dd116369f6
We can only replace phi(X, undef) with X, if X is known not to be poison. Otherwise, the result may be more poisonous on the undef branch. Fixes https://github.com/llvm/llvm-project/issues/68683.
68 lines
1.8 KiB
LLVM
68 lines
1.8 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt -S -passes=mem2reg < %s | FileCheck %s
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define i8 @single_store_literal_poison(i1 %cond) {
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; CHECK-LABEL: define i8 @single_store_literal_poison(
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; CHECK-SAME: i1 [[COND:%.*]]) {
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; CHECK-NEXT: br i1 [[COND]], label %[[IF:.*]], label %[[EXIT:.*]]
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; CHECK: [[IF]]:
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; CHECK-NEXT: br label %[[EXIT]]
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; CHECK: [[EXIT]]:
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; CHECK-NEXT: ret i8 undef
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;
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%a = alloca i8, align 1
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br i1 %cond, label %if, label %exit
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if:
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store i8 poison, ptr %a, align 1
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br label %exit
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exit:
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%v = load i8, ptr %a, align 1
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ret i8 %v
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}
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; FIXME: This is a miscompile.
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define i8 @single_store_maybe_poison(i1 %cond, i8 %x) {
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; CHECK-LABEL: define i8 @single_store_maybe_poison(
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; CHECK-SAME: i1 [[COND:%.*]], i8 [[X:%.*]]) {
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; CHECK-NEXT: br i1 [[COND]], label %[[IF:.*]], label %[[EXIT:.*]]
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; CHECK: [[IF]]:
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; CHECK-NEXT: br label %[[EXIT]]
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; CHECK: [[EXIT]]:
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; CHECK-NEXT: [[A_0:%.*]] = phi i8 [ [[X]], %[[IF]] ], [ undef, [[TMP0:%.*]] ]
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; CHECK-NEXT: ret i8 [[A_0]]
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;
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%a = alloca i8, align 1
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br i1 %cond, label %if, label %exit
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if:
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store i8 %x, ptr %a, align 1
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br label %exit
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exit:
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%v = load i8, ptr %a, align 1
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ret i8 %v
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}
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define i8 @single_store_cant_be_poison(i1 %cond, i8 noundef %x) {
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; CHECK-LABEL: define i8 @single_store_cant_be_poison(
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; CHECK-SAME: i1 [[COND:%.*]], i8 noundef [[X:%.*]]) {
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; CHECK-NEXT: br i1 [[COND]], label %[[IF:.*]], label %[[EXIT:.*]]
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; CHECK: [[IF]]:
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; CHECK-NEXT: br label %[[EXIT]]
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; CHECK: [[EXIT]]:
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; CHECK-NEXT: ret i8 [[X]]
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;
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%a = alloca i8, align 1
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br i1 %cond, label %if, label %exit
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if:
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store i8 %x, ptr %a, align 1
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br label %exit
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exit:
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%v = load i8, ptr %a, align 1
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ret i8 %v
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}
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