https://gcc.gnu.org/g:88f638e276c25e216b3d01c0d7aa25a0d17921d9
commit r16-3037-g88f638e276c25e216b3d01c0d7aa25a0d17921d9
Author: Yang Yujie <yangyu...@loongson.cn>
Date: Wed Aug 6 12:02:44 2025 +0200
bitint: Make sure BEXTC checks extension when optimized
In BEXTC, whether a _BitInt object is properly extended is examined
by a value comparison against a copied object in a wider _BitInt
type that utilizes all of the partial limb.
Since the (implicit) conversion to the wider type may be optimized
away now and cause the result of the comparison to always be true,
we need to cast the copied object down to the original type to
force a extension, so that it can serve as our reference.
* gcc.dg/bitintext.h (BEXTC1): Define. Convert the copied
object back to the original type before comparison.
(BEXTC): Use BEXTC1 for both the signed and the unsigned case.
Diff:
---
gcc/testsuite/gcc.dg/bitintext.h | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/bitintext.h b/gcc/testsuite/gcc.dg/bitintext.h
index d5f2689daec4..f61cf9ae2e1e 100644
--- a/gcc/testsuite/gcc.dg/bitintext.h
+++ b/gcc/testsuite/gcc.dg/bitintext.h
@@ -25,22 +25,20 @@ do_copy (void *p, const void *q, __SIZE_TYPE__ r)
/* Macro to test whether (on targets where psABI requires it) _BitInt
with padding bits have those filled with sign or zero extension. */
#if defined(__s390x__) || defined(__arm__) || defined(__loongarch__)
+#define BEXTC1(x, uns) \
+ do { \
+ uns _BitInt(PROMOTED_SIZE (x) * __CHAR_BIT__) __x; \
+ do_copy (&__x, &(x), sizeof (__x)); \
+ if (__x != (typeof (x)) __x) \
+ __builtin_abort (); \
+ } while (0)
+
#define BEXTC(x) \
- do { \
- if ((typeof (x)) -1 < 0) \
- { \
- _BitInt(PROMOTED_SIZE (x) * __CHAR_BIT__) __x; \
- do_copy (&__x, &(x), sizeof (__x)); \
- if (__x != (x)) \
- __builtin_abort (); \
- } \
- else \
- { \
- unsigned _BitInt(PROMOTED_SIZE (x) * __CHAR_BIT__) __x; \
- do_copy (&__x, &(x), sizeof (__x)); \
- if (__x != (x)) \
- __builtin_abort (); \
- } \
+ do { \
+ if ((typeof (x)) -1 < 0) \
+ BEXTC1 ((x), signed); \
+ else \
+ BEXTC1 ((x), unsigned); \
} while (0)
#else
#define BEXTC(x) do { (void) (x); } while (0)
