https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113510
Vladimir Makarov <vmakarov at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |vmakarov at gcc dot gnu.org
--- Comment #4 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
This is not a RA bug. I believe it is a bug in peephole optimization.
Right after LRA and before peephole2 we have:
(insn 28 13 15 2 (set (reg:SI 12 ip [127])
(const_int 8 [0x8]))
"../../gcc/gcc/testsuite/gcc.c-torture/compile/nested-3.c":17:10 959
{*thumb1_movsi_insn}
(nil))
(insn 15 28 16 2 (set (reg:SI 12 ip [127])
(plus:SI (reg:SI 12 ip [127])
(reg/f:SI 13 sp)))
"../../gcc/gcc/testsuite/gcc.c-torture/compile/nested-3.c":17:10 935
{*thumb1_addsi3}
(nil))
and peephole2 combines these two insns into
(insn 39 13 16 2 (set (reg:SI 12 ip [127])
(plus:SI (reg/f:SI 13 sp)
(const_int 8 [0x8])))
"../../gcc/gcc/testsuite/gcc.c-torture/compile/nested-3.c":17:10 -1
(nil))
which is wrong as output and the 1st operand of *thumb1_addsi3 should be a low
register but r12 is not a low register. If peephole2 took this into account,
it would have not combined the 2 insns and we would have not this PR.
