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(get_condition): Check for overflow when canonicalizing comparison. 

From-SVN: r2863
This commit is contained in:
Richard Kenner 1992-12-11 07:18:53 -05:00
parent 2af69b62de
commit d8cfa4ee64
1 changed files with 29 additions and 20 deletions
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49
gcc/loop.c
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@ -6386,34 +6386,43 @@ get_condition (jump, earliest)
if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC)
return 0;
/* Canonicalize any ordered comparison with integers involving equality. */
if (GET_CODE (op1) == CONST_INT)
/* Canonicalize any ordered comparison with integers involving equality
if we can do computations in the relevant mode and we do not
overflow. */
if (GET_CODE (op1) == CONST_INT
&& GET_MODE (op0) != VOIDmode
&& GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT)
{
HOST_WIDE_INT const_val = INTVAL (op1);
unsigned HOST_WIDE_INT uconst_val = const_val;
unsigned HOST_WIDE_INT max_val
= (unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (op0));
switch (code)
{
case LE:
code = LT;
op1 = GEN_INT (const_val + 1);
break;
{
case LE:
if (const_val != max_val >> 1)
code = LT, op1 = GEN_INT (const_val + 1);
break;
case GE:
code = GT;
op1 = GEN_INT (const_val - 1);
break;
case GE:
if (const_val
!= (((HOST_WIDE_INT) 1
<< (GET_MODE_BITSIZE (GET_MODE (op0)) - 1))))
code = GT, op1 = GEN_INT (const_val - 1);
break;
case LEU:
code = LTU;
op1 = GEN_INT (uconst_val + 1);
break;
case LEU:
if (uconst_val != max_val)
code = LTU, op1 = GEN_INT (uconst_val + 1);
break;
case GEU:
code = GTU;
op1 = GEN_INT (uconst_val - 1);
break;
}
case GEU:
if (uconst_val != 0)
code = GTU, op1 = GEN_INT (uconst_val - 1);
break;
}
}
/* If this was floating-point and we reversed anything other than an