craig.topper added a comment.
No test changes?
The transform would be legal with no signed zeros fast math flag right? I believe that's checked in getNegatedExpression. But not checked in the X86 specific override.
I think the same issue may also exist in ARMInstrVFP.td. It matches both (fneg (fma x, y, z)) and (fma (fneg x), y, (fneg z)) to the same instruction.
// Match @llvm.fma.* intrinsics
// (fneg (fma x, y, z)) -> (vfnma z, x, y)
def : Pat<(fneg (fma (f64 DPR:$Dn), (f64 DPR:$Dm), (f64 DPR:$Ddin))),
(VFNMAD DPR:$Ddin, DPR:$Dn, DPR:$Dm)>,
Requires<[HasVFP4,HasDPVFP]>;
def : Pat<(fneg (fma (f32 SPR:$Sn), (f32 SPR:$Sm), (f32 SPR:$Sdin))),
(VFNMAS SPR:$Sdin, SPR:$Sn, SPR:$Sm)>,
Requires<[HasVFP4]>;
def : Pat<(fneg (fma (f16 HPR:$Sn), (f16 HPR:$Sm), (f16 (f16 HPR:$Sdin)))),
(VFNMAH (f16 HPR:$Sdin), (f16 HPR:$Sn), (f16 HPR:$Sm))>,
Requires<[HasFullFP16]>;
// (fma (fneg x), y, (fneg z)) -> (vfnma z, x, y)
def : Pat<(f64 (fma (fneg DPR:$Dn), DPR:$Dm, (fneg DPR:$Ddin))),
(VFNMAD DPR:$Ddin, DPR:$Dn, DPR:$Dm)>,
Requires<[HasVFP4,HasDPVFP]>;
def : Pat<(f32 (fma (fneg SPR:$Sn), SPR:$Sm, (fneg SPR:$Sdin))),
(VFNMAS SPR:$Sdin, SPR:$Sn, SPR:$Sm)>,
Requires<[HasVFP4]>;
def : Pat<(f16 (fma (fneg (f16 HPR:$Sn)), (f16 HPR:$Sm), (fneg (f16 HPR:$Sdin)))),
(VFNMAH (f16 HPR:$Sdin), (f16 HPR:$Sn), (f16 HPR:$Sm))>,
Requires<[HasFullFP16]>;
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https://reviews.llvm.org/D90901/new/
https://reviews.llvm.org/D90901