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re PR target/70465 (Poor code for x87 asm) 

PR target/70465
	* reg-stack.c (emit_swap_insn): Treat (float_extend:?F (mem:?F))
	and (const_double:?F) like (mem:?F) for the purpose of fxch %st(1)
	elimination by swapping fld*.

	* gcc.target/i386/pr70465-2.c: New test.

From-SVN: r245654
This commit is contained in:
Jakub Jelinek 2017-02-22 18:17:17 +01:00 committed by Jakub Jelinek
parent 6d3daa1afb
commit 888c705092
4 changed files with 49 additions and 5 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
2017-02-22 Jakub Jelinek <jakub@redhat.com>
PR target/70465
* reg-stack.c (emit_swap_insn): Treat (float_extend:?F (mem:?F))
and (const_double:?F) like (mem:?F) for the purpose of fxch %st(1)
elimination by swapping fld*.
2017-02-22 Richard Biener <rguenther@suse.de>
PR tree-optimization/79673

17
gcc/reg-stack.c
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@ -895,12 +895,16 @@ emit_swap_insn (rtx_insn *insn, stack_ptr regstack, rtx reg)
just use
fld b
fld a
if possible. */
if possible. Similarly for fld1, fldz, fldpi etc. instead of any
of the loads or for float extension from memory. */
i1src = SET_SRC (i1set);
if (GET_CODE (i1src) == FLOAT_EXTEND)
i1src = XEXP (i1src, 0);
if (REG_P (i1dest)
&& REGNO (i1dest) == FIRST_STACK_REG
&& MEM_P (SET_SRC (i1set))
&& !side_effects_p (SET_SRC (i1set))
&& (MEM_P (i1src) || GET_CODE (i1src) == CONST_DOUBLE)
&& !side_effects_p (i1src)
&& hard_regno == FIRST_STACK_REG + 1
&& i1 != BB_HEAD (current_block))
{
@ -930,6 +934,9 @@ emit_swap_insn (rtx_insn *insn, stack_ptr regstack, rtx reg)
&& (i2set = single_set (i2)) != NULL_RTX)
{
rtx i2dest = *get_true_reg (&SET_DEST (i2set));
rtx i2src = SET_SRC (i2set);
if (GET_CODE (i2src) == FLOAT_EXTEND)
i2src = XEXP (i2src, 0);
/* If the last two insns before insn that involve
stack regs are loads, where the latter (i1)
pushes onto the register stack and thus
@ -937,9 +944,9 @@ emit_swap_insn (rtx_insn *insn, stack_ptr regstack, rtx reg)
%st to %st(1), consider swapping them. */
if (REG_P (i2dest)
&& REGNO (i2dest) == FIRST_STACK_REG
&& MEM_P (SET_SRC (i2set))
&& (MEM_P (i2src) || GET_CODE (i2src) == CONST_DOUBLE)
/* Ensure i2 doesn't have other side-effects. */
&& !side_effects_p (SET_SRC (i2set))
&& !side_effects_p (i2src)
/* And that the two instructions can actually be
swapped, i.e. there shouldn't be any stores
in between i2 and i1 that might alias with

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-02-22 Jakub Jelinek <jakub@redhat.com>
PR target/70465
* gcc.target/i386/pr70465-2.c: New test.
2017-02-21 Uros Bizjak <ubizjak@gmail.com>
* gcc.dg/pr61441.c: Use dg-add-options ieee.

25
gcc/testsuite/gcc.target/i386/pr70465-2.c Normal file
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@ -0,0 +1,25 @@
/* PR target/70465 */
/* { dg-do compile } */
/* { dg-options "-Ofast -mfpmath=387 -fomit-frame-pointer" } */
/* { dg-final { scan-assembler-not "fxch\t%st.1" } } */
extern float d[1024];
static inline long double
foo (long double a, long double b)
{
return a < b ? a : b;
}
static inline long double
bar (long double a, long double b)
{
return a > b ? a : b;
}
float
baz (void)
{
long double c = d[0];
return foo (bar (c, 0.0l), 1.0l);
}