[Bug target/79593] [6/7 Regression] Poor/Worse code generation for FPU on versions after 6

jakub at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Mon Feb 20 18:40:00 GMT 2017


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79593

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
With -Ofast -m32 -mfpmath=i387 it changed with r244816.

Why do you care about 32-bit code performance (and especially x87)?  That is
pure legacy, people who care about performance should be using -m64 or at least
-msse2 -mfpmath=sse (unless you need long double).

What I said still applies, the reason why the combiner doesn't optimize it is
that it has more than one use, which only goes away at regstack time and there
is no peephole afterwards that could improve it.


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