[dev.ssa] cmd/compile/internal/ssa: Complete 64-bit shifts

Implement correct Go shifts.

Allow multi-line rewrite rules.

Fix offset & alignment in stack alloc.

Change-Id: I0ae9e522c83df9205bbe4ab94bc0e43d16dace58
Reviewed-on: https://go-review.googlesource.com/10891Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/amd64/prog.go

@@ -57,6 +57,8 @@ var progtable = [x86.ALAST]obj.ProgInfo{
 	x86.ACWD:       {gc.OK, AX, AX | DX, 0},
 	x86.ACLD:       {gc.OK, 0, 0, 0},
 	x86.ASTD:       {gc.OK, 0, 0, 0},
+	x86.ACMOVQCC:   {gc.SizeQ | gc.LeftRead | gc.RightRead | gc.RightWrite | gc.UseCarry, 0, 0, 0},
+	x86.ACMOVQCS:   {gc.SizeQ | gc.LeftRead | gc.RightRead | gc.RightWrite | gc.UseCarry, 0, 0, 0},
 	x86.ACMPB:      {gc.SizeB | gc.LeftRead | gc.RightRead | gc.SetCarry, 0, 0, 0},
 	x86.ACMPL:      {gc.SizeL | gc.LeftRead | gc.RightRead | gc.SetCarry, 0, 0, 0},
 	x86.ACMPQ:      {gc.SizeQ | gc.LeftRead | gc.RightRead | gc.SetCarry, 0, 0, 0},

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

@@ -755,6 +755,63 @@ func genValue(v *ssa.Value) {
 		p.From.Offset = v.Aux.(int64)
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = r
+	case ssa.OpAMD64SHLQ:
+		x := regnum(v.Args[0])
+		r := regnum(v)
+		if x != r {
+			if r == x86.REG_CX {
+				log.Fatalf("can't implement %s, target and shift both in CX", v.LongString())
+			}
+			p := Prog(x86.AMOVQ)
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+			x = r
+		}
+		p := Prog(x86.ASHLQ)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = regnum(v.Args[1]) // should be CX
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
+	case ssa.OpAMD64SHRQ:
+		x := regnum(v.Args[0])
+		r := regnum(v)
+		if x != r {
+			if r == x86.REG_CX {
+				log.Fatalf("can't implement %s, target and shift both in CX", v.LongString())
+			}
+			p := Prog(x86.AMOVQ)
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+			x = r
+		}
+		p := Prog(x86.ASHRQ)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = regnum(v.Args[1]) // should be CX
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
+	case ssa.OpAMD64SARQ:
+		x := regnum(v.Args[0])
+		r := regnum(v)
+		if x != r {
+			if r == x86.REG_CX {
+				log.Fatalf("can't implement %s, target and shift both in CX", v.LongString())
+			}
+			p := Prog(x86.AMOVQ)
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+			x = r
+		}
+		p := Prog(x86.ASARQ)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = regnum(v.Args[1]) // should be CX
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
 	case ssa.OpAMD64SHLQconst:
 		x := regnum(v.Args[0])
 		r := regnum(v)
@@ -771,6 +828,89 @@ func genValue(v *ssa.Value) {
 		p.From.Offset = v.Aux.(int64)
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = r
+	case ssa.OpAMD64SHRQconst:
+		x := regnum(v.Args[0])
+		r := regnum(v)
+		if x != r {
+			p := Prog(x86.AMOVQ)
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+			x = r
+		}
+		p := Prog(x86.ASHRQ)
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = v.Aux.(int64)
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
+	case ssa.OpAMD64SARQconst:
+		x := regnum(v.Args[0])
+		r := regnum(v)
+		if x != r {
+			p := Prog(x86.AMOVQ)
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+			x = r
+		}
+		p := Prog(x86.ASARQ)
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = v.Aux.(int64)
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
+	case ssa.OpAMD64SBBQcarrymask:
+		r := regnum(v)
+		p := Prog(x86.ASBBQ)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = r
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
+	case ssa.OpAMD64CMOVQCC:
+		r := regnum(v)
+		x := regnum(v.Args[1])
+		y := regnum(v.Args[2])
+		if x != r && y != r {
+			p := Prog(x86.AMOVQ)
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+			x = r
+		}
+		var p *obj.Prog
+		if x == r {
+			p = Prog(x86.ACMOVQCS)
+			p.From.Reg = y
+		} else {
+			p = Prog(x86.ACMOVQCC)
+			p.From.Reg = x
+		}
+		p.From.Type = obj.TYPE_REG
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
+	case ssa.OpAMD64ANDQ:
+		r := regnum(v)
+		x := regnum(v.Args[0])
+		y := regnum(v.Args[1])
+		if x != r && y != r {
+			p := Prog(x86.AMOVQ)
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+			x = r
+		}
+		p := Prog(x86.AANDQ)
+		p.From.Type = obj.TYPE_REG
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
+		if x == r {
+			p.From.Reg = y
+		} else {
+			p.From.Reg = x
+		}
 	case ssa.OpAMD64LEAQ:
 		p := Prog(x86.ALEAQ)
 		p.From.Type = obj.TYPE_MEM

src/cmd/compile/internal/gc/type.go

@@ -18,6 +18,11 @@ func (t *Type) Size() int64 {
 	return t.Width
 }
 
+func (t *Type) Alignment() int64 {
+	dowidth(t)
+	return int64(t.Align)
+}
+
 func (t *Type) IsBoolean() bool {
 	return t.Etype == TBOOL
 }

src/cmd/compile/internal/ssa/TODO

@@ -20,14 +20,6 @@ Values
    If not that, then cache the interfaces that wrap int64s.
  - OpStore uses 3 args.  Increase the size of argstorage to 3?
 
-Opcodes
- - Rename ops to prevent cross-arch conflicts.  MOVQ -> MOVQamd64 (or
-   MOVQ6?).  Other option: build opcode table in Config instead of globally.
- - It's annoying to list the opcode both in the opcode list and an
-   opInfo map entry.  Specify it one place and use go:generate to
-   produce both?
- - Write barriers
-
 Regalloc
  - Make less arch-dependent
  - Don't spill everything at every basic block boundary.
@@ -38,7 +30,6 @@ Regalloc
 
 Rewrites
  - Strength reduction (both arch-indep and arch-dependent?)
- - Code sequence for shifts >= wordsize
  - Start another architecture (arm?)
  - 64-bit ops on 32-bit machines
  - <regwidth ops.  For example, x+y on int32s on amd64 needs (MOVLQSX (ADDL x y)).
@@ -51,6 +42,9 @@ Common-Subexpression Elimination
  - Can we move control values out of their basic block?
 
 Other
- - Make go:generate less painful.  Have a subpackage that just has the
-   generate commands in it?
  - Use gc.Fatal for errors.  Add a callback to Frontend?
+ - Write barriers
+ - For testing, do something more sophisticated than
+   checkOpcodeCounts.  Michael Matloob suggests using a similar
+   pattern matcher to the rewrite engine to check for certain
+   expression subtrees in the output.

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

@@ -5,19 +5,37 @@
 // x86 register conventions:
 //  - Integer types live in the low portion of registers.
 //    Upper portions are correctly extended.
+//    TODO: reconsider?  The current choice means we need no extension for indexing,
+//    but we do need extension for e.g. 32-bit signed adds.
 //  - Boolean types use the low-order byte of a register.  Upper bytes are junk.
 //  - We do not use AH,BH,CH,DH registers.
 //  - Floating-point types will live in the low natural slot of an sse2 register.
 //    Unused portions are junk.
 
-// These are the lowerings themselves
+// Lowering arithmetic
 (Add <t> x y) && (is64BitInt(t) || isPtr(t)) -> (ADDQ x y)
 (Add <t> x y) && is32BitInt(t) -> (ADDL x y)
-
 (Sub <t> x y) && is64BitInt(t) -> (SUBQ x y)
-
 (Mul <t> x y) && is64BitInt(t) -> (MULQ x y)
-(Lsh <t> x y) && is64BitInt(t) -> (SHLQ x y) // TODO: check y>63
+
+// Lowering shifts
+// Note: unsigned shifts need to return 0 if shift amount is >= 64.
+//   mask = shift >= 64 ? 0 : 0xffffffffffffffff
+//   result = mask & arg << shift
+(Lsh <t> x y) && is64BitInt(t) ->
+	(ANDQ (SHLQ <t> x y) (SBBQcarrymask <t> (CMPQconst <TypeFlags> [int64(64)] y)))
+(Rsh <t> x y) && is64BitInt(t) && !t.IsSigned() ->
+	(ANDQ (SHRQ <t> x y) (SBBQcarrymask <t> (CMPQconst <TypeFlags> [int64(64)] y)))
+
+// Note: signed right shift needs to return 0/-1 if shift amount is >= 64.
+//   if shift > 63 { shift = 63 }
+//   result = arg >> shift
+(Rsh <t> x y) && is64BitInt(t) && t.IsSigned() ->
+	(SARQ <t> x (CMOVQCC <t>
+			(CMPQconst <TypeFlags> [int64(64)] y)
+			(Const <t> [int64(63)])
+			y))
+
 (Less x y) && is64BitInt(v.Args[0].Type) && isSigned(v.Args[0].Type) -> (SETL (CMPQ <TypeFlags> x y))
 
 (Load <t> ptr mem) && t.IsBoolean() -> (MOVBload [int64(0)] ptr mem)
@@ -56,7 +74,11 @@
 (SUBQ <t> (MOVQconst [c]) x) -> (NEGQ (SUBQconst <t> x [c]))
 (MULQ x (MOVQconst [c])) && c.(int64) == int64(int32(c.(int64))) -> (MULQconst [c] x)
 (MULQ (MOVQconst [c]) x) -> (MULQconst [c] x)
+(ANDQ x (MOVQconst [c])) -> (ANDQconst [c] x)
+(ANDQ (MOVQconst [c]) x) -> (ANDQconst [c] x)
 (SHLQ x (MOVQconst [c])) -> (SHLQconst [c] x)
+(SHRQ x (MOVQconst [c])) -> (SHRQconst [c] x)
+(SARQ x (MOVQconst [c])) -> (SARQconst [c] x)
 (CMPQ x (MOVQconst [c])) -> (CMPQconst x [c])
 (CMPQ (MOVQconst [c]) x) -> (InvertFlags (CMPQconst <TypeFlags> x [c]))
 
@@ -101,3 +123,11 @@
 (UGE (InvertFlags cmp) yes no) -> (ULE cmp yes no)
 (EQ (InvertFlags cmp) yes no) -> (EQ cmp yes no)
 (NE (InvertFlags cmp) yes no) -> (NE cmp yes no)
+
+// get rid of >=64 code for constant shifts
+(SBBQcarrymask (CMPQconst [c] (MOVQconst [d]))) && inBounds(d.(int64), c.(int64)) -> (Const [int64(-1)])
+(SBBQcarrymask (CMPQconst [c] (MOVQconst [d]))) && !inBounds(d.(int64), c.(int64)) -> (Const [int64(0)])
+(ANDQconst [c] _) && c.(int64) == 0 -> (MOVQconst [int64(0)])
+(ANDQconst [c] x) && c.(int64) == -1 -> (Copy x)
+(CMOVQCC (CMPQconst [c] (MOVQconst [d])) _ x) && inBounds(d.(int64), c.(int64)) -> (Copy x)
+(CMOVQCC (CMPQconst [c] (MOVQconst [d])) x _) && !inBounds(d.(int64), c.(int64)) -> (Copy x)

src/cmd/compile/internal/ssa/gen/AMD64Ops.go

@@ -72,17 +72,20 @@ func init() {
 
 	gp := buildReg("AX CX DX BX BP SI DI R8 R9 R10 R11 R12 R13 R14 R15")
 	gpsp := gp | buildReg("SP FP")
+	flags := buildReg("FLAGS")
 	gp01 := regInfo{[]regMask{}, 0, []regMask{gp}}
 	gp11 := regInfo{[]regMask{gpsp}, 0, []regMask{gp}}
 	gp21 := regInfo{[]regMask{gpsp, gpsp}, 0, []regMask{gp}}
 	gp21shift := regInfo{[]regMask{gpsp, buildReg("CX")}, 0, []regMask{gp}}
-	gp2flags := regInfo{[]regMask{gpsp, gpsp}, 0, []regMask{buildReg("FLAGS")}}
-	gp1flags := regInfo{[]regMask{gpsp}, 0, []regMask{buildReg("FLAGS")}}
+	gp2flags := regInfo{[]regMask{gpsp, gpsp}, 0, []regMask{flags}}
+	gp1flags := regInfo{[]regMask{gpsp}, 0, []regMask{flags}}
+	flagsgp1 := regInfo{[]regMask{flags}, 0, []regMask{gp}}
 	gpload := regInfo{[]regMask{gpsp, 0}, 0, []regMask{gp}}
 	gploadidx := regInfo{[]regMask{gpsp, gpsp, 0}, 0, []regMask{gp}}
 	gpstore := regInfo{[]regMask{gpsp, gpsp, 0}, 0, nil}
 	gpstoreidx := regInfo{[]regMask{gpsp, gpsp, gpsp, 0}, 0, nil}
-	flagsgp := regInfo{[]regMask{buildReg("FLAGS")}, 0, []regMask{gp}}
+	flagsgp := regInfo{[]regMask{flags}, 0, []regMask{gp}}
+	cmov := regInfo{[]regMask{flags, gp, gp}, 0, []regMask{gp}}
 
 	// Suffixes encode the bit width of various instructions.
 	// Q = 64 bit, L = 32 bit, W = 16 bit, B = 8 bit
@@ -95,15 +98,24 @@ func init() {
 		{name: "SUBQconst", reg: gp11}, // arg0 - aux.(int64)
 		{name: "MULQ", reg: gp21},      // arg0 * arg1
 		{name: "MULQconst", reg: gp11}, // arg0 * aux.(int64)
+		{name: "ANDQ", reg: gp21},      // arg0 & arg1
+		{name: "ANDQconst", reg: gp11}, // arg0 & aux.(int64)
 		{name: "SHLQ", reg: gp21shift}, // arg0 << arg1, shift amount is mod 64
 		{name: "SHLQconst", reg: gp11}, // arg0 << aux.(int64), shift amount 0-63
-		{name: "NEGQ", reg: gp11},      // -arg0
+		{name: "SHRQ", reg: gp21shift}, // unsigned arg0 >> arg1, shift amount is mod 64
+		{name: "SHRQconst", reg: gp11}, // unsigned arg0 >> aux.(int64), shift amount 0-63
+		{name: "SARQ", reg: gp21shift}, // signed arg0 >> arg1, shift amount is mod 64
+		{name: "SARQconst", reg: gp11}, // signed arg0 >> aux.(int64), shift amount 0-63
+
+		{name: "NEGQ", reg: gp11}, // -arg0
 
 		{name: "CMPQ", reg: gp2flags},      // arg0 compare to arg1
 		{name: "CMPQconst", reg: gp1flags}, // arg0 compare to aux.(int64)
 		{name: "TESTQ", reg: gp2flags},     // (arg0 & arg1) compare to 0
 		{name: "TESTB", reg: gp2flags},     // (arg0 & arg1) compare to 0
 
+		{name: "SBBQcarrymask", reg: flagsgp1}, // (int64)(-1) if carry is set, 0 if carry is clear.
+
 		{name: "SETEQ", reg: flagsgp}, // extract == condition from arg0
 		{name: "SETNE", reg: flagsgp}, // extract != condition from arg0
 		{name: "SETL", reg: flagsgp},  // extract signed < condition from arg0
@@ -111,6 +123,8 @@ func init() {
 		{name: "SETGE", reg: flagsgp}, // extract signed >= condition from arg0
 		{name: "SETB", reg: flagsgp},  // extract unsigned < condition from arg0
 
+		{name: "CMOVQCC", reg: cmov}, // carry clear
+
 		{name: "MOVQconst", reg: gp01},  // aux.(int64)
 		{name: "LEAQ", reg: gp21},       // arg0 + arg1 + aux.(int64)
 		{name: "LEAQ2", reg: gp21},      // arg0 + 2*arg1 + aux.(int64)

src/cmd/compile/internal/ssa/gen/rulegen.go

@@ -57,6 +57,7 @@ func genRules(arch arch) {
 
 	// read rule file
 	scanner := bufio.NewScanner(text)
+	rule := ""
 	for scanner.Scan() {
 		line := scanner.Text()
 		if i := strings.Index(line, "//"); i >= 0 {
@@ -64,16 +65,27 @@ func genRules(arch arch) {
 			// it will truncate lines with // inside strings.  Oh well.
 			line = line[:i]
 		}
-		line = strings.TrimSpace(line)
-		if line == "" {
+		rule += " " + line
+		rule = strings.TrimSpace(rule)
+		if rule == "" {
 			continue
 		}
-		op := strings.Split(line, " ")[0][1:]
+		if !strings.Contains(rule, "->") {
+			continue
+		}
+		if strings.HasSuffix(rule, "->") {
+			continue
+		}
+		if unbalanced(rule) {
+			continue
+		}
+		op := strings.Split(rule, " ")[0][1:]
 		if isBlock(op, arch) {
-			blockrules[op] = append(blockrules[op], line)
+			blockrules[op] = append(blockrules[op], rule)
 		} else {
-			oprules[op] = append(oprules[op], line)
+			oprules[op] = append(oprules[op], rule)
 		}
+		rule = ""
 	}
 	if err := scanner.Err(); err != nil {
 		log.Fatalf("scanner failed: %v\n", err)
@@ -105,7 +117,7 @@ func genRules(arch arch) {
 			// split at ->
 			s := strings.Split(rule, "->")
 			if len(s) != 2 {
-				log.Fatalf("no arrow in rule %s", rule)
+				log.Fatalf("rule must contain exactly one arrow: %s", rule)
 			}
 			lhs := strings.TrimSpace(s[0])
 			result := strings.TrimSpace(s[1])
@@ -478,3 +490,17 @@ func blockName(name string, arch arch) string {
 	}
 	return "Block" + arch.name + name
 }
+
+// unbalanced returns true if there aren't the same number of ( and ) in the string.
+func unbalanced(s string) bool {
+	var left, right int
+	for _, c := range s {
+		if c == '(' {
+			left++
+		}
+		if c == ')' {
+			right++
+		}
+	}
+	return left != right
+}

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

@@ -53,19 +53,27 @@ const (
 	OpAMD64SUBQconst
 	OpAMD64MULQ
 	OpAMD64MULQconst
+	OpAMD64ANDQ
+	OpAMD64ANDQconst
 	OpAMD64SHLQ
 	OpAMD64SHLQconst
+	OpAMD64SHRQ
+	OpAMD64SHRQconst
+	OpAMD64SARQ
+	OpAMD64SARQconst
 	OpAMD64NEGQ
 	OpAMD64CMPQ
 	OpAMD64CMPQconst
 	OpAMD64TESTQ
 	OpAMD64TESTB
+	OpAMD64SBBQcarrymask
 	OpAMD64SETEQ
 	OpAMD64SETNE
 	OpAMD64SETL
 	OpAMD64SETG
 	OpAMD64SETGE
 	OpAMD64SETB
+	OpAMD64CMOVQCC
 	OpAMD64MOVQconst
 	OpAMD64LEAQ
 	OpAMD64LEAQ2
@@ -204,6 +212,31 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name: "ANDQ",
+		reg: regInfo{
+			inputs: []regMask{
+				4295032831,
+				4295032831,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
+	{
+		name: "ANDQconst",
+		reg: regInfo{
+			inputs: []regMask{
+				4295032831,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
 	{
 		name: "SHLQ",
 		reg: regInfo{
@@ -229,6 +262,56 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name: "SHRQ",
+		reg: regInfo{
+			inputs: []regMask{
+				4295032831,
+				2,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
+	{
+		name: "SHRQconst",
+		reg: regInfo{
+			inputs: []regMask{
+				4295032831,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
+	{
+		name: "SARQ",
+		reg: regInfo{
+			inputs: []regMask{
+				4295032831,
+				2,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
+	{
+		name: "SARQconst",
+		reg: regInfo{
+			inputs: []regMask{
+				4295032831,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
 	{
 		name: "NEGQ",
 		reg: regInfo{
@@ -292,6 +375,18 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name: "SBBQcarrymask",
+		reg: regInfo{
+			inputs: []regMask{
+				8589934592,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
 	{
 		name: "SETEQ",
 		reg: regInfo{
@@ -364,6 +459,20 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name: "CMOVQCC",
+		reg: regInfo{
+			inputs: []regMask{
+				8589934592,
+				65519,
+				65519,
+			},
+			clobbers: 0,
+			outputs: []regMask{
+				65519,
+			},
+		},
+	},
 	{
 		name: "MOVQconst",
 		reg: regInfo{

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

@@ -108,6 +108,81 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
 		goto endfa1c7cc5ac4716697e891376787f86ce
 	endfa1c7cc5ac4716697e891376787f86ce:
 		;
+	case OpAMD64ANDQ:
+		// match: (ANDQ x (MOVQconst [c]))
+		// cond:
+		// result: (ANDQconst [c] x)
+		{
+			x := v.Args[0]
+			if v.Args[1].Op != OpAMD64MOVQconst {
+				goto endb98096e3bbb90933e39c88bf41c688a9
+			}
+			c := v.Args[1].Aux
+			v.Op = OpAMD64ANDQconst
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = c
+			v.AddArg(x)
+			return true
+		}
+		goto endb98096e3bbb90933e39c88bf41c688a9
+	endb98096e3bbb90933e39c88bf41c688a9:
+		;
+		// match: (ANDQ (MOVQconst [c]) x)
+		// cond:
+		// result: (ANDQconst [c] x)
+		{
+			if v.Args[0].Op != OpAMD64MOVQconst {
+				goto endd313fd1897a0d2bc79eff70159a81b6b
+			}
+			c := v.Args[0].Aux
+			x := v.Args[1]
+			v.Op = OpAMD64ANDQconst
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = c
+			v.AddArg(x)
+			return true
+		}
+		goto endd313fd1897a0d2bc79eff70159a81b6b
+	endd313fd1897a0d2bc79eff70159a81b6b:
+		;
+	case OpAMD64ANDQconst:
+		// match: (ANDQconst [c] _)
+		// cond: c.(int64) == 0
+		// result: (MOVQconst [int64(0)])
+		{
+			c := v.Aux
+			if !(c.(int64) == 0) {
+				goto end383ada81cd8ffa88918387cd221acf5c
+			}
+			v.Op = OpAMD64MOVQconst
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = int64(0)
+			return true
+		}
+		goto end383ada81cd8ffa88918387cd221acf5c
+	end383ada81cd8ffa88918387cd221acf5c:
+		;
+		// match: (ANDQconst [c] x)
+		// cond: c.(int64) == -1
+		// result: (Copy x)
+		{
+			c := v.Aux
+			x := v.Args[0]
+			if !(c.(int64) == -1) {
+				goto end90aef368f20963a6ba27b3e9317ccf03
+			}
+			v.Op = OpCopy
+			v.Aux = nil
+			v.resetArgs()
+			v.AddArg(x)
+			return true
+		}
+		goto end90aef368f20963a6ba27b3e9317ccf03
+	end90aef368f20963a6ba27b3e9317ccf03:
+		;
 	case OpAdd:
 		// match: (Add <t> x y)
 		// cond: (is64BitInt(t) || isPtr(t))
@@ -149,6 +224,57 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
 		goto end35a02a1587264e40cf1055856ff8445a
 	end35a02a1587264e40cf1055856ff8445a:
 		;
+	case OpAMD64CMOVQCC:
+		// match: (CMOVQCC (CMPQconst [c] (MOVQconst [d])) _ x)
+		// cond: inBounds(d.(int64), c.(int64))
+		// result: (Copy x)
+		{
+			if v.Args[0].Op != OpAMD64CMPQconst {
+				goto endb8f4f98b06c41e559bf0323e798c147a
+			}
+			c := v.Args[0].Aux
+			if v.Args[0].Args[0].Op != OpAMD64MOVQconst {
+				goto endb8f4f98b06c41e559bf0323e798c147a
+			}
+			d := v.Args[0].Args[0].Aux
+			x := v.Args[2]
+			if !(inBounds(d.(int64), c.(int64))) {
+				goto endb8f4f98b06c41e559bf0323e798c147a
+			}
+			v.Op = OpCopy
+			v.Aux = nil
+			v.resetArgs()
+			v.AddArg(x)
+			return true
+		}
+		goto endb8f4f98b06c41e559bf0323e798c147a
+	endb8f4f98b06c41e559bf0323e798c147a:
+		;
+		// match: (CMOVQCC (CMPQconst [c] (MOVQconst [d])) x _)
+		// cond: !inBounds(d.(int64), c.(int64))
+		// result: (Copy x)
+		{
+			if v.Args[0].Op != OpAMD64CMPQconst {
+				goto end29407b5c4731ac24b4c25600752cb895
+			}
+			c := v.Args[0].Aux
+			if v.Args[0].Args[0].Op != OpAMD64MOVQconst {
+				goto end29407b5c4731ac24b4c25600752cb895
+			}
+			d := v.Args[0].Args[0].Aux
+			x := v.Args[1]
+			if !(!inBounds(d.(int64), c.(int64))) {
+				goto end29407b5c4731ac24b4c25600752cb895
+			}
+			v.Op = OpCopy
+			v.Aux = nil
+			v.resetArgs()
+			v.AddArg(x)
+			return true
+		}
+		goto end29407b5c4731ac24b4c25600752cb895
+	end29407b5c4731ac24b4c25600752cb895:
+		;
 	case OpAMD64CMPQ:
 		// match: (CMPQ x (MOVQconst [c]))
 		// cond:
@@ -352,23 +478,34 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
 	case OpLsh:
 		// match: (Lsh <t> x y)
 		// cond: is64BitInt(t)
-		// result: (SHLQ x y)
+		// result: (ANDQ (SHLQ <t> x y) (SBBQcarrymask <t> (CMPQconst <TypeFlags> [int64(64)] y)))
 		{
 			t := v.Type
 			x := v.Args[0]
 			y := v.Args[1]
 			if !(is64BitInt(t)) {
-				goto end9f05c9539e51db6ad557989e0c822e9b
+				goto end7002b6d4becf7d1247e3756641ccb0c2
 			}
-			v.Op = OpAMD64SHLQ
+			v.Op = OpAMD64ANDQ
 			v.Aux = nil
 			v.resetArgs()
-			v.AddArg(x)
-			v.AddArg(y)
+			v0 := v.Block.NewValue(v.Line, OpAMD64SHLQ, TypeInvalid, nil)
+			v0.Type = t
+			v0.AddArg(x)
+			v0.AddArg(y)
+			v.AddArg(v0)
+			v1 := v.Block.NewValue(v.Line, OpAMD64SBBQcarrymask, TypeInvalid, nil)
+			v1.Type = t
+			v2 := v.Block.NewValue(v.Line, OpAMD64CMPQconst, TypeInvalid, nil)
+			v2.Type = TypeFlags
+			v2.Aux = int64(64)
+			v2.AddArg(y)
+			v1.AddArg(v2)
+			v.AddArg(v1)
 			return true
 		}
-		goto end9f05c9539e51db6ad557989e0c822e9b
-	end9f05c9539e51db6ad557989e0c822e9b:
+		goto end7002b6d4becf7d1247e3756641ccb0c2
+	end7002b6d4becf7d1247e3756641ccb0c2:
 		;
 	case OpAMD64MOVQload:
 		// match: (MOVQload [off1] (ADDQconst [off2] ptr) mem)
@@ -663,6 +800,140 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
 		goto end0429f947ee7ac49ff45a243e461a5290
 	end0429f947ee7ac49ff45a243e461a5290:
 		;
+	case OpRsh:
+		// match: (Rsh <t> x y)
+		// cond: is64BitInt(t) && !t.IsSigned()
+		// result: (ANDQ (SHRQ <t> x y) (SBBQcarrymask <t> (CMPQconst <TypeFlags> [int64(64)] y)))
+		{
+			t := v.Type
+			x := v.Args[0]
+			y := v.Args[1]
+			if !(is64BitInt(t) && !t.IsSigned()) {
+				goto end9463ddaa21c75f8e15cb9f31472a2e23
+			}
+			v.Op = OpAMD64ANDQ
+			v.Aux = nil
+			v.resetArgs()
+			v0 := v.Block.NewValue(v.Line, OpAMD64SHRQ, TypeInvalid, nil)
+			v0.Type = t
+			v0.AddArg(x)
+			v0.AddArg(y)
+			v.AddArg(v0)
+			v1 := v.Block.NewValue(v.Line, OpAMD64SBBQcarrymask, TypeInvalid, nil)
+			v1.Type = t
+			v2 := v.Block.NewValue(v.Line, OpAMD64CMPQconst, TypeInvalid, nil)
+			v2.Type = TypeFlags
+			v2.Aux = int64(64)
+			v2.AddArg(y)
+			v1.AddArg(v2)
+			v.AddArg(v1)
+			return true
+		}
+		goto end9463ddaa21c75f8e15cb9f31472a2e23
+	end9463ddaa21c75f8e15cb9f31472a2e23:
+		;
+		// match: (Rsh <t> x y)
+		// cond: is64BitInt(t) && t.IsSigned()
+		// result: (SARQ <t> x (CMOVQCC <t> 			(CMPQconst <TypeFlags> [int64(64)] y) 			(Const <t> [int64(63)]) 			y))
+		{
+			t := v.Type
+			x := v.Args[0]
+			y := v.Args[1]
+			if !(is64BitInt(t) && t.IsSigned()) {
+				goto endd297b9e569ac90bf815bd4c425d3b770
+			}
+			v.Op = OpAMD64SARQ
+			v.Aux = nil
+			v.resetArgs()
+			v.Type = t
+			v.AddArg(x)
+			v0 := v.Block.NewValue(v.Line, OpAMD64CMOVQCC, TypeInvalid, nil)
+			v0.Type = t
+			v1 := v.Block.NewValue(v.Line, OpAMD64CMPQconst, TypeInvalid, nil)
+			v1.Type = TypeFlags
+			v1.Aux = int64(64)
+			v1.AddArg(y)
+			v0.AddArg(v1)
+			v2 := v.Block.NewValue(v.Line, OpConst, TypeInvalid, nil)
+			v2.Type = t
+			v2.Aux = int64(63)
+			v0.AddArg(v2)
+			v0.AddArg(y)
+			v.AddArg(v0)
+			return true
+		}
+		goto endd297b9e569ac90bf815bd4c425d3b770
+	endd297b9e569ac90bf815bd4c425d3b770:
+		;
+	case OpAMD64SARQ:
+		// match: (SARQ x (MOVQconst [c]))
+		// cond:
+		// result: (SARQconst [c] x)
+		{
+			x := v.Args[0]
+			if v.Args[1].Op != OpAMD64MOVQconst {
+				goto end031712b4008075e25a5827dcb8dd3ebb
+			}
+			c := v.Args[1].Aux
+			v.Op = OpAMD64SARQconst
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = c
+			v.AddArg(x)
+			return true
+		}
+		goto end031712b4008075e25a5827dcb8dd3ebb
+	end031712b4008075e25a5827dcb8dd3ebb:
+		;
+	case OpAMD64SBBQcarrymask:
+		// match: (SBBQcarrymask (CMPQconst [c] (MOVQconst [d])))
+		// cond: inBounds(d.(int64), c.(int64))
+		// result: (Const [int64(-1)])
+		{
+			if v.Args[0].Op != OpAMD64CMPQconst {
+				goto end35e369f67ebb9423a1d36a808a16777c
+			}
+			c := v.Args[0].Aux
+			if v.Args[0].Args[0].Op != OpAMD64MOVQconst {
+				goto end35e369f67ebb9423a1d36a808a16777c
+			}
+			d := v.Args[0].Args[0].Aux
+			if !(inBounds(d.(int64), c.(int64))) {
+				goto end35e369f67ebb9423a1d36a808a16777c
+			}
+			v.Op = OpConst
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = int64(-1)
+			return true
+		}
+		goto end35e369f67ebb9423a1d36a808a16777c
+	end35e369f67ebb9423a1d36a808a16777c:
+		;
+		// match: (SBBQcarrymask (CMPQconst [c] (MOVQconst [d])))
+		// cond: !inBounds(d.(int64), c.(int64))
+		// result: (Const [int64(0)])
+		{
+			if v.Args[0].Op != OpAMD64CMPQconst {
+				goto end5c767fada028c1cc96210af2cf098aff
+			}
+			c := v.Args[0].Aux
+			if v.Args[0].Args[0].Op != OpAMD64MOVQconst {
+				goto end5c767fada028c1cc96210af2cf098aff
+			}
+			d := v.Args[0].Args[0].Aux
+			if !(!inBounds(d.(int64), c.(int64))) {
+				goto end5c767fada028c1cc96210af2cf098aff
+			}
+			v.Op = OpConst
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = int64(0)
+			return true
+		}
+		goto end5c767fada028c1cc96210af2cf098aff
+	end5c767fada028c1cc96210af2cf098aff:
+		;
 	case OpAMD64SETG:
 		// match: (SETG (InvertFlags x))
 		// cond:
@@ -719,6 +990,26 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
 		goto endcca412bead06dc3d56ef034a82d184d6
 	endcca412bead06dc3d56ef034a82d184d6:
 		;
+	case OpAMD64SHRQ:
+		// match: (SHRQ x (MOVQconst [c]))
+		// cond:
+		// result: (SHRQconst [c] x)
+		{
+			x := v.Args[0]
+			if v.Args[1].Op != OpAMD64MOVQconst {
+				goto endbb0d3a04dd2b810cb3dbdf7ef665f22b
+			}
+			c := v.Args[1].Aux
+			v.Op = OpAMD64SHRQconst
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = c
+			v.AddArg(x)
+			return true
+		}
+		goto endbb0d3a04dd2b810cb3dbdf7ef665f22b
+	endbb0d3a04dd2b810cb3dbdf7ef665f22b:
+		;
 	case OpAMD64SUBQ:
 		// match: (SUBQ x (MOVQconst [c]))
 		// cond:

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

+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+import (
+	"testing"
+)
+
+func TestShiftConstAMD64(t *testing.T) {
+	c := NewConfig("amd64", DummyFrontend{})
+	fun := makeConstShiftFunc(c, 18, OpLsh, TypeUInt64)
+	checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHLQconst: 1, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
+	fun = makeConstShiftFunc(c, 66, OpLsh, TypeUInt64)
+	checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHLQconst: 0, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
+	fun = makeConstShiftFunc(c, 18, OpRsh, TypeUInt64)
+	checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHRQconst: 1, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
+	fun = makeConstShiftFunc(c, 66, OpRsh, TypeUInt64)
+	checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHRQconst: 0, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
+	fun = makeConstShiftFunc(c, 18, OpRsh, TypeInt64)
+	checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SARQconst: 1, OpAMD64CMPQconst: 0})
+	fun = makeConstShiftFunc(c, 66, OpRsh, TypeInt64)
+	checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SARQconst: 1, OpAMD64CMPQconst: 0})
+}
+
+func makeConstShiftFunc(c *Config, amount int64, op Op, typ Type) fun {
+	ptyp := &TypeImpl{Size_: 8, Ptr: true, Name: "ptr"}
+	fun := Fun(c, "entry",
+		Bloc("entry",
+			Valu("mem", OpArg, TypeMem, ".mem"),
+			Valu("FP", OpFP, TypeUInt64, nil),
+			Valu("argptr", OpOffPtr, ptyp, int64(8), "FP"),
+			Valu("resptr", OpOffPtr, ptyp, int64(16), "FP"),
+			Valu("load", OpLoad, typ, nil, "argptr", "mem"),
+			Valu("c", OpConst, TypeUInt64, amount),
+			Valu("shift", op, typ, nil, "load", "c"),
+			Valu("store", OpStore, TypeMem, nil, "resptr", "shift", "mem"),
+			Exit("store")))
+	Compile(fun.f)
+	return fun
+}

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

@@ -33,10 +33,9 @@ func stackalloc(f *Func) {
 			if v.Type.IsMemory() { // TODO: only "regallocable" types
 				continue
 			}
-			n += v.Type.Size()
-			// a := v.Type.Align()
-			// n = (n + a - 1) / a * a  TODO
+			n = align(n, v.Type.Alignment())
 			loc := &LocalSlot{n}
+			n += v.Type.Size()
 			home = setloc(home, v, loc)
 			for _, w := range v.Args {
 				home = setloc(home, w, loc)
@@ -60,15 +59,14 @@ func stackalloc(f *Func) {
 			if len(v.Args) == 1 && (v.Args[0].Op == OpFP || v.Args[0].Op == OpSP || v.Args[0].Op == OpGlobal) {
 				continue
 			}
-			// a := v.Type.Align()
-			// n = (n + a - 1) / a * a  TODO
-			n += v.Type.Size()
+			n = align(n, v.Type.Alignment())
 			loc := &LocalSlot{n}
+			n += v.Type.Size()
 			home = setloc(home, v, loc)
 		}
 	}
 
-	// TODO: align n
+	n = align(n, f.Config.ptrSize)
 	n += f.Config.ptrSize // space for return address.  TODO: arch-dependent
 	f.RegAlloc = home
 	f.FrameSize = n
@@ -114,3 +112,8 @@ func stackalloc(f *Func) {
 		home[fp.ID] = &registers[4] // TODO: arch-dependent
 	}
 }
+
+// align increases n to the next multiple of a.  a must be a power of 2.
+func align(n int64, a int64) int64 {
+	return (n + a - 1) &^ (a - 1)
+}

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

@@ -10,6 +10,7 @@ package ssa
 // Type instances are not guaranteed to be canonical.
 type Type interface {
 	Size() int64 // return the size in bytes
+	Alignment() int64
 
 	IsBoolean() bool // is a named or unnamed boolean type
 	IsInteger() bool //  ... ditto for the others
@@ -30,6 +31,7 @@ type Type interface {
 // Stub implementation for now, until we are completely using ../gc:Type
 type TypeImpl struct {
 	Size_   int64
+	Align   int64
 	Boolean bool
 	Integer bool
 	Signed  bool
@@ -43,32 +45,33 @@ type TypeImpl struct {
 	Name string
 }
 
-func (t *TypeImpl) Size() int64     { return t.Size_ }
-func (t *TypeImpl) IsBoolean() bool { return t.Boolean }
-func (t *TypeImpl) IsInteger() bool { return t.Integer }
-func (t *TypeImpl) IsSigned() bool  { return t.Signed }
-func (t *TypeImpl) IsFloat() bool   { return t.Float }
-func (t *TypeImpl) IsPtr() bool     { return t.Ptr }
-func (t *TypeImpl) IsString() bool  { return t.string }
-func (t *TypeImpl) IsMemory() bool  { return t.Memory }
-func (t *TypeImpl) IsFlags() bool   { return t.Flags }
-func (t *TypeImpl) String() string  { return t.Name }
-func (t *TypeImpl) Elem() Type      { panic("not implemented"); return nil }
-func (t *TypeImpl) PtrTo() Type     { panic("not implemented"); return nil }
+func (t *TypeImpl) Size() int64      { return t.Size_ }
+func (t *TypeImpl) Alignment() int64 { return t.Align }
+func (t *TypeImpl) IsBoolean() bool  { return t.Boolean }
+func (t *TypeImpl) IsInteger() bool  { return t.Integer }
+func (t *TypeImpl) IsSigned() bool   { return t.Signed }
+func (t *TypeImpl) IsFloat() bool    { return t.Float }
+func (t *TypeImpl) IsPtr() bool      { return t.Ptr }
+func (t *TypeImpl) IsString() bool   { return t.string }
+func (t *TypeImpl) IsMemory() bool   { return t.Memory }
+func (t *TypeImpl) IsFlags() bool    { return t.Flags }
+func (t *TypeImpl) String() string   { return t.Name }
+func (t *TypeImpl) Elem() Type       { panic("not implemented"); return nil }
+func (t *TypeImpl) PtrTo() Type      { panic("not implemented"); return nil }
 
 var (
 	// shortcuts for commonly used basic types
-	TypeInt8   = &TypeImpl{Size_: 1, Integer: true, Signed: true, Name: "int8"}
-	TypeInt16  = &TypeImpl{Size_: 2, Integer: true, Signed: true, Name: "int16"}
-	TypeInt32  = &TypeImpl{Size_: 4, Integer: true, Signed: true, Name: "int32"}
-	TypeInt64  = &TypeImpl{Size_: 8, Integer: true, Signed: true, Name: "int64"}
-	TypeUInt8  = &TypeImpl{Size_: 1, Integer: true, Name: "uint8"}
-	TypeUInt16 = &TypeImpl{Size_: 2, Integer: true, Name: "uint16"}
-	TypeUInt32 = &TypeImpl{Size_: 4, Integer: true, Name: "uint32"}
-	TypeUInt64 = &TypeImpl{Size_: 8, Integer: true, Name: "uint64"}
-	TypeBool   = &TypeImpl{Size_: 1, Boolean: true, Name: "bool"}
+	TypeInt8   = &TypeImpl{Size_: 1, Align: 1, Integer: true, Signed: true, Name: "int8"}
+	TypeInt16  = &TypeImpl{Size_: 2, Align: 2, Integer: true, Signed: true, Name: "int16"}
+	TypeInt32  = &TypeImpl{Size_: 4, Align: 4, Integer: true, Signed: true, Name: "int32"}
+	TypeInt64  = &TypeImpl{Size_: 8, Align: 8, Integer: true, Signed: true, Name: "int64"}
+	TypeUInt8  = &TypeImpl{Size_: 1, Align: 1, Integer: true, Name: "uint8"}
+	TypeUInt16 = &TypeImpl{Size_: 2, Align: 2, Integer: true, Name: "uint16"}
+	TypeUInt32 = &TypeImpl{Size_: 4, Align: 4, Integer: true, Name: "uint32"}
+	TypeUInt64 = &TypeImpl{Size_: 8, Align: 8, Integer: true, Name: "uint64"}
+	TypeBool   = &TypeImpl{Size_: 1, Align: 1, Boolean: true, Name: "bool"}
 	//TypeString = types.Typ[types.String]
-	TypeBytePtr = &TypeImpl{Size_: 8, Ptr: true, Name: "*byte"}
+	TypeBytePtr = &TypeImpl{Size_: 8, Align: 8, Ptr: true, Name: "*byte"}
 
 	TypeInvalid = &TypeImpl{Name: "invalid"}