search for: fp32imm0

...ced a bunch of psuedo instructions used for creation of constants without generating loads. e.g. pxor xmm0, xmm0 Here is an example of what i am referring to snipped from X86InstrSSE.td: def FsFLD0SS : I<0xEF, MRMInitReg, (outs FR32:$dst), (ins), "", [(set FR32:$dst, fp32imm0)]>, Requires<[HasSSE1]>, TB, OpSize; My question is why was there a need to define such a pseudo instruction? Wouldn't it be cleaner to use a def: Pat<> which selects: pxor $dst, $dst from: [(set FR32:$dst, fp32imm0)] ? Thanks in advance. -----------...

...When compiling for a target without SSE2 support, there were some 128-bit PXOR instructions in the generated code. I traced it down to the following definition in X86InstrSSE.td: def FsFLD0SS : I<0xEF, MRMInitReg, (outs FR32:$dst), (ins), "", [(set FR32:$dst, fp32imm0)]>, Requires<[HasSSE1]>, TB, OpSize; I tried replacing the HasSSE1 with a HasSSE2 but that didn't do the trick. I noticed that TOT has a different definition and I tried substituting that as well but again no luck. Is there a simple way to make it work with LLVM...

...ithout > SSE2 support, there were some 128-bit PXOR instructions in the generated > code. > > I traced it down to the following definition in X86InstrSSE.td: > >   def FsFLD0SS : I<0xEF, MRMInitReg, (outs FR32:$dst), (ins), "", >                    [(set FR32:$dst, fp32imm0)]>, >                    Requires<[HasSSE1]>, TB, OpSize; > > I tried replacing the HasSSE1 with a HasSSE2 but that didn't do the > trick. I noticed that TOT has a different definition and I tried > substituting that as well but again no luck. Is there a simple way to &g...

Hi Jim, thank you for the quick response. I have used InstAlias in some cases, but these are really simple pseudo instructions where the pseudo instruction is more like a special case of existing one, like using fixed operand or simply a more human understandable way of presenting an operation. I know that there are predicates available to improve matching, but can InstAlias use conditions to