https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108573
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |ebotcazou at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, I believe this has been caused by the r7-4871-g4da41abf84cc6796aa8b
PR78437 change.
/* On RISC machines we must make sure that changing the mode of SRC_REG
as destination register will not affect its reaching uses, which may
read its value in a larger mode because DEF_INSN implicitly sets it
in word mode. */
poly_int64 prec
= GET_MODE_PRECISION (GET_MODE (SET_DEST (*dest_sub_rtx)));
if (WORD_REGISTER_OPERATIONS && known_lt (prec, BITS_PER_WORD))
{
struct df_link *uses = get_uses (def_insn, src_reg);
if (!uses)
return false;
for (df_link *use = uses; use; use = use->next)
if (paradoxical_subreg_p (GET_MODE (*DF_REF_LOC (use->ref)),
GET_MODE (SET_DEST (*dest_sub_rtx))))
return false;
}
The problem is that without -g, there are just 2 uses:
(insn 10029 10027 10052 2 (set (reg:SI 10 a0 [167])
(minus:SI (reg:SI 10 a0 [160])
(reg:SI 9 s1 [165]))) "pr108573.c":12:5 12 {subsi3}
(nil))
and
(insn 10023 9 10027 2 (set (reg:DI 15 a5 [orig:139 _6 ] [139])
(sign_extend:DI (reg:SI 10 a0 [160]))) "pr108573.c":11:5 116
{extendsidi2}
(nil))
but with -g there another one:
(debug_insn 8 7 9 2 (var_location:HI s (minus:HI (subreg:HI (and:DI (reg:DI 10
a0 [160])
(const_int 1 [0x1])) 0)
(subreg:HI (ashiftrt:DI (reg/v:DI 9 s1 [orig:151 l ] [151])
(debug_expr:SI D#1)) 0))) "pr108573.c":12:5 -1
(nil))
Now, because it uses DImode for a0 rather than SImode like the others, without
-g
we don't return false but with -g we do.
Code generation decisions shouldn't be based on the DEBUG_INSN uses.
So, at least in this decision we should ignore debug uses, we can then do
something with the DEBUG_INSNs, reset them, adjust, whatever (I think at least
the above one clearly doesn't care about the upper bits).
