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[llvm][LSR] Fix where invariant on ScaledReg & Scale is violated #112576

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Merged
merged 3 commits into from
Oct 17, 2024
Merged

[llvm][LSR] Fix where invariant on ScaledReg & Scale is violated #112576

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cea80f5
[llvm][LSR] Fix where invariant on ScaledReg & Scale is violated
JOE1994 Oct 16, 2024
8b34778
apply clang-format
JOE1994 Oct 16, 2024
eaa0576
Move test under X86/ & add FileCheck line
JOE1994 Oct 17, 2024
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8 changes: 6 additions & 2 deletions llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -622,6 +622,9 @@ static bool containsAddRecDependentOnLoop(const SCEV *S, const Loop &L) {
/// representation.
/// \see Formula::BaseRegs.
bool Formula::isCanonical(const Loop &L) const {
assert((Scale == 0 || ScaledReg) &&
"ScaledReg must be non-null if Scale is non-zero");

if (!ScaledReg)
return BaseRegs.size() <= 1;

Expand Down Expand Up @@ -3973,9 +3976,10 @@ void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,
F.UnfoldedOffset =
Immediate::getFixed((uint64_t)F.UnfoldedOffset.getFixedValue() +
InnerSumSC->getValue()->getZExtValue());
if (IsScaledReg)
if (IsScaledReg) {
F.ScaledReg = nullptr;
else
F.Scale = 0;
} else
F.BaseRegs.erase(F.BaseRegs.begin() + Idx);
} else if (IsScaledReg)
F.ScaledReg = InnerSum;
Expand Down
30 changes: 30 additions & 0 deletions llvm/test/Transforms/LoopStrengthReduce/X86/pr76504.ll
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@@ -0,0 +1,30 @@
; Reduced from https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=65323 by @RKSimon
;
; RUN: opt -S -passes=loop-reduce %s | FileCheck %s
;
; Make sure we don't trigger an assertion.
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In the future please use filename that are more expressive.
You can still reference the bug number in the comment.


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"

@G = external global i32

define void @foo() {
; CHECK-LABEL: foo
bb8:
br label %bb30

bb30: ; preds = %bb30, %bb8
%l0 = phi i64 [ -2222, %bb8 ], [ %r23, %bb30 ]
%A22 = alloca i16, align 2
%r23 = add nuw i64 1, %l0
%G7 = getelementptr i16, ptr %A22, i64 %r23
%B15 = urem i64 %r23, %r23
%G6 = getelementptr i16, ptr %G7, i64 %B15
%B1 = urem i64 %r23, %r23
%B8 = sub i64 -1, %r23
%B18 = sub i64 %B8, %B1
%G5 = getelementptr i16, ptr %G6, i64 %B18
store ptr %G5, ptr undef, align 8
br label %bb30
}
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