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[InstCombine] Param attributes should be swapped/dropped after swapping operands of commutative intrinsics #115890

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dtcxzyw opened this issue Nov 12, 2024 · 0 comments · May be fixed by #115988
Open

[InstCombine] Param attributes should be swapped/dropped after swapping operands of commutative intrinsics #115890

dtcxzyw opened this issue Nov 12, 2024 · 0 comments · May be fixed by #115988
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llvm:instcombine miscompilation

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dtcxzyw commented Nov 12, 2024 

; bin/opt -passes=instcombine test.ll -S
define i32 @test(i32 %x) {
  %ret = call range(i32 -10, 0) i32 @llvm.umax.i32(i32 range(i32 -10, -8) -10, i32 %x)
  ret i32 %ret
}

define i32 @test(i32 %x) {
  %ret = call range(i32 -10, 0) i32 @llvm.umax.i32(i32 range(i32 -10, -8) %x, i32 -10)
  ret i32 %ret
}

I found this with https://github.com/dtcxzyw/llvm-ub-aware-interpreter.
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[InstCombine] Drop poison-generating/UB-implying param attrs after changing operands dtcxzyw/llvm-project
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