e2c698c7e8
Consider the following case:
```
define i1 @src(i8 %x) {
%cmp = icmp slt i8 %x, -1
%not1 = xor i1 %cmp, true
%or = or i1 %cmp, %not1
%not2 = xor i1 %or, true
ret i1 %not2
}
```
`sinkNotIntoLogicalOp(%or)` calls `freelyInvert(%cmp,
/*IgnoredUser=*/%or)` first. However, as `%cmp` is also used by `Op1 =
%not1`, the RHS of `%or` is set to `%cmp.not = xor i1 %cmp, true`. Thus
`Op1` is out of date in the second call to `freelyInvert`. Similarly,
the second call may change `Op0`. According to the analysis above, I
decided to avoid this fold when one of the operands is also a user of
the other.
Closes https://github.com/llvm/llvm-project/issues/142518.
44 lines
1.5 KiB
LLVM
44 lines
1.5 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=instcombine < %s | FileCheck %s
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define i8 @pr142518(ptr %p, i8 %x, i1 %c) "instcombine-no-verify-fixpoint" {
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; CHECK-LABEL: define i8 @pr142518(
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; CHECK-SAME: ptr [[P:%.*]], i8 [[X:%.*]], i1 [[C:%.*]]) #[[ATTR0:[0-9]+]] {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i8 [[X]], -1
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; CHECK-NEXT: br label %[[LOOP:.*]]
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; CHECK: [[LOOP]]:
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; CHECK-NEXT: [[NOT1:%.*]] = xor i1 [[CMP1]], true
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; CHECK-NEXT: [[OR:%.*]] = or i1 [[CMP1]], [[NOT1]]
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; CHECK-NEXT: [[CMP:%.*]] = xor i1 [[OR]], true
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; CHECK-NEXT: [[EXT2:%.*]] = zext i1 [[CMP]] to i8
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; CHECK-NEXT: store i8 [[EXT2]], ptr [[P]], align 1
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; CHECK-NEXT: br i1 false, label %[[LOOP]], label %[[EXIT:.*]]
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; CHECK: [[EXIT]]:
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; CHECK-NEXT: [[NOT3:%.*]] = xor i1 [[OR]], true
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; CHECK-NEXT: [[EXT3:%.*]] = zext i1 [[NOT3]] to i8
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; CHECK-NEXT: ret i8 [[EXT3]]
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;
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entry:
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%flag = alloca i8, align 1
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%cmp = icmp slt i8 %x, -1
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br label %loop
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loop:
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%phi = phi i1 [ %cmp, %entry ], [ %c, %loop ]
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%not1 = xor i1 %phi, true
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%or = or i1 %cmp, %not1
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%not2 = xor i1 %or, true
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%ext2 = zext i1 %not2 to i8
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store i8 %ext2, ptr %p, align 1
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store i8 1, ptr %flag, align 1
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%flagv = load i8, ptr %flag, align 1
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%cond = icmp eq i8 %flagv, 0
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br i1 %cond, label %loop, label %exit
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exit:
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%not3 = xor i1 %or, true
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%ext3 = zext i1 %not3 to i8
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ret i8 %ext3
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}
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