[PATCH] D29872: Do not legalize large add with addc/adde, introduce addcarry and do it with uaddo/addcarry

[Zvi Rackover via Phabricator via llvm-commits]

zvi added inline comments.


================
Comment at: lib/Target/X86/X86ISelLowering.cpp:23103
+
+  // Let legalize expand this if it isn't a legal type yet.
+  if (!DAG.getTargetLoweringInfo().isTypeLegal(VT))
----------------
deadalnix wrote:
> zvi wrote:
> > I know this also appears at the top of LowerADDC_ADDE_SUBC_SUBE, but why it this check needed?
> Because in that case, the backend wants to run some extra legalization code before coming back there.
At the time this code runs, there should not be any illegal types present in the DAG. 
So i am asking why is there a need to check for illegal types?


https://reviews.llvm.org/D29872