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Don't propagate for a more expensive reg-reg move.

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For i386, it enables optimization like:

        vmovd   %xmm0, %edx
-       vmovd   %xmm0, %eax
+       movl    %edx, %eax

gcc/ChangeLog:

	PR rtl-optimization/104059
	* regcprop.cc (copyprop_hardreg_forward_1): Don't propagate
	for a more expensive reg-reg move.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr104059.c: New test.
This commit is contained in:
liuhongt 2022-01-24 18:17:47 +08:00
parent cc2430c122
commit 0103c2e408
2 changed files with 38 additions and 1 deletions
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17
gcc/regcprop.cc
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@ -892,6 +892,7 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
if (set && REG_P (SET_SRC (set)))
{
rtx src = SET_SRC (set);
rtx dest = SET_DEST (set);
unsigned int regno = REGNO (src);
machine_mode mode = GET_MODE (src);
unsigned int i;
@ -915,7 +916,7 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
/* If the destination is also a register, try to find a source
register in the same class. */
if (REG_P (SET_DEST (set)))
if (REG_P (dest))
{
new_rtx = find_oldest_value_reg (REGNO_REG_CLASS (regno),
src, vd);
@ -943,6 +944,20 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
mode, i, regno);
if (new_rtx != NULL_RTX)
{
/* Don't propagate for a more expensive reg-reg move. */
if (REG_P (dest))
{
enum reg_class from = REGNO_REG_CLASS (regno);
enum reg_class to = REGNO_REG_CLASS (REGNO (dest));
enum reg_class new_from = REGNO_REG_CLASS (i);
unsigned int original_cost
= targetm.register_move_cost (mode, from, to);
unsigned int after_cost
= targetm.register_move_cost (mode, new_from, to);
if (after_cost > original_cost)
continue;
}
if (validate_change (insn, &SET_SRC (set), new_rtx, 0))
{
ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (src);

22
gcc/testsuite/gcc.target/i386/pr104059.c Normal file
View File

@ -0,0 +1,22 @@
/* { dg-do compile } */
/* { dg-options "-mavx2 -O2 -fdump-rtl-cprop_hardreg-details" } */
/* { dg-final { scan-rtl-dump-not {replaced reg [0-9]* with [0-9]*} "cprop_hardreg" } } */
#include<stdint.h>
int test (uint8_t *p, uint32_t t[1][1], int n) {
int sum = 0;
uint32_t a0;
for (int i = 0; i < 4; i++, p++)
t[i][0] = p[0];
for (int i = 0; i < 4; i++) {
{
int t0 = t[0][i] + t[0][i];
a0 = t0;
};
sum += a0;
}
return (((uint16_t)sum) + ((uint32_t)sum >> 16)) >> 1;
}