[PATCH] D54649: [FPEnv] Rough out constrained FCmp intrinsics

Mon Dec 3 08:34:45 PST 2018

uweigand added inline comments.

================
Comment at: lib/Target/X86/X86ISelLowering.cpp:26106
   case ISD::SETCC:              return LowerSETCC(Op, DAG);
+  case ISD::STRICT_FSETCC:      return LowerSTRICT_FSETCC(Op, DAG);
   case ISD::SETCCCARRY:         return LowerSETCCCARRY(Op, DAG);
----------------
cameron.mcinally wrote:
> uweigand wrote:
> > Why do you have this here?   It seems that this can never be called right now (at least without something like my D45576, right?)
> It actually will be called. Some SETCCs are always custom lowered on x86, even for scalars. 
> 
> The other constrained vector operations are all legal or expanded to legal scalar operations. SETCC is the first operation that needs the special lowering.
> 
> Just to be pedantic, I do realize this code is punting right now. The TableGen changes in this patch are quite involved. So I'd like for us to focus on those first. I will handle the STRICT_FSETCC peculiarities in a future patch.
But still, I don't see any place where common code would even call the back-end's getOperationAction on a STRICT_FSETCC.

E.g. when calling getStrictFPOperationAction with a STRICT_FSETCC, it will actually call the back-end with SETCC (not STRICT_FSETCC).  So this should already return Custom for you ...

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D54649/new/

https://reviews.llvm.org/D54649