https://gcc.gnu.org/bugzilla/show_bug.cgi?id=16798
Segher Boessenkool <segher at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |segher at gcc dot gnu.org
--- Comment #7 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Combine starts with
insn_cost 4 for 11: {r122:DI=r126:DI>>0x34;clobber ca:DI;}
REG_DEAD r126:DI
REG_UNUSED ca:DI
insn_cost 8 for 12: r127:DI=[unspec[`*.LC1',%2:DI] 46]
REG_EQUAL `j'
insn_cost 4 for 13: [r127:DI]=r122:DI
REG_DEAD r127:DI
insn_cost 4 for 16: r128:CC=cmp(r122:DI,0)
REG_DEAD r122:DI
and we want 11 and 16 combined (later passes put 16 earlier btw).
But combine does not try to combine anything into 16: the first use of r122
as set in insn 11 is insn 13, not insn 16, and 11+13 does not combine.
But 11+13+16 is not tried. Maybe we should?
