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i386.c (ix86_decompose_address): Avoid useless 0 displacement.

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* config/i386/i386.c (ix86_decompose_address): Avoid useless
	0 displacement.  Add 0 displacement if base is %[er]bp or %r13.

From-SVN: r147982
This commit is contained in:
Jakub Jelinek 2009-05-29 19:00:35 +02:00 • committed by Jakub Jelinek
parent 725fd454ae
commit a0987204c5
2 changed files with 18 additions and 5 deletions
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3
gcc/ChangeLog
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@ -1,5 +1,8 @@
2009-05-29 Jakub Jelinek <jakub@redhat.com>
* config/i386/i386.c (ix86_decompose_address): Avoid useless
0 displacement. Add 0 displacement if base is %[er]bp or %r13.
* config/i386/i386.md (prefix_data16, prefix_rep): Set to 0 for
TYPE_SSE{MULADD,4ARG,IADD1,CVT1} by default.
(prefix_rex): For UNIT_MMX don't imply the prefix by default

20
gcc/config/i386/i386.c
View file

@ -8900,6 +8900,10 @@ ix86_decompose_address (rtx addr, struct ix86_address *out)
base_reg = base && GET_CODE (base) == SUBREG ? SUBREG_REG (base) : base;
index_reg = index && GET_CODE (index) == SUBREG ? SUBREG_REG (index) : index;
/* Avoid useless 0 displacement. */
if (disp == const0_rtx && (base || index))
disp = NULL_RTX;
/* Allow arg pointer and stack pointer as index if there is not scaling. */
if (base_reg && index_reg && scale == 1
&& (index_reg == arg_pointer_rtx
@ -8911,10 +8915,16 @@ ix86_decompose_address (rtx addr, struct ix86_address *out)
tmp = base_reg, base_reg = index_reg, index_reg = tmp;
}
/* Special case: %ebp cannot be encoded as a base without a displacement. */
if ((base_reg == hard_frame_pointer_rtx
|| base_reg == frame_pointer_rtx
|| base_reg == arg_pointer_rtx) && !disp)
/* Special case: %ebp cannot be encoded as a base without a displacement.
Similarly %r13. */
if (!disp
&& base_reg
&& (base_reg == hard_frame_pointer_rtx
|| base_reg == frame_pointer_rtx
|| base_reg == arg_pointer_rtx
|| (REG_P (base_reg)
&& (REGNO (base_reg) == HARD_FRAME_POINTER_REGNUM
|| REGNO (base_reg) == R13_REG))))
disp = const0_rtx;
/* Special case: on K6, [%esi] makes the instruction vector decoded.
@ -8928,7 +8938,7 @@ ix86_decompose_address (rtx addr, struct ix86_address *out)
disp = const0_rtx;
/* Special case: encode reg+reg instead of reg*2. */
if (!base && index && scale && scale == 2)
if (!base && index && scale == 2)
base = index, base_reg = index_reg, scale = 1;
/* Special case: scaling cannot be encoded without base or displacement. */