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re PR middle-end/18293 (Redundant copy operation introduced by expand)

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PR middle-end/18293
	* expmed.c (EXACT_POWER_OF_2_OR_ZERO_P): Move definition earlier.
	(expand_mult): Special case powers of two to avoid synth_mult.
	* loop.c (product_cheap_p): Handle case where expand_mult does
	require/generate any instructions (i.e. multiplication by zero).

From-SVN: r91851
This commit is contained in:
Roger Sayle 2004-12-08 02:15:36 +00:00 committed by Roger Sayle
parent b16bcb178a
commit 58b42e19f7
3 changed files with 31 additions and 6 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2004-12-07 Roger Sayle <roger@eyesopen.com>
PR middle-end/18293
* expmed.c (EXACT_POWER_OF_2_OR_ZERO_P): Move definition earlier.
(expand_mult): Special case powers of two to avoid synth_mult.
* loop.c (product_cheap_p): Handle case where expand_mult does
require/generate any instructions (i.e. multiplication by zero).
2004-12-07 Richard Henderson <rth@redhat.com>
* tree-pretty-print.c (dump_array_domain): Split out from

25
gcc/expmed.c
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@ -54,6 +54,9 @@ static void do_cmp_and_jump (rtx, rtx, enum rtx_code, enum machine_mode, rtx);
static rtx expand_smod_pow2 (enum machine_mode, rtx, HOST_WIDE_INT);
static rtx expand_sdiv_pow2 (enum machine_mode, rtx, HOST_WIDE_INT);
/* Test whether a value is zero of a power of two. */
#define EXACT_POWER_OF_2_OR_ZERO_P(x) (((x) & ((x) - 1)) == 0)
/* Nonzero means divides or modulus operations are relatively cheap for
powers of two, so don't use branches; emit the operation instead.
Usually, this will mean that the MD file will emit non-branch
@ -3024,11 +3027,25 @@ expand_mult (enum machine_mode mode, rtx op0, rtx op1, rtx target,
if (const_op1 && GET_CODE (const_op1) == CONST_INT
&& (unsignedp || !flag_trapv))
{
int mult_cost = rtx_cost (gen_rtx_MULT (mode, op0, op1), SET);
HOST_WIDE_INT coeff = INTVAL (const_op1);
int mult_cost;
if (choose_mult_variant (mode, INTVAL (const_op1), &algorithm, &variant,
/* Special case powers of two. */
if (EXACT_POWER_OF_2_OR_ZERO_P (coeff))
{
if (coeff == 0)
return const0_rtx;
if (coeff == 1)
return op0;
return expand_shift (LSHIFT_EXPR, mode, op0,
build_int_cst (NULL_TREE, floor_log2 (coeff)),
target, unsignedp);
}
mult_cost = rtx_cost (gen_rtx_MULT (mode, op0, op1), SET);
if (choose_mult_variant (mode, coeff, &algorithm, &variant,
mult_cost))
return expand_mult_const (mode, op0, INTVAL (const_op1), target,
return expand_mult_const (mode, op0, coeff, target,
&algorithm, variant);
}
@ -3627,8 +3644,6 @@ expand_sdiv_pow2 (enum machine_mode mode, rtx op0, HOST_WIDE_INT d)
(x mod 12) == (((x & 1023) + ((x >> 8) & ~3)) * 0x15555558 >> 2 * 3) >> 28
*/
#define EXACT_POWER_OF_2_OR_ZERO_P(x) (((x) & ((x) - 1)) == 0)
rtx
expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
rtx op0, rtx op1, rtx target, int unsignedp)

4
gcc/loop.c
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@ -9202,7 +9202,9 @@ product_cheap_p (rtx a, rtx b)
end_sequence ();
win = 1;
if (INSN_P (tmp))
if (tmp == NULL_RTX)
;
else if (INSN_P (tmp))
{
n_insns = 0;
while (tmp != NULL_RTX)