1469d82e1c
As defined in LangRef, branching on `undef` is undefined behavior. This PR aims to remove undefined behavior from tests. As UB tests break Alive2 and may be the root cause of breaking future optimizations. Here's an Alive2 proof for one of the examples: https://alive2.llvm.org/ce/z/TncxhP
35 lines
834 B
LLVM
35 lines
834 B
LLVM
; RUN: opt < %s -S -passes='loop(indvars),loop-unroll' | FileCheck %s
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;
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; PR15570: SEGV: SCEV back-edge info invalid after dead code removal.
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;
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; Indvars creates a SCEV expression for the loop's back edge taken
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; count, then determines that the comparison is always true and
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; removes it.
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;
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; When loop-unroll asks for the expression, it contains a NULL
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; SCEVUnknkown (as a CallbackVH).
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;
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; forgetMemoizedResults should invalidate the backedge taken count expression.
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; CHECK: @test
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; CHECK-NOT: phi
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; CHECK-NOT: icmp
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; CHECK: ret void
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define void @test(i1 %arg) {
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entry:
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%xor1 = xor i32 0, 1
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br label %b17
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b17:
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br i1 %arg, label %b22, label %b18
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b18:
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%phi1 = phi i32 [ %add1, %b18 ], [ %xor1, %b17 ]
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%add1 = add nsw i32 %phi1, -1
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%cmp1 = icmp sgt i32 %add1, 0
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br i1 %cmp1, label %b18, label %b22
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b22:
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ret void
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}
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