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[PATCH]: Optimization of X<->Y register move on HC11
- To: gcc-patches at gcc dot gnu dot org
- Subject: [PATCH]: Optimization of X<->Y register move on HC11
- From: Stephane Carrez <Stephane dot Carrez at worldnet dot fr>
- Date: Sat, 05 May 2001 09:08:00 +0200
Hi!
For a (set (reg x) (reg y)) it is faster to use the sequence 'xgdy; xgdx'
when both 'y' and 'd' are dead (a kind of 3-reg rotation). Likewise for
(set (reg y) (reg x)) with the sequence 'xgdx; xgdy'.
This patch implements this optimization. I've committed it on mainline
and 3_0-branch.
Stephane
2001-05-05 Stephane Carrez <Stephane.Carrez@worldnet.fr>
* config/m68hc11/m68hc11.c (m68hc11_gen_movhi): Optimize moves
between X and Y by using sequences of xgdx and xgdy.
Index: config/m68hc11/m68hc11.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/config/m68hc11/m68hc11.c,v
retrieving revision 1.9
diff -u -p -r1.9 m68hc11.c
--- m68hc11.c 2001/05/04 21:00:37 1.9
+++ m68hc11.c 2001/05/05 06:46:53
@@ -3135,8 +3135,20 @@ m68hc11_gen_movhi (insn, operands)
}
else if (Y_REG_P (operands[1]))
{
- output_asm_insn ("sty\t%t1", operands);
- output_asm_insn ("ldx\t%t1", operands);
+ /* When both D and Y are dead, use the sequence xgdy, xgdx
+ to move Y into X. The D and Y registers are modified. */
+ if (optimize && find_regno_note (insn, REG_DEAD, HARD_Y_REGNUM)
+ && dead_register_here (insn, d_reg))
+ {
+ output_asm_insn ("xgdy", operands);
+ output_asm_insn ("xgdx", operands);
+ CC_STATUS_INIT;
+ }
+ else
+ {
+ output_asm_insn ("sty\t%t1", operands);
+ output_asm_insn ("ldx\t%t1", operands);
+ }
}
else if (SP_REG_P (operands[1]))
{
@@ -3165,8 +3177,20 @@ m68hc11_gen_movhi (insn, operands)
}
else if (X_REG_P (operands[1]))
{
- output_asm_insn ("stx\t%t1", operands);
- output_asm_insn ("ldy\t%t1", operands);
+ /* When both D and X are dead, use the sequence xgdx, xgdy
+ to move X into Y. The D and X registers are modified. */
+ if (optimize && find_regno_note (insn, REG_DEAD, HARD_X_REGNUM)
+ && dead_register_here (insn, d_reg))
+ {
+ output_asm_insn ("xgdx", operands);
+ output_asm_insn ("xgdy", operands);
+ CC_STATUS_INIT;
+ }
+ else
+ {
+ output_asm_insn ("stx\t%t1", operands);
+ output_asm_insn ("ldy\t%t1", operands);
+ }
}
else if (SP_REG_P (operands[1]))
{