[clang][sema] forbid '+f' on output register #75208
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to align with GCC asm: "+f" is not allowed to be used on output register. fix issue: llvm#75019
llvmbot
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clang
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@llvm/pr-subscribers-clang Author: flyingcat (knightXun) Changesto align with GCC asm: "+f" is not allowed to be used on output register. fix issue: #75019 Full diff: https://github.com/llvm/llvm-project/pull/75208.diff 1 Files Affected:
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index 6cd5d618a4aca..57a81e03bc484 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -717,8 +717,15 @@ bool TargetInfo::validateOutputConstraint(ConstraintInfo &Info) const {
if (*Name != '=' && *Name != '+')
return false;
- if (*Name == '+')
+ if (*Name == '+') {
Info.setIsReadWrite();
+ // To align with GCC asm: "=f" is not allowed, the
+ // operand constraints must select a class with a single reg.
+ auto Flag = Name + 1;
+ if (Flag && *Flag == 'f') {
+ return false;
+ }
+ }
Name++;
while (*Name) {
|
phoebewang
reviewed
Dec 13, 2023
Comment on lines
+720
to
+728
| if (*Name == '+') { | ||
| Info.setIsReadWrite(); | ||
| // To align with GCC asm: "=f" is not allowed, the | ||
| // operand constraints must select a class with a single reg. | ||
| auto Flag = Name + 1; | ||
| if (Flag && *Flag == 'f') { | ||
| return false; | ||
| } | ||
| } |
There was a problem hiding this comment.
Need to change from here: https://github.com/llvm/llvm-project/blob/main/clang/lib/Basic/Targets/X86.cpp#L1436
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to align with GCC asm: "+f" is not allowed to be used on output register.
fix issue: #75019