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Re: RFA: Fix rtl-optimization/22258
Joern RENNECKE wrote:
Bernd Schmidt wrote:
Example? Why isn't this caught by cant_combine_insn_p?
Look at the rtl dumps in the PR. none of the combined insns mentions
a CLASS_LIKELY_SPILLED_P register. i3 is insn 31, which is
preceded by insn 30. insn30 is not included in the combination attempt,
put it sets fr0, which is CLASS_LIKLEY_SPILLED_P. insn 30 and
insn 31 (and to some extent the clobber in insn 29) together implement
the return value copy.
Ok, I see. I must say I'm not very fond of introducing hard reg
references into complex insns during combine; I'd prefer
cant_combine_insn_p to just reject any moves involving hardregs. My
initial version of that function did that, but in
Dale Johannesen claims that restricting the test to
CLASS_LIKELY_SPILLED_P is a win on PPC. I'm curious why.