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LoongArch: fix signed overflow in loongarch_emit_int_compare

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Signed overflow is an undefined behavior, so we need to prevent it from
happening, instead of "checking" the result.

gcc/ChangeLog:

	* config/loongarch/loongarch.cc (loongarch_emit_int_compare):
	Avoid signed overflow.
This commit is contained in:
Xi Ruoyao 2022-11-04 01:35:25 +08:00
parent 1f9c79367e
commit d699d32f47
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GPG key ID: ACAAD20E19E710E3
1 changed files with 5 additions and 2 deletions
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7
gcc/config/loongarch/loongarch.cc
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@ -4178,10 +4178,13 @@ loongarch_emit_int_compare (enum rtx_code *code, rtx *op0, rtx *op1)
if (!increment && !decrement)
continue;
if ((increment && rhs == HOST_WIDE_INT_MAX)
|| (decrement && rhs == HOST_WIDE_INT_MIN))
break;
new_rhs = rhs + (increment ? 1 : -1);
if (loongarch_integer_cost (new_rhs)
< loongarch_integer_cost (rhs)
&& (rhs < 0) == (new_rhs < 0))
< loongarch_integer_cost (rhs))
{
*op1 = GEN_INT (new_rhs);
*code = mag_comparisons[i][increment];