[DebugInfo] Extend the InstrRef LDV to support DbgValues with many Ops

[StephenTozer]

Summary

This patch builds on prior support patches to enable support for variadic debug values in InstrRefLDV, allowing DBG_VALUE_LISTs to have their ranges extended.

[Orlando]

LGTM

[jmorse]

Looks good, but, of course, tests.

[StephenTozer]

Added some lit tests, specifically adding variadic test cases to the existing tests which explicitly test the instruction referencing LiveDebugValues.

[Orlando]

Still LGTM!

llvm/test/DebugInfo/MIR/X86/live-debug-values-reg-copy.mir

12

Hardcoded metadata here

15

Here too

llvm/test/DebugInfo/MIR/X86/live-debug-values-restore.mir

785–786

Copy paste?

[glider]

Hi Stephen,

This patch broke Linux kernel builds with KMSAN and -gdwarf-4. Reverting the patch fixes the problem.

[StephenTozer]

In D128212#3745421, @glider wrote:

Hi Stephen,

This patch broke Linux kernel builds with KMSAN and -gdwarf-4. Reverting the patch fixes the problem.

Hi, happy to revert until a fix is found; do you have any more information on the error?

[glider]

Hi Stephen,

The following command line crashes for me on the attached file: clang -std=gnu11 --target=x86_64-linux-gnu -fno-omit-frame-pointer -fsanitize=kernel-memory -fsanitize-memory-param-retval -fsanitize-coverage=trace-pc -fsanitize-coverage=trace-cmp -c extents.i -w -g -O2:

clang: /usr/local/google/src/llvm-git-monorepo/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp:808: void TransferTracker::clobberMloc(LiveDebugValues::LocIdx, LiveDebugValues::ValueIDNum, llvm::MachineBasicBlock::iterator, bool): Assertion `LostMLocIt->second.contains(LocVarIt.second) && "Variable was using this MLoc, but does not appear in " "ActiveMLocs?"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang -std=gnu11 --target=x86_64-linux-gnu -fno-omit-frame-pointer -fsanitize=kernel-memory -fsanitize-memory-param-retval -fsanitize-coverage=trace-pc -fsanitize-coverage=trace-cmp -c extents.i -w -g -O2
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module 'extents.i'.
4.	Running pass 'Live DEBUG_VALUE analysis' on function '@__ext4_ext_check'
 #0 0x0000559c52bd9d61 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x0000559c52bd7b8c llvm::sys::CleanupOnSignal(unsigned long) (/usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang+0x3ce5b8c)
 #2 0x0000559c52b1a5e8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f0cf4b52200 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x12200)
 #4 0x00007f0cf45cb8c1 raise ./signal/../sysdeps/unix/sysv/linux/raise.c:50:1
 #5 0x00007f0cf45b5546 abort ./stdlib/abort.c:81:7
 #6 0x00007f0cf45b542f get_sysdep_segment_value ./intl/loadmsgcat.c:509:8
 #7 0x00007f0cf45b542f _nl_load_domain ./intl/loadmsgcat.c:970:34
 #8 0x00007f0cf45c4242 (/lib/x86_64-linux-gnu/libc.so.6+0x31242)
 #9 0x0000559c520e110f TransferTracker::clobberMloc(LiveDebugValues::LocIdx, LiveDebugValues::ValueIDNum, llvm::MachineInstrBundleIterator<llvm::MachineInstr, false>, bool) (/usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang+0x31ef10f)
#10 0x0000559c520e165f TransferTracker::clobberMloc(LiveDebugValues::LocIdx, llvm::MachineInstrBundleIterator<llvm::MachineInstr, false>, bool) (/usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang+0x31ef65f)
#11 0x0000559c520e18bb LiveDebugValues::InstrRefBasedLDV::transferSpillOrRestoreInst(llvm::MachineInstr&) (.part.0) InstrRefBasedImpl.cpp:0:0
#12 0x0000559c520e2185 LiveDebugValues::InstrRefBasedLDV::transferSpillOrRestoreInst(llvm::MachineInstr&) (/usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang+0x31f0185)
#13 0x0000559c520f09ea LiveDebugValues::InstrRefBasedLDV::process(llvm::MachineInstr&, std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> const*, std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> const*) (/usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang+0x31fe9ea)
#14 0x0000559c520f17ef LiveDebugValues::InstrRefBasedLDV::depthFirstVLocAndEmit(unsigned int, llvm::DenseMap<llvm::LexicalScope const*, llvm::DILocation const*, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::DILocation const*>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>>>&, llvm::SmallVector<llvm::SmallVector<std::pair<llvm::DebugVariable, LiveDebugValues::DbgValue>, 8u>, 8u>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, llvm::SmallVectorImpl<LiveDebugValues::VLocTracker>&, llvm::MachineFunction&, llvm::DenseMap<llvm::DebugVariable, unsigned int, llvm::DenseMapInfo<llvm::DebugVariable, void>, llvm::detail::DenseMapPair<llvm::DebugVariable, unsigned int>>&, llvm::TargetPassConfig const&)::'lambda'(llvm::MachineBasicBlock&)::operator()(llvm::MachineBasicBlock&) const InstrRefBasedImpl.cpp:0:0
#15 0x0000559c520f716d LiveDebugValues::InstrRefBasedLDV::depthFirstVLocAndEmit(unsigned int, llvm::DenseMap<llvm::LexicalScope const*, llvm::DILocation const*, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::DILocation const*>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>>>&, llvm::SmallVector<llvm::SmallVector<std::pair<llvm::DebugVariable, LiveDebugValues::DbgValue>, 8u>, 8u>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, llvm::SmallVectorImpl<LiveDebugValues::VLocTracker>&, llvm::MachineFunction&, llvm::DenseMap<llvm::DebugVariable, unsigned int, llvm::DenseMapInfo<llvm::DebugVariable, void>, llvm::detail::DenseMapPair<llvm::DebugVariable, unsigned int>>&, llvm::TargetPassConfig const&) (/usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang+0x320516d)
#16 0x0000559c520fb700 LiveDebugValues::InstrRefBasedLDV::ExtendRanges(llvm::MachineFunction&, llvm::MachineDominatorTree*, llvm::TargetPassConfig*, unsigned int, unsigned int) (/usr/local/google/src/llvm-git-monorepo/llvm_cmake_build/bin//clang+0x3209700)
#17 0x0000559c51de7da8 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0

Sorry, I haven't managed to reduce it further so far.

extents.i1 KBDownload

[glider]

Oh, actually creduce can do better:

struct b {
  int c;
  int d
};
struct e {
  int f
};
int g;
void i();
void j(struct b *k) { i(k->d); }
int l(struct e *k) {
  int a, b;
  a = k->f;
  struct b *h = k;
  while (a) {
    j(h);
    if (g < b)
      return 0;
    h++;
    a--;
    b = g;
  }
  i(k);
}

[nathanchance]

I too saw a crash in the Linux kernel with this change (no KMSAN), my reduction just finished:

struct rb_node {
  long __rb_parent_color;
} rb_erase(struct rb_node *, int *);
struct journal_node {
  struct rb_node node;
  long sector;
} * do_journal_write_ic_0;
short page_list_location_ic_2;
int page_list_location_section, page_list_location_pl_offset,
    remove_journal_node_ic_1;
int *access_journal___trans_tmp_5;
unsigned do_journal_write_i;
void remove_journal_node(struct journal_node *node) {
  if (__builtin_expect((&node->node)->__rb_parent_color == (long)node, 0))
    asm(".pushsection __bug_table,\"aw\"\n"
        ".popsection\n");
  rb_erase(&node->node, &remove_journal_node_ic_1);
}
_Bool find_newer_committed_node(struct journal_node *);
void do_journal_write() {
  unsigned j;
  for (;;) {
    unsigned k;
    struct journal_node *section_node =
        &do_journal_write_ic_0[do_journal_write_i];
    while (j < k && find_newer_committed_node(&section_node[j])) {
      unsigned sector =
          page_list_location_section * page_list_location_ic_2 + j;
      page_list_location_pl_offset = sector << *access_journal___trans_tmp_5;
      remove_journal_node(&section_node[j]);
      j++;
    }
    while (k && find_newer_committed_node(&section_node[k]))
      k--;
  }
}

$ clang -O2 -gdwarf-5 -c -o /dev/null dm-integrity.i
clang: /home/nathan/cbl/src/llvm-project/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp:810: void TransferTracker::clobberMloc(LocIdx, ValueIDNum, MachineBasicBlock::iterator, bool): Assertion `LostMLocIt->second.contains(LocVarIt.second) && "Variable was using
 this MLoc, but does not appear in " "ActiveMLocs?"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: clang -O2 -gdwarf-5 -c -o /dev/null dm-integrity.i
1.      <eof> parser at end of file
2.      Code generation
3.      Running pass 'Function Pass Manager' on module 'dm-integrity.i'.
4.      Running pass 'Live DEBUG_VALUE analysis' on function '@do_journal_write'
 #0 0x000055e8015a8a03 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x312da03)
 #1 0x000055e8015a6a4e llvm::sys::RunSignalHandlers() (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x312ba4e)
 #2 0x000055e80152bacf (anonymous namespace)::CrashRecoveryContextImpl::HandleCrash(int, unsigned long) CrashRecoveryContext.cpp:0:0
 #3 0x000055e80152bce1 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #4 0x00007f6e6dc1da40 (/usr/lib/libc.so.6+0x38a40)
 #5 0x00007f6e6dc6d4dc (/usr/lib/libc.so.6+0x884dc)
 #6 0x00007f6e6dc1d998 raise (/usr/lib/libc.so.6+0x38998)
 #7 0x00007f6e6dc0753d abort (/usr/lib/libc.so.6+0x2253d)
 #8 0x00007f6e6dc0745c (/usr/lib/libc.so.6+0x2245c)
 #9 0x00007f6e6dc164c6 (/usr/lib/libc.so.6+0x314c6)
#10 0x000055e800d383a8 TransferTracker::clobberMloc(LiveDebugValues::LocIdx, LiveDebugValues::ValueIDNum, llvm::MachineInstrBundleIterator<llvm::MachineInstr, false>, bool) InstrRefBasedImpl.cpp:0:0
#11 0x000055e800d3647d LiveDebugValues::InstrRefBasedLDV::transferSpillOrRestoreInst(llvm::MachineInstr&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x28bb47d)
#12 0x000055e800d47e83 LiveDebugValues::InstrRefBasedLDV::depthFirstVLocAndEmit(unsigned int, llvm::DenseMap<llvm::LexicalScope const*, llvm::DILocation const*, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::DILocation const*>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>>>&, llvm::SmallVector<llvm::SmallVector<std::pair<llvm::DebugVariable, LiveDebugValues::DbgValue>, 8u>, 8u>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, llvm::SmallVectorImpl<LiveDebugValues::VLocTracker>&, llvm::MachineFunction&, llvm::DenseMap<llvm::DebugVariable, unsigned int, llvm::DenseMapInfo<llvm::DebugVariable, void>, llvm::detail::DenseMapPair<llvm::DebugVariable, unsigned int>>&, llvm::TargetPassConfig const&)::$_13::operator()(llvm::MachineBasicBlock&) const InstrRefBasedImpl.cpp:0:0
#13 0x000055e800d4782d LiveDebugValues::InstrRefBasedLDV::depthFirstVLocAndEmit(unsigned int, llvm::DenseMap<llvm::LexicalScope const*, llvm::DILocation const*, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::DILocation const*>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallSet<llvm::DebugVariable, 4u, std::less<llvm::DebugVariable>>>> const&, llvm::DenseMap<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>, llvm::DenseMapInfo<llvm::LexicalScope const*, void>, llvm::detail::DenseMapPair<llvm::LexicalScope const*, llvm::SmallPtrSet<llvm::MachineBasicBlock*, 4u>>>&, llvm::SmallVector<llvm::SmallVector<std::pair<llvm::DebugVariable, LiveDebugValues::DbgValue>, 8u>, 8u>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, std::unique_ptr<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> [], std::default_delete<std::unique_ptr<LiveDebugValues::ValueIDNum [], std::default_delete<LiveDebugValues::ValueIDNum []>> []>>&, llvm::SmallVectorImpl<LiveDebugValues::VLocTracker>&, llvm::MachineFunction&, llvm::DenseMap<llvm::DebugVariable, unsigned int, llvm::DenseMapInfo<llvm::DebugVariable, void>, llvm::detail::DenseMapPair<llvm::DebugVariable, unsigned int>>&, llvm::TargetPassConfig const&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x28cc82d)
#14 0x000055e800d4a189 LiveDebugValues::InstrRefBasedLDV::ExtendRanges(llvm::MachineFunction&, llvm::MachineDominatorTree*, llvm::TargetPassConfig*, unsigned int, unsigned int) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x28cf189)
#15 0x000055e8009b3989 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x2538989)
#16 0x000055e800e8c5b7 llvm::FPPassManager::runOnFunction(llvm::Function&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x2a115b7)
#17 0x000055e800e94061 llvm::FPPassManager::runOnModule(llvm::Module&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x2a19061)
#18 0x000055e800e8cfc5 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x2a11fc5)
#19 0x000055e801dfb46d clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::StringRef, llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x398046d)
#20 0x000055e8021f8a5e clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) CodeGenAction.cpp:0:0
#21 0x000055e802b0447a clang::ParseAST(clang::Sema&, bool, bool) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x468947a)
#22 0x000055e80213b3d0 clang::FrontendAction::Execute() (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x3cc03d0)
#23 0x000055e8020ad53f clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x3c3253f)
#24 0x000055e8021f1ec2 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x3d76ec2)
#25 0x000055e80030901a cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x1e8e01a)
#26 0x000055e800306daf ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#27 0x000055e801f28b72 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::$_1>(long) Job.cpp:0:0
#28 0x000055e80152b94c llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x30b094c)
#29 0x000055e801f286d0 clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x3aad6d0)
#30 0x000055e801ee7d5f clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x3a6cd5f)
#31 0x000055e801ee800e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x3a6d00e)
#32 0x000055e801f04e80 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x3a89e80)
#33 0x000055e80030647b clang_main(int, char**) (/home/nathan/tmp/tmp.gmGKPVYoUk/install/llvm/2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a/bin/clang-16+0x1e8b47b)
#34 0x00007f6e6dc082d0 (/usr/lib/libc.so.6+0x232d0)
#35 0x00007f6e6dc0838a __libc_start_main (/usr/lib/libc.so.6+0x2338a)
#36 0x000055e8003039e5 _start /build/glibc/src/glibc/csu/../sysdeps/x86_64/start.S:117:0
clang-16: error: clang frontend command failed with exit code 134 (use -v to see invocation)
ClangBuiltLinux clang version 16.0.0 (https://github.com/llvm/llvm-project 2cb9e1ac422f46de0ab728c6c9d50ebafbfe372a)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: ...
clang-16: note: diagnostic msg: Error generating preprocessed source(s) - no preprocessable inputs.

The parent commit is fine.

[StephenTozer]

Looks like a fairly trivial fix - the assert in question is erroneous, and will potentially be triggered by any DBG_VALUE_LIST that contains duplicate register entries. I'll make the change, do another round of local testing, and then resubmit the patch.

llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h

 
 public:
   VLocTracker(const OverlapMap &O, const DIExpression *EmptyExpr)
       : OverlappingFragments(O), EmptyProperties(EmptyExpr, false, false) {}
 
   void defVar(const MachineInstr &MI, const DbgValueProperties &Properties,
               const SmallVectorImpl<DbgOpID> &DebugOps) {
     assert(MI.isDebugValue() || MI.isDebugRef());
-    assert(DebugOps.size() <= 1);
     DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
                       MI.getDebugLoc()->getInlinedAt());
     DbgValue Rec = (DebugOps.size() > 0)
                        ? DbgValue(DebugOps, Properties)
                        : DbgValue(Properties, DbgValue::Undef);
 
     // Attempt insertion; overwrite if it's already mapped.
     auto Result = Vars.insert(std::make_pair(Var, Rec));

llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp

bool InstrRefBasedLDV::transferDebugValue(const MachineInstr &MI) {
   DbgValueProperties Properties(MI);
 
   // If there are no instructions in this lexical scope, do no location tracking
   // at all, this variable shouldn't get a legitimate location range.
   auto *Scope = LS.findLexicalScope(MI.getDebugLoc().get());
   if (Scope == nullptr)
     return true; // handled it; by doing nothing
 
-  // For now, ignore DBG_VALUE_LISTs when extending ranges. Allow it to
-  // contribute to locations in this block, but don't propagate further.
-  // Interpret it like a DBG_VALUE $noreg.
-  if (MI.isDebugValueList()) {
-    SmallVector<DbgOpID> EmptyDebugOps;
-    SmallVector<ResolvedDbgOp> EmptyResolvedDebugOps;
-    if (VTracker)
-      VTracker->defVar(MI, Properties, EmptyDebugOps);
-    if (TTracker)
-      TTracker->redefVar(MI, Properties, EmptyResolvedDebugOps);
-    return true;
-  }
-
   // MLocTracker needs to know that this register is read, even if it's only
   // read by a debug inst.
   for (const MachineOperand &MO : MI.debug_operands())
     if (MO.isReg() && MO.getReg() != 0)
       (void)MTracker->readReg(MO.getReg());
 
   // If we're preparing for the second analysis (variables), the machine value
   // locations are already solved, and we report this DBG_VALUE and the value

llvm/test/DebugInfo/MIR/X86/live-debug-values-fragments.mir

 #
 # The third function checks that DBG_VALUEs without fragments are seen as
 # overlapping any DBG_VALUE with a fragment.
 #
 # CHECK-LABEL: foo
 # CHECK-LABEL: bb.3.bb3:
 # CHECK:      DBG_VALUE $ecx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 0, 32)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}}, 
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 32)
+# CHECK-SAME:                 $ecx, $r8d
 # CHECK-NEXT: DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 32, 32)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}}, 
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 32, 32)
+# CHECK-SAME:                 $ebx, $r10d
 # CHECK-NEXT: XOR32rr
 # CHECK-NEXT: RET64
 #
 # CHECK-LABEL: bar
 # CHECK-LABEL: bb.0.entry:
 # CHECK:      DBG_VALUE $cx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 0, 16)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}}, 
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 16)
+# CHECK-SAME:                 $cx, $r8w
 
 # CHECK-LABEL: bb.1.bb1:
 # CHECK:      DBG_VALUE $cx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 0, 16)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 16)
+# CHECK-SAME:                 $cx, $r8w
+# CHECK-NEXT: MOV32rr
 # CHECK-NEXT: MOV32rr
 # CHECK-NEXT: DBG_VALUE $ax, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 8, 16)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 8, 16)
+# CHECK-SAME:                 $ax, $r9w
 # CHECK-NEXT: JMP_1
 
 # CHECK-LABEL: bb.2.bb2:
 # CHECK-NOT:  DBG_VALUE
+# CHECK-NOT:  DBG_VALUE_LIST
 # CHECK:      DBG_VALUE $cx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 8, 16)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 8, 16)
+# CHECK-SAME:                 $cx, $r8w
+# CHECK-NEXT: MOV32rr
+# CHECK-NEXT: ADD32ri8
 # CHECK-NEXT: MOV32rr
 # CHECK-NEXT: ADD32ri8
 # CHECK-NEXT: DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 32, 32)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 32, 32)
+# CHECK-SAME:                 $ebx, $r10d
 # CHECK-NEXT: JMP_1
 
 # CHECK-LABEL: bb.3.bb3:
 # CHECK:      DBG_VALUE $cx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 8, 16)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 8, 16)
+# CHECK-SAME:                 $cx, $r8w
 # CHECK-NEXT: DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 32, 32)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 32, 32)
+# CHECK-SAME:                 $ebx, $r10d
 # CHECK-NEXT: XOR32rr
 # CHECK-NEXT: RET64
 
 # CHECK-LABEL: baz
 # CHECK-LABEL: bb.0.entry:
 # CHECK:      DBG_VALUE $cx,  $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 0, 16)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 16)
+# CHECK-SAME:                 $cx, $r8w
 # CHECK-NEXT: JMP_1 %bb.1
 #
 # CHECK-LABEL: bb.1.bb1:
 # CHECK:      DBG_VALUE $cx,  $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 0, 16)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 16)
+# CHECK-SAME:                 $cx, $r8w
+# CHECK-NEXT: MOV32rr
 # CHECK-NEXT: MOV32rr
 # CHECK-NEXT: DBG_VALUE $rdi, $noreg, !{{[0-9]+}}, !DIExpression()
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}}, !DIExpression({{[^)]+}}), $rdi, $rdi
 # CHECK-NEXT: JMP_1 %bb.2
 #
 # CHECK-LABEL: bb.2.bb2:
 # CHECK-NOT:  DBG_VALUE $cx
+# CHECK-NOT:  DBG_VALUE_LIST {{.+}}, $cx
 # CHECK:      DBG_VALUE $rdi, $noreg, !{{[0-9]+}}, !DIExpression()
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}}, !DIExpression({{[^)]+}}), $rdi, $rdi
+# CHECK-NEXT: MOV32rr
+# CHECK-NEXT: ADD32ri8
 # CHECK-NEXT: MOV32rr
 # CHECK-NEXT: ADD32ri8
 # CHECK-NEXT: DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 32, 32)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 32, 32)
+# CHECK-SAME:                 $ebx, $r10d
 # CHECK-NEXT: JMP_1 %bb.3
 #
 # CHECK-LABEL: bb.3.bb3:
 # CHECK-NOT:  DBG_VALUE $rdi
 # CHECK-NOT:  DBG_VALUE $cx
+# CHECK-NOT:  DBG_VALUE_LIST {{.+}}, $rdi
+# CHECK-NOT:  DBG_VALUE_LIST {{.+}}, $cx
 # CHECK:      DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
 # CHECK-SAME:                 !DIExpression(DW_OP_LLVM_fragment, 32, 32)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME:                 !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 32, 32)
+# CHECK-SAME:                 $ebx, $r10d
 # CHECK-NEXT: XOR32rr
 # CHECK-NEXT: RET64
 
 --- |
   target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
   target triple = "x86_64-unknown-linux-gnu"
   
   define i32 @foo(i32* %bees, i32* %output) !dbg !4 {
--- |
   !llvm.dbg.cu = !{!1}
   
   !100 = !{i32 2, !"Dwarf Version", i32 4}
   !0 = !{i32 2, !"Debug Info Version", i32 3}
   !1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, producer: "beards", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
   !2 = !DIFile(filename: "bees.cpp", directory: ".")
   !3 = !DILocalVariable(name: "flannel", scope: !4, file: !2, line: 1, type: !16)
   !4 = distinct !DISubprogram(name: "nope", scope: !2, file: !2, line: 1, spFlags: DISPFlagDefinition, unit: !1, retainedNodes: !13, type: !14, isDefinition: true)
+  !5 = !DILocalVariable(name: "panel", scope: !4, file: !2, line: 1, type: !16)
   !8 = !DILocation(line: 4, scope: !4)
-  !13 = !{!3}
+  !13 = !{!3, !5}
   !14 = !DISubroutineType(types: !15)
   !15 = !{!16}
   !16 = !DIBasicType(name: "looong", size: 64, align: 64, encoding: DW_ATE_signed)
   !40 = distinct !DISubprogram(name: "toast", scope: !2, file: !2, line: 1, spFlags: DISPFlagDefinition, unit: !1, retainedNodes: !53, type: !14, isDefinition: true)
   !43 = !DILocalVariable(name: "charm", scope: !40, file: !2, line: 1, type: !16)
+  !44 = !DILocalVariable(name: "calm", scope: !40, file: !2, line: 1, type: !16)
   !48 = !DILocation(line: 4, scope: !40)
-  !53 = !{!43}
+  !53 = !{!43, !44}
   !80 = distinct !DISubprogram(name: "mort", scope: !2, file: !2, line: 1, spFlags: DISPFlagDefinition, unit: !1, retainedNodes: !93, type: !14, isDefinition: true)
+  !81 = distinct !DISubprogram(name: "floor", scope: !2, file: !2, line: 1, spFlags: DISPFlagDefinition, unit: !1, retainedNodes: !93, type: !14, isDefinition: true)
   !83 = !DILocalVariable(name: "bodkin", scope: !80, file: !2, line: 1, type: !16)
+  !84 = !DILocalVariable(name: "goblin", scope: !80, file: !2, line: 1, type: !16)
   !88 = !DILocation(line: 4, scope: !80)
-  !93 = !{!83}
+  !93 = !{!83, !84}
 
 ...
 ---
 name:            foo
 tracksRegLiveness: true
 registers:       []
 liveins:         
   - { reg: '$rdi', virtual-reg: '' }
 body:             |
   bb.0.entry:
     successors: %bb.1
     liveins: $rdi
   
     $ecx = XOR32rr undef $ecx, undef $ecx, implicit-def $eflags
+    $r8d = XOR32rr undef $r8d, undef $r8d, implicit-def $eflags
     JMP_1 %bb.1
   
   bb.1.bb1 (align 4):
     successors: %bb.2
-    liveins: $ecx, $rdi
+    liveins: $ecx, $edx, $rdi, $r8d
   
     $eax = MOV32rr killed $ecx, implicit-def $rax
+    $r9d = MOV32rr killed $r8d, implicit-def $r9
     DBG_VALUE $eax, $noreg, !3, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !8
+    DBG_VALUE_LIST !5, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_LLVM_fragment, 0, 32), $eax, $r9d, debug-location !8
     JMP_1 %bb.2
   
   bb.2.bb2:
     successors: %bb.3
-    liveins: $eax
+    liveins: $eax, $r9d
   
     $ebx = MOV32rr $eax
     $ebx = ADD32ri8 $ebx, 3, implicit-def dead $eflags, implicit killed $rbx, implicit-def $rbx
+    $r10d = MOV32rr $r9d
+    $r10d = ADD32ri8 $r10d, 3, implicit-def dead $eflags, implicit killed $rbx, implicit-def $rbx
     DBG_VALUE $ebx, $noreg, !3, !DIExpression(DW_OP_LLVM_fragment, 32, 32), debug-location !8
+    DBG_VALUE_LIST !5, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_LLVM_fragment, 32, 32), $ebx, $r10d, debug-location !8
     JMP_1 %bb.3
 
   bb.3.bb3:
-    liveins: $eax, $ebx
+    liveins: $eax, $ebx, $r9d, $r10d
     $eax = XOR32rr killed $eax, killed $ebx, implicit-def $eflags
     RET64 $eax, debug-location !8
 
 ...
 ---
 name:            bar
 tracksRegLiveness: true
 registers:       []
 liveins:         
   - { reg: '$rdi', virtual-reg: '' }
 body:             |
   bb.0.entry:
     successors: %bb.1
     liveins: $rdi
   
     $ecx = XOR32rr undef $ecx, undef $ecx, implicit-def $eflags
+    $r8d = XOR32rr undef $r8d, undef $r8d, implicit-def $eflags
     DBG_VALUE $cx, $noreg, !43, !DIExpression(DW_OP_LLVM_fragment, 0, 16), debug-location !48
+    DBG_VALUE_LIST !44, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_LLVM_fragment, 0, 16), $cx, $r8w, debug-location !48
     JMP_1 %bb.1
   
   bb.1.bb1:
     successors: %bb.2
-    liveins: $ecx, $rdi
+    liveins: $ecx, $r8d, $rdi
   
     $eax = MOV32rr killed $ecx, implicit-def $rax
+    $r9d = MOV32rr killed $r8d, implicit-def $rax
     DBG_VALUE $ax, $noreg, !43, !DIExpression(DW_OP_LLVM_fragment, 8, 16), debug-location !48
+    DBG_VALUE_LIST !44, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_LLVM_fragment, 8, 16), $ax, $r9w, debug-location !48
     JMP_1 %bb.2
   
   bb.2.bb2:
     successors: %bb.3
-    liveins: $eax
+    liveins: $eax, $r9d
   
     $ebx = MOV32rr $eax
     $ebx = ADD32ri8 $ebx, 3, implicit-def dead $eflags, implicit killed $rbx, implicit-def $rbx
+    $r10d = MOV32rr $r9d
+    $r10d = ADD32ri8 $r10d, 3, implicit-def dead $eflags, implicit killed $rbx, implicit-def $rbx
     DBG_VALUE $ebx, $noreg, !43, !DIExpression(DW_OP_LLVM_fragment, 32, 32), debug-location !48
+    DBG_VALUE_LIST !44, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_LLVM_fragment, 32, 32), $ebx, $r10d, debug-location !48
     JMP_1 %bb.3
 
   bb.3.bb3:
-    liveins: $eax, $ebx
+    liveins: $eax, $ebx, $r9d, $r10d
     $eax = XOR32rr killed $eax, killed $ebx, implicit-def $eflags
     RET64 $eax, debug-location !48
 
 ...
 ---
 name:            baz
 tracksRegLiveness: true
 registers:       []
 liveins:         
   - { reg: '$rdi', virtual-reg: '' }
 body:             |
   bb.0.entry:
     successors: %bb.1
     liveins: $rdi
   
     $ecx = XOR32rr undef $ecx, undef $ecx, implicit-def $eflags
+    $r8d = XOR32rr undef $r8d, undef $r8d, implicit-def $eflags
     DBG_VALUE $cx, $noreg, !83, !DIExpression(DW_OP_LLVM_fragment, 0, 16), debug-location !88
+    DBG_VALUE_LIST !84, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_LLVM_fragment, 0, 16), $cx, $r8w, debug-location !88
     JMP_1 %bb.1
   
   bb.1.bb1:
     successors: %bb.2
-    liveins: $ecx, $rdi
+    liveins: $ecx, $r8d, $rdi
   
     $eax = MOV32rr killed $ecx, implicit-def $rax
+    $r9d = MOV32rr killed $r8d, implicit-def $r9
     DBG_VALUE $rdi, $noreg, !83, !DIExpression(), debug-location !88
+    DBG_VALUE_LIST !84, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), $rdi, $rdi, debug-location !88
     JMP_1 %bb.2
   
   bb.2.bb2:
     successors: %bb.3
-    liveins: $eax
+    liveins: $eax, $r9d
   
     $ebx = MOV32rr $eax
     $ebx = ADD32ri8 $ebx, 3, implicit-def dead $eflags, implicit killed $rbx, implicit-def $rbx
+    $r10d = MOV32rr $r9d
+    $r10d = ADD32ri8 $r10d, 3, implicit-def dead $eflags, implicit killed $r10, implicit-def $r10
     DBG_VALUE $ebx, $noreg, !83, !DIExpression(DW_OP_LLVM_fragment, 32, 32), debug-location !88
+    DBG_VALUE_LIST !84, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_LLVM_fragment, 32, 32), $ebx, $r10d, debug-location !88
     JMP_1 %bb.3
 
   bb.3.bb3:
     liveins: $eax, $ebx
     $eax = XOR32rr killed $eax, killed $ebx, implicit-def $eflags
     RET64 $eax, debug-location !88
 
 ...

llvm/test/DebugInfo/MIR/X86/live-debug-values-reg-copy.mir

 # RUN: llc -run-pass=livedebugvalues %s -o - | FileCheck %s
 #
 # This test tests tracking variables value transferring from one register to another.
 # This example is altered additionally in order to test transferring from one float register
 # to another. The altered instructions are labeled below.
 #
 # CHECK: ![[ARG1:.*]] = !DILocalVariable(name: "arg1"
+# CHECK: ![[VAR1:.*]] = !DILocalVariable(name: "var1"
 # CHECK: DBG_VALUE $ebx, $noreg, ![[ARG1]], !DIExpression(), debug-location
+# CHECK: DBG_VALUE_LIST ![[VAR1]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), $ebx, $r13d
 # CHECK: $r12d = MOV32rr killed $ebx, implicit-def $r12
+# CHECK-NEXT: DBG_VALUE_LIST !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), $r12d, $r13d
 # CHECK-NEXT: DBG_VALUE $r12d, $noreg, ![[ARG1]], !DIExpression(), debug-location
+# CHECK: $r10d = MOV32rr killed $r13d, implicit-def $r10
+# CHECK-NEXT: DBG_VALUE_LIST !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), $r12d, $r10d
 --- |
   ; ModuleID = 'live-debug-values-reg-copy.ll'
   source_filename = "live-debug-values-reg-copy.c"
   target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
   target triple = "x86_64-unknown-linux-gnu"
 
   define dso_local i32 @foo(i32 %arg1) local_unnamed_addr !dbg !7 {
   entry:
--- |
   !3 = !{i32 2, !"Dwarf Version", i32 4}
   !4 = !{i32 2, !"Debug Info Version", i32 3}
   !5 = !{i32 1, !"wchar_size", i32 4}
   !6 = !{!"clang version 7.0.0 "}
   !7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 6, type: !8, isLocal: false, isDefinition: true, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !11)
   !8 = !DISubroutineType(types: !9)
   !9 = !{!10, !10}
   !10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-  !11 = !{!12}
+  !11 = !{!12, !13}
   !12 = !DILocalVariable(name: "arg1", arg: 1, scope: !7, file: !1, line: 6, type: !10)
+  !13 = !DILocalVariable(name: "var1", arg: 1, scope: !7, file: !1, line: 6, type: !10)
   !15 = !DILocation(line: 6, column: 13, scope: !7)
   !20 = !{!21, !21, i64 0}
   !21 = !{!"int", !22, i64 0}
   !22 = !{!"omnipotent char", !23, i64 0}
   !23 = !{!"Simple C/C++ TBAA"}
 
 ...
 ---
 name:            foo
 alignment:       16
 exposesReturnsTwice: false
 legalized:       false
 regBankSelected: false
 selected:        false
 tracksRegLiveness: true
 registers:
 liveins:
   - { reg: '$edi', virtual-reg: '' }
+  - { reg: '$r8d', virtual-reg: '' }
 frameInfo:
   isFrameAddressTaken: false
   isReturnAddressTaken: false
   hasStackMap:     false
   hasPatchPoint:   false
-  stackSize:       40
-  offsetAdjustment: -40
+  stackSize:       48
+  offsetAdjustment: -48
   maxAlignment:    4
   adjustsStack:    true
   hasCalls:        true
   stackProtector:  ''
   maxCallFrameSize: 0
   hasOpaqueSPAdjustment: false
   hasVAStart:      false
   hasMustTailInVarArgFunc: false
   savePoint:       ''
   restorePoint:    ''
 fixedStack:
-  - { id: 0, type: spill-slot, offset: -32, size: 8, alignment: 16, stack-id: default,
+  - { id: 0, type: spill-slot, offset: -48, size: 8, alignment: 16, stack-id: default,
       callee-saved-register: '$rbx', callee-saved-restored: true }
-  - { id: 1, type: spill-slot, offset: -24, size: 8, alignment: 8, stack-id: default,
+  - { id: 1, type: spill-slot, offset: -40, size: 8, alignment: 8, stack-id: default,
       callee-saved-register: '$r12', callee-saved-restored: true }
-  - { id: 2, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
+  - { id: 2, type: spill-slot, offset: -32, size: 8, alignment: 16, stack-id: default,
       callee-saved-register: '$rbp', callee-saved-restored: true }
+  - { id: 3, type: spill-slot, offset: -24, size: 8, alignment: 16, stack-id: default,
+      callee-saved-register: '$r13', callee-saved-restored: true }
+  - { id: 4, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
+      callee-saved-register: '$r10', callee-saved-restored: true }
 stack:
   - { id: 0, name: local1, type: default, offset: -36, size: 4, alignment: 4,
       stack-id: default, callee-saved-register: '', callee-saved-restored: true,
       debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
 constants:
 body:             |
   bb.0.entry:
     successors: %bb.1(0x40000000), %bb.2(0x40000000)
-    liveins: $edi, $rbp, $r12, $rbx
+    liveins: $edi, $rbp, $r8, $r10, $r13, $r12, $rbx
 
     DBG_VALUE $edi, $noreg, !12, !DIExpression(), debug-location !15
-    frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
+    DBG_VALUE_LIST !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), $edi, $r8d, debug-location !15
+    frame-setup PUSH64r killed $r10, implicit-def $rsp, implicit $rsp
     CFI_INSTRUCTION def_cfa_offset 16
-    frame-setup PUSH64r killed $r12, implicit-def $rsp, implicit $rsp
+    frame-setup PUSH64r killed $r13, implicit-def $rsp, implicit $rsp
     CFI_INSTRUCTION def_cfa_offset 24
-    frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp
+    frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
     CFI_INSTRUCTION def_cfa_offset 32
-    $rsp = frame-setup SUB64ri8 $rsp, 16, implicit-def dead $eflags
+    frame-setup PUSH64r killed $r12, implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 40
+    frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp
     CFI_INSTRUCTION def_cfa_offset 48
-    CFI_INSTRUCTION offset $rbx, -32
-    CFI_INSTRUCTION offset $r12, -24
-    CFI_INSTRUCTION offset $rbp, -16
+    $rsp = frame-setup SUB64ri8 $rsp, 16, implicit-def dead $eflags
+    CFI_INSTRUCTION def_cfa_offset 56
+    CFI_INSTRUCTION offset $rbx, -48
+    CFI_INSTRUCTION offset $rbx, -40
+    CFI_INSTRUCTION offset $r12, -32
+    CFI_INSTRUCTION offset $rbp, -24
+    CFI_INSTRUCTION offset $r13,  -16
     renamable $ebx = COPY $edi, implicit-def $rbx
+    renamable $r13d = COPY $r8d, implicit-def $r13
     DBG_VALUE $ebx, $noreg, !12, !DIExpression(), debug-location !15
+    DBG_VALUE_LIST !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), $ebx, $r13d, debug-location !15
     renamable $rdi = LEA64r $rsp, 1, $noreg, 12, $noreg
+    renamable $r8 = LEA64r $rsp, 1, $noreg, 12, $noreg
     CALL64pcrel32 @init, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, debug-location !15
     renamable $edi = MOV32rm $rsp, 1, $noreg, 12, $noreg :: (dereferenceable load (s32) from %ir.local1, !tbaa !20)
     renamable $edi = ADD32rr killed renamable $edi, renamable $ebx, implicit-def dead $eflags, debug-location !15
-    CALL64pcrel32 @coeficient, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !15
+    renamable $r8d = MOV32rm $rsp, 1, $noreg, 12, $noreg :: (dereferenceable load (s32) from %ir.local1, !tbaa !20)
+    renamable $r8d = ADD32rr killed renamable $r8d, renamable $r13d, implicit-def dead $eflags, debug-location !15
+    CALL64pcrel32 @coeficient, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit $r8d, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !15
     renamable $ebp = COPY $eax, debug-location !15
     CMP32ri8 $eax, 33, implicit-def $eflags, debug-location !15
     JCC_1 %bb.2, 12, implicit killed $eflags, debug-location !15
     JMP_1 %bb.1, debug-location !15
 
   bb.1.if.then:
     successors: %bb.3(0x80000000)
-    liveins: $ebp, $rbx
+    liveins: $ebp, $rbx, $r13
 
     $edi = COPY renamable $ebx, debug-location !15
+    $r8d = COPY renamable $r13d, debug-location !15
     CALL64pcrel32 @externFunc, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !15
     renamable $eax = KILL $eax, implicit-def $rax, debug-location !15
     renamable $eax = nsw ADD32rm renamable $eax, $rsp, 1, $noreg, 12, $noreg, implicit-def dead $eflags, implicit killed $rax, implicit-def $rax, debug-location !15 :: (dereferenceable load (s32) from %ir.local1, !tbaa !20)
     JMP_1 %bb.3, debug-location !15
 
   bb.2.if.else:
     successors: %bb.3(0x80000000)
-    liveins: $ebp, $rbx
+    liveins: $ebp, $r13, $rbx
 
     $edi = COPY renamable $ebx, debug-location !15
+    $r8d = COPY renamable $r13d, debug-location !15
     CALL64pcrel32 @externFunc2, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !15
     renamable $eax = KILL $eax, implicit-def $rax, debug-location !15
     renamable $eax = nsw ADD32rm renamable $eax, $rsp, 1, $noreg, 12, $noreg, implicit-def dead $eflags, implicit killed $rax, implicit-def $rax, debug-location !15 :: (dereferenceable load (s32) from %ir.local1, !tbaa !20)
 
   bb.3.if.end:
-    liveins: $ebp, $rax, $rbx, $r12
+    liveins: $ebp, $rax, $rbx, $r13, $r12, $r10
     ; Instruction below is added in order to test moving variable's value from one register to another.
     $r12d = MOV32rr killed $ebx, implicit-def $r12
+    $r10d = MOV32rr killed $r13d, implicit-def $r10
     renamable $eax = nsw LEA64_32r killed renamable $rax, 4, killed renamable $rbx, 0, $noreg, debug-location !15
     renamable $eax = nsw IMUL32rr killed renamable $eax, killed renamable $ebp, implicit-def dead $eflags, debug-location !15
     $rsp = frame-destroy ADD64ri8 $rsp, 16, implicit-def dead $eflags, debug-location !15
-    CFI_INSTRUCTION def_cfa_offset 32, debug-location !15
+    CFI_INSTRUCTION def_cfa_offset 48, debug-location !15
     $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !15
-    CFI_INSTRUCTION def_cfa_offset 24, debug-location !15
+    CFI_INSTRUCTION def_cfa_offset 40, debug-location !15
     $r12 = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !15
-    CFI_INSTRUCTION def_cfa_offset 16, debug-location !15
+    CFI_INSTRUCTION def_cfa_offset 32, debug-location !15
     $rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !15
+    CFI_INSTRUCTION def_cfa_offset 24, debug-location !15
+    $r13 = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !15
+    CFI_INSTRUCTION def_cfa_offset 16, debug-location !15
+    $r13 = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !15
     CFI_INSTRUCTION def_cfa_offset 8, debug-location !15
     RET 0, $eax, debug-location !15
 
 ...

llvm/test/DebugInfo/MIR/X86/live-debug-values-restore.mir

 # RUN: llc -run-pass livedebugvalues -march=x86-64 -o - %s \
 # RUN:  -experimental-debug-variable-locations=true | FileCheck %s
 
 # Generated from the following source with:
 # clang -g -mllvm -stop-before=livedebugvalues -S -O2 test.c -o test.mir
 # Then more functions added to test for extra behaviours with complex
 # expressions:
 #   'g': test for a crash from PR42773
 #   'h': complex expressions should be restored
 #   'i': spills should be restored across block boundaries
 #   'j': indirect DBG_VALUEs should be indirect after restoration
+#   'k': variadic debug values should be restored
 
 # #define FORCE_SPILL() \
 #   __asm volatile("" : : : \
 #                    "rax", "rbx", "rcx", "rdx", "rsi", "rdi", "rbp", "r8", \
 #                    "r9", "r10", "r11", "r12", "r13", "r14", "r15")
 # int f(int *p) {
 #   if (p) {
 #     FORCE_SPILL();
 #   }
 #   return *(p + 1);
 # }
 
 # Pick out DILocalVariable numbers for "p", "q" and "r" etc
 # CHECK: ![[PVAR:[0-9]+]] = !DILocalVariable(name: "p",
 # CHECK: ![[QVAR:[0-9]+]] = !DILocalVariable(name: "q",
 # CHECK: ![[RVAR:[0-9]+]] = !DILocalVariable(name: "r",
 # CHECK: ![[SVAR:[0-9]+]] = !DILocalVariable(name: "s",
 # CHECK: ![[TVAR:[0-9]+]] = !DILocalVariable(name: "t",
+# CHECK: ![[UVAR:[0-9]+]] = !DILocalVariable(name: "u",
 
 # Ascertain that the spill has been recognized and manifested in a DBG_VALUE.
 # CHECK: MOV64mr $rsp,{{.*-8.*}}killed{{.*}}$rdi :: (store (s64) into %stack.0)
 # CHECK-NEXT: DBG_VALUE $rsp,{{.*}}![[PVAR]],{{.*}}!DIExpression(DW_OP_constu, 8, DW_OP_minus)
 
 # Check for the restore.
 # CHECK: $rdi = MOV64rm $rsp,{{.*-8.*}}:: (load (s64) from %stack.0)
 # CHECK-NEXT: $rax = MOV64ri 0
if.then:                                          ; preds = %entry
     tail call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"(), !dbg !409, !srcloc !411
     br label %if.end, !dbg !412
   
   if.end:                                           ; preds = %entry, %if.then
     %add.ptr = getelementptr inbounds i32, i32* %p, i64 1, !dbg !413
     %0 = load i32, i32* %add.ptr, align 4, !dbg !414, !tbaa !24
     ret i32 %0, !dbg !415
   }
  
+  define dso_local i32 @k(i32* readonly %p) local_unnamed_addr !dbg !507 {
+  entry:
+    call void @llvm.dbg.value(metadata i32* %p, metadata !513, metadata !DIExpression()), !dbg !514
+    %tobool = icmp eq i32* %p, null, !dbg !515
+    br i1 %tobool, label %if.end, label %if.then, !dbg !517
+  
+  if.then:                                          ; preds = %entry
+    tail call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"(), !dbg !518, !srcloc !520
+    br label %if.end, !dbg !521
+  
+  if.end:                                           ; preds = %entry, %if.then
+    %add.ptr = getelementptr inbounds i32, i32* %p, i64 1, !dbg !522
+    %0 = load i32, i32* %add.ptr, align 4, !dbg !523, !tbaa !24
+    ret i32 %0, !dbg !528
+  }
+
   declare void @llvm.dbg.value(metadata, metadata, metadata)
   
   !llvm.dbg.cu = !{!0}
   !llvm.module.flags = !{!3, !4, !5}
   !llvm.ident = !{!6}
   
   !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 9.0.0 (https://git.llvm.org/git/clang.git/ 57a6ce7ac318de98e3e777e09cb9ed8282b5cc03) (https://git.llvm.org/git/llvm.git/ ff54a19e4912d7f15cb02798a7f2048441bff751)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
   !1 = !DIFile(filename: "test2.c", directory: "/home/test")
--- |
   !21 = !DILocation(line: 8, column: 3, scope: !19)
   !22 = !DILocation(line: 9, column: 14, scope: !7)
   !23 = !DILocation(line: 9, column: 10, scope: !7)
   !24 = !{!25, !25, i64 0}
   !25 = !{!"int", !26, i64 0}
   !26 = !{!"omnipotent char", !27, i64 0}
   !27 = !{!"Simple C/C++ TBAA"}
   !28 = !DILocation(line: 9, column: 3, scope: !7)
+  !29 = !DILocalVariable(name: "p0", scope: !7, file: !1, line: 5, type: !11)
   !101 = !DIBasicType(name: "looong int", size: 64, encoding: DW_ATE_signed)
   !107 = distinct !DISubprogram(name: "g", scope: !0, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !112)
   !112 = !{!113}
   !113 = !DILocalVariable(name: "q", arg: 1, scope: !107, file: !1, line: 105, type: !101)
   !114 = !DILocation(line: 105, column: 12, scope: !107)
   !115 = !DILocation(line: 106, column: 7, scope: !116)
   !116 = distinct !DILexicalBlock(scope: !107, file: !1, line: 106, column: 7)
   !117 = !DILocation(line: 106, column: 7, scope: !107)
--- |
   !408 = !DILocation(line: 106, column: 7, scope: !402)
   !409 = !DILocation(line: 107, column: 5, scope: !410)
   !410 = distinct !DILexicalBlock(scope: !407, file: !1, line: 106, column: 10)
   !411 = !{i32 -2147471544}
   !412 = !DILocation(line: 108, column: 3, scope: !410)
   !413 = !DILocation(line: 109, column: 14, scope: !402)
   !414 = !DILocation(line: 109, column: 10, scope: !402)
   !415 = !DILocation(line: 109, column: 3, scope: !402)
+  !501 = !DIBasicType(name: "looong int", size: 64, encoding: DW_ATE_signed)
+  !507 = distinct !DISubprogram(name: "k", scope: !0, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !512)
+  !512 = !{!513}
+  !513 = !DILocalVariable(name: "u", arg: 1, scope: !507, file: !1, line: 105, type: !501)
+  !514 = !DILocation(line: 105, column: 12, scope: !507)
+  !515 = !DILocation(line: 106, column: 7, scope: !516)
+  !516 = distinct !DILexicalBlock(scope: !507, file: !1, line: 106, column: 7)
+  !517 = !DILocation(line: 106, column: 7, scope: !507)
+  !518 = !DILocation(line: 107, column: 5, scope: !519)
+  !519 = distinct !DILexicalBlock(scope: !516, file: !1, line: 106, column: 10)
+  !520 = !{i32 -2147471544}
+  !521 = !DILocation(line: 108, column: 3, scope: !519)
+  !522 = !DILocation(line: 109, column: 14, scope: !507)
+  !523 = !DILocation(line: 109, column: 10, scope: !507)
+  !528 = !DILocation(line: 109, column: 3, scope: !507)
+
 ...
 ---
 name:            f
 alignment:       16
 exposesReturnsTwice: false
 legalized:       false
 regBankSelected: false
 selected:        false
body:             |
   
   bb.2.if.end:
     liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
   
     renamable $eax = MOV32rm killed renamable $rdi, 1, $noreg, 4, $noreg, debug-location !414 :: (load (s32) from %ir.add.ptr, !tbaa !24)
     RET64 $eax, debug-location !415
 
 ...
+---
+# Test that if the values used by a variable with a variadic debug value are
+# spilt and restored, we correctly track each value individually.
+# This third function tests that complex expressions are spilt, and restored
+# correctly within a basic block.
+
+# CHECK-LABEL: name: k
+# CHECK-LABEL: bb.0.entry:
+# CHECK:       DBG_VALUE_LIST ![[UVAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_plus), $rdi, $r10
+# CHECK-LABEL: bb.1.if.then:
+# CHECK:       DBG_VALUE_LIST ![[UVAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_plus), $rdi, $r10
+# CHECK:       DBG_VALUE_LIST ![[UVAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_plus), $rsp, $r10
+# CHECK:       DBG_VALUE_LIST ![[UVAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_constu, 16, DW_OP_minus, DW_OP_deref, DW_OP_plus), $rsp, $rsp
+# CHECK:       DBG_VALUE_LIST ![[UVAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_constu, 16, DW_OP_minus, DW_OP_deref, DW_OP_plus), $rdi, $rsp
+# CHECK:       DBG_VALUE_LIST ![[UVAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_plus), $rdi, $r10
+# CHECK-LABEL: bb.2.if.end:
+# CHECK:       DBG_VALUE_LIST ![[UVAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_plus), $rdi, $r10
+
+name:            k
+alignment:       16
+tracksRegLiveness: true
+liveins:         
+  - { reg: '$rdi', virtual-reg: '' }
+  - { reg: '$r10', virtual-reg: '' }
+frameInfo:       
+  stackSize:       48
+  offsetAdjustment: -48
+  maxAlignment:    8
+  cvBytesOfCalleeSavedRegisters: 48
+  localFrameSize:  0
+fixedStack:      
+  - { id: 0, type: spill-slot, offset: -56, size: 8, alignment: 8, stack-id: default,
+      callee-saved-register: '$rbx', callee-saved-restored: true, debug-info-variable: '', 
+      debug-info-expression: '', debug-info-location: '' }
+  - { id: 1, type: spill-slot, offset: -48, size: 8, alignment: 16, stack-id: default,
+      callee-saved-register: '$r12', callee-saved-restored: true, debug-info-variable: '', 
+      debug-info-expression: '', debug-info-location: '' }
+  - { id: 2, type: spill-slot, offset: -40, size: 8, alignment: 8, stack-id: default,
+      callee-saved-register: '$r13', callee-saved-restored: true, debug-info-variable: '', 
+      debug-info-expression: '', debug-info-location: '' }
+  - { id: 3, type: spill-slot, offset: -32, size: 8, alignment: 16, stack-id: default,
+      callee-saved-register: '$r14', callee-saved-restored: true, debug-info-variable: '', 
+      debug-info-expression: '', debug-info-location: '' }
+  - { id: 4, type: spill-slot, offset: -24, size: 8, alignment: 8, stack-id: default,
+      callee-saved-register: '$r15', callee-saved-restored: true, debug-info-variable: '', 
+      debug-info-expression: '', debug-info-location: '' }
+  - { id: 5, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
+      callee-saved-register: '$rbp', callee-saved-restored: true, debug-info-variable: '', 
+      debug-info-expression: '', debug-info-location: '' }
+stack:           
+  - { id: 0, name: '', type: spill-slot, offset: -64, size: 8, alignment: 8, 
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 1, name: '', type: spill-slot, offset: -72, size: 8, alignment: 8, 
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+constants:       []
+body:             |
+  bb.0.entry:
+    successors: %bb.2(0x30000000), %bb.1(0x50000000)
+    liveins: $rdi, $r10, $rbx, $r12, $r13, $r14, $r15, $rbp
+  
+    DBG_VALUE_LIST !513, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_LLVM_arg, 1, DW_OP_plus), $rdi, $r10, debug-location !514
+    TEST64rr renamable $rdi, renamable $rdi, implicit-def $eflags, debug-location !515
+    JCC_1 %bb.2, 4, implicit $eflags, debug-location !517
+  
+  bb.1.if.then:
+    successors: %bb.2(0x80000000)
+    liveins: $rdi, $r10, $rbp, $r15, $r14, $r13, $r12, $rbx
+  
+    frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 16
+    frame-setup PUSH64r killed $r15, implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 24
+    frame-setup PUSH64r killed $r14, implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 32
+    frame-setup PUSH64r killed $r13, implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 40
+    frame-setup PUSH64r killed $r12, implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 48
+    frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 56
+    CFI_INSTRUCTION offset $rbx, -56
+    CFI_INSTRUCTION offset $r12, -48
+    CFI_INSTRUCTION offset $r13, -40
+    CFI_INSTRUCTION offset $r14, -32
+    CFI_INSTRUCTION offset $r15, -24
+    CFI_INSTRUCTION offset $rbp, -16
+    MOV64mr $rsp, 1, $noreg, -8, $noreg, killed renamable $rdi :: (store (s64) into %stack.0)
+    MOV64mr $rsp, 1, $noreg, -16, $noreg, killed renamable $r10 :: (store (s64) into %stack.1)
+    INLINEASM &"", 1, 12, implicit-def dead early-clobber $rax, 12, implicit-def dead early-clobber $rbx, 12, implicit-def dead early-clobber $rcx, 12, implicit-def dead early-clobber $rdx, 12, implicit-def dead early-clobber $rsi, 12, implicit-def dead early-clobber $rdi, 12, implicit-def dead early-clobber $rbp, 12, implicit-def dead early-clobber $r8, 12, implicit-def dead early-clobber $r9, 12, implicit-def dead early-clobber $r10, 12, implicit-def dead early-clobber $r11, 12, implicit-def dead early-clobber $r12, 12, implicit-def dead early-clobber $r13, 12, implicit-def dead early-clobber $r14, 12, implicit-def dead early-clobber $r15, 12, implicit-def dead early-clobber $eflags, !520, debug-location !518
+    renamable $rdi = MOV64rm $rsp, 1, $noreg, -8, $noreg :: (load (s64) from %stack.0)
+    renamable $r10 = MOV64rm $rsp, 1, $noreg, -16, $noreg :: (load (s64) from %stack.1)
+    ; Clobber stack location to force variable location to move to $rdi.
+    $rax = MOV64ri 0
+    MOV64mr $rsp, 1, _, -8, _, renamable $rax :: (store (s64) into %stack.0)
+    MOV64mr $rsp, 1, _, -16, _, killed renamable $rax :: (store (s64) into %stack.1)
+    $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 48
+    $r12 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 40
+    $r13 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 32
+    $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 24
+    $r15 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 16
+    $rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    CFI_INSTRUCTION def_cfa_offset 8
+  
+  bb.2.if.end:
+    liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
+  
+    renamable $eax = MOV32rm killed renamable $rdi, 1, $noreg, 4, $noreg, debug-location !523 :: (load (s32) from %ir.add.ptr, !tbaa !24)
+    RET64 $eax, debug-location !528
+
+
+
+...

llvm/test/DebugInfo/MIR/X86/live-debug-values-stack-clobber.mir

 #   FORCE_SPILL();
 #   bees++;
 #   return quux;
 # }
 # -------->8--------
 #
 # CHECK:       ![[ANUM:[0-9]+]] = !DILocalVariable(name: "a"
 # CHECK:       ![[BNUM:[0-9]+]] = !DILocalVariable(name: "b"
+# CHECK:       ![[CNUM:[0-9]+]] = !DILocalVariable(name: "c"
 #
 # These variables should be spilt,
 # CHECK-LABEL: bb.1.if.end:
 # CHECK:       MOV64mr $rsp, 1, $noreg, 16, $noreg, killed renamable $rsi
+# CHECK-NEXT:  DBG_VALUE_LIST ![[CNUM]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 16, DW_OP_deref
+# CHECK-SAME:  $rsp, $rdi
 # CHECK-NEXT:  DBG_VALUE $rsp, 0, ![[BNUM]], !DIExpression(
 # CHECK-NEXT:  MOV64mr $rsp, 1, $noreg, 8, $noreg, killed renamable $rdi
+# CHECK-NEXT:  DBG_VALUE_LIST ![[CNUM]], !DIExpression({{[^)]+}}DW_OP_LLVM_arg, 1, DW_OP_plus_uconst, 8, DW_OP_deref
+# CHECK-SAME:  $rsp, $rsp
 # CHECK-NEXT:  DBG_VALUE $rsp, 0, ![[ANUM]], !DIExpression(
 # CHECK-NEXT:  INLINEASM
 #
 # Then the location of "a" should be terminated when overwritten
 # CHECK-LABEL: bb.3.if.end3:
 # CHECK:       CALL64pcrel32 @sum
 # CHECK-NEXT:  MOV64mr $rsp, 1, $noreg, 8, $noreg, $rax
+# CHECK-NEXT:  DBG_VALUE_LIST ![[CNUM]], !DIExpression({{[^)]*}}), $noreg, $noreg
 # CHECK-NEXT:  DBG_VALUE $noreg, $noreg, ![[ANUM]], !DIExpression()
 # CHECK-NEXT:  INLINEASM
 
 --- |
   target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
   target triple = "x86_64-unknown-linux-gnu"
   
   @bees = external global i32, !dbg !0
--- |
   !10 = !{i32 1, !"wchar_size", i32 4}
   !12 = distinct !DISubprogram(name: "f", scope: !3, file: !3, line: 15, type: !13, scopeLine: 15, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !16)
   !13 = !DISubroutineType(types: !14)
   !14 = !{!15, !15, !15}
   !15 = !DIBasicType(name: "long int", size: 64, encoding: DW_ATE_signed)
   !16 = !{!17, !18, !19}
   !17 = !DILocalVariable(name: "a", arg: 1, scope: !12, file: !3, line: 15, type: !15)
   !18 = !DILocalVariable(name: "b", arg: 2, scope: !12, file: !3, line: 15, type: !15)
-  !19 = !DILocalVariable(name: "quux", scope: !12, file: !3, line: 23, type: !7)
+  !19 = !DILocalVariable(name: "c", scope: !12, file: !3, line: 23, type: !7)
   !28 = !DILocation(line: 1, column: 1, scope: !12)
 
 ...
 ---
 name:            f
 tracksRegLiveness: true
 liveins:
   - { reg: '$rdi', virtual-reg: '' }
body:             |
   bb.0.entry:
     successors: %bb.4, %bb.1
     liveins: $rdi, $rsi, $rbp, $r15, $r14, $r13, $r12, $rbx
   
     DBG_VALUE $rdi, $noreg, !17, !DIExpression(), debug-location !28
     DBG_VALUE $rdi, $noreg, !17, !DIExpression(), debug-location !28
     DBG_VALUE $rsi, $noreg, !18, !DIExpression(), debug-location !28
     DBG_VALUE $rsi, $noreg, !18, !DIExpression(), debug-location !28
+    DBG_VALUE_LIST !19, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), $rsi, $rdi, debug-location !28
     frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp, debug-location !28
     frame-setup PUSH64r killed $r15, implicit-def $rsp, implicit $rsp, debug-location !28
     frame-setup PUSH64r killed $r14, implicit-def $rsp, implicit $rsp, debug-location !28
     frame-setup PUSH64r killed $r13, implicit-def $rsp, implicit $rsp, debug-location !28
     frame-setup PUSH64r killed $r12, implicit-def $rsp, implicit $rsp, debug-location !28
     frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp, debug-location !28
     $rsp = frame-setup SUB64ri8 $rsp, 24, implicit-def dead $eflags
     renamable $ecx = MOV32rm $rip, 1, $noreg, @bees, $noreg, debug-location !28 :: (volatile dereferenceable load (s32) from @bees)