[patch] h8300.md: Add a new peephole2.
Kazu Hirata
kazu@cs.umass.edu
Wed Feb 12 23:33:00 GMT 2003
Hi,
Attached is a patch to add a new peephole2. The new peephole2
transforms
cmp.l #-1,er1 ; compare -1 and er1
beq .L7 ; branch if equal
into
mov.l er1,er2 ; copy er1 to er2
inc.l #1,er2 ; increment er2
beq .L7 ; branch if equal
when er1 does not die, but a scratch register, er2 in this case, is
available. This transformation saves 2 bytes. The constants are
limited to -2, -1, 1, and 2.
Tested on h8300 port. Committed.
Kazu Hirata
2003-02-12 Kazu Hirata <kazu@cs.umass.edu>
* config/h8300/h8300.md (a peephole2): New.
Index: h8300.md
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/h8300/h8300.md,v
retrieving revision 1.163
diff -u -r1.163 h8300.md
--- h8300.md 12 Feb 2003 14:10:21 -0000 1.163
+++ h8300.md 12 Feb 2003 23:07:15 -0000
@@ -3561,6 +3561,36 @@
gen_rtx_NE (VOIDmode, cc0_rtx, const0_rtx) :
gen_rtx_EQ (VOIDmode, cc0_rtx, const0_rtx));")
+;; For constants like -1, -2, 1, 2, it is still cheaper to make a copy
+;; of the register being tested, do the subtraction on the copy, and
+;; then test the copy. We avoid this transformation if we see more
+;; than one copy of the same compare insn.
+
+(define_peephole2
+ [(match_scratch:SI 4 "r")
+ (set (cc0)
+ (compare:SI (match_operand:SI 0 "register_operand" "")
+ (match_operand:SI 1 "incdec_operand" "")))
+ (set (pc)
+ (if_then_else (match_operator 3 "eqne_operator"
+ [(cc0) (const_int 0)])
+ (label_ref (match_operand 2 "" ""))
+ (pc)))]
+ "(TARGET_H8300H || TARGET_H8300S)
+ && !peep2_reg_dead_p (1, operands[0])
+ && !rtx_equal_p (PATTERN (insn),
+ PATTERN (next_nonnote_insn (next_nonnote_insn (insn))))"
+ [(set (cc0)
+ (match_dup 0))
+ (set (pc)
+ (if_then_else (match_op_dup 3 [(cc0) (const_int 0)])
+ (label_ref (match_dup 2))
+ (pc)))]
+ "emit_move_insn (operands[4], operands[0]);
+ operands[0] = operands[4];
+ operands[1] = GEN_INT (- INTVAL (operands[1]));
+ split_adds_subs (SImode, operands, 1);")
+
;; Narrow the mode of testing if possible.
(define_peephole2
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