On Tue, 6 Feb 2018, Vincent Lefevre wrote: > Well, if I add -std=c99 or -std=c11, the failure disappears. The > reason is that GCC generates a FMA (indeed, this new machine has > a FMA), but this occurs across different C statements. So, maybe > not a bug, but a bad feature, IMHO.
Use -ffp-contract=off to disable all contraction, or -ffp-contract=on to disable it between statements (which currently actually disables all contraction, as the FMA generation doesn't know what was originally a single source expression). The default in the absence of such -std options is -ffp-contract=fast (allowing contraction including between different statements). -- Joseph S. Myers jos...@codesourcery.com
