[llvm] 79daafc - Reland: [DWARF] Allow cross-CU references of subprogram definitions

Vedant Kumar via llvm-commits llvm-commits at lists.llvm.org
Mon Jan 27 10:55:02 PST 2020


Thanks a lot for the reproducer, I was able to debug using the ld.lld driver on macOS. I found the issue: call site tags weren’t emitted correctly specifically in split-dwarf + LTO mode. I’ve added a reduced test (llvm/test/DebugInfo/X86/fission-call-site.ll) and relanded the patch in e08f205f. @Brian you may have encountered this issue earlier, please let me know if the updated version of the patch causes any problems.

vedant

> On Jan 27, 2020, at 6:19 AM, Hans Wennborg <hans at chromium.org> wrote:
> 
> Thanks for the revert. I don't know if you saw Nico's reply on the
> bug, but yes the reproducer should work on Darwin.
> 
> On Fri, Jan 24, 2020 at 6:10 PM Vedant Kumar <vedant_kumar at apple.com> wrote:
>> 
>> I think this is hitting null-assigned-to-a-reference UB, as before CalleeSP is passed to constructCallSiteEntryDIE, it must pass through getOrCreateSubprogramDIE which always returns non-null.
>> 
>> Can I use the reproducer on Darwin? I’ll try building lld and revert 79daafc90308787b52a5d3a7586e82acd5e374b3 for now.
>> 
>> To github.com:llvm/llvm-project.git
>>   0ebc8e6c421..802bec89617  master -> master
>> 
>> vedant
>> 
>>> On Jan 24, 2020, at 4:11 PM, Hans Wennborg <hans at chromium.org> wrote:
>>> 
>>> We're hitting an assert due to this again in Chromium, see
>>> https://bugs.chromium.org/p/chromium/issues/detail?id=1045592#c15 for
>>> a reproducer.
>>> Can you take a look?
>>> 
>>> On Fri, Dec 20, 2019 at 3:27 PM Vedant Kumar via llvm-commits
>>> <llvm-commits at lists.llvm.org> wrote:
>>>> 
>>>> 
>>>> Author: Vedant Kumar
>>>> Date: 2019-12-20T15:26:31-08:00
>>>> New Revision: 79daafc90308787b52a5d3a7586e82acd5e374b3
>>>> 
>>>> URL: https://github.com/llvm/llvm-project/commit/79daafc90308787b52a5d3a7586e82acd5e374b3
>>>> DIFF: https://github.com/llvm/llvm-project/commit/79daafc90308787b52a5d3a7586e82acd5e374b3.diff
>>>> 
>>>> LOG: Reland: [DWARF] Allow cross-CU references of subprogram definitions
>>>> 
>>>> This allows a call site tag in CU A to reference a callee DIE in CU B
>>>> without resorting to creating an incomplete duplicate DIE for the callee
>>>> inside of CU A.
>>>> 
>>>> We already allow cross-CU references of subprogram declarations, so it
>>>> doesn't seem like definitions ought to be special.
>>>> 
>>>> This improves entry value evaluation and tail call frame synthesis in
>>>> the LTO setting. During LTO, it's common for cross-module inlining to
>>>> produce a call in some CU A where the callee resides in a different CU,
>>>> and there is no declaration subprogram for the callee anywhere. In this
>>>> case llvm would (unnecessarily, I think) emit an empty DW_TAG_subprogram
>>>> in order to fill in the call site tag. That empty 'definition' defeats
>>>> entry value evaluation etc., because the debugger can't figure out what
>>>> it means.
>>>> 
>>>> As a follow-up, maybe we could add a DWARF verifier check that a
>>>> DW_TAG_subprogram at least has a DW_AT_name attribute.
>>>> 
>>>> Update:
>>>> 
>>>> Reland with a fix to create a declaration DIE when the declaration is
>>>> missing from the CU's retainedTypes list. The declaration is left out
>>>> of the retainedTypes list in two cases:
>>>> 
>>>> 1) Re-compiling pre-r266445 bitcode (in which declarations weren't added
>>>>  to the retainedTypes list), and
>>>> 2) Doing LTO function importing (which doesn't update the retainedTypes
>>>>  list).
>>>> 
>>>> It's possible to handle (1) and (2) by modifying the retainedTypes list
>>>> (in AutoUpgrade, or in the LTO importing logic resp.), but I don't see
>>>> an advantage to doing it this way, as it would cause more DWARF to be
>>>> emitted compared to creating the declaration DIEs lazily.
>>>> 
>>>> Tested with a stage2 ThinLTO+RelWithDebInfo build of clang, and with a
>>>> ReleaseLTO-g build of the test suite.
>>>> 
>>>> rdar://46577651, rdar://57855316, rdar://57840415
>>>> 
>>>> Differential Revision: https://reviews.llvm.org/D70350
>>>> 
>>>> Added:
>>>>   llvm/test/DebugInfo/AArch64/unretained-declaration-subprogram.ll
>>>>   llvm/test/DebugInfo/X86/lto-cross-cu-call-origin-ref.ll
>>>> 
>>>> Modified:
>>>>   llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>>   llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>>>   llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
>>>>   llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>>>> 
>>>> Removed:
>>>> 
>>>> 
>>>> 
>>>> ################################################################################
>>>> diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>> index 5707f962b4be..b2b98f19ca1c 100644
>>>> --- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>> +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>> @@ -972,8 +972,8 @@ DIE &DwarfCompileUnit::constructCallSiteEntryDIE(
>>>>    addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
>>>>               MachineLocation(CallReg));
>>>>  } else {
>>>> -    DIE *CalleeDIE = getOrCreateSubprogramDIE(CalleeSP);
>>>> -    assert(CalleeDIE && "Could not create DIE for call site entry origin");
>>>> +    DIE *CalleeDIE = getDIE(CalleeSP);
>>>> +    assert(CalleeDIE && "Could not find DIE for call site entry origin");
>>>>    addDIEEntry(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_origin),
>>>>                *CalleeDIE);
>>>>  }
>>>> 
>>>> diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>>> index 739cbaf694f5..d1a36299dc4a 100644
>>>> --- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>>> +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>>> @@ -540,6 +540,14 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU,
>>>>  }
>>>> }
>>>> 
>>>> +DIE &DwarfDebug::constructSubprogramDefinitionDIE(const DISubprogram *SP) {
>>>> +  DICompileUnit *Unit = SP->getUnit();
>>>> +  assert(SP->isDefinition() && "Subprogram not a definition");
>>>> +  assert(Unit && "Subprogram definition without parent unit");
>>>> +  auto &CU = getOrCreateDwarfCompileUnit(Unit);
>>>> +  return *CU.getOrCreateSubprogramDIE(SP);
>>>> +}
>>>> +
>>>> /// Try to interpret values loaded into registers that forward parameters
>>>> /// for \p CallMI. Store parameters with interpreted value into \p Params.
>>>> static void collectCallSiteParameters(const MachineInstr *CallMI,
>>>> @@ -750,6 +758,17 @@ void DwarfDebug::constructCallSiteEntryDIEs(const DISubprogram &SP,
>>>>        if (!CalleeDecl || !CalleeDecl->getSubprogram())
>>>>          continue;
>>>>        CalleeSP = CalleeDecl->getSubprogram();
>>>> +
>>>> +        if (CalleeSP->isDefinition()) {
>>>> +          // Ensure that a subprogram DIE for the callee is available in the
>>>> +          // appropriate CU.
>>>> +          constructSubprogramDefinitionDIE(CalleeSP);
>>>> +        } else {
>>>> +          // Create the declaration DIE if it is missing. This is required to
>>>> +          // support compilation of old bitcode with an incomplete list of
>>>> +          // retained metadata.
>>>> +          CU.getOrCreateSubprogramDIE(CalleeSP);
>>>> +        }
>>>>      }
>>>> 
>>>>      // TODO: Omit call site entries for runtime calls (objc_msgSend, etc).
>>>> @@ -906,6 +925,8 @@ DwarfDebug::getOrCreateDwarfCompileUnit(const DICompileUnit *DIUnit) {
>>>>  }
>>>> 
>>>>  // Create DIEs for function declarations used for call site debug info.
>>>> +  // Note: Declaration subprograms imported by LTO are not added to the unit's
>>>> +  // list of retained types, so their DIEs are not constructed here.
>>>>  for (auto Scope : DIUnit->getRetainedTypes())
>>>>    if (auto *SP = dyn_cast_or_null<DISubprogram>(Scope))
>>>>      NewCU.getOrCreateSubprogramDIE(SP);
>>>> 
>>>> diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
>>>> index f90dd48458ea..fd82b1f98055 100644
>>>> --- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
>>>> +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
>>>> @@ -442,6 +442,9 @@ class DwarfDebug : public DebugHandlerBase {
>>>>  /// Construct a DIE for this abstract scope.
>>>>  void constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU, LexicalScope *Scope);
>>>> 
>>>> +  /// Construct a DIE for the subprogram definition \p SP and return it.
>>>> +  DIE &constructSubprogramDefinitionDIE(const DISubprogram *SP);
>>>> +
>>>>  /// Construct DIEs for call site entries describing the calls in \p MF.
>>>>  void constructCallSiteEntryDIEs(const DISubprogram &SP, DwarfCompileUnit &CU,
>>>>                                  DIE &ScopeDIE, const MachineFunction &MF);
>>>> 
>>>> diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>>>> index 53747aef77fd..1aba956c48de 100644
>>>> --- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>>>> +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>>>> @@ -188,8 +188,9 @@ int64_t DwarfUnit::getDefaultLowerBound() const {
>>>> 
>>>> /// Check whether the DIE for this MDNode can be shared across CUs.
>>>> bool DwarfUnit::isShareableAcrossCUs(const DINode *D) const {
>>>> -  // When the MDNode can be part of the type system, the DIE can be shared
>>>> -  // across CUs.
>>>> +  // When the MDNode can be part of the type system (this includes subprogram
>>>> +  // declarations *and* subprogram definitions, even local definitions), the
>>>> +  // DIE must be shared across CUs.
>>>>  // Combining type units and cross-CU DIE sharing is lower value (since
>>>>  // cross-CU DIE sharing is used in LTO and removes type redundancy at that
>>>>  // level already) but may be implementable for some value in projects
>>>> @@ -197,9 +198,7 @@ bool DwarfUnit::isShareableAcrossCUs(const DINode *D) const {
>>>>  // together.
>>>>  if (isDwoUnit() && !DD->shareAcrossDWOCUs())
>>>>    return false;
>>>> -  return (isa<DIType>(D) ||
>>>> -          (isa<DISubprogram>(D) && !cast<DISubprogram>(D)->isDefinition())) &&
>>>> -         !DD->generateTypeUnits();
>>>> +  return (isa<DIType>(D) || isa<DISubprogram>(D)) && !DD->generateTypeUnits();
>>>> }
>>>> 
>>>> DIE *DwarfUnit::getDIE(const DINode *D) const {
>>>> 
>>>> diff  --git a/llvm/test/DebugInfo/AArch64/unretained-declaration-subprogram.ll b/llvm/test/DebugInfo/AArch64/unretained-declaration-subprogram.ll
>>>> new file mode 100644
>>>> index 000000000000..17ead0e81242
>>>> --- /dev/null
>>>> +++ b/llvm/test/DebugInfo/AArch64/unretained-declaration-subprogram.ll
>>>> @@ -0,0 +1,44 @@
>>>> +; RUN: llc -mtriple=arm64-apple-ios -filetype=obj < %s -o %t.o
>>>> +; RUN: llvm-dwarfdump %t.o | FileCheck %s -implicit-check-not=DW_TAG_subprogram
>>>> +
>>>> +; The declaration subprogram for "function" is not in the CU's list of
>>>> +; retained types. Test that a DWARF call site entry can still be constructed.
>>>> +
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name {{.*}}__hidden#3_
>>>> +; CHECK:   DW_TAG_call_site
>>>> +; CHECK:     DW_AT_call_origin (0x{{0+}}[[FUNCTION_DIE:.*]])
>>>> +
>>>> +; CHECK: 0x{{0+}}[[FUNCTION_DIE]]: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name {{.*}}function
>>>> +
>>>> +target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
>>>> +target triple = "arm64-apple-ios9.0.0"
>>>> +
>>>> +define i32 @main() local_unnamed_addr !dbg !8 {
>>>> +  %1 = tail call [2 x i64] @function([2 x i64] zeroinitializer), !dbg !11
>>>> +  %2 = extractvalue [2 x i64] %1, 0, !dbg !11
>>>> +  %3 = trunc i64 %2 to i32, !dbg !11
>>>> +  ret i32 %3, !dbg !12
>>>> +}
>>>> +
>>>> +declare !dbg !13 [2 x i64] @function([2 x i64]) local_unnamed_addr
>>>> +
>>>> +!llvm.module.flags = !{!0, !1, !2, !3, !4}
>>>> +!llvm.dbg.cu = !{!5}
>>>> +!llvm.ident = !{!7}
>>>> +
>>>> +!0 = !{i32 2, !"SDK Version", [2 x i32] [i32 13, i32 4]}
>>>> +!1 = !{i32 7, !"Dwarf Version", i32 4}
>>>> +!2 = !{i32 2, !"Debug Info Version", i32 3}
>>>> +!3 = !{i32 1, !"wchar_size", i32 4}
>>>> +!4 = !{i32 7, !"PIC Level", i32 2}
>>>> +!5 = distinct !DICompileUnit(language: DW_LANG_C99, file: !6, producer: "__hidden#0_", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, nameTableKind: None)
>>>> +!6 = !DIFile(filename: "__hidden#1_", directory: "__hidden#2_")
>>>> +!7 = !{!"Apple clang version 11.0.0 (llvm-project fa407d93fd5e618d76378c1ce4e4f517e0563278) (+internal-os)"}
>>>> +!8 = distinct !DISubprogram(name: "__hidden#3_", scope: !6, file: !6, line: 9, type: !9, scopeLine: 9, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !5)
>>>> +!9 = !DISubroutineType(types: !10)
>>>> +!10 = !{}
>>>> +!11 = !DILocation(line: 12, column: 10, scope: !8)
>>>> +!12 = !DILocation(line: 13, column: 3, scope: !8)
>>>> +!13 = !DISubprogram(name: "function", scope: !6, file: !6, line: 7, type: !9, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
>>>> 
>>>> diff  --git a/llvm/test/DebugInfo/X86/lto-cross-cu-call-origin-ref.ll b/llvm/test/DebugInfo/X86/lto-cross-cu-call-origin-ref.ll
>>>> new file mode 100644
>>>> index 000000000000..db14b06fc517
>>>> --- /dev/null
>>>> +++ b/llvm/test/DebugInfo/X86/lto-cross-cu-call-origin-ref.ll
>>>> @@ -0,0 +1,223 @@
>>>> +; RUN: llc -mtriple=x86_64-apple-darwin -filetype=obj < %s -o %t.o
>>>> +; RUN: llvm-dwarfdump %t.o | FileCheck %s -implicit-check-not=DW_TAG_subprogram
>>>> +; RUN: llvm-dwarfdump --verify %t.o
>>>> +
>>>> +; This test checks that cross-CU references within call site tags to subprogram
>>>> +; definitions are well-formed. There are 5 cases checked in this test. Each set
>>>> +; of checks is numbered and has a brief summary.
>>>> +
>>>> +; Instructions to regenerate the IR:
>>>> +; clang -O1 -g -emit-llvm -o a.bc -c a.c
>>>> +; clang -O1 -g -emit-llvm -o b.bc -c b.c
>>>> +; llvm-link -o linked.bc a.bc b.bc
>>>> +; opt -O1 linked.bc -o merged.bc
>>>> +
>>>> +; Source:
>>>> +; // a.c
>>>> +; __attribute__((optnone)) void noinline_func_in_a() {}
>>>> +;
>>>> +; __attribute__((optnone)) static void foo() {}
>>>> +; __attribute__((always_inline)) void always_inline_helper_in_a_that_calls_foo() {
>>>> +;   foo();
>>>> +; }
>>>> +;
>>>> +; extern void func_from_b();
>>>> +; void call_func_in_b_from_a() {
>>>> +;   func_from_b();
>>>> +; }
>>>> +;
>>>> +; // b.c
>>>> +; extern void noinline_func_in_a();
>>>> +; void call_noinline_func_in_a_from_b() {
>>>> +;   noinline_func_in_a();
>>>> +; }
>>>> +;
>>>> +; __attribute__((optnone)) void foo() {}
>>>> +; extern void always_inline_helper_in_a_that_calls_foo();
>>>> +; void call_both_foos_from_b() {
>>>> +;   foo();
>>>> +;   always_inline_helper_in_a_that_calls_foo();
>>>> +; }
>>>> +;
>>>> +; __attribute__((optnone)) void func_from_b() {}
>>>> +; void call_func_in_b_from_b() {
>>>> +;   func_from_b();
>>>> +; }
>>>> +
>>>> +; === CU for a.c ===
>>>> +
>>>> +; CHECK: DW_TAG_compile_unit
>>>> +; CHECK:   DW_AT_name ("a.c")
>>>> +
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("func_from_b")
>>>> +; CHECK:   DW_AT_declaration (true)
>>>> +
>>>> +; CHECK: 0x{{0+}}[[NOINLINE_FUNC_IN_A:.*]]: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("noinline_func_in_a")
>>>> +
>>>> +; 1) Check that "always_inline_helper_in_a_that_calls_foo" calls the "foo" in
>>>> +; a.c, and *not* the "foo" in b.c.
>>>> +; CHECK: 0x{{0+}}[[ALWAYS_INLINE_HELPER_IN_A:.*]]: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_abstract_origin ({{.*}} "always_inline_helper_in_a_that_calls_foo")
>>>> +; CHECK:   DW_TAG_call_site
>>>> +; CHECK-NEXT: DW_AT_call_origin (0x{{0+}}[[FOO_IN_A:.*]])
>>>> +
>>>> +; CHECK: 0x{{0+}}[[FOO_IN_A]]: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("foo")
>>>> +
>>>> +; 2) Check that "call_func_in_b_from_a" has a cross-CU ref into b.c.
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("call_func_in_b_from_a")
>>>> +; CHECK:   DW_TAG_call_site
>>>> +; CHECK-NEXT: DW_AT_call_origin (0x{{0+}}[[FUNC_FROM_B:.*]])
>>>> +
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("always_inline_helper_in_a_that_calls_foo")
>>>> +; CHECK:   DW_AT_inline (DW_INL_inlined)
>>>> +
>>>> +; === CU for b.c ===
>>>> +
>>>> +; CHECK: DW_TAG_compile_unit
>>>> +; CHECK:   DW_AT_name ("b.c")
>>>> +
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("noinline_func_in_a")
>>>> +; CHECK:   DW_AT_declaration (true)
>>>> +
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("always_inline_helper_in_a_that_calls_foo")
>>>> +; CHECK:   DW_AT_declaration (true)
>>>> +
>>>> +; 3) Validate the cross-CU ref from "call_func_in_b_from_a" in a.c.
>>>> +; CHECK: 0x{{0+}}[[FUNC_FROM_B]]: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("func_from_b")
>>>> +
>>>> +; 4) Validate the cross-CU ref from "call_noinline_func_in_a_from_b" in b.c.
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("call_noinline_func_in_a_from_b")
>>>> +; CHECK:   DW_TAG_call_site
>>>> +; CHECK-NEXT: DW_AT_call_origin (0x{{0+}}[[NOINLINE_FUNC_IN_A]])
>>>> +
>>>> +; CHECK: 0x{{0+}}[[FOO_IN_B:.*]]: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("foo")
>>>> +
>>>> +; 5) Validate that we correctly emit a cross-CU ref when the call is inlined
>>>> +; from another CU.
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("call_both_foos_from_b")
>>>> +; CHECK:   DW_TAG_call_site
>>>> +; CHECK-NEXT: DW_AT_call_origin (0x{{0+}}[[FOO_IN_B]])
>>>> +; CHECK:   DW_TAG_call_site
>>>> +; CHECK-NEXT: DW_AT_call_origin (0x{{0+}}[[FOO_IN_A]])
>>>> +
>>>> +; CHECK: DW_TAG_subprogram
>>>> +; CHECK:   DW_AT_name ("call_func_in_b_from_b")
>>>> +; CHECK:   DW_TAG_call_site
>>>> +; CHECK-NEXT: DW_AT_call_origin (0x{{0+}}[[FUNC_FROM_B]])
>>>> +
>>>> +target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
>>>> +target triple = "x86_64-apple-macosx10.14.0"
>>>> +
>>>> +define void @noinline_func_in_a() local_unnamed_addr #0 !dbg !17 {
>>>> +entry:
>>>> +  ret void, !dbg !20
>>>> +}
>>>> +
>>>> +define void @always_inline_helper_in_a_that_calls_foo() local_unnamed_addr #1 !dbg !21 {
>>>> +entry:
>>>> +  tail call fastcc void @foo.2(), !dbg !22
>>>> +  ret void, !dbg !23
>>>> +}
>>>> +
>>>> +define internal fastcc void @foo.2() unnamed_addr #0 !dbg !24 {
>>>> +entry:
>>>> +  ret void, !dbg !25
>>>> +}
>>>> +
>>>> +define void @call_func_in_b_from_a() local_unnamed_addr !dbg !26 {
>>>> +entry:
>>>> +  tail call void @func_from_b() #3, !dbg !27
>>>> +  ret void, !dbg !28
>>>> +}
>>>> +
>>>> +define void @call_noinline_func_in_a_from_b() local_unnamed_addr !dbg !29 {
>>>> +entry:
>>>> +  tail call void @noinline_func_in_a() #3, !dbg !30
>>>> +  ret void, !dbg !31
>>>> +}
>>>> +
>>>> +define void @foo() local_unnamed_addr #0 !dbg !32 {
>>>> +entry:
>>>> +  ret void, !dbg !33
>>>> +}
>>>> +
>>>> +define void @call_both_foos_from_b() local_unnamed_addr !dbg !34 {
>>>> +entry:
>>>> +  tail call void @foo(), !dbg !35
>>>> +  tail call fastcc void @foo.2() #3, !dbg !36
>>>> +  ret void, !dbg !38
>>>> +}
>>>> +
>>>> +define void @func_from_b() local_unnamed_addr #0 !dbg !39 {
>>>> +entry:
>>>> +  ret void, !dbg !40
>>>> +}
>>>> +
>>>> +define void @call_func_in_b_from_b() local_unnamed_addr !dbg !41 {
>>>> +entry:
>>>> +  tail call void @func_from_b(), !dbg !42
>>>> +  ret void, !dbg !43
>>>> +}
>>>> +
>>>> +attributes #0 = { noinline }
>>>> +attributes #1 = { alwaysinline }
>>>> +
>>>> +!llvm.dbg.cu = !{!0, !7}
>>>> +!llvm.ident = !{!12, !12}
>>>> +!llvm.module.flags = !{!13, !14, !15, !16}
>>>> +
>>>> +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (git at github.com:llvm/llvm-project.git 310e85309f870ee7347ef979d7d8da9bf28e92ea)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
>>>> +!1 = !DIFile(filename: "a.c", directory: "/Users/vsk/tmp/lto-entry-vals")
>>>> +!2 = !{}
>>>> +!3 = !{!4}
>>>> +!4 = !DISubprogram(name: "func_from_b", scope: !1, file: !1, line: 8, type: !5, spFlags: DISPFlagOptimized, retainedNodes: !2)
>>>> +!5 = !DISubroutineType(types: !6)
>>>> +!6 = !{null, null}
>>>> +!7 = distinct !DICompileUnit(language: DW_LANG_C99, file: !8, producer: "clang version 10.0.0 (git at github.com:llvm/llvm-project.git 310e85309f870ee7347ef979d7d8da9bf28e92ea)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !9, nameTableKind: None)
>>>> +!8 = !DIFile(filename: "b.c", directory: "/Users/vsk/tmp/lto-entry-vals")
>>>> +!9 = !{!10, !11}
>>>> +!10 = !DISubprogram(name: "noinline_func_in_a", scope: !8, file: !8, line: 1, type: !5, spFlags: DISPFlagOptimized, retainedNodes: !2)
>>>> +!11 = !DISubprogram(name: "always_inline_helper_in_a_that_calls_foo", scope: !8, file: !8, line: 7, type: !5, spFlags: DISPFlagOptimized, retainedNodes: !2)
>>>> +!12 = !{!"clang version 10.0.0 (git at github.com:llvm/llvm-project.git 310e85309f870ee7347ef979d7d8da9bf28e92ea)"}
>>>> +!13 = !{i32 7, !"Dwarf Version", i32 4}
>>>> +!14 = !{i32 2, !"Debug Info Version", i32 3}
>>>> +!15 = !{i32 1, !"wchar_size", i32 4}
>>>> +!16 = !{i32 7, !"PIC Level", i32 2}
>>>> +!17 = distinct !DISubprogram(name: "noinline_func_in_a", scope: !1, file: !1, line: 1, type: !18, scopeLine: 1, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
>>>> +!18 = !DISubroutineType(types: !19)
>>>> +!19 = !{null}
>>>> +!20 = !DILocation(line: 1, column: 53, scope: !17)
>>>> +!21 = distinct !DISubprogram(name: "always_inline_helper_in_a_that_calls_foo", scope: !1, file: !1, line: 4, type: !18, scopeLine: 4, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
>>>> +!22 = !DILocation(line: 5, column: 3, scope: !21)
>>>> +!23 = !DILocation(line: 6, column: 1, scope: !21)
>>>> +!24 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 3, type: !18, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
>>>> +!25 = !DILocation(line: 3, column: 45, scope: !24)
>>>> +!26 = distinct !DISubprogram(name: "call_func_in_b_from_a", scope: !1, file: !1, line: 9, type: !18, scopeLine: 9, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
>>>> +!27 = !DILocation(line: 10, column: 3, scope: !26)
>>>> +!28 = !DILocation(line: 11, column: 1, scope: !26)
>>>> +!29 = distinct !DISubprogram(name: "call_noinline_func_in_a_from_b", scope: !8, file: !8, line: 2, type: !18, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !7, retainedNodes: !2)
>>>> +!30 = !DILocation(line: 3, column: 3, scope: !29)
>>>> +!31 = !DILocation(line: 4, column: 1, scope: !29)
>>>> +!32 = distinct !DISubprogram(name: "foo", scope: !8, file: !8, line: 6, type: !18, scopeLine: 6, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !7, retainedNodes: !2)
>>>> +!33 = !DILocation(line: 6, column: 38, scope: !32)
>>>> +!34 = distinct !DISubprogram(name: "call_both_foos_from_b", scope: !8, file: !8, line: 8, type: !18, scopeLine: 8, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !7, retainedNodes: !2)
>>>> +!35 = !DILocation(line: 9, column: 3, scope: !34)
>>>> +!36 = !DILocation(line: 5, column: 3, scope: !21, inlinedAt: !37)
>>>> +!37 = distinct !DILocation(line: 10, column: 3, scope: !34)
>>>> +!38 = !DILocation(line: 11, column: 1, scope: !34)
>>>> +!39 = distinct !DISubprogram(name: "func_from_b", scope: !8, file: !8, line: 13, type: !18, scopeLine: 13, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !7, retainedNodes: !2)
>>>> +!40 = !DILocation(line: 13, column: 46, scope: !39)
>>>> +!41 = distinct !DISubprogram(name: "call_func_in_b_from_b", scope: !8, file: !8, line: 14, type: !18, scopeLine: 14, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !7, retainedNodes: !2)
>>>> +!42 = !DILocation(line: 15, column: 3, scope: !41)
>>>> +!43 = !DILocation(line: 16, column: 1, scope: !41)
>>>> 
>>>> 
>>>> 
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