[PATCH] D62731: Add support for options -frounding-math, ftrapping-math, -fp-model=, and -fp-exception-behavior=, : Specify floating point behavior

[John McCall via Phabricator via cfe-commits]

rjmccall added a comment.

Is the exception-strictness of `-frounding-math` actually considered to be specified behavior, or is it just a consequence of the current implementation?  There are definitely some optimizations that we can't do under strict FP exceptions that we can still do in principle while respecting a dynamic FP rounding mode; for example, the rounding mode can only be changed by a call (or inline assembly), so you can still reorder FP operations around "lesser" side effects, like stores.  We can document it even if it's not required behavior, but we should be clear about what it is.

My suggested wording started with a sentence briefly summarizing what the option did that I think you accidentally dropped.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D62731/new/

https://reviews.llvm.org/D62731