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.
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@ -1,3 +1,8 @@
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2020-04-06 Jakub Jelinek <jakub@redhat.com>
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* cselib.c (cselib_subst_to_values): For SP_DERIVED_VALUE_P
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+ const0_rtx return the SP_DERIVED_VALUE_P.
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2020-04-06 Richard Sandiford <richard.sandiford@arm.com>
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PR rtl-optimization/92989
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18
gcc/cselib.c
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gcc/cselib.c
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@ -2090,13 +2090,17 @@ cselib_subst_to_values (rtx x, machine_mode memmode)
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{
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rtx t = cselib_subst_to_values (XEXP (x, 0), memmode);
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if (GET_CODE (t) == VALUE)
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for (struct elt_loc_list *l = CSELIB_VAL_PTR (t)->locs;
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l; l = l->next)
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if (GET_CODE (l->loc) == PLUS
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&& GET_CODE (XEXP (l->loc, 0)) == VALUE
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&& SP_DERIVED_VALUE_P (XEXP (l->loc, 0))
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&& CONST_INT_P (XEXP (l->loc, 1)))
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return plus_constant (Pmode, l->loc, INTVAL (XEXP (x, 1)));
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{
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if (SP_DERIVED_VALUE_P (t) && XEXP (x, 1) == const0_rtx)
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return t;
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for (struct elt_loc_list *l = CSELIB_VAL_PTR (t)->locs;
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l; l = l->next)
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if (GET_CODE (l->loc) == PLUS
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&& GET_CODE (XEXP (l->loc, 0)) == VALUE
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&& SP_DERIVED_VALUE_P (XEXP (l->loc, 0))
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&& CONST_INT_P (XEXP (l->loc, 1)))
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return plus_constant (Pmode, l->loc, INTVAL (XEXP (x, 1)));
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}
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if (t != XEXP (x, 0))
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{
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copy = shallow_copy_rtx (x);
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