https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97142
--- Comment #11 from Segher Boessenkool <segher at gcc dot gnu.org> --- (In reply to luoxhu from comment #10) > If not built with fast-math, gimple_has_side_effects will return true and > cause the expand_call_stmt fail to expand the "_1 = fmod (x_2(D), y_3(D));" > to internal function. X86 also produces "bl fmod" for O3 build. > > > xlF expands the fmod to below ASM, no FMA generated? > > > 0000000010000900 <ggl>: > 10000900: 8c 03 01 10 vspltisw v0,1 > 10000904: 00 00 24 c8 lfd f1,0(r4) > 10000908: 00 00 03 c8 lfd f0,0(r3) > 1000090c: e2 03 40 f0 xvcvsxwdp vs2,vs32 > 10000910: c0 09 62 f0 xsdivdp vs3,vs2,vs1 > 10000914: 80 19 80 f0 xsmuldp vs4,vs0,vs3 > 10000918: 64 21 a0 f0 xsrdpiz vs5,vs4 > 1000091c: 88 2d 01 f0 xsnmsubadp vs0,vs1,vs5 > 10000920: 18 00 20 fc frsp f1,f0 > 10000924: 20 00 80 4e blr xsnmsubadp is an FMA. Multiply-subtract in this case, but that is just a sign switch -- I often say FMA for all of fmadd, fnmadd, fnmsub, fmsub, and their VSX counterparts. "Anything that does a multiply-type operation followed by an addition-type operation". (And often call integer MADs "FMA" as well, which is totally wrong, but :-) )
