[PATCH] Lower FNEG ( FABS (x) ) -> FNABS (x) [X86 codegen] PR20578

[Sanjay Patel]

================
Comment at: lib/Target/X86/X86ISelLowering.cpp:12344
@@ +12343,3 @@
+  if (IsFABS)
+    for (SDNode *User : Op->uses())
+      if (User->getOpcode() == ISD::FNEG)
----------------
spatel wrote:
> delena wrote:
> > I think this check is not necessary because the graph always comes from bottom.
> Thanks for looking at this, Elena.
> 
> Without this check, all of the vector tests in the proposed test file fail because we process the FNEG first. I don't know why this is different between scalar and vector, but it is.
Sorry - that should have been process the *FABS* first.

http://reviews.llvm.org/D5201