https://github.com/topperc created
https://github.com/llvm/llvm-project/pull/113871
f cannot be used as an output constraint. We already errored for '=f' but not
'+f'.
Fixes #113692.
>From 48c30e1a7d82c7124abbe6980b0495f6e05a5753 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.top...@sifive.com>
Date: Sun, 27 Oct 2024 23:44:31 -0700
Subject: [PATCH] [X86] Don't allow '+f' as an inline asm constraint.
f cannot be used as an output constraint. We already errored for
'=f' but not '+f'.
Fixes #113692.
---
clang/lib/Basic/Targets/X86.cpp | 2 +-
clang/test/Sema/asm.c | 6 ++++++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/clang/lib/Basic/Targets/X86.cpp b/clang/lib/Basic/Targets/X86.cpp
index d067ec218b5270..700c2f9a5dbd18 100644
--- a/clang/lib/Basic/Targets/X86.cpp
+++ b/clang/lib/Basic/Targets/X86.cpp
@@ -1465,7 +1465,7 @@ bool X86TargetInfo::validateAsmConstraint(
}
case 'f': // Any x87 floating point stack register.
// Constraint 'f' cannot be used for output operands.
- if (Info.ConstraintStr[0] == '=')
+ if (Info.ConstraintStr[0] == '=' || Info.ConstraintStr[0] == '+')
return false;
Info.setAllowsRegister();
return true;
diff --git a/clang/test/Sema/asm.c b/clang/test/Sema/asm.c
index 6cd95c71604d44..28ef3ec6ce09c2 100644
--- a/clang/test/Sema/asm.c
+++ b/clang/test/Sema/asm.c
@@ -204,6 +204,12 @@ double f_output_constraint(void) {
return result;
}
+double f_output_constraint_2(void) {
+ double result;
+ __asm("foo1": "+f" (result)); // expected-error {{invalid output constraint
'+f' in asm}}
+ return result;
+}
+
void fn1(void) {
int l;
__asm__(""
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