[M68k] Fix incorrect boolean content type #152572
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@llvm/pr-subscribers-backend-m68k Author: Dan Salvato (dansalvato) ChangesM68k's SETCC instruction ( For example, this IR: define dso_local signext range(i8 0, 2) i8 @<!-- -->testBool(i32 noundef %a) local_unnamed_addr #<!-- -->0 {
entry:
%cmp = icmp eq i32 %a, 4660
%. = zext i1 %cmp to i8
ret i8 %.
}would previously build as: testBool: ; @<!-- -->testBool
cmpi.l #<!-- -->4660, (4,%sp)
seq %d0
and.l #<!-- -->255, %d0
rtsNotice the testBool: ; @<!-- -->testBool
cmpi.l #<!-- -->4660, (4,%sp)
seq %d0
and.l #<!-- -->1, %d0
rtsFull diff: https://github.com/llvm/llvm-project/pull/152572.diff 1 Files Affected:
diff --git a/llvm/lib/Target/M68k/M68kISelLowering.cpp b/llvm/lib/Target/M68k/M68kISelLowering.cpp
index 594ea9f48c201..c6a20e211df7d 100644
--- a/llvm/lib/Target/M68k/M68kISelLowering.cpp
+++ b/llvm/lib/Target/M68k/M68kISelLowering.cpp
@@ -51,7 +51,7 @@ M68kTargetLowering::M68kTargetLowering(const M68kTargetMachine &TM,
MVT PtrVT = MVT::i32;
- setBooleanContents(ZeroOrOneBooleanContent);
+ setBooleanContents(ZeroOrNegativeOneBooleanContent);
auto *RegInfo = Subtarget.getRegisterInfo();
setStackPointerRegisterToSaveRestore(RegInfo->getStackRegister());
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Requesting review from @mshockwave |
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M68k's SETCC instruction (`scc`) distinctly fills the destination byte with all 1s. If boolean contents are set to `ZeroOrOneBooleanContent`, LLVM can mistakenly think the destination holds `0x01` instead of `0xff` and emit broken code as a result. This change corrects the boolean content type to `ZeroOrNegativeOneBooleanContent`.
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Updates comments for clarification.
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Thank you, please feel free to merge on my behalf since I don't have write access to the repo. |
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M68k's SETCC instruction (`scc`) distinctly fills the destination byte
with all 1s. If boolean contents are set to `ZeroOrOneBooleanContent`,
LLVM can mistakenly think the destination holds `0x01` instead of `0xff`
and emit broken code as a result. This change corrects the boolean
content type to `ZeroOrNegativeOneBooleanContent`.
For example, this IR:
```llvm
define dso_local signext range(i8 0, 2) i8 @testBool(i32 noundef %a) local_unnamed_addr #0 {
entry:
%cmp = icmp eq i32 %a, 4660
%. = zext i1 %cmp to i8
ret i8 %.
}
```
would previously build as:
```asm
testBool: ; @testBool
cmpi.l llvm#4660, (4,%sp)
seq %d0
and.l llvm#255, %d0
rts
```
Notice the `zext` is erroneously not clearing the low bits, and thus the
register returns with 255 instead of 1. This patch fixes the issue:
```asm
testBool: ; @testBool
cmpi.l llvm#4660, (4,%sp)
seq %d0
and.l llvm#1, %d0
rts
```
Most of the tests containing `scc` suffered from the same value error as
described above, so those tests have been updated to match the new
output (which also logically corrects them).
M68k's SETCC instruction (`scc`) distinctly fills the destination byte
with all 1s. If boolean contents are set to `ZeroOrOneBooleanContent`,
LLVM can mistakenly think the destination holds `0x01` instead of `0xff`
and emit broken code as a result. This change corrects the boolean
content type to `ZeroOrNegativeOneBooleanContent`.
For example, this IR:
```llvm
define dso_local signext range(i8 0, 2) i8 @testBool(i32 noundef %a) local_unnamed_addr #0 {
entry:
%cmp = icmp eq i32 %a, 4660
%. = zext i1 %cmp to i8
ret i8 %.
}
```
would previously build as:
```asm
testBool: ; @testBool
cmpi.l llvm#4660, (4,%sp)
seq %d0
and.l llvm#255, %d0
rts
```
Notice the `zext` is erroneously not clearing the low bits, and thus the
register returns with 255 instead of 1. This patch fixes the issue:
```asm
testBool: ; @testBool
cmpi.l llvm#4660, (4,%sp)
seq %d0
and.l llvm#1, %d0
rts
```
Most of the tests containing `scc` suffered from the same value error as
described above, so those tests have been updated to match the new
output (which also logically corrects them).
M68k's SETCC instruction (
scc) distinctly fills the destination byte with all 1s. If boolean contents are set toZeroOrOneBooleanContent, LLVM can mistakenly think the destination holds0x01instead of0xffand emit broken code as a result. This change corrects the boolean content type toZeroOrNegativeOneBooleanContent.For example, this IR:
would previously build as:
Notice the
zextis erroneously not clearing the low bits, and thus the register returns with 255 instead of 1. This patch fixes the issue:Most of the tests containing
sccsuffered from the same value error as described above, so those tests have been updated to match the new output (which also logically corrects them).