https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118921
Bug ID: 118921
Summary: C++ frontend does not honor GCC pragma optimize
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tnfchris at gcc dot gnu.org
Target Milestone: ---
The following example:
# pragma STDC FP_CONTRACT ON
# if __GNUC__ >= 4
# pragma GCC optimize ("no-fast-math,fp-contract=on")
# endif
# ifdef __FAST_MATH__
# error Hey yo, What you doing on FAST_MATH??
# endif
--
compiles with gcc -Ofast but not with g++ -Ofast,
it looks like the macro does not get undefined for g++, but the pragma does get
processed:
#include <math.h>
# pragma STDC FP_CONTRACT ON
# if __GNUC__ >= 4
# pragma GCC optimize ("no-fast-math,fp-contract=off")
# endif
void foo (float *f, float *g, int n)
{
for (int i = 0; i < n; i++)
f[i] += 2.6f * g[i];
}
shows that for both GCC and G++ the FMA doesn't get formed.
Is the pragma supposed to update the CPP define?
