for (const auto *Operand : FuncInfo->operands()) {
+      const auto *MD = cast<MDNode>(Operand);
+      auto *GUID = mdconst::dyn_extract<ConstantInt>(MD->getOperand(0));
+      auto *Hash = mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
+      auto *Name = cast<MDString>(MD->getOperand(2));
+      auto *S = C.getObjectFileInfo()->getPseudoProbeDescSection(
+          TM->getFunctionSections() ? Name->getString() : StringRef());
+
+      Streamer.SwitchSection(S);
+      Streamer.emitInt64(GUID->getZExtValue());
+      Streamer.emitInt64(Hash->getZExtValue());
+      Streamer.emitULEB128IntValue(Name->getString().size());
+      Streamer.emitBytes(Name->getString());
+    }
+  }
+
   unsigned Version = 0;
   unsigned Flags = 0;
   StringRef Section;
 
   GetObjCImageInfo(M, Version, Flags, Section);
   if (!Section.empty()) {
     auto *S = C.getELFSection(Section, ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
     Streamer.SwitchSection(S);

llvm/lib/IR/MDBuilder.cpp

 
 MDNode *MDBuilder::createIrrLoopHeaderWeight(uint64_t Weight) {
   Metadata *Vals[] = {
     createString("loop_header_weight"),
     createConstant(ConstantInt::get(Type::getInt64Ty(Context), Weight)),
   };
   return MDNode::get(Context, Vals);
 }
+
+MDNode *MDBuilder::createPseudoProbeDesc(uint64_t GUID, uint64_t Hash,
+                                         Function *F) {
+  auto *Int64Ty = Type::getInt64Ty(Context);
+  SmallVector<Metadata *, 3> Ops(3);
+  Ops[0] = createConstant(ConstantInt::get(Int64Ty, GUID));
+  Ops[1] = createConstant(ConstantInt::get(Int64Ty, Hash));
+  Ops[2] = createString(F->getName());
+  return MDNode::get(Context, Ops);
+}

llvm/lib/MC/CMakeLists.txt

add_llvm_component_library(LLVMMC
   MCLabel.cpp
   MCLinkerOptimizationHint.cpp
   MCMachOStreamer.cpp
   MCMachObjectTargetWriter.cpp
   MCNullStreamer.cpp
   MCObjectFileInfo.cpp
   MCObjectStreamer.cpp
   MCObjectWriter.cpp
+  MCPseudoProbe.cpp
   MCRegisterInfo.cpp
   MCSchedule.cpp
   MCSection.cpp
   MCSectionCOFF.cpp
   MCSectionELF.cpp
   MCSectionMachO.cpp
   MCSectionWasm.cpp
   MCSectionXCOFF.cpp

llvm/lib/MC/MCAsmStreamer.cpp

 #include "llvm/MC/MCCodeView.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCFixupKindInfo.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstPrinter.h"
 #include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCPseudoProbe.h"
 #include "llvm/MC/MCRegister.h"
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbolXCOFF.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/FormattedStream.h"
void EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except,
                         SMLoc Loc) override;
   void EmitWinEHHandlerData(SMLoc Loc) override;
 
   void emitCGProfileEntry(const MCSymbolRefExpr *From,
                           const MCSymbolRefExpr *To, uint64_t Count) override;
 
   void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override;
 
+  void emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
+                       uint64_t Attr,
+                       const MCPseudoProbeInlineStack &InlineStack) override;
+
   void emitBundleAlignMode(unsigned AlignPow2) override;
   void emitBundleLock(bool AlignToEnd) override;
   void emitBundleUnlock() override;
 
   Optional<std::pair<bool, std::string>>
   emitRelocDirective(const MCExpr &Offset, StringRef Name, const MCExpr *Expr,
                      SMLoc Loc, const MCSubtargetInfo &STI) override;
 
void MCAsmStreamer::emitInstruction(const MCInst &Inst,
 
   StringRef Comments = CommentToEmit;
   if (Comments.size() && Comments.back() != '\n')
     GetCommentOS() << "\n";
 
   EmitEOL();
 }
 
+void MCAsmStreamer::emitPseudoProbe(
+    uint64_t Guid, uint64_t Index, uint64_t Type, uint64_t Attr,
+    const MCPseudoProbeInlineStack &InlineStack) {
+  OS << "\t.pseudoprobe\t" << Guid << " " << Index << " " << Type << " "
+     << Attr;
+  // Emit inline stack like
+  //  @ GUIDmain:3 @ GUIDCaller:1 @ GUIDDirectCaller:11
+  for (const auto &Site : InlineStack)
+    OS << " @ " << std::get<0>(Site) << ":" << std::get<1>(Site);
+  EmitEOL();
+}
+
 void MCAsmStreamer::emitBundleAlignMode(unsigned AlignPow2) {
   OS << "\t.bundle_align_mode " << AlignPow2;
   EmitEOL();
 }
 
 void MCAsmStreamer::emitBundleLock(bool AlignToEnd) {
   OS << "\t.bundle_lock";
   if (AlignToEnd)

llvm/lib/MC/MCAssembler.cpp

uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
   case MCFragment::FT_Dwarf:
     return cast<MCDwarfLineAddrFragment>(F).getContents().size();
   case MCFragment::FT_DwarfFrame:
     return cast<MCDwarfCallFrameFragment>(F).getContents().size();
   case MCFragment::FT_CVInlineLines:
     return cast<MCCVInlineLineTableFragment>(F).getContents().size();
   case MCFragment::FT_CVDefRange:
     return cast<MCCVDefRangeFragment>(F).getContents().size();
+  case MCFragment::FT_PseudoProbe:
+    return cast<MCPseudoProbeAddrFragment>(F).getContents().size();
   case MCFragment::FT_Dummy:
     llvm_unreachable("Should not have been added");
   }
 
   llvm_unreachable("invalid fragment kind");
 }
 
 void MCAsmLayout::layoutFragment(MCFragment *F) {
case MCFragment::FT_CVInlineLines: {
     OS << OF.getContents();
     break;
   }
   case MCFragment::FT_CVDefRange: {
     const auto &DRF = cast<MCCVDefRangeFragment>(F);
     OS << DRF.getContents();
     break;
   }
+  case MCFragment::FT_PseudoProbe: {
+    const MCPseudoProbeAddrFragment &PF = cast<MCPseudoProbeAddrFragment>(F);
+    OS << PF.getContents();
+    break;
+  }
   case MCFragment::FT_Dummy:
     llvm_unreachable("Should not have been added");
   }
 
   assert(OS.tell() - Start == FragmentSize &&
          "The stream should advance by fragment size");
 }
 
for (MCFragment &Frag : Sec) {
         break;
       }
       case MCFragment::FT_DwarfFrame: {
         MCDwarfCallFrameFragment &DF = cast<MCDwarfCallFrameFragment>(Frag);
         Fixups = DF.getFixups();
         Contents = DF.getContents();
         break;
       }
+      case MCFragment::FT_PseudoProbe: {
+        MCPseudoProbeAddrFragment &PF = cast<MCPseudoProbeAddrFragment>(Frag);
+        Fixups = PF.getFixups();
+        Contents = PF.getContents();
+        break;
+      }
       }
       for (const MCFixup &Fixup : Fixups) {
         uint64_t FixedValue;
         bool IsResolved;
         MCValue Target;
         std::tie(Target, FixedValue, IsResolved) =
             handleFixup(Layout, Frag, Fixup);
         getBackend().applyFixup(*this, Fixup, Target, Contents, FixedValue,

 
 bool MCAssembler::relaxCVDefRange(MCAsmLayout &Layout,
                                   MCCVDefRangeFragment &F) {
   unsigned OldSize = F.getContents().size();
   getContext().getCVContext().encodeDefRange(Layout, F);
   return OldSize != F.getContents().size();
 }
 
+bool MCAssembler::relaxPseudoProbeAddr(MCAsmLayout &Layout,
+                                       MCPseudoProbeAddrFragment &PF) {
+  uint64_t OldSize = PF.getContents().size();
+  int64_t AddrDelta;
+  bool Abs = PF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
+  assert(Abs && "We created a pseudo probe with an invalid expression");
+  (void)Abs;
+  SmallVectorImpl<char> &Data = PF.getContents();
+  Data.clear();
+  raw_svector_ostream OSE(Data);
+  PF.getFixups().clear();
+
+  // Relocations should not be needed in general except on RISC-V which we are
+  // not targeting for now.
+  assert(!getBackend().requiresDiffExpressionRelocations());
+  // AddrDelta is a signed integer
+  encodeSLEB128(AddrDelta, OSE, OldSize);
+  return OldSize != Data.size();
+}
+
 bool MCAssembler::relaxFragment(MCAsmLayout &Layout, MCFragment &F) {
   switch(F.getKind()) {
   default:
     return false;
   case MCFragment::FT_Relaxable:
     assert(!getRelaxAll() &&
            "Did not expect a MCRelaxableFragment in RelaxAll mode");
     return relaxInstruction(Layout, cast<MCRelaxableFragment>(F));
   case MCFragment::FT_Dwarf:
     return relaxDwarfLineAddr(Layout, cast<MCDwarfLineAddrFragment>(F));
   case MCFragment::FT_DwarfFrame:
     return relaxDwarfCallFrameFragment(Layout,
                                        cast<MCDwarfCallFrameFragment>(F));
   case MCFragment::FT_LEB:
     return relaxLEB(Layout, cast<MCLEBFragment>(F));
   case MCFragment::FT_BoundaryAlign:
     return relaxBoundaryAlign(Layout, cast<MCBoundaryAlignFragment>(F));
   case MCFragment::FT_CVInlineLines:
     return relaxCVInlineLineTable(Layout, cast<MCCVInlineLineTableFragment>(F));
   case MCFragment::FT_CVDefRange:
     return relaxCVDefRange(Layout, cast<MCCVDefRangeFragment>(F));
+  case MCFragment::FT_PseudoProbe:
+    return relaxPseudoProbeAddr(Layout, cast<MCPseudoProbeAddrFragment>(F));
   }
 }
 
 bool MCAssembler::layoutSectionOnce(MCAsmLayout &Layout, MCSection &Sec) {
   // Holds the first fragment which needed relaxing during this layout. It will
   // remain NULL if none were relaxed.
   // When a fragment is relaxed, all the fragments following it should get
   // invalidated because their offset is going to change.

llvm/lib/MC/MCFragment.cpp

case FT_SymbolId:
       delete cast<MCSymbolIdFragment>(this);
       return;
     case FT_CVInlineLines:
       delete cast<MCCVInlineLineTableFragment>(this);
       return;
     case FT_CVDefRange:
       delete cast<MCCVDefRangeFragment>(this);
       return;
+    case FT_PseudoProbe:
+      delete cast<MCPseudoProbeAddrFragment>(this);
+      return;
     case FT_Dummy:
       delete cast<MCDummyFragment>(this);
       return;
   }
 }
 
 // Debugging methods
 
LLVM_DUMP_METHOD void MCFragment::dump() const {
   case MCFragment::FT_Org:   OS << "MCOrgFragment"; break;
   case MCFragment::FT_Dwarf: OS << "MCDwarfFragment"; break;
   case MCFragment::FT_DwarfFrame: OS << "MCDwarfCallFrameFragment"; break;
   case MCFragment::FT_LEB:   OS << "MCLEBFragment"; break;
   case MCFragment::FT_BoundaryAlign: OS<<"MCBoundaryAlignFragment"; break;
   case MCFragment::FT_SymbolId:    OS << "MCSymbolIdFragment"; break;
   case MCFragment::FT_CVInlineLines: OS << "MCCVInlineLineTableFragment"; break;
   case MCFragment::FT_CVDefRange: OS << "MCCVDefRangeTableFragment"; break;
+  case MCFragment::FT_PseudoProbe:
+    OS << "MCPseudoProbe";
+    break;
   case MCFragment::FT_Dummy: OS << "MCDummyFragment"; break;
   }
 
   OS << "<MCFragment " << (const void *)this << " LayoutOrder:" << LayoutOrder
      << " Offset:" << Offset << " HasInstructions:" << hasInstructions();
   if (const auto *EF = dyn_cast<MCEncodedFragment>(this))
     OS << " BundlePadding:" << static_cast<unsigned>(EF->getBundlePadding());
   OS << ">";
case MCFragment::FT_CVDefRange: {
     OS << "\n       ";
     for (std::pair<const MCSymbol *, const MCSymbol *> RangeStartEnd :
          F->getRanges()) {
       OS << " RangeStart:" << RangeStartEnd.first;
       OS << " RangeEnd:" << RangeStartEnd.second;
     }
     break;
   }
+  case MCFragment::FT_PseudoProbe: {
+    const auto *OF = cast<MCPseudoProbeAddrFragment>(this);
+    OS << "\n       ";
+    OS << " AddrDelta:" << OF->getAddrDelta();
+    break;
+  }
   case MCFragment::FT_Dummy:
     break;
   }
   OS << ">";
 }
 #endif

llvm/lib/MC/MCObjectFileInfo.cpp

void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
 
   FaultMapSection =
       Ctx->getELFSection(".llvm_faultmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 
   EHFrameSection =
       Ctx->getELFSection(".eh_frame", EHSectionType, EHSectionFlags);
 
   StackSizesSection = Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, 0);
+
+  PseudoProbeSection = Ctx->getELFSection(".pseudo_probe", DebugSecType, 0);
+  PseudoProbeDescSection =
+      Ctx->getELFSection(".pseudo_probe_desc", DebugSecType, 0);
 }
 
 void MCObjectFileInfo::initCOFFMCObjectFileInfo(const Triple &T) {
   EHFrameSection =
       Ctx->getCOFFSection(".eh_frame", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
                                            COFF::IMAGE_SCN_MEM_READ,
                           SectionKind::getData());
 
MCObjectFileInfo::getBBAddrMapSection(const MCSection &TextSec) const {
   }
 
   // Use the text section's begin symbol and unique ID to create a separate
   // .llvm_bb_addr_map section associated with every unique text section.
   return Ctx->getELFSection(".llvm_bb_addr_map", ELF::SHT_LLVM_BB_ADDR_MAP,
                             Flags, 0, GroupName, ElfSec.getUniqueID(),
                             cast<MCSymbolELF>(TextSec.getBeginSymbol()));
 }
+
+MCSection *
+MCObjectFileInfo::getPseudoProbeSection(const MCSection *TextSec) const {
+  if (Env == IsELF) {
+    auto *ElfSec = static_cast<const MCSectionELF *>(TextSec);
+    // Create a separate section for probes that comes with a comdat function.
+    if (const MCSymbol *Group = ElfSec->getGroup()) {
+      auto *S = static_cast<MCSectionELF *>(PseudoProbeSection);
+      auto Flags = S->getFlags() | ELF::SHF_GROUP;
+      return Ctx->getELFSection(S->getName(), S->getType(), Flags,
+                                S->getEntrySize(), Group->getName());
+    }
+  }
+  return PseudoProbeSection;
+}
+
+MCSection *
+MCObjectFileInfo::getPseudoProbeDescSection(StringRef FuncName) const {
+  if (Env == IsELF) {
+    // Create a separate comdat group for each function's descriptor in order
+    // for the linker to deduplicate. The duplication, must be from different
+    // tranlation unit, can come from:
+    //  1. Inline functions defined in header files;
+    //  2. ThinLTO imported funcions;
+    //  3. Weak-linkage definitions.
+    // Use a concatenation of the section name and the function name as the
+    // group name so that descriptor-only groups won't be folded with groups of
+    // code.
+    if (TT.supportsCOMDAT() && !FuncName.empty()) {
+      auto *S = static_cast<MCSectionELF *>(PseudoProbeDescSection);
+      auto Flags = S->getFlags() | ELF::SHF_GROUP;
+      return Ctx->getELFSection(S->getName(), S->getType(), Flags,
+                                S->getEntrySize(),
+                                S->getName() + "_" + FuncName);
+    }
+  }
+  return PseudoProbeDescSection;
+}

llvm/lib/MC/MCObjectStreamer.cpp

void MCObjectStreamer::finishImpl() {
 
   // If we are generating dwarf for assembly source files dump out the sections.
   if (getContext().getGenDwarfForAssembly())
     MCGenDwarfInfo::Emit(this);
 
   // Dump out the dwarf file & directory tables and line tables.
   MCDwarfLineTable::Emit(this, getAssembler().getDWARFLinetableParams());
 
+  // Emit pseudo probes for the current module.
+  MCPseudoProbeTable::emit(this);
+
   // Update any remaining pending labels with empty data fragments.
   flushPendingLabels();
 
   resolvePendingFixups();
   getAssembler().Finish();
 }

llvm/lib/MC/MCParser/AsmParser.cpp

enum DirectiveKind {
     DK_SLEB128,
     DK_ULEB128,
     DK_ERR,
     DK_ERROR,
     DK_WARNING,
     DK_PRINT,
     DK_ADDRSIG,
     DK_ADDRSIG_SYM,
+    DK_PSEUDO_PROBE,
     DK_END
   };
 
   /// Maps directive name --> DirectiveKind enum, for
   /// directives parsed by this class.
   StringMap<DirectiveKind> DirectiveKindMap;
 
   // Codeview def_range type parsing.
private:
   bool parseDirectiveError(SMLoc DirectiveLoc, bool WithMessage);
 
   // ".warning"
   bool parseDirectiveWarning(SMLoc DirectiveLoc);
 
   // .print <double-quotes-string>
   bool parseDirectivePrint(SMLoc DirectiveLoc);
 
+  // .pseudoprobe
+  bool parseDirectivePseudoProbe();
+
   // Directives to support address-significance tables.
   bool parseDirectiveAddrsig();
   bool parseDirectiveAddrsigSym();
 
   void initializeDirectiveKindMap();
   void initializeCVDefRangeTypeMap();
 };
 
if (IDVal.startswith(".") && IDVal != ".") {
     case DK_DS_X:
       return parseDirectiveDS(IDVal, 12);
     case DK_PRINT:
       return parseDirectivePrint(IDLoc);
     case DK_ADDRSIG:
       return parseDirectiveAddrsig();
     case DK_ADDRSIG_SYM:
       return parseDirectiveAddrsigSym();
+    case DK_PSEUDO_PROBE:
+      return parseDirectivePseudoProbe();
     }
 
     return Error(IDLoc, "unknown directive");
   }
 
   // __asm _emit or __asm __emit
   if (ParsingMSInlineAsm && (IDVal == "_emit" || IDVal == "__emit" ||
                              IDVal == "_EMIT" || IDVal == "__EMIT"))
void AsmParser::initializeDirectiveKindMap() {
   DirectiveKindMap[".ds.l"] = DK_DS_L;
   DirectiveKindMap[".ds.p"] = DK_DS_P;
   DirectiveKindMap[".ds.s"] = DK_DS_S;
   DirectiveKindMap[".ds.w"] = DK_DS_W;
   DirectiveKindMap[".ds.x"] = DK_DS_X;
   DirectiveKindMap[".print"] = DK_PRINT;
   DirectiveKindMap[".addrsig"] = DK_ADDRSIG;
   DirectiveKindMap[".addrsig_sym"] = DK_ADDRSIG_SYM;
+  DirectiveKindMap[".pseudoprobe"] = DK_PSEUDO_PROBE;
 }
 
 MCAsmMacro *AsmParser::parseMacroLikeBody(SMLoc DirectiveLoc) {
   AsmToken EndToken, StartToken = getTok();
 
   unsigned NestLevel = 0;
   while (true) {
     // Check whether we have reached the end of the file.
bool AsmParser::parseDirectiveAddrsigSym() {
   if (check(parseIdentifier(Name),
             "expected identifier in '.addrsig_sym' directive"))
     return true;
   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
   getStreamer().emitAddrsigSym(Sym);
   return false;
 }
 
+bool AsmParser::parseDirectivePseudoProbe() {
+  int64_t Guid;
+  int64_t Index;
+  int64_t Type;
+  int64_t Attr;
+
+  if (getLexer().is(AsmToken::Integer)) {
+    if (parseIntToken(Guid, "unexpected token in '.pseudoprobe' directive"))
+      return true;
+  }
+
+  if (getLexer().is(AsmToken::Integer)) {
+    if (parseIntToken(Index, "unexpected token in '.pseudoprobe' directive"))
+      return true;
+  }
+
+  if (getLexer().is(AsmToken::Integer)) {
+    if (parseIntToken(Type, "unexpected token in '.pseudoprobe' directive"))
+      return true;
+  }
+
+  if (getLexer().is(AsmToken::Integer)) {
+    if (parseIntToken(Attr, "unexpected token in '.pseudoprobe' directive"))
+      return true;
+  }
+
+  // Parse inline stack like @ GUID:11:12 @ GUID:1:11 @ GUID:3:21
+  MCPseudoProbeInlineStack InlineStack;
+
+  while (getLexer().is(AsmToken::At)) {
+    // eat @
+    Lex();
+
+    int64_t CallerGuid = 0;
+    if (getLexer().is(AsmToken::Integer)) {
+      if (parseIntToken(CallerGuid,
+                        "unexpected token in '.pseudoprobe' directive"))
+        return true;
+    }
+
+    // eat colon
+    if (getLexer().is(AsmToken::Colon))
+      Lex();
+
+    int64_t CallerProbeId = 0;
+    if (getLexer().is(AsmToken::Integer)) {
+      if (parseIntToken(CallerProbeId,
+                        "unexpected token in '.pseudoprobe' directive"))
+        return true;
+    }
+
+    InlineSite Site = {CallerGuid, CallerProbeId};
+    InlineStack.push_back(Site);
+  }
+
+  if (parseToken(AsmToken::EndOfStatement,
+                 "unexpected token in '.pseudoprobe' directive"))
+    return true;
+
+  getStreamer().emitPseudoProbe(Guid, Index, Type, Attr, InlineStack);
+  return false;
+}
+
 // We are comparing pointers, but the pointers are relative to a single string.
 // Thus, this should always be deterministic.
 static int rewritesSort(const AsmRewrite *AsmRewriteA,
                         const AsmRewrite *AsmRewriteB) {
   if (AsmRewriteA->Loc.getPointer() < AsmRewriteB->Loc.getPointer())
     return -1;
   if (AsmRewriteB->Loc.getPointer() < AsmRewriteA->Loc.getPointer())
     return 1;

llvm/lib/MC/MCPseudoProbe.cpp

+//===- lib/MC/MCPseudoProbe.cpp - Pseudo probe encoding support ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCPseudoProbe.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCObjectFileInfo.h"
+#include "llvm/MC/MCObjectStreamer.h"
+#include "llvm/MC/MCStreamer.h"
+
+#define DEBUG_TYPE "mcpseudoprobe"
+
+using namespace llvm;
+
+#ifndef NDEBUG
+int MCPseudoProbeTable::DdgPrintIndent = 0;
+#endif
+
+static const MCExpr *buildSymbolDiff(MCObjectStreamer *MCOS, const MCSymbol *A,
+                                     const MCSymbol *B) {
+  MCContext &Context = MCOS->getContext();
+  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
+  const MCExpr *ARef = MCSymbolRefExpr::create(A, Variant, Context);
+  const MCExpr *BRef = MCSymbolRefExpr::create(B, Variant, Context);
+  const MCExpr *AddrDelta =
+      MCBinaryExpr::create(MCBinaryExpr::Sub, ARef, BRef, Context);
+  return AddrDelta;
+}
+
+void MCPseudoProbe::emit(MCObjectStreamer *MCOS,
+                         const MCPseudoProbe *LastProbe) const {
+  // Emit Index
+  MCOS->emitULEB128IntValue(Index);
+  // Emit Type and the flag:
+  // Type (0 - block probe, 1 - indirect call), with bit 5 to 7 for attributes.
+  // Flag (0 - code address, 128 - address delta). This indicates whether the
+  // following field is a symbolic code address or an address delta.
+  assert(Type <= 0xF && Attributes <= 0x7);
+  uint8_t PackedType = Type | (Attributes << 4);
+  uint8_t Flag = LastProbe ? ((int8_t)MCPseudoProbeFlag::AddressDelta << 7) : 0;
+  MCOS->emitInt8(Flag | PackedType);
+
+  if (LastProbe) {
+    // Emit the delta between the address label and LastProbe.
+    const MCExpr *AddrDelta =
+        buildSymbolDiff(MCOS, Label, LastProbe->getLabel());
+    int64_t Delta;
+    if (AddrDelta->evaluateAsAbsolute(Delta, MCOS->getAssemblerPtr())) {
+      MCOS->emitSLEB128IntValue(Delta);
+    } else {
+      MCOS->insert(new MCPseudoProbeAddrFragment(AddrDelta));
+    }
+  } else {
+    // Emit label as a symbolic code address.
+    MCOS->emitSymbolValue(
+        Label, MCOS->getContext().getAsmInfo()->getCodePointerSize());
+  }
+
+  LLVM_DEBUG({
+    dbgs().indent(MCPseudoProbeTable::DdgPrintIndent);
+    dbgs() << "Probe: " << Index << "\n";
+  });
+}
+
+MCPseudoProbeInlineTree::~MCPseudoProbeInlineTree() {
+  for (auto &Inlinee : Inlinees)
+    delete Inlinee.second;
+}
+
+MCPseudoProbeInlineTree *
+MCPseudoProbeInlineTree::getOrAddNode(InlineSite Site) {
+  auto Iter = Inlinees.find(Site);
+  if (Iter == Inlinees.end()) {
+    auto Node = new MCPseudoProbeInlineTree(std::get<0>(Site));
+    Inlinees[Site] = Node;
+    return Node;
+  } else {
+    return Iter->second;
+  }
+}
+
+void MCPseudoProbeInlineTree::addPseudoProbe(
+    const MCPseudoProbe &Probe, const MCPseudoProbeInlineStack &InlineStack) {
+  // The function should not be called on the root.
+  assert(isRoot());
+
+  // When it comes here, the input look like:
+  //    Probe: GUID of C, ...
+  //    InlineStack: [88, A], [66, B]
+  // which means, Function A inlines function B at call site with a probe id of
+  // 88, and B inlines C at probe 66. The tri-tree expects a tree path like {[0,
+  // A], [88, B], [66, C]} to locate the tree node where the probe should be
+  // added. Note that the edge [0, A] means A is the top-level function we are
+  // emitting probes for.
+
+  // Make a [0, A] edge.
+  // An empty inline stack means the function that the probe originates from
+  // is a top-level function.
+  InlineSite Top;
+  if (InlineStack.empty()) {
+    Top = InlineSite(Probe.getGuid(), 0);
+  } else {
+    Top = InlineSite(std::get<0>(InlineStack.back()), 0);
+  }
+
+  auto *Cur = getOrAddNode(Top);
+
+  // Make interior edges by walking the inline stack. Once it's done, Cur should
+  // point to the node that the probe originates from.
+  if (!InlineStack.empty()) {
+    auto Iter = InlineStack.begin();
+    auto Index = std::get<1>(*Iter);
+    Iter++;
+    for (; Iter != InlineStack.end(); Iter++) {
+      // Make an edge by using the previous probe id and current GUID.
+      Cur = Cur->getOrAddNode(InlineSite(std::get<0>(*Iter), Index));
+      Index = std::get<1>(*Iter);
+    }
+    Cur = Cur->getOrAddNode(InlineSite(Probe.getGuid(), Index));
+  }
+
+  Cur->Probes.push_back(Probe);
+}
+
+void MCPseudoProbeInlineTree::emit(MCObjectStreamer *MCOS,
+                                   const MCPseudoProbe *&LastProbe) {
+  LLVM_DEBUG({
+    dbgs().indent(MCPseudoProbeTable::DdgPrintIndent);
+    dbgs() << "Group [\n";
+    MCPseudoProbeTable::DdgPrintIndent += 2;
+  });
+  // Emit probes grouped by GUID.
+  if (Guid != 0) {
+    LLVM_DEBUG({
+      dbgs().indent(MCPseudoProbeTable::DdgPrintIndent);
+      dbgs() << "GUID: " << Guid << "\n";
+    });
+    // Emit Guid
+    MCOS->emitInt64(Guid);
+    // Emit number of probes in this node
+    MCOS->emitULEB128IntValue(Probes.size());
+    // Emit number of direct inlinees
+    MCOS->emitULEB128IntValue(Inlinees.size());
+    // Emit probes in this group
+    for (const auto &Probe : Probes) {
+      Probe.emit(MCOS, LastProbe);
+      LastProbe = &Probe;
+    }
+  } else {
+    assert(Probes.empty());
+  }
+
+  // Emit descendent
+  for (const auto &Inlinee : Inlinees) {
+    if (Guid) {
+      // Emit probe index
+      MCOS->emitULEB128IntValue(std::get<1>(Inlinee.first));
+      LLVM_DEBUG({
+        dbgs().indent(MCPseudoProbeTable::DdgPrintIndent);
+        dbgs() << "InlineSite: " << std::get<1>(Inlinee.first) << "\n";
+      });
+    }
+    // Emit the group
+    Inlinee.second->emit(MCOS, LastProbe);
+  }
+
+  LLVM_DEBUG({
+    MCPseudoProbeTable::DdgPrintIndent -= 2;
+    dbgs().indent(MCPseudoProbeTable::DdgPrintIndent);
+    dbgs() << "]\n";
+  });
+}
+
+void MCPseudoProbeSection::emit(MCObjectStreamer *MCOS) {
+  MCContext &Ctx = MCOS->getContext();
+
+  for (auto &ProbeSec : MCProbeDivisions) {
+    const MCPseudoProbe *LastProbe = nullptr;
+    if (auto *S =
+            Ctx.getObjectFileInfo()->getPseudoProbeSection(ProbeSec.first)) {
+      // Switch to the .pseudoprobe section or a comdat group.
+      MCOS->SwitchSection(S);
+      // Emit probes grouped by GUID.
+      ProbeSec.second.emit(MCOS, LastProbe);
+    }
+  }
+}
+
+//
+// This emits the pseudo probe tables.
+//
+void MCPseudoProbeTable::emit(MCObjectStreamer *MCOS) {
+  MCContext &Ctx = MCOS->getContext();
+  auto &ProbeTable = Ctx.getMCPseudoProbeTable();
+
+  // Bail out early so we don't switch to the pseudo_probe section needlessly
+  // and in doing so create an unnecessary (if empty) section.
+  auto &ProbeSections = ProbeTable.getProbeSections();
+  if (ProbeSections.empty())
+    return;
+
+  LLVM_DEBUG(MCPseudoProbeTable::DdgPrintIndent = 0);
+
+  // Put out the probe.
+  ProbeSections.emit(MCOS);
+}

llvm/lib/MC/MCStreamer.cpp

 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCCodeView.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCDwarf.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstPrinter.h"
 #include "llvm/MC/MCObjectFileInfo.h"
+#include "llvm/MC/MCPseudoProbe.h"
 #include "llvm/MC/MCRegister.h"
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSection.h"
 #include "llvm/MC/MCSectionCOFF.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCWin64EH.h"
 #include "llvm/MC/MCWinEH.h"
 #include "llvm/Support/Casting.h"

 
 void MCStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &) {
   // Scan for values.
   for (unsigned i = Inst.getNumOperands(); i--;)
     if (Inst.getOperand(i).isExpr())
       visitUsedExpr(*Inst.getOperand(i).getExpr());
 }
 
+void MCStreamer::emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
+                                 uint64_t Attr,
+                                 const MCPseudoProbeInlineStack &InlineStack) {
+  auto &Context = getContext();
+
+  // Create a symbol at in the current section for use in the probe.
+  MCSymbol *ProbeSym = Context.createTempSymbol();
+
+  // Set the value of the symbol to use for the MCPseudoProbe.
+  emitLabel(ProbeSym);
+
+  // Create a (local) probe entry with the symbol.
+  MCPseudoProbe Probe(ProbeSym, Guid, Index, Type, Attr);
+
+  // Add the probe entry to this section's entries.
+  Context.getMCPseudoProbeTable().getProbeSections().addPseudoProbe(
+      getCurrentSectionOnly(), Probe, InlineStack);
+}
+
 void MCStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
                                         unsigned Size) {
   // Get the Hi-Lo expression.
   const MCExpr *Diff =
       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
                               MCSymbolRefExpr::create(Lo, Context), Context);
 
   const MCAsmInfo *MAI = Context.getAsmInfo();

llvm/lib/Transforms/IPO/SampleProfileProbe.cpp

 #include <vector>
 
 using namespace llvm;
 #define DEBUG_TYPE "sample-profile-probe"
 
 STATISTIC(ArtificialDbgLine,
           "Number of probes that have an artificial debug line");
 
-SampleProfileProber::SampleProfileProber(Function &Func) : F(&Func) {
+SampleProfileProber::SampleProfileProber(Function &Func,
+                                         const std::string &CurModuleUniqueId)
+    : F(&Func), CurModuleUniqueId(CurModuleUniqueId) {
   BlockProbeIds.clear();
   CallProbeIds.clear();
   LastProbeId = (uint32_t)PseudoProbeReservedId::Last;
   computeProbeIdForBlocks();
   computeProbeIdForCallsites();
+  computeCFGHash();
+}
+
+// Compute Hash value for the CFG: the lower 32 bits are CRC32 of the index
+// value of each BB in the CFG. The higher 32 bits record the number of edges
+// preceded by the number of indirect calls.
+// This is derived from FuncPGOInstrumentation<Edge, BBInfo>::computeCFGHash().
+void SampleProfileProber::computeCFGHash() {
+  std::vector<uint8_t> Indexes;
+  JamCRC JC;
+  for (auto &BB : *F) {
+    auto *TI = BB.getTerminator();
+    for (unsigned I = 0, E = TI->getNumSuccessors(); I != E; ++I) {
+      auto *Succ = TI->getSuccessor(I);
+      auto Index = getBlockId(Succ);
+      for (int J = 0; J < 4; J++)
+        Indexes.push_back((uint8_t)(Index >> (J * 8)));
+    }
+  }
+
+  JC.update(Indexes);
+
+  FunctionHash = (uint64_t)CallProbeIds.size() << 48 |
+                 (uint64_t)Indexes.size() << 32 | JC.getCRC();
+  // Reserve bit 60-63 for other information purpose.
+  FunctionHash &= 0x0FFFFFFFFFFFFFFF;
+  assert(FunctionHash != 0);
+  LLVM_DEBUG(dbgs() << "\nFunction Hash Computation for " << F->getName()
+                    << ":\n"
+                    << " CRC = " << JC.getCRC() << ", Edges = "
+                    << Indexes.size() << ", ICSites = " << CallProbeIds.size()
+                    << ", Hash = " << FunctionHash << "\n");
 }
 
 void SampleProfileProber::computeProbeIdForBlocks() {
   for (auto &BB : *F) {
     BlockProbeIds[&BB] = ++LastProbeId;
   }
 }
 
for (auto &I : CallProbeIds) {
     // type of a callsite probe. This gets rid of the dependency on plumbing a
     // customized metadata through the codegen pipeline.
     uint32_t V = PseudoProbeDwarfDiscriminator::packProbeData(Index, Type);
     if (auto DIL = Call->getDebugLoc()) {
       DIL = DIL->cloneWithDiscriminator(V);
       Call->setDebugLoc(DIL);
     }
   }
+
+  // Create module-level metadata that contains function info necessary to
+  // synthesize probe-based sample counts,  which are
+  // - FunctionGUID
+  // - FunctionHash.
+  // - FunctionName
+  auto Hash = getFunctionHash();
+  auto *MD = MDB.createPseudoProbeDesc(Guid, Hash, &F);
+  auto *NMD = M->getNamedMetadata(PseudoProbeDescMetadataName);
+  assert(NMD);
+  NMD->addOperand(MD);
+
+  // Preserve a comdat group to hold all probes materialized later. This
+  // allows that when the function is considered dead and removed, the
+  // materialized probes are disposed too.
+  // Imported functions are defined in another module. They do not need
+  // the following handling since same care will be taken for them in their
+  // original module. The pseudo probes inserted into an imported functions
+  // above will naturally not be emitted since the imported function is free
+  // from object emission. However they will be emitted together with the
+  // inliner functions that the imported function is inlined into. We are not
+  // creating a comdat group for an import function since it's useless anyway.
+  if (!F.isDeclarationForLinker()) {
+    if (TM) {
+      auto Triple = TM->getTargetTriple();
+      if (Triple.supportsCOMDAT() && TM->getFunctionSections()) {
+        GetOrCreateFunctionComdat(F, Triple, CurModuleUniqueId);
+      }
+    }
+  }
 }
 
 PreservedAnalyses SampleProfileProbePass::run(Module &M,
                                               ModuleAnalysisManager &AM) {
+  auto ModuleId = getUniqueModuleId(&M);
+  // Create the pseudo probe desc metadata beforehand.
+  // Note that modules with only data but no functions will require this to
+  // be set up so that they will be known as probed later.
+  M.getOrInsertNamedMetadata(PseudoProbeDescMetadataName);
+
   for (auto &F : M) {
     if (F.isDeclaration())
       continue;
-    SampleProfileProber ProbeManager(F);
+    SampleProfileProber ProbeManager(F, ModuleId);
     ProbeManager.instrumentOneFunc(F, TM);
   }
 
   return PreservedAnalyses::none();
 }

llvm/test/Transforms/SampleProfile/pseudo-probe-emit-inline.ll

+; REQUIRES: x86_64-linux
+; RUN: opt < %s -passes='pseudo-probe,cgscc(inline)' -function-sections -mtriple=x86_64-unknown-linux-gnu -S -o %t
+; RUN: FileCheck %s < %t --check-prefix=CHECK-IL
+; RUN: llc -pseudo-probe-for-profiling -function-sections <%t -filetype=asm -o %t1
+; RUN: FileCheck %s < %t1 --check-prefix=CHECK-ASM
+; RUN: llc -pseudo-probe-for-profiling -function-sections <%t -filetype=obj -o %t2
+; RUN: llvm-objdump --section-headers  %t2 | FileCheck %s --check-prefix=CHECK-OBJ
+; RUN: llvm-mc -filetype=asm <%t1 -o %t3
+; RUN: FileCheck %s < %t3 --check-prefix=CHECK-ASM
+; RUN: llvm-mc -filetype=obj <%t1 -o %t4
+; RUN: llvm-objdump --section-headers  %t4 | FileCheck %s --check-prefix=CHECK-OBJ
+
+define dso_local void @foo2() !dbg !7 {
+; CHECK-IL:  call void @llvm.pseudoprobe(i64 [[#GUID1:]], i64 1, i32 0), !dbg ![[#]]
+; CHECK-ASM: .pseudoprobe [[#GUID1:]] 1 0 0
+  ret void, !dbg !10
+}
+
+define dso_local void @foo() #0 !dbg !11 {
+; CHECK-IL:  call void @llvm.pseudoprobe(i64 [[#GUID2:]], i64 1, i32 0), !dbg ![[#]]
+; CHECK-IL:  call void @llvm.pseudoprobe(i64 [[#GUID1]], i64 1, i32 0), !dbg ![[#DL1:]]
+; CHECK-ASM: .pseudoprobe [[#GUID2:]] 1 0 0
+; CHECK-ASM: .pseudoprobe [[#GUID1]] 1 0 0 @ [[#GUID2]]:2
+  call void @foo2(), !dbg !12
+  ret void, !dbg !13
+}
+
+define dso_local i32 @entry() !dbg !14 {
+; CHECK-IL:  call void @llvm.pseudoprobe(i64 [[#GUID3:]], i64 1, i32 0), !dbg ![[#]]
+; CHECK-IL:  call void @llvm.pseudoprobe(i64 [[#GUID2]], i64 1, i32 0), !dbg ![[#DL2:]]
+; CHECK-IL:  call void @llvm.pseudoprobe(i64 [[#GUID1]], i64 1, i32 0), !dbg ![[#DL3:]]
+; CHECK-ASM: .pseudoprobe [[#GUID3:]] 1 0 0
+; CHECK-ASM: .pseudoprobe [[#GUID2]] 1 0 0 @ [[#GUID3]]:2
+; CHECK-ASM: .pseudoprobe [[#GUID1]] 1 0 0 @ [[#GUID3]]:2 @ [[#GUID2]]:2
+  call void @foo(), !dbg !18
+  ret i32 0, !dbg !19
+}
+
+
+; CHECK-IL: ![[#SCOPE1:]] = distinct !DISubprogram(name: "foo2"
+; CHECK-IL: ![[#SCOPE2:]] = distinct !DISubprogram(name: "foo"
+; CHECK-IL: ![[#DL1]] = !DILocation(line: 3, column: 1,  scope: ![[#SCOPE1]], inlinedAt: ![[#INL1:]])
+; CHECK-IL: ![[#INL1]] = distinct !DILocation(line: 7, column: 3, scope: ![[#BL1:]])
+;; A discriminator of 134217751 which is 0x8000017 in hexdecimal, stands for a direct call probe
+;; with an index of 2.
+; CHECK-IL: ![[#BL1]] = !DILexicalBlockFile(scope: ![[#SCOPE2]], file: !1, discriminator: 134217751)
+; CHECK-IL: ![[#SCOPE3:]] = distinct !DISubprogram(name: "entry"
+; CHECK-IL: ![[#DL2]] = !DILocation(line: 7, column: 3,  scope: ![[#SCOPE2]], inlinedAt: ![[#INL2:]])
+; CHECK-IL: ![[#INL2]] = distinct !DILocation(line: 11, column: 3, scope: ![[#BL2:]])
+; CHECK-IL: ![[#BL2]] = !DILexicalBlockFile(scope: ![[#SCOPE3]], file: !1, discriminator: 134217751)
+; CHECK-IL: ![[#DL3]] = !DILocation(line: 3, column: 1,  scope: ![[#SCOPE1]], inlinedAt: ![[#INL3:]])
+; CHECK-IL: ![[#INL3]] = distinct !DILocation(line: 7, column: 3,  scope: ![[#BL1]], inlinedAt: ![[#INL2]])
+
+
+; Check the generation of .pseudo_probe_desc section
+; CHECK-ASM: .section .pseudo_probe_desc,"G",@progbits,.pseudo_probe_desc_foo2,comdat
+; CHECK-ASM-NEXT: .quad [[#GUID1]]
+; CHECK-ASM-NEXT: .quad [[#HASH1:]]
+; CHECK-ASM-NEXT: .byte 4
+; CHECK-ASM-NEXT: .ascii "foo2"
+; CHECK-ASM-NEXT: .section .pseudo_probe_desc,"G",@progbits,.pseudo_probe_desc_foo,comdat
+; CHECK-ASM-NEXT: .quad [[#GUID2]]
+; CHECK-ASM-NEXT: .quad [[#HASH2:]]
+; CHECK-ASM-NEXT: .byte 3
+; CHECK-ASM-NEXT: .ascii "foo"
+; CHECK-ASM-NEXT: .section .pseudo_probe_desc,"G",@progbits,.pseudo_probe_desc_entry,comdat
+; CHECK-ASM-NEXT: .quad [[#GUID3]]
+; CHECK-ASM-NEXT: .quad [[#HASH3:]]
+; CHECK-ASM-NEXT: .byte 5
+; CHECK-ASM-NEXT: .ascii "entry"
+
+; CHECK-OBJ: .pseudo_probe_desc
+; CHECK-OBJ: .pseudo_probe
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, emissionKind: FullDebug)
+!1 = !DIFile(filename: "foo.c", directory: "any")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = distinct !DISubprogram(name: "foo2", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null}
+!10 = !DILocation(line: 3, column: 1, scope: !7)
+!11 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 6, type: !8, scopeLine: 6, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!12 = !DILocation(line: 7, column: 3, scope: !11)
+!13 = !DILocation(line: 8, column: 1, scope: !11)
+!14 = distinct !DISubprogram(name: "entry", scope: !1, file: !1, line: 10, type: !15, scopeLine: 10, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!15 = !DISubroutineType(types: !16)
+!16 = !{!17}
+!17 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!18 = !DILocation(line: 11, column: 3, scope: !14)
+!19 = !DILocation(line: 12, column: 3, scope: !14)

llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll

-; REQUIRES: x86-registered-target
+; REQUIRES: x86_64-linux
 ; RUN: opt < %s -passes=pseudo-probe -function-sections -S -o %t
 ; RUN: FileCheck %s < %t --check-prefix=CHECK-IL
 ; RUN: llc %t -pseudo-probe-for-profiling -stop-after=pseudo-probe-inserter -o - | FileCheck %s --check-prefix=CHECK-MIR
-;
+; RUN: llc %t -pseudo-probe-for-profiling -function-sections -filetype=asm -o %t1
+; RUN: FileCheck %s < %t1 --check-prefix=CHECK-ASM
+; RUN: llc %t -pseudo-probe-for-profiling -function-sections -filetype=obj -o %t2
+; RUN: llvm-objdump --section-headers  %t2 | FileCheck %s --check-prefix=CHECK-OBJ
+; RUN: llvm-mc %t1 -filetype=obj -o %t3
+; RUN: llvm-objdump --section-headers  %t3 | FileCheck %s --check-prefix=CHECK-OBJ
+
 ;; Check the generation of pseudoprobe intrinsic call.
 
 define void @foo(i32 %x) !dbg !3 {
 bb0:
   %cmp = icmp eq i32 %x, 0
 ; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID:]], i64 1, i32 0), !dbg ![[#FAKELINE:]]
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID:]], 1, 0, 0
+; CHECK-ASM: .pseudoprobe [[#GUID:]] 1 0 0
   br i1 %cmp, label %bb1, label %bb2
 
 bb1:
 ; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID:]], i64 2, i32 0), !dbg ![[#FAKELINE]]
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 3, 0, 0
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 4, 0, 0
+; CHECK-ASM: .pseudoprobe [[#GUID]] 3 0 0
+; CHECK-ASM: .pseudoprobe [[#GUID]] 4 0 0
   br label %bb3
 
 bb2:
 ; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID:]], i64 3, i32 0), !dbg ![[#FAKELINE]]
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 2, 0, 0
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 4, 0, 0
+; CHECK-ASM: .pseudoprobe [[#GUID]] 2 0 0
+; CHECK-ASM: .pseudoprobe [[#GUID]] 4 0 0
   br label %bb3
 
 bb3:
 ; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID]], i64 4, i32 0), !dbg ![[#REALLINE:]]
   ret void, !dbg !12
 }
 
 declare void @bar(i32 %x) 
 
 define internal void @foo2(void (i32)* %f) !dbg !4 {
 entry:
 ; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID2:]], i64 1, i32 0)
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID2:]], 1, 0, 0
+; CHECK-ASM: .pseudoprobe [[#GUID2:]] 1 0 0
 ; Check pseudo_probe metadata attached to the indirect call instruction.
 ; CHECK-IL: call void %f(i32 1), !dbg ![[#PROBE0:]]
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID2]], 2, 1, 0
+; CHECK-ASM: .pseudoprobe [[#GUID2]] 2 1 0
   call void %f(i32 1), !dbg !13
 ; Check pseudo_probe metadata attached to the direct call instruction.
 ; CHECK-IL: call void @bar(i32 1), !dbg ![[#PROBE1:]]
 ; CHECK-MIR: PSEUDO_PROBE [[#GUID2]], 3, 2, 0
+; CHECK-ASM: .pseudoprobe [[#GUID2]] 3 2 0
   call void @bar(i32 1)
   ret void
 }
 
 ; CHECK-IL: ![[#FOO:]] = distinct !DISubprogram(name: "foo"
 ; CHECK-IL: ![[#FAKELINE]] = !DILocation(line: 0, scope: ![[#FOO]])
 ; CHECK-IL: ![[#REALLINE]] = !DILocation(line: 2, scope: ![[#FOO]])
 ; CHECK-IL: ![[#PROBE0]] = !DILocation(line: 2, column: 20, scope: ![[#SCOPE0:]])
 ;; A discriminator of 67108887 which is 0x4000017 in hexdecimal, stands for a direct call probe
 ;; with an index of 2.
 ; CHECK-IL: ![[#SCOPE0]] = !DILexicalBlockFile(scope: ![[#]], file: ![[#]], discriminator: 67108887)
 ; CHECK-IL: ![[#PROBE1]] = !DILocation(line: 0, scope: ![[#SCOPE1:]])
 ;; A discriminator of 134217759 which is 0x800001f in hexdecimal, stands for a direct call probe
 ;; with an index of 3.
 ; CHECK-IL: ![[#SCOPE1]] = !DILexicalBlockFile(scope: ![[#]], file: ![[#]], discriminator: 134217759)
 
+; Check the generation of .pseudo_probe_desc section
+; CHECK-ASM: .section .pseudo_probe_desc,"G",@progbits,.pseudo_probe_desc_foo,comdat
+; CHECK-ASM-NEXT: .quad [[#GUID]]
+; CHECK-ASM-NEXT: .quad [[#HASH:]]
+; CHECK-ASM-NEXT: .byte  3
+; CHECK-ASM-NEXT: .ascii  "foo"
+; CHECK-ASM-NEXT: .section  .pseudo_probe_desc,"G",@progbits,.pseudo_probe_desc_foo2,comdat
+; CHECK-ASM-NEXT: .quad [[#GUID2]]
+; CHECK-ASM-NEXT: .quad [[#HASH2:]]
+; CHECK-ASM-NEXT: .byte 4
+; CHECK-ASM-NEXT: .ascii  "foo2"
+
+; CHECK-OBJ-COUNT-2: .pseudo_probe_desc
+; CHECK-OBJ-COUNT-2: .pseudo_probe
 
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!9, !10}
 
 !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1)
 !1 = !DIFile(filename: "test.c", directory: "")
 !2 = !{}
 !3 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !5, unit: !0, retainedNodes: !2)