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--- trunk/gcc/simplify-rtx.c 2011/10/28 05:55:10 180603
+++ trunk/gcc/simplify-rtx.c 2011/10/28 06:35:31 180604
@@ -4352,10 +4352,20 @@
{
rtx x = XEXP (op0, 0);
rtx c = XEXP (op0, 1);
+ enum rtx_code invcode = op0code == PLUS ? MINUS : PLUS;
+ rtx tem = simplify_gen_binary (invcode, cmp_mode, op1, c);
- c = simplify_gen_binary (op0code == PLUS ? MINUS : PLUS,
- cmp_mode, op1, c);
- return simplify_gen_relational (code, mode, cmp_mode, x, c);
+ /* Detect an infinite recursive condition, where we oscillate at this
+ simplification case between:
+ A + B == C <---> C - B == A,
+ where A, B, and C are all constants with non-simplifiable expressions,
+ usually SYMBOL_REFs. */
+ if (GET_CODE (tem) == invcode
+ && CONSTANT_P (x)
+ && rtx_equal_p (c, XEXP (tem, 1)))
+ return NULL_RTX;
+
+ return simplify_gen_relational (code, mode, cmp_mode, x, tem);
}
/* (ne:SI (zero_extract:SI FOO (const_int 1) BAR) (const_int 0))) is
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