MIPS: avoid $gp store if global_pointer is not $gp

$GP is used for expanding GOT load, but in the afterward passes,
a temporary register is tried to replace $gp.

If sucess, we have no need to store and reload $gp. The example
of failure is that the function calls a preemtive function.

We shouldn't use $GP for any other purpose in the code we generate.
If a user's inline asm code clobbers $GP, it's their duty to save
and restore $GP.

gcc
	* config/mips/mips.cc (mips_compute_frame_info): If another
	register is used as global_pointer, mark $GP live false.

gcc/testsuite
	* gcc.target/mips/mips.exp (mips_option_groups):
	Add -mxgot/-mno-xgot options.
	* gcc.target/mips/xgot-n32-avoid-gp.c: New test.
	* gcc.target/mips/xgot-n32-need-gp.c: New test.

0 files changed, 0 insertions, 0 deletions