re PR target/91769 (wrong code with -O2 on MIPS)

re PR target/91769 (wrong code with -O2 on MIPS)

Fix PR target/91769

This fixes the issue by checking that addr's base reg is not part of dest
multiword reg instead just checking the first reg of dest.

gcc/ChangeLog:

2019-10-03  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

	PR target/91769
	* config/mips/mips.c (mips_split_move): Use reg_overlap_mentioned_p
	instead of REGNO equality check on addr.reg.

gcc/testsuite/ChangeLog:

2019-10-03  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

	PR target/91769
	* gcc.target/mips/pr91769.c: New test.

From-SVN: r276525