cmd/compile: merge shifts into LEAs

Change-Id: I5a43c354f36184ae64a52268023c3222da3026d8
Reviewed-on: https://go-review.googlesource.com/20880
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Todd Neal <todd@tneal.org>

src/cmd/compile/internal/ssa/gen/AMD64.rules

@@ -571,7 +571,7 @@
 (ADDQ x (LEAQ [c] {s} y)) && x.Op != OpSB && y.Op != OpSB -> (LEAQ1 [c] {s} x y)
 (ADDQ (LEAQ [c] {s} x) y) && x.Op != OpSB && y.Op != OpSB -> (LEAQ1 [c] {s} x y)
 
-// fold ADDQconst into leaqX
+// fold ADDQconst into LEAQx
 (ADDQconst [c] (LEAQ1 [d] {s} x y)) -> (LEAQ1 [c+d] {s} x y)
 (ADDQconst [c] (LEAQ2 [d] {s} x y)) -> (LEAQ2 [c+d] {s} x y)
 (ADDQconst [c] (LEAQ4 [d] {s} x y)) -> (LEAQ4 [c+d] {s} x y)
@@ -585,6 +585,18 @@
 (LEAQ8 [c] {s} (ADDQconst [d] x) y) && x.Op != OpSB -> (LEAQ8 [c+d] {s} x y)
 (LEAQ8 [c] {s} x (ADDQconst [d] y)) && y.Op != OpSB -> (LEAQ8 [c+8*d] {s} x y)
 
+// fold shifts into LEAQx
+(LEAQ1 [c] {s} x (SHLQconst [1] y)) -> (LEAQ2 [c] {s} x y)
+(LEAQ1 [c] {s} (SHLQconst [1] x) y) -> (LEAQ2 [c] {s} y x)
+(LEAQ1 [c] {s} x (SHLQconst [2] y)) -> (LEAQ4 [c] {s} x y)
+(LEAQ1 [c] {s} (SHLQconst [2] x) y) -> (LEAQ4 [c] {s} y x)
+(LEAQ1 [c] {s} x (SHLQconst [3] y)) -> (LEAQ8 [c] {s} x y)
+(LEAQ1 [c] {s} (SHLQconst [3] x) y) -> (LEAQ8 [c] {s} y x)
+
+(LEAQ2 [c] {s} x (SHLQconst [1] y)) -> (LEAQ4 [c] {s} x y)
+(LEAQ2 [c] {s} x (SHLQconst [2] y)) -> (LEAQ8 [c] {s} x y)
+(LEAQ4 [c] {s} x (SHLQconst [1] y)) -> (LEAQ8 [c] {s} x y)
+
 // reverse ordering of compare instruction
 (SETL (InvertFlags x)) -> (SETG x)
 (SETG (InvertFlags x)) -> (SETL x)

src/cmd/compile/internal/ssa/rewriteAMD64.go

@@ -4195,6 +4195,132 @@ func rewriteValueAMD64_OpAMD64LEAQ1(v *Value, config *Config) bool {
 		v.AddArg(y)
 		return true
 	}
+	// match: (LEAQ1 [c] {s} x (SHLQconst [1] y))
+	// cond:
+	// result: (LEAQ2 [c] {s} x y)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		x := v.Args[0]
+		if v.Args[1].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[1].AuxInt != 1 {
+			break
+		}
+		y := v.Args[1].Args[0]
+		v.reset(OpAMD64LEAQ2)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(x)
+		v.AddArg(y)
+		return true
+	}
+	// match: (LEAQ1 [c] {s} (SHLQconst [1] x) y)
+	// cond:
+	// result: (LEAQ2 [c] {s} y x)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		if v.Args[0].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[0].AuxInt != 1 {
+			break
+		}
+		x := v.Args[0].Args[0]
+		y := v.Args[1]
+		v.reset(OpAMD64LEAQ2)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(y)
+		v.AddArg(x)
+		return true
+	}
+	// match: (LEAQ1 [c] {s} x (SHLQconst [2] y))
+	// cond:
+	// result: (LEAQ4 [c] {s} x y)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		x := v.Args[0]
+		if v.Args[1].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[1].AuxInt != 2 {
+			break
+		}
+		y := v.Args[1].Args[0]
+		v.reset(OpAMD64LEAQ4)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(x)
+		v.AddArg(y)
+		return true
+	}
+	// match: (LEAQ1 [c] {s} (SHLQconst [2] x) y)
+	// cond:
+	// result: (LEAQ4 [c] {s} y x)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		if v.Args[0].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[0].AuxInt != 2 {
+			break
+		}
+		x := v.Args[0].Args[0]
+		y := v.Args[1]
+		v.reset(OpAMD64LEAQ4)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(y)
+		v.AddArg(x)
+		return true
+	}
+	// match: (LEAQ1 [c] {s} x (SHLQconst [3] y))
+	// cond:
+	// result: (LEAQ8 [c] {s} x y)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		x := v.Args[0]
+		if v.Args[1].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[1].AuxInt != 3 {
+			break
+		}
+		y := v.Args[1].Args[0]
+		v.reset(OpAMD64LEAQ8)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(x)
+		v.AddArg(y)
+		return true
+	}
+	// match: (LEAQ1 [c] {s} (SHLQconst [3] x) y)
+	// cond:
+	// result: (LEAQ8 [c] {s} y x)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		if v.Args[0].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[0].AuxInt != 3 {
+			break
+		}
+		x := v.Args[0].Args[0]
+		y := v.Args[1]
+		v.reset(OpAMD64LEAQ8)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(y)
+		v.AddArg(x)
+		return true
+	}
 	// match: (LEAQ1 [off1] {sym1} (LEAQ [off2] {sym2} x) y)
 	// cond: canMergeSym(sym1, sym2) && x.Op != OpSB
 	// result: (LEAQ1 [addOff(off1,off2)] {mergeSym(sym1,sym2)} x y)
@@ -4290,6 +4416,48 @@ func rewriteValueAMD64_OpAMD64LEAQ2(v *Value, config *Config) bool {
 		v.AddArg(y)
 		return true
 	}
+	// match: (LEAQ2 [c] {s} x (SHLQconst [1] y))
+	// cond:
+	// result: (LEAQ4 [c] {s} x y)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		x := v.Args[0]
+		if v.Args[1].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[1].AuxInt != 1 {
+			break
+		}
+		y := v.Args[1].Args[0]
+		v.reset(OpAMD64LEAQ4)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(x)
+		v.AddArg(y)
+		return true
+	}
+	// match: (LEAQ2 [c] {s} x (SHLQconst [2] y))
+	// cond:
+	// result: (LEAQ8 [c] {s} x y)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		x := v.Args[0]
+		if v.Args[1].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[1].AuxInt != 2 {
+			break
+		}
+		y := v.Args[1].Args[0]
+		v.reset(OpAMD64LEAQ8)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(x)
+		v.AddArg(y)
+		return true
+	}
 	// match: (LEAQ2 [off1] {sym1} (LEAQ [off2] {sym2} x) y)
 	// cond: canMergeSym(sym1, sym2) && x.Op != OpSB
 	// result: (LEAQ2 [addOff(off1,off2)] {mergeSym(sym1,sym2)} x y)
@@ -4362,6 +4530,27 @@ func rewriteValueAMD64_OpAMD64LEAQ4(v *Value, config *Config) bool {
 		v.AddArg(y)
 		return true
 	}
+	// match: (LEAQ4 [c] {s} x (SHLQconst [1] y))
+	// cond:
+	// result: (LEAQ8 [c] {s} x y)
+	for {
+		c := v.AuxInt
+		s := v.Aux
+		x := v.Args[0]
+		if v.Args[1].Op != OpAMD64SHLQconst {
+			break
+		}
+		if v.Args[1].AuxInt != 1 {
+			break
+		}
+		y := v.Args[1].Args[0]
+		v.reset(OpAMD64LEAQ8)
+		v.AuxInt = c
+		v.Aux = s
+		v.AddArg(x)
+		v.AddArg(y)
+		return true
+	}
 	// match: (LEAQ4 [off1] {sym1} (LEAQ [off2] {sym2} x) y)
 	// cond: canMergeSym(sym1, sym2) && x.Op != OpSB
 	// result: (LEAQ4 [addOff(off1,off2)] {mergeSym(sym1,sym2)} x y)