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[DebugInfo][LSR] Fix assertion failure salvaging IV with offset > 64 bits wide #110979

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Merged
merged 1 commit into from
Oct 3, 2024
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[DebugInfo][LSR] Fix assertion failure salvaging IV with offset > 64 bits wide #110979

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2 changes: 2 additions & 0 deletions llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6869,6 +6869,8 @@ static bool SalvageDVI(llvm::Loop *L, ScalarEvolution &SE,
SE.computeConstantDifference(DVIRec.SCEVs[i], SCEVInductionVar)) {
if (Offset->getSignificantBits() <= 64)
SalvageExpr->createOffsetExpr(Offset->getSExtValue(), LSRInductionVar);
else
return false;
} else if (!SalvageExpr->createIterCountExpr(DVIRec.SCEVs[i], IterCountExpr,
SE))
return false;
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40 changes: 40 additions & 0 deletions llvm/test/Transforms/LoopStrengthReduce/debuginfo-scev-salvage-large-width.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
; RUN: opt -S -loop-reduce %s | FileCheck %s

;; We (currently?) can't salvage an IV if the offset is wider than 64 bits.
;; Check we poison it instead.

; CHECK: #dbg_value(i[[#]] poison, ![[#]], !DIExpression(), ![[#]])

define i16 @main() {
entry:
br label %for.cond29

for.cond29: ; preds = %for.body32, %entry
%il_1000.0 = phi i128 [ 0, %entry ], [ %inc72, %for.body32 ]
%l_995.0 = phi i128 [ 4704496199548239085565, %entry ], [ %inc70, %for.body32 ]
#dbg_value(i128 %l_995.0, !4, !DIExpression(), !9)
%cmp30 = icmp slt i128 %il_1000.0, 0
br i1 %cmp30, label %for.body32, label %for.cond.cleanup31

for.cond.cleanup31: ; preds = %for.cond29
ret i16 0

for.body32: ; preds = %for.cond29
%inc70 = add i128 %l_995.0, 1
%inc72 = add i128 %il_1000.0, 1
br label %for.cond29
}

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3}

!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, retainedTypes: !2, globals: !2, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "foo.c", directory: "/tmp")
!2 = !{}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !DILocalVariable(name: "l_995", scope: !5, file: !1, line: 414, type: !7)
!5 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 397, type: !6, scopeLine: 398, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
!6 = !DISubroutineType(types: !2)
!7 = !DIDerivedType(tag: DW_TAG_typedef, name: "__uint128_t", file: !1, baseType: !8)
!8 = !DIBasicType(name: "unsigned __int128", size: 128, encoding: DW_ATE_unsigned)
!9 = !DILocation(line: 0, scope: !5)
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