[dev.ssa] cmd/compile/internal/ssa: rewrite rules for const comparisons

Shaves ~8k off the go binary on darwin x64.

Change-Id: I73396af44ae28cd4cfc675290d6858f304d45b76
Reviewed-on: https://go-review.googlesource.com/16456
Run-TryBot: Todd Neal <todd@tneal.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/ssa/gen/generic.rules

@@ -37,6 +37,57 @@
 (Neq16 x x) -> (ConstBool [0])
 (Neq8 x x) -> (ConstBool [0])
 
+// constant comparisons
+(Eq64 (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(int64(c) == int64(d))])
+(Eq32 (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(int32(c) == int32(d))])
+(Eq16 (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(int16(c) == int16(d))])
+(Eq8  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(int8(c)  == int8(d))])
+
+(Neq64 (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(int64(c) != int64(d))])
+(Neq32 (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(int32(c) != int32(d))])
+(Neq16 (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(int16(c) != int16(d))])
+(Neq8  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(int8(c)  != int8(d))])
+
+(Greater64 (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(int64(c) > int64(d))])
+(Greater32 (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(int32(c) > int32(d))])
+(Greater16 (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(int16(c) > int16(d))])
+(Greater8  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(int8(c)  > int8(d))])
+
+(Greater64U (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(uint64(c) > uint64(d))])
+(Greater32U (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(uint32(c) > uint32(d))])
+(Greater16U (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(uint16(c) > uint16(d))])
+(Greater8U  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(uint8(c)  > uint8(d))])
+
+(Geq64 (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(int64(c) >= int64(d))])
+(Geq32 (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(int32(c) >= int32(d))])
+(Geq16 (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(int16(c) >= int16(d))])
+(Geq8  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(int8(c)  >= int8(d))])
+
+(Geq64U (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(uint64(c) >= uint64(d))])
+(Geq32U (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(uint32(c) >= uint32(d))])
+(Geq16U (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(uint16(c) >= uint16(d))])
+(Geq8U  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(uint8(c)  >= uint8(d))])
+
+(Less64 (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(int64(c) < int64(d))])
+(Less32 (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(int32(c) < int32(d))])
+(Less16 (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(int16(c) < int16(d))])
+(Less8  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(int8(c)  < int8(d))])
+
+(Less64U (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(uint64(c) < uint64(d))])
+(Less32U (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(uint32(c) < uint32(d))])
+(Less16U (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(uint16(c) < uint16(d))])
+(Less8U  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(uint8(c)  < uint8(d))])
+
+(Leq64 (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(int64(c) <= int64(d))])
+(Leq32 (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(int32(c) <= int32(d))])
+(Leq16 (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(int16(c) <= int16(d))])
+(Leq8  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(int8(c)  <= int8(d))])
+
+(Leq64U (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(uint64(c) <= uint64(d))])
+(Leq32U (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(uint32(c) <= uint32(d))])
+(Leq16U (Const16 [c]) (Const16 [d])) -> (ConstBool [b2i(uint16(c) <= uint16(d))])
+(Leq8U  (Const8  [c]) (Const8  [d])) -> (ConstBool [b2i(uint8(c)  <= uint8(d))])
+
 // simplifications
 (Or64 x x) -> x
 (Or32 x x) -> x