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Re: PATCH: tune ARM's rtx_costs function
- From: James Lemke <jim at wasabisystems dot com>
- To: Richard dot Earnshaw at arm dot com
- Cc: Ben Elliston <bje at wasabisystems dot com>, gcc-patches at gcc dot gnu dot org
- Date: 09 Oct 2003 12:48:42 -0400
- Subject: Re: PATCH: tune ARM's rtx_costs function
- Organization:
- References: <200310080849.h988neY07765@pc960.cambridge.arm.com>
Try 3...
Timings at -O0 soon.
Jim.
2003-07-07 James Lemke <jim@wasabisystems.com>
* config/arm/arm.c (arm_rtx_costs): Improve for xscale multiply.
* config/arm/arm.md (addsi3): Use new pseudo.
* testsuite/gcc.dg/arm-g2.c: New file.
Index: gcc/config/arm/arm.c
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/config/arm/arm.c,v
retrieving revision 1.294
diff -u -r1.294 arm.c
--- gcc/config/arm/arm.c 7 Oct 2003 08:49:35 -0000 1.294
+++ gcc/config/arm/arm.c 9 Oct 2003 13:40:15 -0000
@@ -3315,19 +3315,41 @@
{
unsigned HOST_WIDE_INT i = (INTVAL (XEXP (x, 1))
& (unsigned HOST_WIDE_INT) 0xffffffff);
- int add_cost = const_ok_for_arm (i) ? 4 : 8;
- int j;
+ int cost, const_ok = const_ok_for_arm (i);
+ int j, booth_unit_size;
+
+ if (arm_tune_xscale)
+ {
+ unsigned HOST_WIDE_INT masked_const;
+
+ /* The cost will be related to two insns.
+ First a load of the constant (MOV or LDR), then a multiply. */
+ cost = 2;
+ if (! const_ok)
+ cost += 1; /* LDR is probably more expensive because
+ of longer result latency. */
+ masked_const = i & 0xffff8000;
+ if (masked_const != 0 && masked_const != 0xffff8000)
+ {
+ masked_const = i & 0xf8000000;
+ if (masked_const == 0 || masked_const == 0xf8000000)
+ cost += 1;
+ else
+ cost += 2;
+ }
+ return cost;
+ }
/* Tune as appropriate. */
- int booth_unit_size = ((tune_flags & FL_FAST_MULT) ? 8 : 2);
-
+ cost = const_ok ? 4 : 8;
+ booth_unit_size = ((tune_flags & FL_FAST_MULT) ? 8 : 2);
for (j = 0; i && j < 32; j += booth_unit_size)
{
i >>= booth_unit_size;
- add_cost += 2;
+ cost += 2;
}
- return add_cost;
+ return cost;
}
return (((tune_flags & FL_FAST_MULT) ? 8 : 30)
Index: gcc/config/arm/arm.md
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/config/arm/arm.md,v
retrieving revision 1.141
diff -u -r1.141 arm.md
--- gcc/config/arm/arm.md 7 Oct 2003 08:49:36 -0000 1.141
+++ gcc/config/arm/arm.md 9 Oct 2003 13:28:16 -0000
@@ -520,8 +520,7 @@
if (TARGET_ARM && GET_CODE (operands[2]) == CONST_INT)
{
arm_split_constant (PLUS, SImode, INTVAL (operands[2]), operands[0],
- operands[1],
- (no_new_pseudos ? 0 : preserve_subexpressions_p ()));
+ operands[1], ! no_new_pseudos);
DONE;
}
"
--
James Lemke jim@wasabisystems.com Orillia, Ontario
http://www.wasabisystems.com