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Elide expand_constructor if move by pieces is preferred

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Elide expand_constructor when the constructor is static storage and not
mostly zeros and we can move it by pieces prefer to do so since that's
usually more efficient than performing a series of stores from immediates.

2021-05-21  Richard Biener  <rguenther@suse.de>
	    H.J. Lu  <hjl.tools@gmail.com>

gcc/

	PR middle-end/90773
	* expr.c (expand_constructor): Elide expand_constructor if
	move by pieces is preferred.

gcc/testsuite/

	* gcc.target/i386/pr90773-24.c: New test.
	* gcc.target/i386/pr90773-25.c: Likewise.
This commit is contained in:
H.J. Lu 2021-05-21 05:16:20 -07:00
parent 5d42db5333
commit 53fb833d63
3 changed files with 61 additions and 0 deletions
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13
gcc/expr.c
View file

@ -8523,6 +8523,19 @@ expand_constructor (tree exp, rtx target, enum expand_modifier modifier,
return constructor;
}
/* If the CTOR is available in static storage and not mostly
zeros and we can move it by pieces prefer to do so since
that's usually more efficient than performing a series of
stores from immediates. */
if (avoid_temp_mem
&& TREE_STATIC (exp)
&& TREE_CONSTANT (exp)
&& tree_fits_uhwi_p (TYPE_SIZE_UNIT (type))
&& can_move_by_pieces (tree_to_uhwi (TYPE_SIZE_UNIT (type)),
TYPE_ALIGN (type))
&& ! mostly_zeros_p (exp))
return NULL_RTX;
/* Handle calls that pass values in multiple non-contiguous
locations. The Irix 6 ABI has examples of this. */
if (target == 0 || ! safe_from_p (target, exp, 1)

23
gcc/testsuite/gcc.target/i386/pr90773-24.c Normal file
View file

@ -0,0 +1,23 @@
/* { dg-do compile { target { ! ia32 } } } */
/* { dg-options "-O2 -march=x86-64" } */
struct S
{
long long s1 __attribute__ ((aligned (8)));
unsigned s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14;
};
const struct S array[] = {
{ 0, 60, 640, 2112543726, 39682, 48, 16, 33, 10, 96, 2, 0, 0, 4 }
};
void
foo (struct S *x)
{
x[0] = array[0];
}
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, \\(%\[\^,\]+\\)" 1 } } */
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 16\\(%\[\^,\]+\\)" 1 } } */
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 32\\(%\[\^,\]+\\)" 1 } } */
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 48\\(%\[\^,\]+\\)" 1 } } */

25
gcc/testsuite/gcc.target/i386/pr90773-25.c Normal file
View file

@ -0,0 +1,25 @@
/* { dg-do compile { target { ! ia32 } } } */
/* { dg-options "-O2 -march=x86-64" } */
struct S
{
long long s1 __attribute__ ((aligned (8)));
unsigned s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14;
};
const struct S array[] = {
{ 0, }
};
void
foo (struct S *x)
{
x[0] = array[0];
}
/* { dg-final { scan-assembler-not "movdqa" } } */
/* { dg-final { scan-assembler-times "pxor\[\\t \]%xmm\[0-9\]+, %xmm\[0-9\]+" 1 } } */
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, \\(%\[\^,\]+\\)" 1 } } */
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 16\\(%\[\^,\]+\\)" 1 } } */
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 32\\(%\[\^,\]+\\)" 1 } } */
/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 48\\(%\[\^,\]+\\)" 1 } } */