powerpc: Fix feraiseexcept and feclearexcept macros

System Internals / glibc - Matheus Castanho [linux.ibm.com] - 6 March 2020 14:10 EST

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.

1c252f0e7e powerpc: Fix feraiseexcept and feclearexcept macros
sysdeps/powerpc/bits/fenvinline.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Upstream: sourceware.org

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