Hi all,
This hunk that slightly reduces the cost of immediate moves doesn't actually
have any effect.
In the whole of SPEC2006 it didn't make a difference. In any case, I'd like to
move to a point
where we use COSTS_N_INSNS units for our costs and not increment decrement them
by one.
This patch removes that bit of logic and makes it slightly cleaner to look at.
As far as I know
its logic has never been confirmed in practice.
Bootstrapped and tested on arm.
Ok for trunk?
Thanks,
Kyrill
2015-04-22 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
* config/arm/arm.c (arm_new_rtx_costs): Do not lower cost
immediate moves.
commit e225669ff70f09520007b7898b170fb8fa75281f
Author: Kyrylo Tkachov <kyrylo.tkac...@arm.com>
Date: Wed Apr 8 10:18:23 2015 +0100
[ARM] Do not lower cost of setting core reg to constant. It doesn't have any effect
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 0ef05c9..03988ac 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -9725,11 +9725,7 @@ arm_new_rtx_costs (rtx x, enum rtx_code code, enum rtx_code outer_code,
and we would otherwise be unable to work out the true cost. */
*cost = rtx_cost (SET_DEST (x), SET, 0, speed_p);
outer_code = SET;
- /* Slightly lower the cost of setting a core reg to a constant.
- This helps break up chains and allows for better scheduling. */
- if (REG_P (SET_DEST (x))
- && REGNO (SET_DEST (x)) <= LR_REGNUM)
- *cost -= 1;
+
x = SET_SRC (x);
/* Immediate moves with an immediate in the range [0, 255] can be
encoded in 16 bits in Thumb mode. */
