Hi,
This patch is a small optimization for the RL78 target that uses the
'clrb' instruction where possible when performing a zero-extend instead
of 'mov'ing a literal #0. This saves a byte on each operation.
Regards,
Richard
2014-03-27 Richard Hulme <pepe...@yahoo.com>
* config/rl78/rl78-real.md (zero_extendqihi2_real):
Minor optimization to use clrb instruction where possible,
which is 1 byte shorter than 'mov'ing #0.
---
gcc/config/rl78/rl78-real.md | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/gcc/config/rl78/rl78-real.md b/gcc/config/rl78/rl78-real.md
index 27ff60f..3503a02 100644
--- a/gcc/config/rl78/rl78-real.md
+++ b/gcc/config/rl78/rl78-real.md
@@ -77,12 +77,13 @@
;;---------- Conversions ------------------------
(define_insn "*zero_extendqihi2_real"
- [(set (match_operand:HI 0 "nonimmediate_operand" "=rv,A")
- (zero_extend:HI (match_operand:QI 1 "general_operand" "0,a")))]
+ [(set (match_operand:HI 0 "nonimmediate_operand"
"=Bv,DT,A")
+ (zero_extend:HI (match_operand:QI 1 "general_operand" "0,0,a")))]
"rl78_real_insns_ok ()"
"@
+ clrb\t%Q0
mov\t%Q0, #0
- mov\tx, a \;mov\ta, #0"
+ mov\tx, a \;clrb\ta"
)
(define_insn "*extendqihi2_real"
--
1.7.9.5
