https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55212
--- Comment #133 from Kazumoto Kojima <kkojima at gcc dot gnu.org> --- Created attachment 58834 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58834&action=edit a testcase for r0-starvation issue with -mlra The second one I've found has a bit lengthy testcases for -O2 -mlra. It seems that LRA fails with r0-starvation for the pseudo code sequence like 98: r361:SI=sign_extend([r332:SI+0x2]) 607: r178:SI=r361:SI 101: r360:HI=r178:SI 606: [r336:SI+r359:SI]=r360:HI for example, which tries to use R0_REGS for both r361 and r359. If I remember correctly, a similar issue for mov<mode> was already known to be problematic with LRA and was handled specifically in sh.cc:prepare_move_operands.
