[PATCH] D102673: [ConstantFolding] Fold constrained arithmetic intrinsics

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

Can you fix the formatting, so we don't have clang-tidy warnings? Those pop-up boxes are getting in the way of reading the code here in Phab.



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Comment at: llvm/lib/Analysis/ConstantFolding.cpp:1910-1911
+  RoundingMode RM = RoundingMode::Dynamic;
+  Optional<RoundingMode> ORM = CI->getRoundingMode();
+  if (ORM)
+    RM = *ORM;
----------------
sepavloff wrote:
> spatel wrote:
> > I think this would be easier to read if we made it more like the code above here:
> > 
> > ```
> >   Optional<RoundingMode> ORM = CI->getRoundingMode();
> >   // If no rounding mode is specified by the intrinsic or the mode is dynamic,
> >   // try to evaluate using the default mode. If it does not raise an inexact
> >   // exception, rounding was not applied so the result is independent of
> >   // rounding mode. 
> >   if (!ORM || *ORM == RoundingMode::Dynamic) 
> >     return RoundingMode::NearestTiesToEven;
> >   // Use the mode specified by the intrinsic.
> >   return *ORM;
> > ```
> > That's assuming I'm reading it correctly right now - are there tests with no RM specified on the intrinsic?
> > That's assuming I'm reading it correctly right now - are there tests with no RM specified on the intrinsic?
> 
> No, all affected intrinsics have such argument. Bu in other places such check is made, so I put it here also. 
I am not understanding something then.
If the metadata args for rounding mode and exception behavior are required by the LangRef:
https://llvm.org/docs/LangRef.html#llvm-experimental-constrained-fadd-intrinsic
...then why is the result of `getRoundingMode()` or `getExceptionBehavior()` an `Optional` value? If it is not valid IR without those args, we shouldn't be adding compile-time checks for things that can't happen.


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https://reviews.llvm.org/D102673