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The way we currently define congruency for two PHIExpression(s) is: 1) The operands to the phi functions are congruent 2) The PHIs are defined in the same BasicBlock. NewGVN works under the assumption that phi operands are in predecessor order, or at least in some consistent order. OTOH, is valid IR: patatino: %meh = phi i16 [ %0, %winky ], [ %conv1, %tinky ] %banana = phi i16 [ %0, %tinky ], [ %conv1, %winky ] br label %end and the in-memory representations of the two SSA registers have an inconsistent order. This violation of NewGVN assumptions results into two PHIs found congruent when they're not. While we think it's useful to have always a consistent order enforced, let's fix this in NewGVN sorting uses in predecessor order before creating a PHI expression. Differential Revision: https://reviews.llvm.org/D32990 llvm-svn: 302552
43 lines
1.3 KiB
LLVM
43 lines
1.3 KiB
LLVM
; PR32952: Don't erroneously consider congruent two phi nodes which
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; have the same arguments but different incoming edges.
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; RUN: opt -newgvn -S %s | FileCheck %s
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@a = common global i16 0, align 2
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@.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
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define i32 @tinkywinky() {
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entry:
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%0 = load i16, i16* @a, align 2
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%conv = sext i16 %0 to i32
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%neg = xor i32 %conv, -1
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%conv1 = trunc i32 %neg to i16
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%conv3 = zext i16 %conv1 to i32
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%cmp = icmp slt i32 %conv, %conv3
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br i1 %cmp, label %tinky, label %winky
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tinky:
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store i16 2, i16* @a, align 2
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br label %patatino
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winky:
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br label %patatino
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patatino:
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; CHECK: %meh = phi i16 [ %0, %winky ], [ %conv1, %tinky ]
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; CHECK: %banana = phi i16 [ %0, %tinky ], [ %conv1, %winky ]
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%meh = phi i16 [ %0, %winky ], [ %conv1, %tinky ]
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%banana = phi i16 [ %0, %tinky ], [ %conv1, %winky ]
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br label %end
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end:
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; CHECK: %promoted = zext i16 %banana to i32
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; CHECK: %other = zext i16 %meh to i32
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%promoted = zext i16 %banana to i32
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%other = zext i16 %meh to i32
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%first = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0), i32 %promoted)
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%second = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0), i32 %other)
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ret i32 0
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}
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declare i32 @printf(i8*, ...)
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