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cselib: Fix endless cselib loop on (plus:P (reg) (const_int 0)) 

getopt.c hangs the compiler on h8300-elf with -O2 -g, because the
IL contains addition of constant 0, the first PLUS operand is determined
to have the SP_DERIVED_VALUE_P and the new code in cselib recurses
indefinitely on seeing SP_DERIVED_VALUE_P with locs of
(plus:P SP_DERIVED_VALUE_P (const_int 0)).

Fixed by making sure cselib_subst_to_values canonicalizes it, hashing
already hashes it the same too.

2020-04-06  Jakub Jelinek  <jakub@redhat.com>

	* cselib.c (cselib_subst_to_values): For SP_DERIVED_VALUE_P
	+ const0_rtx return the SP_DERIVED_VALUE_P.
This commit is contained in:
Jakub Jelinek 2020-04-07 00:27:10 +02:00
parent e0fd9ce257
commit 8662d05934
2 changed files with 16 additions and 7 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2020-04-06 Jakub Jelinek <jakub@redhat.com>
* cselib.c (cselib_subst_to_values): For SP_DERIVED_VALUE_P
+ const0_rtx return the SP_DERIVED_VALUE_P.
2020-04-06 Richard Sandiford <richard.sandiford@arm.com>
PR rtl-optimization/92989

18
gcc/cselib.c
View File

@ -2090,13 +2090,17 @@ cselib_subst_to_values (rtx x, machine_mode memmode)
{
rtx t = cselib_subst_to_values (XEXP (x, 0), memmode);
if (GET_CODE (t) == VALUE)
for (struct elt_loc_list *l = CSELIB_VAL_PTR (t)->locs;
l; l = l->next)
if (GET_CODE (l->loc) == PLUS
&& GET_CODE (XEXP (l->loc, 0)) == VALUE
&& SP_DERIVED_VALUE_P (XEXP (l->loc, 0))
&& CONST_INT_P (XEXP (l->loc, 1)))
return plus_constant (Pmode, l->loc, INTVAL (XEXP (x, 1)));
{
if (SP_DERIVED_VALUE_P (t) && XEXP (x, 1) == const0_rtx)
return t;
for (struct elt_loc_list *l = CSELIB_VAL_PTR (t)->locs;
l; l = l->next)
if (GET_CODE (l->loc) == PLUS
&& GET_CODE (XEXP (l->loc, 0)) == VALUE
&& SP_DERIVED_VALUE_P (XEXP (l->loc, 0))
&& CONST_INT_P (XEXP (l->loc, 1)))
return plus_constant (Pmode, l->loc, INTVAL (XEXP (x, 1)));
}
if (t != XEXP (x, 0))
{
copy = shallow_copy_rtx (x);