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i386 address_cost tweek
- To: Richard Henderson <rth at redhat dot com>, Jan Hubicka <jh at suse dot cz>, gcc-patches at gcc dot gnu dot org
- Subject: i386 address_cost tweek
- From: Jan Hubicka <jh at suse dot cz>
- Date: Tue, 7 Aug 2001 22:00:30 +0200
Hi,
the is second half of the strength reduction tweek. I wanted to benchmark it
first and I got only improvements (noticeable - 12% in artifical benchmarks, I
am not sure how much in practical, at least I got no degradation).
Bootstrapped/regtested i386 toghether with my previous patch.
Honza
Tue Aug 7 21:58:43 CEST 2001 Jan Hubicka <jh@suse.cz>
* i386.c (ix86_address_cost): Be more curefull about preferring
complex addresses.
Index: gcc/config/i386/i386.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/config/i386/i386.c,v
retrieving revision 1.292
diff -c -3 -p -r1.292 i386.c
*** i386.c 2001/08/04 16:46:00 1.292
--- i386.c 2001/08/07 18:36:27
*************** ix86_address_cost (x)
*** 3039,3045 ****
rtx x;
{
struct ix86_address parts;
! int cost = 1;
if (!ix86_decompose_address (x, &parts))
abort ();
--- 3039,3045 ----
rtx x;
{
struct ix86_address parts;
! int cost = 3;
if (!ix86_decompose_address (x, &parts))
abort ();
*************** ix86_address_cost (x)
*** 3047,3052 ****
--- 3047,3056 ----
/* More complex memory references are better. */
if (parts.disp && parts.disp != const0_rtx)
cost--;
+ if (parts.disp && GET_CODE (parts.disp) == CONST)
+ cost--;
+ if (parts.scale != 1)
+ cost--;
/* Attempt to minimize number of registers in the address. */
if ((parts.base
*************** ix86_address_cost (x)
*** 3054,3067 ****
|| (parts.index
&& (!REG_P (parts.index)
|| REGNO (parts.index) >= FIRST_PSEUDO_REGISTER)))
! cost++;
if (parts.base
&& (!REG_P (parts.base) || REGNO (parts.base) >= FIRST_PSEUDO_REGISTER)
&& parts.index
&& (!REG_P (parts.index) || REGNO (parts.index) >= FIRST_PSEUDO_REGISTER)
&& parts.base != parts.index)
! cost++;
/* AMD-K6 don't like addresses with ModR/M set to 00_xxx_100b,
since it's predecode logic can't detect the length of instructions
--- 3058,3071 ----
|| (parts.index
&& (!REG_P (parts.index)
|| REGNO (parts.index) >= FIRST_PSEUDO_REGISTER)))
! cost += 3;
if (parts.base
&& (!REG_P (parts.base) || REGNO (parts.base) >= FIRST_PSEUDO_REGISTER)
&& parts.index
&& (!REG_P (parts.index) || REGNO (parts.index) >= FIRST_PSEUDO_REGISTER)
&& parts.base != parts.index)
! cost += 3;
/* AMD-K6 don't like addresses with ModR/M set to 00_xxx_100b,
since it's predecode logic can't detect the length of instructions