Thomas Symalla 18839aec4e [AMDGPU] Detect kills in register sets when trying to form V_CMPX instructions. (#68293) ...

During the SIOptimizeExecMasking pass, we try to form V_CMPX
instructions by detecting S_AND_SAVEEXEC and V_MOV instructions.
Generally, we require the input operand of the V_MOV, which is the input
operand to the to-be-formed V_CMPX, to be alive. This is forced by
clearing the kill flags on the operand after V_CMPX has been generated.

However, if we have a kill of a register set that contains said
register, this will not be detected by clearKillFlags.
With this change, possible additional kill-flag candidates will be
detected during the final call to findInstrBackwards and then, the kill
flag will be removed to keep all registers in the set alive.

Co-authored-by: Thomas Symalla <thomas.symalla@amd.com>

2023-11-02 10:36:27 +01:00

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