+Mon Mar 15 16:01:52 1999 Jim Wilson <wilson@cygnus.com>
+
+ * config/misp/mips.h (REGISTER_MOVE_COST): Make the cost of moving
+ from HI/LO/HILO/MD into general registers the same as for one
+ of moving general registers to HI/LO/HILO/MD.
+
Mon Mar 15 12:39:38 1999 Nick Clifton <nickc@cygnus.com>
* config/m32r/m32r.c (init_idents): New function. Initialise
that the constraints of the insn are met. Setting a cost of
other than 2 will allow reload to verify that the constraints are
met. You should do this if the `movM' pattern's constraints do
- not allow such copying. */
+ not allow such copying.
+
+ ??? We make make the cost of moving from HI/LO/HILO/MD into general
+ registers the same as for one of moving general registers to
+ HI/LO/HILO/MD for TARGET_MIPS16 in order to prevent allocating a
+ pseudo to HI/LO/HILO/MD. This might hurt optimizations though, it
+ isn't clear if it is wise. And it might not work in all cases. We
+ could solve the DImode LO reg problem by using a multiply, just like
+ reload_{in,out}si. We could solve the SImode/HImode HI reg problem
+ by using divide instructions. divu puts the remainder in the HI
+ reg, so doing a divide by -1 will move the value in the HI reg for
+ all values except -1. We could handle that case by using a signed
+ divide, e.g. -1 / 2 (or maybe 1 / -2?). We'd have to emit a
+ compare/branch to test the input value to see which instruction we
+ need to use. This gets pretty messy, but it is feasible. */
#define REGISTER_MOVE_COST(FROM, TO) \
((FROM) == M16_REGS && GR_REG_CLASS_P (TO) ? 2 \
&& ((TO) == M16_REGS || (TO) == M16_NA_REGS)) ? 6 \
: (((FROM) == HI_REG || (FROM) == LO_REG \
|| (FROM) == MD_REGS || (FROM) == HILO_REG) \
- && GR_REG_CLASS_P (TO)) ? (TARGET_MIPS16 ? 8 : 6) \
+ && GR_REG_CLASS_P (TO)) ? (TARGET_MIPS16 ? 12 : 6) \
: (((TO) == HI_REG || (TO) == LO_REG \
|| (TO) == MD_REGS || (TO) == HILO_REG) \
&& GR_REG_CLASS_P (FROM)) ? (TARGET_MIPS16 ? 12 : 6) \