https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70245
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Uroš Bizjak from comment #9)
> Please disable the pattern for gcc-6, and let's fix replace_rtx for gcc-7.
Disabling the peephole2 entirely would be too aggressive, if we want to avoid
the problems with that, we could as well just guard it with
&& !reg_overlap_mentioned_p (operands[0], operands[2])
or perhaps even allow simple cases like:
&& (!reg_overlap_mentioned_p (operands[0], operands[2])
|| rtx_equal_p (operands[0], XEXP (operands[2], 0)))
and in that case of simple REG just replace_equiv_address.
But, the simplify_replace_rtx patch I've attached will do pretty much the same,
it will try to do the peephole2, and punt if the result is not valid address.
simplify_replace_rtx doesn't simplify anything if there is no change, so e.g.
the
!reg_overlap_mentioned_p (operands[0], operands[2]) case would always work as
it used to.
Though, I'm worried about all the other replace_rtx uses in the backends:
config/epiphany/epiphany.md: replace_rtx (operands[2], operands[9],
operands[3]);
config/epiphany/epiphany.md: replace_rtx (operands[2], operands[0],
operands[10]);
config/i386/i386.c: replace_rtx (DF_REF_INSN (ref), reg, scopy);
config/rl78/rl78.c: OP (op) = replace_rtx (OP (op), gen_rtx_REG
(HImode, SP_REG), HL);
config/rs6000/rs6000.c: real = replace_rtx (real, reg2, rreg);
config/rs6000/rs6000.c: real = replace_rtx (real, reg,
config/sh/sh.md: replace_rtx (operands[4], operands[0], operands[1]);
config/xtensa/xtensa.c: PATTERN (insn) = replace_rtx (copy_rtx
(PATTERN (insn)),
The i386.c one is fine, reg is a pseudo, and there should be pointer
equivalency for pseudos I think. What about all the others?
