[PATCH] D28883: DAG: Recognize no-signed-zeros-fp-math attribute

[Justin Lebar via Phabricator via llvm-commits]

jlebar added inline comments.


================
Comment at: lib/Target/TargetMachine.cpp:91
+  if (Options.UnsafeFPMath) {
+    // Should this imply the others?
+    Options.NoSignedZerosFPMath = true;
----------------
jlebar wrote:
> Personally I'd prefer to do this in a separate patch, and to make a reasonable attempt at updating our documentation to say that this implies the others.  It was only after working on these flags for a few weeks that I even realized that UnsafeFPMath implies the others in IR (and therefore that it should imply the others elsewhere).
> 
> I even went as far as to add a separate unsafe-fp-math flag to XLA separate from the fast-math flag.  Oops.  :)
Oh, I see why you're doing it here -- you don't want to regress existing codegen that sets UnsafeFPMath but not this flag (which is new).

I guess you have to do it this way.  We should still do this with the intent to update the docs and set the other flags, though.


https://reviews.llvm.org/D28883