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[dev.ssa] cmd/compile/internal/ssa: more simplifications and normalization

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Found by inspecting random generated code.

Change-Id: I57d0fed7c3a8dc91fd13cdccb4819101f9976ec9
Reviewed-on: https://go-review.googlesource.com/19413
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Alexandru Moșoi 2016-02-09 19:13:43 +01:00 committed by Alexandru Moșoi
parent d0d04d2d6c
commit fd458ba499
2 changed files with 1036 additions and 1 deletions
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69
src/cmd/compile/internal/ssa/gen/generic.rules
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@ -76,7 +76,7 @@
(Neq16 (Const16 <t> [c]) (Add16 (Const16 <t> [d]) x)) -> (Neq16 (Const16 <t> [c-d]) x)
(Neq8 (Const8 <t> [c]) (Add8 (Const8 <t> [d]) x)) -> (Neq8 (Const8 <t> [c-d]) x)
// canonicalize: swap arguments for commutative opertions when one argument is a constant.
// canonicalize: swap arguments for commutative operations when one argument is a constant.
(Eq64 x (Const64 <t> [c])) && x.Op != OpConst64 -> (Eq64 (Const64 <t> [c]) x)
(Eq32 x (Const32 <t> [c])) && x.Op != OpConst32 -> (Eq32 (Const32 <t> [c]) x)
(Eq16 x (Const16 <t> [c])) && x.Op != OpConst16 -> (Eq16 (Const16 <t> [c]) x)
@ -92,11 +92,31 @@
(Add16 x (Const16 <t> [c])) && x.Op != OpConst16 -> (Add16 (Const16 <t> [c]) x)
(Add8 x (Const8 <t> [c])) && x.Op != OpConst8 -> (Add8 (Const8 <t> [c]) x)
(Mul64 x (Const64 <t> [c])) && x.Op != OpConst64 -> (Mul64 (Const64 <t> [c]) x)
(Mul32 x (Const32 <t> [c])) && x.Op != OpConst32 -> (Mul32 (Const32 <t> [c]) x)
(Mul16 x (Const16 <t> [c])) && x.Op != OpConst16 -> (Mul16 (Const16 <t> [c]) x)
(Mul8 x (Const8 <t> [c])) && x.Op != OpConst8 -> (Mul8 (Const8 <t> [c]) x)
(Sub64 x (Const64 <t> [c])) && x.Op != OpConst64 -> (Add64 (Const64 <t> [-c]) x)
(Sub32 x (Const32 <t> [c])) && x.Op != OpConst32 -> (Add32 (Const32 <t> [-c]) x)
(Sub16 x (Const16 <t> [c])) && x.Op != OpConst16 -> (Add16 (Const16 <t> [-c]) x)
(Sub8 x (Const8 <t> [c])) && x.Op != OpConst8 -> (Add8 (Const8 <t> [-c]) x)
(And64 x (Const64 <t> [c])) && x.Op != OpConst64 -> (And64 (Const64 <t> [c]) x)
(And32 x (Const32 <t> [c])) && x.Op != OpConst32 -> (And32 (Const32 <t> [c]) x)
(And16 x (Const16 <t> [c])) && x.Op != OpConst16 -> (And16 (Const16 <t> [c]) x)
(And8 x (Const8 <t> [c])) && x.Op != OpConst8 -> (And8 (Const8 <t> [c]) x)
(Or64 x (Const64 <t> [c])) && x.Op != OpConst64 -> (Or64 (Const64 <t> [c]) x)
(Or32 x (Const32 <t> [c])) && x.Op != OpConst32 -> (Or32 (Const32 <t> [c]) x)
(Or16 x (Const16 <t> [c])) && x.Op != OpConst16 -> (Or16 (Const16 <t> [c]) x)
(Or8 x (Const8 <t> [c])) && x.Op != OpConst8 -> (Or8 (Const8 <t> [c]) x)
(Xor64 x (Const64 <t> [c])) && x.Op != OpConst64 -> (Xor64 (Const64 <t> [c]) x)
(Xor32 x (Const32 <t> [c])) && x.Op != OpConst32 -> (Xor32 (Const32 <t> [c]) x)
(Xor16 x (Const16 <t> [c])) && x.Op != OpConst16 -> (Xor16 (Const16 <t> [c]) x)
(Xor8 x (Const8 <t> [c])) && x.Op != OpConst8 -> (Xor8 (Const8 <t> [c]) x)
// rewrite shifts of 8/16/32 bit consts into 64 bit consts to reduce
// the number of the other rewrite rules for const shifts
(Lsh64x32 <t> x (Const32 [c])) -> (Lsh64x64 x (Const64 <t> [int64(uint32(c))]))
@ -153,6 +173,21 @@
(Rsh8x64 x (Const64 [0])) -> x
(Rsh8Ux64 x (Const64 [0])) -> x
// zero shifted.
// TODO: other bit sizes.
(Lsh64x64 (Const64 [0]) _) -> (Const64 [0])
(Rsh64x64 (Const64 [0]) _) -> (Const64 [0])
(Rsh64Ux64 (Const64 [0]) _) -> (Const64 [0])
(Lsh64x32 (Const64 [0]) _) -> (Const64 [0])
(Rsh64x32 (Const64 [0]) _) -> (Const64 [0])
(Rsh64Ux32 (Const64 [0]) _) -> (Const64 [0])
(Lsh64x16 (Const64 [0]) _) -> (Const64 [0])
(Rsh64x16 (Const64 [0]) _) -> (Const64 [0])
(Rsh64Ux16 (Const64 [0]) _) -> (Const64 [0])
(Lsh64x8 (Const64 [0]) _) -> (Const64 [0])
(Rsh64x8 (Const64 [0]) _) -> (Const64 [0])
(Rsh64Ux8 (Const64 [0]) _) -> (Const64 [0])
// large left shifts of all values, and right shifts of unsigned values
(Lsh64x64 _ (Const64 [c])) && uint64(c) >= 64 -> (Const64 [0])
(Rsh64Ux64 _ (Const64 [c])) && uint64(c) >= 64 -> (Const64 [0])
@ -236,22 +271,54 @@
(Or32 x x) -> x
(Or16 x x) -> x
(Or8 x x) -> x
(Or64 (Const64 [0]) x) -> x
(Or32 (Const32 [0]) x) -> x
(Or16 (Const16 [0]) x) -> x
(Or8 (Const8 [0]) x) -> x
(Or64 (Const64 [-1]) _) -> (Const64 [-1])
(Or32 (Const32 [-1]) _) -> (Const32 [-1])
(Or16 (Const16 [-1]) _) -> (Const16 [-1])
(Or8 (Const8 [-1]) _) -> (Const8 [-1])
(And64 x x) -> x
(And32 x x) -> x
(And16 x x) -> x
(And8 x x) -> x
(And64 (Const64 [-1]) x) -> x
(And32 (Const32 [-1]) x) -> x
(And16 (Const16 [-1]) x) -> x
(And8 (Const8 [-1]) x) -> x
(And64 (Const64 [0]) _) -> (Const64 [0])
(And32 (Const32 [0]) _) -> (Const32 [0])
(And16 (Const16 [0]) _) -> (Const16 [0])
(And8 (Const8 [0]) _) -> (Const8 [0])
(Xor64 x x) -> (Const64 [0])
(Xor32 x x) -> (Const32 [0])
(Xor16 x x) -> (Const16 [0])
(Xor8 x x) -> (Const8 [0])
(Xor64 (Const64 [0]) x) -> x
(Xor32 (Const32 [0]) x) -> x
(Xor16 (Const16 [0]) x) -> x
(Xor8 (Const8 [0]) x) -> x
(Add64 (Const64 [0]) x) -> x
(Add32 (Const32 [0]) x) -> x
(Add16 (Const16 [0]) x) -> x
(Add8 (Const8 [0]) x) -> x
(Sub64 x x) -> (Const64 [0])
(Sub32 x x) -> (Const32 [0])
(Sub16 x x) -> (Const16 [0])
(Sub8 x x) -> (Const8 [0])
(Mul64 (Const64 [0]) _) -> (Const64 [0])
(Mul32 (Const32 [0]) _) -> (Const32 [0])
(Mul16 (Const16 [0]) _) -> (Const16 [0])
(Mul8 (Const8 [0]) _) -> (Const8 [0])
(Com8 (Com8 x)) -> x
(Com16 (Com16 x)) -> x
(Com32 (Com32 x)) -> x
(Com64 (Com64 x)) -> x
(Neg8 (Sub8 x y)) -> (Sub8 y x)
(Neg16 (Sub16 x y)) -> (Sub16 y x)
(Neg32 (Sub32 x y)) -> (Sub32 y x)
(Neg64 (Sub64 x y)) -> (Sub64 y x)
// simplifications often used for lengths. e.g. len(s[i:i+5])==5
(Sub64 (Add64 x y) x) -> y

968
src/cmd/compile/internal/ssa/rewritegeneric.go
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