[PATCH] D14067: [FPEnv Core 02/14] Add FPEnv access flags to fast-math flags

[David Majnemer via llvm-commits]

majnemer added a subscriber: majnemer.
majnemer added a comment.

I'd like to propose a mildly different design; I'd phrase the two flags using a positive perspective:

- `nexc`: Assume that floating-point exceptions are not relevant.
- `nrnd`: Assume that the rounding-mode is round-to-nearest (ties even).

This has the nice property that `fast` is the union of all flags and, in general, keeps things consistent with all the other fast math flags.  The general pattern is that adding flags permits further optimization; places where this is violated have been a wellspring of bugs (namely `volatile`).

Older bitcode would have to be auto-upgraded to add those flags onto older instructions.


Repository:
  rL LLVM

http://reviews.llvm.org/D14067