2 Commits

Author SHA1 Message Date
Craig Topper
b6e2796114 [X86][TwoAddressInstructionPass] Teach tryInstructionCommute to continue checking for commutable FMA operands in more cases.
Previously we would only check for another commutable operand if the first commute was an aggressive commute.

But if we have two kill operands and neither is tied to the def at the start, we should consider both operands as the one to use as the new def.

This improves the loop in the fma-commute-loop.ll test. This test is derived from a post from discourse here https://llvm.discourse.group/t/unnecessary-vmovapd-instructions-generated-can-you-hint-in-favor-of-vfmadd231pd/582

Differential Revision: https://reviews.llvm.org/D75016
2020-03-01 16:38:08 -08:00
Craig Topper
76128cf624 [X86] Add FMA commuting test case for D75016
This test case shows extra moves due to not fully considering all
commuting opportunities.
2020-02-27 20:41:26 -08:00