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[InstCombine][DebugInfo] Update debug value uses in freelyInvertAllUsersOf #137013

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[InstCombine][DebugInfo] Update debug value uses in freelyInvertAllUsersOf #137013

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8d37b69
[InstCombine] Add pre-commit tests. NFC.
dtcxzyw Apr 23, 2025
0eb30b7
[InstCombine] Update debug value uses in `freelyInvertAllUsersOf`
dtcxzyw Apr 23, 2025
252ba6f
[InstCombine] Simplify code. NFC.
dtcxzyw Apr 25, 2025
4af0ede
[InstCombine] Simplify tests. NFC.
dtcxzyw Apr 25, 2025
1de469b
[InstCombine] Address review comments. NFC.
dtcxzyw Apr 25, 2025
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12 changes: 12 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1396,6 +1396,18 @@ void InstCombinerImpl::freelyInvertAllUsersOf(Value *I, Value *IgnoredUser) {
"canFreelyInvertAllUsersOf() ?");
}
}

// Update pre-existing debug value uses.
SmallVector<DbgValueInst *, 4> DbgValues;
SmallVector<DbgVariableRecord *, 4> DbgVariableRecords;
llvm::findDbgValues(DbgValues, I, &DbgVariableRecords);

SmallVector<uint64_t, 1> Ops = {dwarf::DW_OP_not};
for (auto *DVI : DbgValues)
DVI->setExpression(DIExpression::prependOpcodes(DVI->getExpression(), Ops));

for (DbgVariableRecord *DVR : DbgVariableRecords)
DVR->setExpression(DIExpression::prependOpcodes(DVR->getExpression(), Ops));
}

/// Given a 'sub' instruction, return the RHS of the instruction if the LHS is a
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70 changes: 70 additions & 0 deletions llvm/test/Transforms/InstCombine/debuginfo-invert.ll
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@@ -0,0 +1,70 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes=instcombine -S %s -o - | FileCheck %s

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Please can you add a comment describing what's being tested? IMO this is especially important for debug info tests using update_test_checks.py.

I'm not a huge fan of using update_test_checks.py for debug info tests like this (they become difficult to understand, and increase the chance the test is erroneously updated with debug info errors in the future), but I don't think we have a concrete "policy" on it (people may disagree with my opinion on it...), and this test is simple enough, so I won't push back on it.

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Done

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define i32 @test(i32 noundef %x, i32 noundef %y) !dbg !10 {
; CHECK-LABEL: define i32 @test(
; CHECK-SAME: i32 noundef [[X:%.*]], i32 noundef [[Y:%.*]]) !dbg [[DBG10:![0-9]+]] {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: #dbg_value(i32 [[X]], [[META15:![0-9]+]], !DIExpression(), [[META18:![0-9]+]])
; CHECK-NEXT: #dbg_value(i32 [[Y]], [[META16:![0-9]+]], !DIExpression(), [[META18]])
; CHECK-NEXT: [[CMP_NOT:%.*]] = icmp eq i32 [[X]], 0, !dbg [[DBG19:![0-9]+]]
; CHECK-NEXT: #dbg_value(i1 [[CMP_NOT]], [[META17:![0-9]+]], !DIExpression(DW_OP_not, DW_OP_LLVM_convert, 1, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned, DW_OP_stack_value), [[META18]])
; CHECK-NEXT: [[TMP0:%.*]] = and i32 [[Y]], 1, !dbg [[DBG20:![0-9]+]]
; CHECK-NEXT: [[AND:%.*]] = select i1 [[CMP_NOT]], i32 0, i32 [[TMP0]], !dbg [[DBG20]]
; CHECK-NEXT: ret i32 [[AND]], !dbg [[DBG21:![0-9]+]]
;
entry:
#dbg_value(i32 %x, !15, !DIExpression(), !18)
#dbg_value(i32 %y, !16, !DIExpression(), !18)
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I don't think we need these two #dbg_values?

%cmp = icmp ne i32 %x, 0, !dbg !19
%conv = zext i1 %cmp to i32, !dbg !19
#dbg_value(i32 %conv, !17, !DIExpression(), !18)
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nit: Can you please indent the dbg_value two spaces? That's how LLVM prints them, and it helps them stand out.

%and = and i32 %conv, %y, !dbg !20
ret i32 %and, !dbg !21
}

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
!llvm.ident = !{!9}

!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 21.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "test.c", directory: "/", checksumkind: CSK_MD5, checksum: "b2d9ffc7905684d8b7c3b52a3136e57c")
!2 = !{i32 7, !"Dwarf Version", i32 5}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !{i32 1, !"wchar_size", i32 4}
!5 = !{i32 8, !"PIC Level", i32 2}
!6 = !{i32 7, !"PIE Level", i32 2}
!7 = !{i32 7, !"uwtable", i32 2}
!8 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
!9 = !{!"clang version 21.0.0git"}
!10 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 1, type: !11, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !14)
!11 = !DISubroutineType(types: !12)
!12 = !{!13, !13, !13}
!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!14 = !{!15, !16, !17}
!15 = !DILocalVariable(name: "x", arg: 1, scope: !10, file: !1, line: 1, type: !13)
!16 = !DILocalVariable(name: "y", arg: 2, scope: !10, file: !1, line: 1, type: !13)
!17 = !DILocalVariable(name: "z", scope: !10, file: !1, line: 2, type: !13)
!18 = !DILocation(line: 0, scope: !10)
!19 = !DILocation(line: 2, column: 13, scope: !10)
!20 = !DILocation(line: 3, column: 12, scope: !10)
!21 = !DILocation(line: 3, column: 3, scope: !10)
;.
; CHECK: [[META0:![0-9]+]] = distinct !DICompileUnit(language: DW_LANG_C11, file: [[META1:![0-9]+]], producer: "{{.*}}clang version {{.*}}", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
; CHECK: [[META1]] = !DIFile(filename: "test.c", directory: {{.*}})
; CHECK: [[DBG10]] = distinct !DISubprogram(name: "test", scope: [[META1]], file: [[META1]], line: 1, type: [[META11:![0-9]+]], scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: [[META0]], retainedNodes: [[META14:![0-9]+]])
; CHECK: [[META11]] = !DISubroutineType(types: [[META12:![0-9]+]])
; CHECK: [[META12]] = !{[[META13:![0-9]+]], [[META13]], [[META13]]}
; CHECK: [[META13]] = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
; CHECK: [[META14]] = !{[[META15]], [[META16]], [[META17]]}
; CHECK: [[META15]] = !DILocalVariable(name: "x", arg: 1, scope: [[DBG10]], file: [[META1]], line: 1, type: [[META13]])
; CHECK: [[META16]] = !DILocalVariable(name: "y", arg: 2, scope: [[DBG10]], file: [[META1]], line: 1, type: [[META13]])
; CHECK: [[META17]] = !DILocalVariable(name: "z", scope: [[DBG10]], file: [[META1]], line: 2, type: [[META13]])
; CHECK: [[META18]] = !DILocation(line: 0, scope: [[DBG10]])
; CHECK: [[DBG19]] = !DILocation(line: 2, column: 13, scope: [[DBG10]])
; CHECK: [[DBG20]] = !DILocation(line: 3, column: 12, scope: [[DBG10]])
; CHECK: [[DBG21]] = !DILocation(line: 3, column: 3, scope: [[DBG10]])
;.
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