Alex Richardson 2259ce8c91 [RISC-V] ADDI/ORI/XORI x, 0 should be as cheap as a move
The isTriviallyRematerializable hook is only called for instructions that are
tagged as isAsCheapAsAMove. Since ADDI 0 is used for "mv" it should definitely
be marked with "isAsCheapAsAMove". This change avoids one stack spill in most of
the atomic-rmw.ll tests functions. It also avoids stack spills in two of our
out-of-tree CHERI tests.
ORI/XORI with zero may or may not be the same as a move micro-architecturally,
but since we are already doing it for register == x0, we might as well
do the same if the immediate is zero.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D86480
2020-08-27 10:32:22 +01:00
..
2019-06-18 14:29:45 +00:00
2019-09-17 11:15:35 +00:00
2019-09-17 11:15:35 +00:00