Descriptive symbol names for machine basic block sections

[snehasish]

Summary

Today symbol names generated for machine basic block sections use a unary encoding to reduce bloat. This is essential when every basic block in the binary is assigned a symbol however with basic block clusters (rG05192e585ce175b55f2a26b83b4ed7882785c8e6) when we only need to generate a few non-temporary symbols we can assign more descriptive names making them more user friendly. With this change -

• Cold cluster section for function foo is named "foo.cold"
• Exception cluster section for function foo is named "foo.eh"
• Other cluster sections identified by their ids are named "foo.ID"

Using this format works well with existing tools. It will demangle as expected and works with existing symbolizers, profilers and debuggers out of the box.

$ c++filt _Z3foov.cold
foo() [clone .cold]

$ c++filt _Z3foov.eh
foo() [clone .eh]

$c++filt _Z3foov.1234
foo() [clone 1234]

Tests for basicblock-sections are updated with some cleanup where appropriate.

[tmsriram]

llvm/lib/CodeGen/MachineBasicBlock.cpp

87

Just a comment: I like this because it will demangle as expected and works well with existing symbolizers, profilers and debuggers out of the box.

$ c++filt _Z3foov.cold
foo() [clone .cold]

$ c++filt _Z3foov.eh
foo() [clone .eh]

$c++filt _Z3foov.1234
foo() [clone 1234]

93

getParent() is just MF, so MF->getName()

[snehasish]

llvm/lib/CodeGen/MachineBasicBlock.cpp

87

Good point, added this to the differential description.

[tmsriram]

LGTM, but please wait for Eli's comments before pushing.

[efriedma]

Some minor suggestions for the string manipulation; otherwise looks fine.

llvm/lib/CodeGen/MachineBasicBlock.cpp

83–93

We usually prefer something like Twine(Prefix) + ".BB." + MF->getName().

91

Not that it's likely to matter much, but Twine(SectionID.Number) is probably a little more efficient. (With std::string, the compiler has to work very hard to prove it doesn't need to allocate memory.)

Ctx.getOrCreateSymbol(MF->getName() + "." + Twine(SectionID.Number)) would also avoid the temporary string, but maybe that's not worth the readability cost.

97

You don't need to explicitly cast "_" to Twine.

[snehasish]

Updated string types based on reviewer comments.

[snehasish]

@efriedma Thanks for the pointers on LLVM string types. Updated the diff with changes, please take a look. Thanks!

llvm/lib/CodeGen/MachineBasicBlock.cpp

91

In this case SmallString operator+= accepts a StringRef so just Suffix += "." + Twine(SectionID.Number); does not compile. Rewriting this in a different way makes it less readable so I decided to leave it as it is.

[efriedma]

LGTM

llvm/lib/CodeGen/MachineBasicBlock.cpp

 
 /// Return the MCSymbol for this basic block.
 MCSymbol *MachineBasicBlock::getSymbol() const {
   if (!CachedMCSymbol) {
     const MachineFunction *MF = getParent();
     MCContext &Ctx = MF->getContext();
     auto Prefix = Ctx.getAsmInfo()->getPrivateLabelPrefix();
 
-    // We emit a non-temporary symbol for every basic block if we have BBLabels
-    // or -- with basic block sections -- when a basic block begins a section.
-    bool BasicBlockSymbols = isBeginSection() || MF->hasBBLabels();
-    auto Delimiter = BasicBlockSymbols ? "." : "_";
     assert(getNumber() >= 0 && "cannot get label for unreachable MBB");
 
-    // With Basic Block Sections, we emit a symbol for every basic block. To
-    // keep the size of strtab small, we choose a unary encoding which can
-    // compress the symbol names significantly.  The basic blocks for function
-    // foo are named a.BB.foo, aa.BB.foo, and so on.
-    if (BasicBlockSymbols) {
+    // We emit a non-temporary symbol for every basic block if we have BBLabels
+    // or -- with basic block sections -- when a basic block begins a section.
+    // With basic block symbols, we use a unary encoding which can
+    // compress the symbol names significantly. For basic block sections where
+    // this block is the first in a cluster, we use a non-temp descriptive name.
+    // Otherwise we fall back to use temp label.
+    if (MF->hasBBLabels()) {
       auto Iter = MF->getBBSectionsSymbolPrefix().begin();
       if (getNumber() < 0 ||
           getNumber() >= (int)MF->getBBSectionsSymbolPrefix().size())
         report_fatal_error("Unreachable MBB: " + Twine(getNumber()));
+      // The basic blocks for function foo are named a.BB.foo, aa.BB.foo, and
+      // so on.
       std::string Prefix(Iter + 1, Iter + getNumber() + 1);
       std::reverse(Prefix.begin(), Prefix.end());
       CachedMCSymbol =
-          Ctx.getOrCreateSymbol(Prefix + Twine(Delimiter) + "BB" +
-                                Twine(Delimiter) + Twine(MF->getName()));
+          Ctx.getOrCreateSymbol(Twine(Prefix) + ".BB." + Twine(MF->getName()));
+    } else if (MF->hasBBSections() && isBeginSection()) {
+      SmallString<5> Suffix;
+      if (SectionID == MBBSectionID::ColdSectionID) {
+        Suffix += ".cold";
+      } else if (SectionID == MBBSectionID::ExceptionSectionID) {
+        Suffix += ".eh";
+      } else {
+        Suffix += "." + std::to_string(SectionID.Number);
+      }
+      CachedMCSymbol = Ctx.getOrCreateSymbol(MF->getName() + Suffix);
     } else {
-      CachedMCSymbol = Ctx.getOrCreateSymbol(
-          Twine(Prefix) + "BB" + Twine(MF->getFunctionNumber()) +
-          Twine(Delimiter) + Twine(getNumber()));
+      CachedMCSymbol = Ctx.getOrCreateSymbol(Twine(Prefix) + "BB" +
+                                             Twine(MF->getFunctionNumber()) +
+                                             "_" + Twine(getNumber()));
     }
   }
   return CachedMCSymbol;
 }
 
 
 raw_ostream &llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) {
   MBB.print(OS);

llvm/test/CodeGen/X86/basicblock-sections-clusters-branches.ll

 ; Test2: Basic blocks #1 and #3 will be placed in the same section.
 ; The rest (#0 and #2) go into the function's section.
 ; This means #1 must fall through to #3, and #0 must fall through to #2.
 ; #2 must have an explicit jump to #3.
 ; RUN: echo '!foo' > %t2
 ; RUN: echo '!!1 3' >> %t2
 ; RUN: llc < %s -O0 -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t2 | FileCheck %s -check-prefix=LINUX-SECTIONS2
 
-define void @foo(i1 zeroext) {
+define void @foo(i1 zeroext) nounwind {
   %2 = alloca i8, align 1
   %3 = zext i1 %0 to i8
   store i8 %3, i8* %2, align 1
   %4 = load i8, i8* %2, align 1
   %5 = trunc i8 %4 to i1
   br i1 %5, label %6, label %8
 
 6:                                                ; preds = %1

 }
 
 declare i32 @bar() #1
 
 declare i32 @baz() #1
 
 ; LINUX-SECTIONS1:      .section  .text.foo,"ax",@progbits
 ; LINUX-SECTIONS1-LABEL:  foo:
-; LINUX-SECTIONS1:    jne a.BB.foo
+; LINUX-SECTIONS1:    jne foo.1
 ; LINUX-SECTIONS1-NOT:    {{jne|je|jmp}}
 ; LINUX-SECTIONS1-LABEL:  # %bb.2:
-; LINUX-SECTIONS1:    jmp raa.BB.foo
+; LINUX-SECTIONS1:    jmp foo.cold
 ; LINUX-SECTIONS1:    .section        .text.foo,"ax",@progbits,unique,1
-; LINUX-SECTIONS1-LABEL:  a.BB.foo:
-; LINUX-SECTIONS1:    jmp raa.BB.foo
+; LINUX-SECTIONS1-LABEL:  foo.1:
+; LINUX-SECTIONS1:    jmp foo.cold
 ; LINUX-SECTIONS1:    .section        .text.unlikely.foo,"ax",@progbits
-; LINUX-SECTIONS1-LABEL:  raa.BB.foo:
+; LINUX-SECTIONS1-LABEL:  foo.cold:
 
 ; LINUX-SECTIONS2:    .section        .text.foo,"ax",@progbits
 ; LINUX-SECTIONS2-LABEL:  foo:
-; LINUX-SECTIONS2:    jne a.BB.foo
+; LINUX-SECTIONS2:    jne foo.0
 ; LINUX-SECTIONS2-NOT:    {{jne|je|jmp}}
 ; LINUX-SECTIONS2-LABEL:  # %bb.2:
 ; LINUX-SECTIONS2:    jmp .LBB0_3
 ; LINUX-SECTIONS2:    .section        .text.foo,"ax",@progbits,unique,1
-; LINUX-SECTIONS2:    a.BB.foo:
+; LINUX-SECTIONS2:    foo.0:
 ; LINUX-SECTIONS2-NOT:    {{jne|je|jmp}}
 ; LINUX-SECTIONS2:    .LBB0_3:

llvm/test/CodeGen/X86/basicblock-sections-clusters-eh.ll

 ; BB cluster section test for exception handling.
 ;
 ; Test1: Basic blocks #1 and #3 are landing pads and must be in the same section.
 ; Basic block 2 will be placed in a unique section, but #1 and #3 are placed in the special exception section.
 ; The rest will be placed in a section along with the entry basic block.
 ; RUN: echo '!main' > %t1
 ; RUN: echo '!!1 2' >> %t1
 ; RUN: llc < %s -O0 -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t1 | FileCheck %s -check-prefix=LINUX-SECTIONS1
 ;
 ; Test2: Basic blocks #1, #2, and #3 go into a separate section.
 ; No separate exception section will be created as #1 and #3 are already in one section.
 ; The rest will be placed in a section along with the entry basic block.
 ; RUN: echo '!main' > %t2
 ; RUN: echo '!!1 2 3' >> %t2
 ; RUN: llc < %s -O0 -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t2 | FileCheck %s -check-prefix=LINUX-SECTIONS2
-;
 
 @_ZTIi = external constant i8*
 
 define i32 @main() uwtable optsize ssp personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
 entry:
   invoke void @_Z1fv() optsize
           to label %try.cont unwind label %lpad1
 

 ; LINUX-SECTIONS1-LABEL:  main:
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1-LABEL:  .LBB0_4:
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1-LABEL:  .LBB0_5:
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1-LABEL:  .LBB0_6:
 ; LINUX-SECTIONS1:    .section  .text.main,"ax",@progbits,unique,1
-; LINUX-SECTIONS1-LABEL:  al.BB.main:
+; LINUX-SECTIONS1-LABEL:  main.0:
 ; LINUX-SECTIONS1:    .section  .text.eh.main,"ax",@progbits
-; LINUX-SECTIONS1-LABEL:  l.BB.main:
+; LINUX-SECTIONS1-LABEL:  main.eh:
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1-LABEL:  .LBB0_3:
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1:    .section  .text.main,"ax",@progbits
 ; LINUX-SECTIONS1-LABEL:  .Lfunc_end0
 
 
 ; LINUX-SECTIONS2:    .section  .text.main,"ax",@progbits
 ; LINUX-SECTIONS2-LABEL:  main:
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  .LBB0_4:
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  .LBB0_5:
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  .LBB0_6:
 ; LINUX-SECTIONS2:    .section  .text.main,"ax",@progbits,unique,1
-; LINUX-SECTIONS2-LABEL:  l.BB.main:
+; LINUX-SECTIONS2-LABEL:  main.0:
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  .LBB0_2:
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  .LBB0_3:
 ; LINUX-SECTIONS2:    .section  .text.main,"ax",@progbits
 ; LINUX-SECTIONS2-LABEL:  .Lfunc_end0

llvm/test/CodeGen/X86/basicblock-sections-clusters.ll

 ; BB cluster section tests.
 ;
 ; Test1: Basic blocks #0 (entry) and #2 will be placed in the same section.
 ; Basic block 1 will be placed in a unique section.
 ; The rest will be placed in the cold section.
 ; RUN: echo '!foo' > %t1
 ; RUN: echo '!!0 2' >> %t1
 ; RUN: echo '!!1' >> %t1
 ; RUN: llc < %s -O0 -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t1 | FileCheck %s -check-prefix=LINUX-SECTIONS1
 ;
 ; Test2: Basic blocks #1 and #3 will be placed in the same section.
 ; All other BBs (including the entry block) go into the function's section.
 ; RUN: echo '!foo' > %t2
 ; RUN: echo '!!1 3' >> %t2
 ; RUN: llc < %s -O0 -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t2 | FileCheck %s -check-prefix=LINUX-SECTIONS2
 
-define void @foo(i1 zeroext) {
+define void @foo(i1 zeroext) nounwind {
   %2 = alloca i8, align 1
   %3 = zext i1 %0 to i8
   store i8 %3, i8* %2, align 1
   %4 = load i8, i8* %2, align 1
   %5 = trunc i8 %4 to i1
   br i1 %5, label %6, label %8
 
 6:                                                ; preds = %1

 declare i32 @baz() #1
 
 ; LINUX-SECTIONS1:      .section  .text.foo,"ax",@progbits
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1-LABEL:  foo:
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1-LABEL:  # %bb.2:
 ; LINUX-SECTIONS1:    .section        .text.foo,"ax",@progbits,unique,1
-; LINUX-SECTIONS1-LABEL:  a.BB.foo:
+; LINUX-SECTIONS1-LABEL:  foo.1:
 ; LINUX-SECTIONS1-LABEL:  .Ltmp0:
-; LINUX-SECTIONS1-NEXT:   .size a.BB.foo, .Ltmp0-a.BB.foo
+; LINUX-SECTIONS1-NEXT:        .size   foo.1, .Ltmp0-foo.1
 ; LINUX-SECTIONS1-NOT:    .section
 ; LINUX-SECTIONS1:    .section        .text.unlikely.foo,"ax",@progbits
-; LINUX-SECTIONS1-LABEL:  raa.BB.foo:
+; LINUX-SECTIONS1-LABEL:  foo.cold:
 ; LINUX-SECTIONS1:      .section  .text.foo,"ax",@progbits
 ; LINUX-SECTIONS1-LABEL:  .Lfunc_end0:
 ; LINUX-SECTIONS1-NEXT:   .size foo, .Lfunc_end0-foo
 
 ; LINUX-SECTIONS2:    .section        .text.foo,"ax",@progbits
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  foo:
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  # %bb.2:
 ; LINUX-SECTIONS2:    .section        .text.foo,"ax",@progbits,unique,1
-; LINUX-SECTIONS2-NEXT:   a.BB.foo:
+; LINUX-SECTIONS2-NEXT:   foo.0:
 ; LINUX-SECTIONS2-NOT:    .section
 ; LINUX-SECTIONS2-LABEL:  .LBB0_3:
 ; LINUX-SECTIONS2-LABEL:  .Ltmp0:
-; LINUX-SECTIONS2-NEXT:   .size a.BB.foo, .Ltmp0-a.BB.foo
+; LINUX-SECTIONS2-NEXT:        .size   foo.0, .Ltmp0-foo.0
 ; LINUX-SECTIONS2:    .section        .text.foo,"ax",@progbits
 ; LINUX-SECTIONS2-LABEL:  .Lfunc_end0:
 ; LINUX-SECTIONS2-NEXT:   .size foo, .Lfunc_end0-foo
-

llvm/test/CodeGen/X86/basicblock-sections-cold.ll

 ; Check if basic blocks that don't get unique sections are placed in cold sections.
 ; Basic block with id 1 and 2 must be in the cold section.
 ; RUN: echo '!_Z3bazb' > %t
 ; RUN: echo '!!0' >> %t
-; RUN: cat %t
 ; RUN: llc < %s -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t -unique-bb-section-names | FileCheck %s -check-prefix=LINUX-SECTIONS
 
-define void @_Z3bazb(i1 zeroext) {
+define void @_Z3bazb(i1 zeroext) nounwind {
   %2 = alloca i8, align 1
   %3 = zext i1 %0 to i8
   store i8 %3, i8* %2, align 1
   %4 = load i8, i8* %2, align 1
   %5 = trunc i8 %4 to i1
   br i1 %5, label %6, label %8
 
 6:                                                ; preds = %1

 
 declare i32 @_Z3barv() #1
 
 declare i32 @_Z3foov() #1
 
 ; LINUX-SECTIONS: .section        .text._Z3bazb,"ax",@progbits
 ; LINUX-SECTIONS: _Z3bazb:
 ; Check that the basic block with id 1 doesn't get a section.
-; LINUX-SECTIONS-NOT: .section        .text._Z3bazb.r.BB._Z3bazb,"ax",@progbits,unique
+; LINUX-SECTIONS-NOT: .section        .text._Z3bazb._Z3bazb.1,"ax",@progbits,unique
 ; Check that a single cold section is started here and id 1 and 2 blocks are placed here.
 ; LINUX-SECTIONS: .section  .text.unlikely._Z3bazb,"ax",@progbits
-; LINUX-SECTIONS: r.BB._Z3bazb:
-; LINUX-SECTIONS-NOT: .section        .text._Z3bazb.rr.BB._Z3bazb,"ax",@progbits,unique
+; LINUX-SECTIONS: _Z3bazb.cold:
+; LINUX-SECTIONS-NOT: .section        .text._Z3bazb._Z3bazb.2,"ax",@progbits,unique
 ; LINUX-SECTIONS: .LBB0_2:
 ; LINUX-SECTIONS: .size   _Z3bazb, .Lfunc_end{{[0-9]}}-_Z3bazb

llvm/test/CodeGen/X86/basicblock-sections-directjumps.ll

 
 declare i32 @_Z3barv() #1
 
 declare i32 @_Z3foov() #1
 
 
 ; LINUX-SECTIONS: .section        .text._Z3bazb,"ax",@progbits
 ; LINUX-SECTIONS: _Z3bazb:
-; LINUX-SECTIONS: jmp a.BB._Z3bazb
-; LINUX-SECTIONS: .section        .text._Z3bazb.a.BB._Z3bazb,"ax",@progbits
-; LINUX-SECTIONS: a.BB._Z3bazb:
-; LINUX-SECTIONS: jmp aa.BB._Z3bazb
-; LINUX-SECTIONS: .section        .text._Z3bazb.aa.BB._Z3bazb,"ax",@progbits
-; LINUX-SECTIONS: aa.BB._Z3bazb:
-; LINUX-SECTIONS: jmp raa.BB._Z3bazb
+; LINUX-SECTIONS: jmp _Z3bazb.1
+; LINUX-SECTIONS: .section        .text._Z3bazb._Z3bazb.1,"ax",@progbits
+; LINUX-SECTIONS: _Z3bazb.1:
+; LINUX-SECTIONS: jmp _Z3bazb.2
+; LINUX-SECTIONS: .section        .text._Z3bazb._Z3bazb.2,"ax",@progbits
+; LINUX-SECTIONS: _Z3bazb.2:
+; LINUX-SECTIONS: jmp _Z3bazb.3

llvm/test/CodeGen/X86/basicblock-sections-eh.ll

 declare i32 @__gxx_personality_v0(...)
 ; Function Attrs: nounwind readnone
 declare i32 @llvm.eh.typeid.for(i8*) #1
 declare i8* @__cxa_begin_catch(i8*)
 declare void @__cxa_end_catch()
 
 ;LINUX-SECTIONS: .section .text._Z3foob,"ax",@progbits
 ;LINUX-SECTIONS: _Z3foob:
-;LINUX-SECTIONS: .section       .text._Z3foob.laara.BB._Z3foob,"ax",@progbits
-;LINUX-SECTIONS: l{{[a|r]*}}.BB._Z3foob:
+;LINUX-SECTIONS: .section       .text._Z3foob._Z3foob.{{[0-9]+}},"ax",@progbits
+;LINUX-SECTIONS-LABEL: _Z3foob.{{[0-9]+}}:
+;LINUX-SECTIONS:        calll   __cxa_begin_catch

llvm/test/CodeGen/X86/basicblock-sections-list.ll

 ; Check the basic block sections list option.
 ; RUN: echo '!_Z3foob' > %t
 ; RUN: llc < %s -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t -unique-bb-section-names | FileCheck %s -check-prefix=LINUX-SECTIONS
 
-define i32 @_Z3foob(i1 zeroext %0) #0 {
+define i32 @_Z3foob(i1 zeroext %0) nounwind {
   %2 = alloca i32, align 4
   %3 = alloca i8, align 1
   %4 = zext i1 %0 to i8
   store i8 %4, i8* %3, align 1
   %5 = load i8, i8* %3, align 1
   %6 = trunc i8 %5 to i1
   %7 = zext i1 %6 to i32
   %8 = icmp sgt i32 %7, 0

 13:                                               ; preds = %11, %9
   %14 = load i32, i32* %2, align 4
   ret i32 %14
 }
 
 declare i32 @_Z3barv() #1
 declare i32 @_Z3bazv() #1
 
-define i32 @_Z3zipb(i1 zeroext %0) #0 {
+define i32 @_Z3zipb(i1 zeroext %0) nounwind {
   %2 = alloca i32, align 4
   %3 = alloca i8, align 1
   %4 = zext i1 %0 to i8
   store i8 %4, i8* %3, align 1
   %5 = load i8, i8* %3, align 1
   %6 = trunc i8 %5 to i1
   %7 = zext i1 %6 to i32
   %8 = icmp sgt i32 %7, 0

 
 13:                                               ; preds = %11, %9
   %14 = load i32, i32* %2, align 4
   ret i32 %14
 }
 
 ; LINUX-SECTIONS: .section        .text._Z3foob,"ax",@progbits
 ; LINUX-SECTIONS: _Z3foob:
-; LINUX-SECTIONS: .section        .text._Z3foob.a.BB._Z3foob,"ax",@progbits
-; LINUX-SECTIONS: a.BB._Z3foob:
-; LINUX-SECTIONS: .section        .text._Z3foob.aa.BB._Z3foob,"ax",@progbits
-; LINUX-SECTIONS: aa.BB._Z3foob:
-; LINUX-SECTIONS: .section        .text._Z3foob.raa.BB._Z3foob,"ax",@progbits
-; LINUX-SECTIONS: raa.BB._Z3foob:
+; LINUX-SECTIONS: .section        .text._Z3foob._Z3foob.1,"ax",@progbits
+; LINUX-SECTIONS: _Z3foob.1:
+; LINUX-SECTIONS: .section        .text._Z3foob._Z3foob.2,"ax",@progbits
+; LINUX-SECTIONS: _Z3foob.2:
+; LINUX-SECTIONS: .section        .text._Z3foob._Z3foob.3,"ax",@progbits
+; LINUX-SECTIONS: _Z3foob.3:
 
 ; LINUX-SECTIONS: .section        .text._Z3zipb,"ax",@progbits
 ; LINUX-SECTIONS: _Z3zipb:
-; LINUX-SECTIONS-NOT: .section        .text._Z3zipb.a.BB._Z3zipb,"ax",@progbits
-; LINUX-SECTIONS-NOT: a.BB._Z3zipb:
-; LINUX-SECTIONS-NOT: .section        .text._Z3zipb.aa.BB._Z3zipb,"ax",@progbits
-; LINUX-SECTIONS-NOT: aa.BB._Z3zipb:
-; LINUX-SECTIONS-NOT: .section        .text._Z3zipb.raa.BB._Z3zipb,"ax",@progbits
-; LINUX-SECTIONS-NOT: raa.BB._Z3zipb:
+; LINUX-SECTIONS-NOT: .section        .text._Z3zipb._Z3zipb.{{[0-9]+}},"ax",@progbits
+; LINUX-SECTIONS-NOT: _Z3zipb.{{[0-9]+}}:

llvm/test/CodeGen/X86/basicblock-sections-listbb.ll

 ; Fine-grained basic block sections, subset of basic blocks in a function.
 ; Only basic block with id 2 must get a section.
 ; RUN: echo '!_Z3bazb' > %t
 ; RUN: echo '!!2' >> %t
 ; RUN: llc < %s -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=%t -unique-bb-section-names | FileCheck %s -check-prefix=LINUX-SECTIONS
 
-define void @_Z3bazb(i1 zeroext) {
+define void @_Z3bazb(i1 zeroext) nounwind {
   %2 = alloca i8, align 1
   %3 = zext i1 %0 to i8
   store i8 %3, i8* %2, align 1
   %4 = load i8, i8* %2, align 1
   %5 = trunc i8 %4 to i1
   br i1 %5, label %6, label %8
 
 6:                                                ; preds = %1
   %7 = call i32 @_Z3barv()
   br label %10
 
 8:                                                ; preds = %1
   %9 = call i32 @_Z3foov()
   br label %10
 
 10:                                               ; preds = %8, %6
   ret void
 }
 
 declare i32 @_Z3barv() #1
 
 declare i32 @_Z3foov() #1
 
+; Check that the correct block is found using the call insts for foo and bar.
+;
 ; LINUX-SECTIONS: .section        .text._Z3bazb,"ax",@progbits
 ; LINUX-SECTIONS: _Z3bazb:
 ; Check that the basic block with id 1 doesn't get a section.
-; LINUX-SECTIONS-NOT: .section        .text._Z3bazb.r.BB._Z3bazb,"ax",@progbits
-; LINUX-SECTIONS: # %bb.1:
-; LINUX-SECTIONS: .section        .text._Z3bazb.rr.BB._Z3bazb,"ax",@progbits
-; LINUX-SECTIONS: rr.BB._Z3bazb:
+; LINUX-SECTIONS-NOT: .section        .text._Z3bazb._Z3bazb.{{[0-9]+}},"ax",@progbits
+; LINUX-SECTIONS-LABEL: # %bb.1:
+; LINUX-SECTIONS-NEXT:        callq   _Z3barv
+; LINUX-SECTIONS: .section        .text._Z3bazb._Z3bazb.{{[0-9]+}},"ax",@progbits
+; LINUX-SECTIONS-LABEL: _Z3bazb.{{[0-9]+}}:
+; LINUX-SECTIONS-NEXT:        callq   _Z3foov
 ; LINUX-SECTIONS: .Ltmp0:
-; LINUX-SECTIONS-NEXT: .size   rr.BB._Z3bazb, .Ltmp0-rr.BB._Z3bazb
+; LINUX-SECTIONS-NEXT: .size   _Z3bazb.{{[0-9]+}}, .Ltmp0-_Z3bazb.{{[0-9]+}}

llvm/test/CodeGen/X86/basicblock-sections-mir-parse.mir

bb.3 (%ir-block.9, bbsections 3):
     $rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp
     CFI_INSTRUCTION def_cfa $rsp, 8
     RETQ implicit $eax
 
 ...
 
 # CHECK: _Z3foob:
 # CHECK: .section .text,"ax",@progbits,unique
-# CHECK: a.BB._Z3foob:
+# CHECK: _Z3foob.1:
 # CHECK: .section .text,"ax",@progbits,unique
-# CHECK: aa.BB._Z3foob:
+# CHECK: _Z3foob.2:
 # CHECK: .section .text,"ax",@progbits,unique
-# CHECK: aaa.BB._Z3foob:
+# CHECK: _Z3foob.3:

llvm/test/CodeGen/X86/basicblock-sections.ll

 ; RUN: llc < %s -mtriple=x86_64-pc-linux -function-sections -basicblock-sections=all -unique-bb-section-names | FileCheck %s -check-prefix=LINUX-SECTIONS
 ; RUN: llc < %s -mtriple=i386-unknown-linux-gnu  -function-sections -basicblock-sections=all -unique-bb-section-names | FileCheck %s -check-prefix=LINUX-SECTIONS
 
-define void @_Z3bazb(i1 zeroext) {
+define void @_Z3bazb(i1 zeroext) nounwind {
   %2 = alloca i8, align 1
   %3 = zext i1 %0 to i8
   store i8 %3, i8* %2, align 1
   %4 = load i8, i8* %2, align 1
   %5 = trunc i8 %4 to i1
   br i1 %5, label %6, label %8
 
 6:                                                ; preds = %1

 
 declare i32 @_Z3barv() #1
 
 declare i32 @_Z3foov() #1
 
 
 ; LINUX-SECTIONS: .section        .text._Z3bazb,"ax",@progbits
 ; LINUX-SECTIONS: _Z3bazb:
-; LINUX-SECTIONS: .section        .text._Z3bazb.r.BB._Z3bazb,"ax",@progbits
-; LINUX-SECTIONS: r.BB._Z3bazb:
+; LINUX-SECTIONS: .section        .text._Z3bazb._Z3bazb.1,"ax",@progbits
+; LINUX-SECTIONS: _Z3bazb.1:
 ; LINUX-SECTIONS: .Ltmp0:
-; LINUX-SECTIONS-NEXT: .size   r.BB._Z3bazb, .Ltmp0-r.BB._Z3bazb
-; LINUX-SECTIONS: .section        .text._Z3bazb.rr.BB._Z3bazb,"ax",@progbits
-; LINUX-SECTIONS: rr.BB._Z3bazb:
+; LINUX-SECTIONS-NEXT: .size   _Z3bazb.1, .Ltmp0-_Z3bazb.1
+; LINUX-SECTIONS: .section        .text._Z3bazb._Z3bazb.2,"ax",@progbits
+; LINUX-SECTIONS: _Z3bazb.2:
 ; LINUX-SECTIONS: .Ltmp1:
-; LINUX-SECTIONS-NEXT: .size   rr.BB._Z3bazb, .Ltmp1-rr.BB._Z3bazb
+; LINUX-SECTIONS-NEXT: .size   _Z3bazb.2, .Ltmp1-_Z3bazb.2