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[PATCH] powerpc: Fix feraiseexcept and feclearexcept macros
- From: Matheus Castanho <msc at linux dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Tue, 3 Mar 2020 15:20:38 -0300
- Subject: [PATCH] powerpc: Fix feraiseexcept and feclearexcept macros
A recent change to fenvinline.h modified the check if __e is a
a power of 2 inside feraiseexcept and feclearexcept macros. It
introduced the use of the powerof2 macro but also removed the
if statement checking whether __e != 0 before issuing an mtfsb*
instruction. This is problematic because powerof2 (0) evaluates
to 1 and without the removed if __e is allowed to be 0 when
__builtin_clz is called. In that case the value 32 is passed
to __MTFSB*, which is invalid.
This commit uses __builtin_popcount instead of powerof2 to fix this
issue and avoid the extra check for __e != 0. This was the approach
used by the initial versions of that previous patch.
---
sysdeps/powerpc/bits/fenvinline.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sysdeps/powerpc/bits/fenvinline.h b/sysdeps/powerpc/bits/fenvinline.h
index 89ea38a4f8..f2d095a72f 100644
--- a/sysdeps/powerpc/bits/fenvinline.h
+++ b/sysdeps/powerpc/bits/fenvinline.h
@@ -75,7 +75,7 @@
int __e = __excepts; \
int __ret = 0; \
if (__builtin_constant_p (__e) \
- && powerof2 (__e) \
+ && __builtin_popcount (__e) == 1 \
&& __e != FE_INVALID) \
{ \
__MTFSB1 ((__builtin_clz (__e))); \
@@ -91,7 +91,7 @@
int __e = __excepts; \
int __ret = 0; \
if (__builtin_constant_p (__e) \
- && powerof2 (__e) \
+ && __builtin_popcount (__e) == 1 \
&& __e != FE_INVALID) \
{ \
__MTFSB0 ((__builtin_clz (__e))); \
--
2.21.1