Hi Guys,
I am applying the patch below to add a peephole optimization to the RX
backend. It was suggested by Kazuhio Inaoka at Renesas Japan, and
adapted by me to use peephole2 system. It finds a register move
followed by a comparison of the moved register against zero and
replaces the two instructions with a single addition instruction. The
addition does not actually do anything since the value being added is
zero, but as a side effect it moves the register and performs the
comparison.
Cheers
Nick
gcc/ChangeLog
2011-05-17 Kazuhio Inaoka <kazuhiro.inaoka...@renesas.com>
Nick Clifton <ni...@redhat.com>
* config/rx/rx.md: Add peepholes to match a register move followed
by a comparison of the moved register. Replace these with an
addition of zero that does both actions in one instruction.
Index: gcc/config/rx/rx.md
===================================================================
--- gcc/config/rx/rx.md (revision 173815)
+++ gcc/config/rx/rx.md (working copy)
@@ -904,6 +904,39 @@
(set_attr "length" "3,4,5,6,7,6")]
)
+;; Peepholes to match:
+;; (set (reg A) (reg B))
+;; (set (CC) (compare:CC (reg A/reg B) (const_int 0)))
+;; and replace them with the addsi3_flags pattern, using an add
+;; of zero to copy the register and set the condition code bits.
+(define_peephole2
+ [(set (match_operand:SI 0 "register_operand")
+ (match_operand:SI 1 "register_operand"))
+ (set (reg:CC CC_REG)
+ (compare:CC (match_dup 0)
+ (const_int 0)))]
+ ""
+ [(parallel [(set (match_dup 0)
+ (plus:SI (match_dup 1) (const_int 0)))
+ (set (reg:CC_ZSC CC_REG)
+ (compare:CC_ZSC (plus:SI (match_dup 1) (const_int 0))
+ (const_int 0)))])]
+)
+
+(define_peephole2
+ [(set (match_operand:SI 0 "register_operand")
+ (match_operand:SI 1 "register_operand"))
+ (set (reg:CC CC_REG)
+ (compare:CC (match_dup 1)
+ (const_int 0)))]
+ ""
+ [(parallel [(set (match_dup 0)
+ (plus:SI (match_dup 1) (const_int 0)))
+ (set (reg:CC_ZSC CC_REG)
+ (compare:CC_ZSC (plus:SI (match_dup 1) (const_int 0))
+ (const_int 0)))])]
+)
+
(define_expand "adddi3"
[(set (match_operand:DI 0 "register_operand")
(plus:DI (match_operand:DI 1 "register_operand")
