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cmd/compile: remove walkmul

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Replace with generic rewrite rules.

Change-Id: I3ee32076cfd9db5801f1a7bdbb73a994255884a9
Reviewed-on: https://go-review.googlesource.com/36323
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2017-02-04 21:20:23 -08:00
parent 6aee6b895c
commit 47d2a4dafa
3 changed files with 198 additions and 80 deletions
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88
src/cmd/compile/internal/gc/walk.go
View File

@ -542,23 +542,26 @@ opswitch:
Warn("shift bounds check elided")
}
// Use results from call expression as arguments for complex.
case OAND,
OSUB,
OHMUL,
OMUL,
OLT,
OLE,
OGE,
OGT,
OADD,
OOR,
OXOR,
OCOMPLEX:
if n.Op == OCOMPLEX && n.Left == nil && n.Right == nil {
OXOR:
n.Left = walkexpr(n.Left, init)
n.Right = walkexpr(n.Right, init)
case OCOMPLEX:
// Use results from call expression as arguments for complex.
if n.Left == nil && n.Right == nil {
n.Left = n.List.First()
n.Right = n.List.Second()
}
n.Left = walkexpr(n.Left, init)
n.Right = walkexpr(n.Right, init)
@ -1071,11 +1074,6 @@ opswitch:
n.Right = typecheck(n.Right, Erv)
n.Right = walkexpr(n.Right, init)
case OMUL:
n.Left = walkexpr(n.Left, init)
n.Right = walkexpr(n.Right, init)
n = walkmul(n, init)
case ODIV, OMOD:
n.Left = walkexpr(n.Left, init)
n.Right = walkexpr(n.Right, init)
@ -3398,76 +3396,6 @@ func walkinrange(n *Node, init *Nodes) *Node {
return cmp
}
// walkmul rewrites integer multiplication by powers of two as shifts.
// The result of walkmul MUST be assigned back to n, e.g.
// n.Left = walkmul(n.Left, init)
func walkmul(n *Node, init *Nodes) *Node {
if !n.Type.IsInteger() {
return n
}
var nr *Node
var nl *Node
if n.Right.Op == OLITERAL {
nl = n.Left
nr = n.Right
} else if n.Left.Op == OLITERAL {
nl = n.Right
nr = n.Left
} else {
return n
}
neg := 0
// x*0 is 0 (and side effects of x).
var pow int
var w int
if nr.Int64() == 0 {
cheapexpr(nl, init)
Nodconst(n, n.Type, 0)
goto ret
}
// nr is a constant.
pow = powtwo(nr)
if pow < 0 {
return n
}
if pow >= 1000 {
// negative power of 2, like -16
neg = 1
pow -= 1000
}
w = int(nl.Type.Width * 8)
if pow+1 >= w { // too big, shouldn't happen
return n
}
nl = cheapexpr(nl, init)
if pow == 0 {
// x*1 is x
n = nl
goto ret
}
n = nod(OLSH, nl, nodintconst(int64(pow)))
ret:
if neg != 0 {
n = nod(OMINUS, n, nil)
}
n = typecheck(n, Erv)
n = walkexpr(n, init)
return n
}
// walkdiv rewrites division by a constant as less expensive
// operations.
// The result of walkdiv MUST be assigned back to n, e.g.

10
src/cmd/compile/internal/ssa/gen/generic.rules
View File

@ -120,6 +120,16 @@
(Mul32 (Const32 [-1]) x) -> (Neg32 x)
(Mul64 (Const64 [-1]) x) -> (Neg64 x)
// Convert multiplication by a power of two to a shift.
(Mul8 <t> n (Const8 [c])) && isPowerOfTwo(c) -> (Lsh8x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
(Mul16 <t> n (Const16 [c])) && isPowerOfTwo(c) -> (Lsh16x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
(Mul32 <t> n (Const32 [c])) && isPowerOfTwo(c) -> (Lsh32x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
(Mul64 <t> n (Const64 [c])) && isPowerOfTwo(c) -> (Lsh64x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
(Mul8 <t> n (Const8 [c])) && t.IsSigned() && isPowerOfTwo(-c) -> (Neg8 (Lsh8x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
(Mul16 <t> n (Const16 [c])) && t.IsSigned() && isPowerOfTwo(-c) -> (Neg16 (Lsh16x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
(Mul32 <t> n (Const32 [c])) && t.IsSigned() && isPowerOfTwo(-c) -> (Neg32 (Lsh32x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
(Mul64 <t> n (Const64 [c])) && t.IsSigned() && isPowerOfTwo(-c) -> (Neg64 (Lsh64x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
(Mod8 (Const8 [c]) (Const8 [d])) && d != 0 -> (Const8 [int64(int8(c % d))])
(Mod16 (Const16 [c]) (Const16 [d])) && d != 0 -> (Const16 [int64(int16(c % d))])
(Mod32 (Const32 [c]) (Const32 [d])) && d != 0 -> (Const32 [int64(int32(c % d))])

180
src/cmd/compile/internal/ssa/rewritegeneric.go
View File

@ -5458,6 +5458,51 @@ func rewriteValuegeneric_OpMul16(v *Value, config *Config) bool {
v.AddArg(x)
return true
}
// match: (Mul16 <t> n (Const16 [c]))
// cond: isPowerOfTwo(c)
// result: (Lsh16x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst16 {
break
}
c := v_1.AuxInt
if !(isPowerOfTwo(c)) {
break
}
v.reset(OpLsh16x64)
v.Type = t
v.AddArg(n)
v0 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v0.AuxInt = log2(c)
v.AddArg(v0)
return true
}
// match: (Mul16 <t> n (Const16 [c]))
// cond: t.IsSigned() && isPowerOfTwo(-c)
// result: (Neg16 (Lsh16x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst16 {
break
}
c := v_1.AuxInt
if !(t.IsSigned() && isPowerOfTwo(-c)) {
break
}
v.reset(OpNeg16)
v0 := b.NewValue0(v.Pos, OpLsh16x64, t)
v0.AddArg(n)
v1 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v1.AuxInt = log2(-c)
v0.AddArg(v1)
v.AddArg(v0)
return true
}
// match: (Mul16 x (Const16 <t> [c]))
// cond: x.Op != OpConst16
// result: (Mul16 (Const16 <t> [c]) x)
@ -5533,6 +5578,51 @@ func rewriteValuegeneric_OpMul32(v *Value, config *Config) bool {
v.AddArg(x)
return true
}
// match: (Mul32 <t> n (Const32 [c]))
// cond: isPowerOfTwo(c)
// result: (Lsh32x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst32 {
break
}
c := v_1.AuxInt
if !(isPowerOfTwo(c)) {
break
}
v.reset(OpLsh32x64)
v.Type = t
v.AddArg(n)
v0 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v0.AuxInt = log2(c)
v.AddArg(v0)
return true
}
// match: (Mul32 <t> n (Const32 [c]))
// cond: t.IsSigned() && isPowerOfTwo(-c)
// result: (Neg32 (Lsh32x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst32 {
break
}
c := v_1.AuxInt
if !(t.IsSigned() && isPowerOfTwo(-c)) {
break
}
v.reset(OpNeg32)
v0 := b.NewValue0(v.Pos, OpLsh32x64, t)
v0.AddArg(n)
v1 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v1.AuxInt = log2(-c)
v0.AddArg(v1)
v.AddArg(v0)
return true
}
// match: (Mul32 x (Const32 <t> [c]))
// cond: x.Op != OpConst32
// result: (Mul32 (Const32 <t> [c]) x)
@ -5735,6 +5825,51 @@ func rewriteValuegeneric_OpMul64(v *Value, config *Config) bool {
v.AddArg(x)
return true
}
// match: (Mul64 <t> n (Const64 [c]))
// cond: isPowerOfTwo(c)
// result: (Lsh64x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst64 {
break
}
c := v_1.AuxInt
if !(isPowerOfTwo(c)) {
break
}
v.reset(OpLsh64x64)
v.Type = t
v.AddArg(n)
v0 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v0.AuxInt = log2(c)
v.AddArg(v0)
return true
}
// match: (Mul64 <t> n (Const64 [c]))
// cond: t.IsSigned() && isPowerOfTwo(-c)
// result: (Neg64 (Lsh64x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst64 {
break
}
c := v_1.AuxInt
if !(t.IsSigned() && isPowerOfTwo(-c)) {
break
}
v.reset(OpNeg64)
v0 := b.NewValue0(v.Pos, OpLsh64x64, t)
v0.AddArg(n)
v1 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v1.AuxInt = log2(-c)
v0.AddArg(v1)
v.AddArg(v0)
return true
}
// match: (Mul64 x (Const64 <t> [c]))
// cond: x.Op != OpConst64
// result: (Mul64 (Const64 <t> [c]) x)
@ -5937,6 +6072,51 @@ func rewriteValuegeneric_OpMul8(v *Value, config *Config) bool {
v.AddArg(x)
return true
}
// match: (Mul8 <t> n (Const8 [c]))
// cond: isPowerOfTwo(c)
// result: (Lsh8x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(c)]))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst8 {
break
}
c := v_1.AuxInt
if !(isPowerOfTwo(c)) {
break
}
v.reset(OpLsh8x64)
v.Type = t
v.AddArg(n)
v0 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v0.AuxInt = log2(c)
v.AddArg(v0)
return true
}
// match: (Mul8 <t> n (Const8 [c]))
// cond: t.IsSigned() && isPowerOfTwo(-c)
// result: (Neg8 (Lsh8x64 <t> n (Const64 <config.fe.TypeUInt64()> [log2(-c)])))
for {
t := v.Type
n := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpConst8 {
break
}
c := v_1.AuxInt
if !(t.IsSigned() && isPowerOfTwo(-c)) {
break
}
v.reset(OpNeg8)
v0 := b.NewValue0(v.Pos, OpLsh8x64, t)
v0.AddArg(n)
v1 := b.NewValue0(v.Pos, OpConst64, config.fe.TypeUInt64())
v1.AuxInt = log2(-c)
v0.AddArg(v1)
v.AddArg(v0)
return true
}
// match: (Mul8 x (Const8 <t> [c]))
// cond: x.Op != OpConst8
// result: (Mul8 (Const8 <t> [c]) x)