Currently there are optimizations for the fsub instruction that do not fire for a constrained fsub. Add some of these optimizations.
Optimizations that require teaching the IR matchers about the constrained intrinsics are for a future patch.
kpn on Aug 2 2021, 9:19 AM.Authored by
Update for review comments. Instructions that are "maytrap" where a SNaN may be seen must not be eliminated.
I've also added tests for transforms that won't fire due to a lack of IR matcher support. We're going through codepaths we weren't before so we're testing what we weren't before.
Please add the test file as a preliminary commit. Then update here to show the code diffs. Also as part of this patch, apply comments on the tests that are intentionally not changing and/or are expected to change later (TODO).