Remove global call sets: postreload.c

Remove global call sets: postreload.c

The "|= fixed_regs" in reload_combine isn't necessary, since the
set is only used to determine which values have changed (rather than,
for example, which registers are available for use).

In reload_cse_move2add we can be accurate about which registers
are still available.  BLKmode indicates a continuation of the
previous register, and since clobbers_reg_p handles multi-register
values, it's enough to skip over BLKmode entries and just test the
start register.

2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* postreload.c (reload_combine_recognize_pattern): Use crtl->abi
	when deciding whether a register is free for use after RA.
	(reload_combine): Remove unnecessary use of fixed_reg_set.
	(reload_cse_move2add): Use insn_callee_abi to get the ABI of the
	call insn target.  Use reg_mode when testing whether a register
	is no longer available.

From-SVN: r276328