[PATCH] D74436: Change clang option -ffp-model=precise to select ffp-contract=on

Fri Feb 14 08:32:27 PST 2020

jsji added a comment.

In D74436#1875320 <https://reviews.llvm.org/D74436#1875320>, @mibintc wrote:

> @jsji Will your backend tolerate -ffp-contract=on if optimizations are not disabled, e.g. -O2?  We are proposing that the default floating point model be -ffp-model=precise, and with precise model, the ffp-contract=on. However you are right we don't want the frontend to create FMA when optimizations are disabled -O0

We normally default to `-ffp-contract=on ` only for -O3 and above (for legacy compilers XL/gcc on PowerPC).
But yes, I think we are OK to accept  `-ffp-contract=on` (not `-ffp-contract=fast`)  at -O2 if there are strong justifications to do so on clang.

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D74436/new/

https://reviews.llvm.org/D74436