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(expand_expr): In NOP_EXPR case, truncate and reextend integer constants.

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From-SVN: r2987
This commit is contained in:
Richard Stallman 1992-12-30 07:08:14 +00:00
parent fb92d909c6
commit 12342f9055
1 changed files with 37 additions and 1 deletions
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38
gcc/expr.c
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@ -4134,7 +4134,43 @@ expand_expr (exp, target, tmode, modifier)
return target;
}
op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, mode, 0);
if (GET_MODE (op0) == mode || GET_MODE (op0) == VOIDmode)
if (GET_MODE (op0) == mode)
return op0;
/* If arg is a constant integer being extended from a narrower mode,
we must really truncate to get the extended bits right. Otherwise
(unsigned long) (unsigned char) ("\377"[0])
would come out as ffffffff. */
if (GET_MODE (op0) == VOIDmode
&& (GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))))
< GET_MODE_BITSIZE (mode)))
{
/* MODE must be narrower than HOST_BITS_PER_INT. */
int width = GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))));
if (width < HOST_BITS_PER_WIDE_INT)
{
HOST_WIDE_INT val = (GET_CODE (op0) == CONST_INT ? INTVAL (op0)
: CONST_DOUBLE_LOW (op0));
if (TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)))
|| !(val & ((HOST_WIDE_INT) 1 << (width - 1))))
val &= ((HOST_WIDE_INT) 1 << width) - 1;
else
val |= ~(((HOST_WIDE_INT) 1 << width) - 1);
op0 = GEN_INT (val);
}
else
{
op0 = (simplify_unary_operation
((TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)))
? ZERO_EXTEND : SIGN_EXTEND),
mode, op0,
TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)))));
if (op0 == 0)
abort ();
}
}
if (GET_MODE (op0) == VOIDmode)
return op0;
if (modifier == EXPAND_INITIALIZER)
return gen_rtx (unsignedp ? ZERO_EXTEND : SIGN_EXTEND, mode, op0);