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[GVNHoist] drop debug location according to the debug info guide 

According to the LLVM debug info update guide: https://llvm.org/docs/HowToUpdateDebugInfo.html,
"Hoisting identical instructions which appear in several successor
blocks into a predecessor block. In this case there is no single
merged instruction. The rule for dropping locations applies".

Thanks to Yuanbo Li for reporting this.

Reviewed By: dblaikie

Reviewers: sebpop, tejohnson, dblaikie

Differential Revision: https://reviews.llvm.org/D122730
This commit is contained in:
Aditya Kumar 2022-03-30 13:20:44 -07:00
parent 01ad70fd1d
commit 368681f803
2 changed files with 62 additions and 0 deletions
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2
llvm/lib/Transforms/Scalar/GVNHoist.cpp
View File

@ -1149,6 +1149,8 @@ std::pair<unsigned, unsigned> GVNHoist::hoist(HoistingPointList &HPL) {
DFSNumber[Repl] = DFSNumber[Last]++;
}
// Drop debug location as per debug info update guide.
Repl->dropLocation();
NR += removeAndReplace(InstructionsToHoist, Repl, DestBB, MoveAccess);
if (isa<LoadInst>(Repl))

60
llvm/test/Transforms/GVNHoist/hoist-drop-debug-info.ll Normal file
View File

@ -0,0 +1,60 @@
; RUN: opt -S -gvn-hoist < %s | FileCheck %s
; Check that the debug info is dropped as per the debug info update guide
@G = external global i32, align 4
; CHECK-LABEL: @foo
; CHECK-NOT: store {{.*}}dbg
define void @foo(i32 %c1) !dbg !6 {
entry:
call void @llvm.dbg.value(metadata i32 0, metadata !9, metadata !DIExpression()), !dbg !11
switch i32 %c1, label %exit1 [
i32 0, label %sw0
i32 1, label %sw1
], !dbg !11
sw0: ; preds = %entry
store i32 1, i32* @G, align 4, !dbg !12
br label %exit, !dbg !13
sw1: ; preds = %entry
store i32 1, i32* @G, align 4, !dbg !14
br label %exit, !dbg !15
exit1: ; preds = %entry
store i32 1, i32* @G, align 4, !dbg !16
ret void, !dbg !17
exit: ; preds = %sw1, %sw0
ret void, !dbg !18
}
; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
declare void @llvm.dbg.value(metadata, metadata, metadata) #0
attributes #0 = { nofree nosync nounwind readnone speculatable willreturn }
!llvm.dbg.cu = !{!0}
!llvm.debugify = !{!3, !4}
!llvm.module.flags = !{!5}
!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "abc.ll", directory: "/")
!2 = !{}
!3 = !{i32 8}
!4 = !{i32 1}
!5 = !{i32 2, !"Debug Info Version", i32 3}
!6 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: null, file: !1, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
!7 = !DISubroutineType(types: !2)
!8 = !{!9}
!9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
!10 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
!11 = !DILocation(line: 1, column: 1, scope: !6)
!12 = !DILocation(line: 2, column: 1, scope: !6)
!13 = !DILocation(line: 3, column: 1, scope: !6)
!14 = !DILocation(line: 4, column: 1, scope: !6)
!15 = !DILocation(line: 5, column: 1, scope: !6)
!16 = !DILocation(line: 6, column: 1, scope: !6)
!17 = !DILocation(line: 7, column: 1, scope: !6)
!18 = !DILocation(line: 8, column: 1, scope: !6)