[Bug target/78386] [PPC] Optimization -O2 and higher cause math inconsistency

[gromero at linux dot vnet.ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78386

--- Comment #9 from Gustavo Romero <gromero at linux dot vnet.ibm.com> ---
Both -ffp-contract=off and -std=c11 (with -O3) do not damage the precision:

CFLAGS=-I. -g -static -O3 -ffp-contract=off            # Precision is OK
CFLAGS=-I. -g -static -std=c11 -O3                     # Precision is OK
CFLAGS=-I. -g -static -std=c11 -ffp-contract=off -O3   # Precision is OK
CFLAGS=-I. -g -static -O3                              # Precision is NOT OK