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[SimplifyCFG] Remap rewritten debug intrinsic operands.

FoldBranchToCommonDest clones instructions to a different basic block,
but handles debug intrinsics in a separate path. Previously, when
cloning debug intrinsics, their operands were not updated to reference
the correct cloned values. As a result, we would emit debug.value
intrinsics with broken operand references which are discarded in later
passes. This leads to incorrect debuginfo that reports incorrect values
for variables.

Fix this by remapping debug intrinsic operands when cloning them.

Fixes https://bugs.llvm.org/show_bug.cgi?id=45667.

Differential Revision: https://reviews.llvm.org/D79602
This commit is contained in:
Ricky Zhou 2020-05-08 10:55:27 -07:00 committed by Vedant Kumar
parent 9de716fac1
commit 30d6c2bb93
2 changed files with 142 additions and 3 deletions

View File

@ -2898,9 +2898,14 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, MemorySSAUpdater *MSSAU,
// could replace PBI's branch probabilities with BI's.
// Copy any debug value intrinsics into the end of PredBlock.
for (Instruction &I : *BB)
if (isa<DbgInfoIntrinsic>(I))
I.clone()->insertBefore(PBI);
for (Instruction &I : *BB) {
if (isa<DbgInfoIntrinsic>(I)) {
Instruction *NewI = I.clone();
RemapInstruction(NewI, VMap,
RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
NewI->insertBefore(PBI);
}
}
return true;
}

View File

@ -0,0 +1,134 @@
; RUN: opt %s -simplifycfg -verify -S -o - | FileCheck %s
;
; Verify that SimplifyCFG does not invalidate operands for
; llvm.dbg.value intrinsics.
;
; Reduced from the following example, compiled with
; -O1 -g -fno-exceptions -fno-discard-value-names:
;
; void test() {
; bool a = false;
; bool b = false;
; bool c = false;
; [&a, &b, &c] { b = true; }();
;
; if (a || b || c) {
; __builtin_debugtrap();
; }
; }
; CHECK: _Z4testv
; CHECK-NOT: llvm.dbg.value(metadata !
; CHECK: ret void
%class.anon = type { i8*, i8*, i8* }
; Function Attrs: nounwind uwtable
define dso_local void @_Z4testv() local_unnamed_addr !dbg !7 {
entry:
%a = alloca i8, align 1
%b = alloca i8, align 1
%c = alloca i8, align 1
%ref.tmp = alloca %class.anon, align 8
call void @llvm.dbg.value(metadata i8* %a, metadata !12, metadata !DIExpression(DW_OP_deref)), !dbg !16
call void @llvm.dbg.value(metadata i8 0, metadata !12, metadata !DIExpression()), !dbg !16
store i8 0, i8* %a, align 1, !dbg !16
call void @llvm.dbg.value(metadata i8* %b, metadata !14, metadata !DIExpression(DW_OP_deref)), !dbg !16
call void @llvm.dbg.value(metadata i8 0, metadata !14, metadata !DIExpression()), !dbg !16
store i8 0, i8* %b, align 1, !dbg !16
call void @llvm.dbg.value(metadata i8* %c, metadata !15, metadata !DIExpression(DW_OP_deref)), !dbg !16
call void @llvm.dbg.value(metadata i8 0, metadata !15, metadata !DIExpression()), !dbg !16
store i8 0, i8* %c, align 1, !dbg !16
%0 = bitcast %class.anon* %ref.tmp to i8*, !dbg !16
%1 = getelementptr inbounds %class.anon, %class.anon* %ref.tmp, i64 0, i32 0, !dbg !16
store i8* %a, i8** %1, align 8, !dbg !16
%2 = getelementptr inbounds %class.anon, %class.anon* %ref.tmp, i64 0, i32 1, !dbg !16
store i8* %b, i8** %2, align 8, !dbg !16
%3 = getelementptr inbounds %class.anon, %class.anon* %ref.tmp, i64 0, i32 2, !dbg !16
store i8* %c, i8** %3, align 8, !dbg !16
call fastcc void @"_ZZ4testvENK3$_0clEv"(%class.anon* nonnull %ref.tmp), !dbg !16
%4 = load i8, i8* %a, align 1, !dbg !17
call void @llvm.dbg.value(metadata i8 %4, metadata !12, metadata !DIExpression()), !dbg !16
%tobool = icmp eq i8 %4, 0, !dbg !17
br i1 %tobool, label %lor.lhs.false, label %if.then, !dbg !17
lor.lhs.false: ; preds = %entry
%5 = load i8, i8* %b, align 1, !dbg !17
call void @llvm.dbg.value(metadata i8 %5, metadata !14, metadata !DIExpression()), !dbg !16
%tobool1 = icmp eq i8 %5, 0, !dbg !17
br i1 %tobool1, label %lor.lhs.false2, label %if.then, !dbg !17
lor.lhs.false2: ; preds = %lor.lhs.false
%6 = load i8, i8* %c, align 1, !dbg !17
call void @llvm.dbg.value(metadata i8 %6, metadata !15, metadata !DIExpression()), !dbg !16
%tobool3 = icmp eq i8 %6, 0, !dbg !17
br i1 %tobool3, label %if.end, label %if.then, !dbg !16
if.then: ; preds = %lor.lhs.false2, %lor.lhs.false, %entry
call void @llvm.debugtrap(), !dbg !19
br label %if.end, !dbg !19
if.end: ; preds = %lor.lhs.false2, %if.then
call void @llvm.dbg.value(metadata i8* %c, metadata !15, metadata !DIExpression(DW_OP_deref)), !dbg !16
call void @llvm.dbg.value(metadata i8* %b, metadata !14, metadata !DIExpression(DW_OP_deref)), !dbg !16
call void @llvm.dbg.value(metadata i8* %a, metadata !12, metadata !DIExpression(DW_OP_deref)), !dbg !16
ret void, !dbg !16
}
; Function Attrs: inlinehint nounwind uwtable
define internal fastcc void @"_ZZ4testvENK3$_0clEv"(%class.anon* %this) unnamed_addr align 2 !dbg !21 {
entry:
call void @llvm.dbg.value(metadata %class.anon* %this, metadata !34, metadata !DIExpression()), !dbg !36
%0 = getelementptr inbounds %class.anon, %class.anon* %this, i32 0, i32 1, !dbg !36
%1 = load i8*, i8** %0, align 8, !dbg !36
store i8 1, i8* %1, align 1, !dbg !36
ret void, !dbg !36
}
; Function Attrs: nounwind
declare void @llvm.debugtrap()
; Function Attrs: nounwind readnone speculatable
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_C_plus_plus, file: !1, producer: "clang version 8.0.1-4 (tags/RELEASE_801/final)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "test.cc", directory: "/dir")
!2 = !{}
!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 8.0.1-4 (tags/RELEASE_801/final)"}
!7 = distinct !DISubprogram(name: "test", linkageName: "_Z4testv", scope: !8, file: !8, line: 1, type: !9, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
!8 = !DIFile(filename: "test.cc", directory: "/dir")
!9 = !DISubroutineType(types: !10)
!10 = !{null}
!11 = !{!12, !14, !15}
!12 = !DILocalVariable(name: "a", scope: !7, file: !8, line: 2, type: !13)
!13 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
!14 = !DILocalVariable(name: "b", scope: !7, file: !8, line: 3, type: !13)
!15 = !DILocalVariable(name: "c", scope: !7, file: !8, line: 4, type: !13)
!16 = !DILocation(line: 2, scope: !7)
!17 = !DILocation(line: 7, scope: !18)
!18 = distinct !DILexicalBlock(scope: !7, file: !8, line: 7)
!19 = !DILocation(line: 8, scope: !20)
!20 = distinct !DILexicalBlock(scope: !18, file: !8, line: 7)
!21 = distinct !DISubprogram(name: "operator()", linkageName: "_ZZ4testvENK3$_0clEv", scope: !22, file: !8, line: 5, type: !28, scopeLine: 5, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, declaration: !32, retainedNodes: !33)
!22 = distinct !DICompositeType(tag: DW_TAG_class_type, scope: !7, file: !8, line: 5, size: 192, flags: DIFlagTypePassByValue, elements: !23)
!23 = !{!24, !26, !27}
!24 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !22, file: !8, line: 5, baseType: !25, size: 64)
!25 = !DIDerivedType(tag: DW_TAG_reference_type, baseType: !13, size: 64)
!26 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !22, file: !8, line: 5, baseType: !25, size: 64, offset: 64)
!27 = !DIDerivedType(tag: DW_TAG_member, name: "c", scope: !22, file: !8, line: 5, baseType: !25, size: 64, offset: 128)
!28 = !DISubroutineType(types: !29)
!29 = !{null, !30}
!30 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !31, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
!31 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !22)
!32 = !DISubprogram(name: "operator()", scope: !22, file: !8, line: 5, type: !28, scopeLine: 5, flags: DIFlagPublic | DIFlagPrototyped, spFlags: DISPFlagOptimized)
!33 = !{!34}
!34 = !DILocalVariable(name: "this", arg: 1, scope: !21, type: !35, flags: DIFlagArtificial | DIFlagObjectPointer)
!35 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !31, size: 64)
!36 = !DILocation(line: 0, scope: !21)