As observed by @mikaelholmen, PR #130988
"[AMDGPU] Implement IR expansion for frem instruction" introduced a
regression on x86. Its changes led to the pass being skipped on
functions with the optnone attribute. @bjope also noted that a check
concerning the optnone handling is wrong.
This patch fixes both issues which together fixes the regression. During
the review it was observed that, even before PR #130988, the pass would
not run on optnone functions with the new pass manager. This is also
fixed.
This patch implements a correctly rounded expansion of the frem
instruction in LLVM IR. This is useful for target architectures for
which such an expansion is too involved to be implement in ISel
Lowering. The expansion is based on the code from the AMD device libs
and has been tested successfully against the OpenCL conformance tests on
amdgpu. The expansion is implemented in the preexisting "expand-fp"
pass. It replaces the expansion of "frem" in ISel for the amdgpu target;
it is enabled for targets which do not directly support "frem" and for
which no matching "fmod" LibCall is available.
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Co-authored-by: Matt Arsenault <Matthew.Arsenault@amd.com>
This is meant as a preparation for PR #130988 "[AMDGPU] Implement IR
expansion for frem instruction" which implements the expansion of
another instruction in this pass. The more general name seems more
appropriate given this change and quite reasonable even without it.
