cmd/compile: add intrinsics for runtime/internal/math on 386 and amd64

Add generic, 386 and amd64 specific ops and SSA rules for multiplication
with overflow and branching based on overflow flags. Use these to intrinsify
runtime/internal/math.MulUinptr.

On amd64
  mul, overflow := math.MulUintptr(a, b)
  if overflow {
is lowered to two instructions:
  MULQ SI
  JO 0x10ee35c

No codegen tests as codegen can not currently test unexported internal runtime
functions.

amd64:
name              old time/op  new time/op  delta
MulUintptr/small  1.16ns ± 5%  0.88ns ± 6%  -24.36%  (p=0.000 n=19+20)
MulUintptr/large  10.7ns ± 1%   1.1ns ± 1%  -89.28%  (p=0.000 n=17+19)

Change-Id: If60739a86f820e5044d677276c21df90d3c7a86a
Reviewed-on: https://go-review.googlesource.com/c/141820
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -315,6 +315,13 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 			m.To.Reg = x86.REG_DX
 		}
 
+	case ssa.OpAMD64MULQU, ssa.OpAMD64MULLU:
+		// Arg[0] is already in AX as it's the only register we allow
+		// results lo in AX
+		p := s.Prog(v.Op.Asm())
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = v.Args[1].Reg()
+
 	case ssa.OpAMD64MULQU2:
 		// Arg[0] is already in AX as it's the only register we allow
 		// results hi in DX, lo in AX
@@ -979,7 +986,8 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		ssa.OpAMD64SETGF, ssa.OpAMD64SETGEF,
 		ssa.OpAMD64SETB, ssa.OpAMD64SETBE,
 		ssa.OpAMD64SETORD, ssa.OpAMD64SETNAN,
-		ssa.OpAMD64SETA, ssa.OpAMD64SETAE:
+		ssa.OpAMD64SETA, ssa.OpAMD64SETAE,
+		ssa.OpAMD64SETO:
 		p := s.Prog(v.Op.Asm())
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = v.Reg()
@@ -1122,6 +1130,8 @@ var blockJump = [...]struct {
 	ssa.BlockAMD64GE:  {x86.AJGE, x86.AJLT},
 	ssa.BlockAMD64LE:  {x86.AJLE, x86.AJGT},
 	ssa.BlockAMD64GT:  {x86.AJGT, x86.AJLE},
+	ssa.BlockAMD64OS:  {x86.AJOS, x86.AJOC},
+	ssa.BlockAMD64OC:  {x86.AJOC, x86.AJOS},
 	ssa.BlockAMD64ULT: {x86.AJCS, x86.AJCC},
 	ssa.BlockAMD64UGE: {x86.AJCC, x86.AJCS},
 	ssa.BlockAMD64UGT: {x86.AJHI, x86.AJLS},
@@ -1183,6 +1193,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 	case ssa.BlockAMD64EQ, ssa.BlockAMD64NE,
 		ssa.BlockAMD64LT, ssa.BlockAMD64GE,
 		ssa.BlockAMD64LE, ssa.BlockAMD64GT,
+		ssa.BlockAMD64OS, ssa.BlockAMD64OC,
 		ssa.BlockAMD64ULT, ssa.BlockAMD64UGT,
 		ssa.BlockAMD64ULE, ssa.BlockAMD64UGE:
 		jmp := blockJump[b.Kind]

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

@@ -2913,6 +2913,14 @@ func init() {
 			},
 			all...)
 	}
+	addF("runtime/internal/math", "MulUintptr",
+		func(s *state, n *Node, args []*ssa.Value) *ssa.Value {
+			if s.config.PtrSize == 4 {
+				return s.newValue2(ssa.OpMul32uover, types.NewTuple(types.Types[TUINT], types.Types[TUINT]), args[0], args[1])
+			}
+			return s.newValue2(ssa.OpMul64uover, types.NewTuple(types.Types[TUINT], types.Types[TUINT]), args[0], args[1])
+		},
+		sys.AMD64, sys.I386)
 	add("runtime", "KeepAlive",
 		func(s *state, n *Node, args []*ssa.Value) *ssa.Value {
 			data := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, args[0])

src/cmd/compile/internal/ssa/gen/386.rules

@@ -17,6 +17,9 @@
 (Mul(32|64)F x y) -> (MULS(S|D) x y)
 (Mul32uhilo x y) -> (MULLQU x y)
 
+(Select0 (Mul32uover x y)) -> (Select0 <typ.UInt32> (MULLU x y))
+(Select1 (Mul32uover x y)) -> (SETO (Select1 <types.TypeFlags> (MULLU x y)))
+
 (Avg32u x y) -> (AVGLU x y)
 
 (Div32F x y) -> (DIVSS x y)
@@ -369,6 +372,7 @@
 (If (SETBE cmp) yes no) -> (ULE cmp yes no)
 (If (SETA  cmp) yes no) -> (UGT cmp yes no)
 (If (SETAE cmp) yes no) -> (UGE cmp yes no)
+(If (SETO  cmp) yes no) -> (OS cmp yes no)
 
 // Special case for floating point - LF/LEF not generated
 (If (SETGF  cmp) yes no) -> (UGT  cmp yes no)
@@ -398,6 +402,7 @@
 (NE (TESTB (SETBE cmp) (SETBE cmp)) yes no) -> (ULE cmp yes no)
 (NE (TESTB (SETA  cmp) (SETA  cmp)) yes no) -> (UGT cmp yes no)
 (NE (TESTB (SETAE cmp) (SETAE cmp)) yes no) -> (UGE cmp yes no)
+(NE (TESTB (SETO cmp) (SETO cmp)) yes no) -> (OS cmp yes no)
 
 // Special case for floating point - LF/LEF not generated
 (NE (TESTB (SETGF  cmp) (SETGF  cmp)) yes no) -> (UGT  cmp yes no)

src/cmd/compile/internal/ssa/gen/386Ops.go

@@ -207,6 +207,8 @@ func init() {
 		{name: "MULL", argLength: 2, reg: gp21, asm: "IMULL", commutative: true, resultInArg0: true, clobberFlags: true}, // arg0 * arg1
 		{name: "MULLconst", argLength: 1, reg: gp11, asm: "IMUL3L", aux: "Int32", clobberFlags: true},                    // arg0 * auxint
 
+		{name: "MULLU", argLength: 2, reg: regInfo{inputs: []regMask{ax, gpsp}, outputs: []regMask{ax, 0}, clobbers: dx}, typ: "(UInt32,Flags)", asm: "MULL", commutative: true, clobberFlags: true}, // Let x = arg0*arg1 (full 32x32->64  unsigned multiply). Returns uint32(x), and flags set to overflow if uint32(x) != x.
+
 		{name: "HMULL", argLength: 2, reg: gp21hmul, commutative: true, asm: "IMULL", clobberFlags: true}, // (arg0 * arg1) >> width
 		{name: "HMULLU", argLength: 2, reg: gp21hmul, commutative: true, asm: "MULL", clobberFlags: true}, // (arg0 * arg1) >> width
 
@@ -326,6 +328,7 @@ func init() {
 		{name: "SETBE", argLength: 1, reg: readflags, asm: "SETLS"}, // extract unsigned <= condition from arg0
 		{name: "SETA", argLength: 1, reg: readflags, asm: "SETHI"},  // extract unsigned > condition from arg0
 		{name: "SETAE", argLength: 1, reg: readflags, asm: "SETCC"}, // extract unsigned >= condition from arg0
+		{name: "SETO", argLength: 1, reg: readflags, asm: "SETOS"},  // extract if overflow flag is set from arg0
 		// Need different opcodes for floating point conditions because
 		// any comparison involving a NaN is always FALSE and thus
 		// the patterns for inverting conditions cannot be used.
@@ -553,6 +556,8 @@ func init() {
 		{name: "LE"},
 		{name: "GT"},
 		{name: "GE"},
+		{name: "OS"},
+		{name: "OC"},
 		{name: "ULT"},
 		{name: "ULE"},
 		{name: "UGT"},

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

@@ -16,6 +16,10 @@
 (Mul(64|32|16|8)  x y) -> (MUL(Q|L|L|L)  x y)
 (Mul(32|64)F x y) -> (MULS(S|D) x y)
 
+(Select0 (Mul64uover x y)) -> (Select0 <typ.UInt64> (MULQU x y))
+(Select0 (Mul32uover x y)) -> (Select0 <typ.UInt32> (MULLU x y))
+(Select1 (Mul(64|32)uover x y)) -> (SETO (Select1 <types.TypeFlags> (MUL(Q|L)U x y)))
+
 (Hmul(64|32)  x y) -> (HMUL(Q|L)  x y)
 (Hmul(64|32)u x y) -> (HMUL(Q|L)U x y)
 
@@ -480,6 +484,7 @@
 (If (SETBE cmp) yes no) -> (ULE cmp yes no)
 (If (SETA  cmp) yes no) -> (UGT cmp yes no)
 (If (SETAE cmp) yes no) -> (UGE cmp yes no)
+(If (SETO cmp) yes no) -> (OS cmp yes no)
 
 // Special case for floating point - LF/LEF not generated
 (If (SETGF  cmp) yes no) -> (UGT  cmp yes no)
@@ -542,6 +547,7 @@
 (NE (TESTB (SETBE cmp) (SETBE cmp)) yes no) -> (ULE cmp yes no)
 (NE (TESTB (SETA  cmp) (SETA  cmp)) yes no) -> (UGT cmp yes no)
 (NE (TESTB (SETAE cmp) (SETAE cmp)) yes no) -> (UGE cmp yes no)
+(NE (TESTB (SETO cmp) (SETO cmp)) yes no) -> (OS cmp yes no)
 
 // Recognize bit tests: a&(1<<b) != 0 for b suitably bounded
 // Note that BTx instructions use the carry bit, so we need to convert tests for zero flag

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

@@ -210,6 +210,9 @@ func init() {
 		{name: "MULQconst", argLength: 1, reg: gp11, asm: "IMUL3Q", aux: "Int32", clobberFlags: true},                    // arg0 * auxint
 		{name: "MULLconst", argLength: 1, reg: gp11, asm: "IMUL3L", aux: "Int32", clobberFlags: true},                    // arg0 * auxint
 
+		{name: "MULLU", argLength: 2, reg: regInfo{inputs: []regMask{ax, gpsp}, outputs: []regMask{ax, 0}, clobbers: dx}, typ: "(UInt32,Flags)", asm: "MULL", commutative: true, clobberFlags: true}, // Let x = arg0*arg1 (full 32x32->64  unsigned multiply). Returns uint32(x), and flags set to overflow if uint32(x) != x.
+		{name: "MULQU", argLength: 2, reg: regInfo{inputs: []regMask{ax, gpsp}, outputs: []regMask{ax, 0}, clobbers: dx}, typ: "(UInt64,Flags)", asm: "MULQ", commutative: true, clobberFlags: true}, // Let x = arg0*arg1 (full 64x64->128 unsigned multiply). Returns uint64(x), and flags set to overflow if uint64(x) != x.
+
 		{name: "HMULQ", argLength: 2, reg: gp21hmul, commutative: true, asm: "IMULQ", clobberFlags: true}, // (arg0 * arg1) >> width
 		{name: "HMULL", argLength: 2, reg: gp21hmul, commutative: true, asm: "IMULL", clobberFlags: true}, // (arg0 * arg1) >> width
 		{name: "HMULQU", argLength: 2, reg: gp21hmul, commutative: true, asm: "MULQ", clobberFlags: true}, // (arg0 * arg1) >> width
@@ -468,6 +471,7 @@ func init() {
 		{name: "SETBE", argLength: 1, reg: readflags, asm: "SETLS"}, // extract unsigned <= condition from arg0
 		{name: "SETA", argLength: 1, reg: readflags, asm: "SETHI"},  // extract unsigned > condition from arg0
 		{name: "SETAE", argLength: 1, reg: readflags, asm: "SETCC"}, // extract unsigned >= condition from arg0
+		{name: "SETO", argLength: 1, reg: readflags, asm: "SETOS"},  // extract if overflow flag is set from arg0
 		// Variants that store result to memory
 		{name: "SETEQstore", argLength: 3, reg: gpstoreconst, asm: "SETEQ", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"}, // extract == condition from arg1 to arg0+auxint+aux, arg2=mem
 		{name: "SETNEstore", argLength: 3, reg: gpstoreconst, asm: "SETNE", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"}, // extract != condition from arg1 to arg0+auxint+aux, arg2=mem
@@ -754,6 +758,8 @@ func init() {
 		{name: "LE"},
 		{name: "GT"},
 		{name: "GE"},
+		{name: "OS"},
+		{name: "OC"},
 		{name: "ULT"},
 		{name: "ULE"},
 		{name: "UGT"},

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

@@ -55,6 +55,9 @@ var genericOps = []opData{
 	{name: "Mul32uhilo", argLength: 2, typ: "(UInt32,UInt32)", commutative: true}, // arg0 * arg1, returns (hi, lo)
 	{name: "Mul64uhilo", argLength: 2, typ: "(UInt64,UInt64)", commutative: true}, // arg0 * arg1, returns (hi, lo)
 
+	{name: "Mul32uover", argLength: 2, typ: "(UInt32,Bool)", commutative: true}, // Let x = arg0*arg1 (full 32x32-> 64 unsigned multiply), returns (uint32(x), (uint32(x) != x))
+	{name: "Mul64uover", argLength: 2, typ: "(UInt64,Bool)", commutative: true}, // Let x = arg0*arg1 (full 64x64->128 unsigned multiply), returns (uint64(x), (uint64(x) != x))
+
 	// Weird special instructions for use in the strength reduction of divides.
 	// These ops compute unsigned (arg0 + arg1) / 2, correct to all
 	// 32/64 bits, even when the intermediate result of the add has 33/65 bits.

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

@@ -22,6 +22,8 @@ const (
 	Block386LE
 	Block386GT
 	Block386GE
+	Block386OS
+	Block386OC
 	Block386ULT
 	Block386ULE
 	Block386UGT
@@ -37,6 +39,8 @@ const (
 	BlockAMD64LE
 	BlockAMD64GT
 	BlockAMD64GE
+	BlockAMD64OS
+	BlockAMD64OC
 	BlockAMD64ULT
 	BlockAMD64ULE
 	BlockAMD64UGT
@@ -130,6 +134,8 @@ var blockString = [...]string{
 	Block386LE:  "LE",
 	Block386GT:  "GT",
 	Block386GE:  "GE",
+	Block386OS:  "OS",
+	Block386OC:  "OC",
 	Block386ULT: "ULT",
 	Block386ULE: "ULE",
 	Block386UGT: "UGT",
@@ -145,6 +151,8 @@ var blockString = [...]string{
 	BlockAMD64LE:  "LE",
 	BlockAMD64GT:  "GT",
 	BlockAMD64GE:  "GE",
+	BlockAMD64OS:  "OS",
+	BlockAMD64OC:  "OC",
 	BlockAMD64ULT: "ULT",
 	BlockAMD64ULE: "ULE",
 	BlockAMD64UGT: "UGT",
@@ -278,6 +286,7 @@ const (
 	Op386SBBLconst
 	Op386MULL
 	Op386MULLconst
+	Op386MULLU
 	Op386HMULL
 	Op386HMULLU
 	Op386MULLQU
@@ -364,6 +373,7 @@ const (
 	Op386SETBE
 	Op386SETA
 	Op386SETAE
+	Op386SETO
 	Op386SETEQF
 	Op386SETNEF
 	Op386SETORD
@@ -500,6 +510,8 @@ const (
 	OpAMD64MULL
 	OpAMD64MULQconst
 	OpAMD64MULLconst
+	OpAMD64MULLU
+	OpAMD64MULQU
 	OpAMD64HMULQ
 	OpAMD64HMULL
 	OpAMD64HMULQU
@@ -705,6 +717,7 @@ const (
 	OpAMD64SETBE
 	OpAMD64SETA
 	OpAMD64SETAE
+	OpAMD64SETO
 	OpAMD64SETEQstore
 	OpAMD64SETNEstore
 	OpAMD64SETLstore
@@ -2083,6 +2096,8 @@ const (
 	OpHmul64u
 	OpMul32uhilo
 	OpMul64uhilo
+	OpMul32uover
+	OpMul64uover
 	OpAvg32u
 	OpAvg64u
 	OpDiv8
@@ -3114,6 +3129,24 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name:         "MULLU",
+		argLen:       2,
+		commutative:  true,
+		clobberFlags: true,
+		asm:          x86.AMULL,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 1},   // AX
+				{1, 255}, // AX CX DX BX SP BP SI DI
+			},
+			clobbers: 4, // DX
+			outputs: []outputInfo{
+				{1, 0},
+				{0, 1}, // AX
+			},
+		},
+	},
 	{
 		name:         "HMULL",
 		argLen:       2,
@@ -4378,6 +4411,16 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name:   "SETO",
+		argLen: 1,
+		asm:    x86.ASETOS,
+		reg: regInfo{
+			outputs: []outputInfo{
+				{0, 239}, // AX CX DX BX BP SI DI
+			},
+		},
+	},
 	{
 		name:         "SETEQF",
 		argLen:       1,
@@ -6271,6 +6314,42 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name:         "MULLU",
+		argLen:       2,
+		commutative:  true,
+		clobberFlags: true,
+		asm:          x86.AMULL,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 1},     // AX
+				{1, 65535}, // AX CX DX BX SP BP SI DI R8 R9 R10 R11 R12 R13 R14 R15
+			},
+			clobbers: 4, // DX
+			outputs: []outputInfo{
+				{1, 0},
+				{0, 1}, // AX
+			},
+		},
+	},
+	{
+		name:         "MULQU",
+		argLen:       2,
+		commutative:  true,
+		clobberFlags: true,
+		asm:          x86.AMULQ,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 1},     // AX
+				{1, 65535}, // AX CX DX BX SP BP SI DI R8 R9 R10 R11 R12 R13 R14 R15
+			},
+			clobbers: 4, // DX
+			outputs: []outputInfo{
+				{1, 0},
+				{0, 1}, // AX
+			},
+		},
+	},
 	{
 		name:         "HMULQ",
 		argLen:       2,
@@ -9293,6 +9372,16 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name:   "SETO",
+		argLen: 1,
+		asm:    x86.ASETOS,
+		reg: regInfo{
+			outputs: []outputInfo{
+				{0, 65519}, // AX CX DX BX BP SI DI R8 R9 R10 R11 R12 R13 R14 R15
+			},
+		},
+	},
 	{
 		name:           "SETEQstore",
 		auxType:        auxSymOff,
@@ -27899,6 +27988,18 @@ var opcodeTable = [...]opInfo{
 		commutative: true,
 		generic:     true,
 	},
+	{
+		name:        "Mul32uover",
+		argLen:      2,
+		commutative: true,
+		generic:     true,
+	},
+	{
+		name:        "Mul64uover",
+		argLen:      2,
+		commutative: true,
+		generic:     true,
+	},
 	{
 		name:    "Avg32u",
 		argLen:  2,

src/cmd/compile/internal/ssa/rewrite386.go

@@ -637,6 +637,10 @@ func rewriteValue386(v *Value) bool {
 		return rewriteValue386_OpRsh8x64_0(v)
 	case OpRsh8x8:
 		return rewriteValue386_OpRsh8x8_0(v)
+	case OpSelect0:
+		return rewriteValue386_OpSelect0_0(v)
+	case OpSelect1:
+		return rewriteValue386_OpSelect1_0(v)
 	case OpSignExt16to32:
 		return rewriteValue386_OpSignExt16to32_0(v)
 	case OpSignExt8to16:
@@ -23707,6 +23711,59 @@ func rewriteValue386_OpRsh8x8_0(v *Value) bool {
 		return true
 	}
 }
+func rewriteValue386_OpSelect0_0(v *Value) bool {
+	b := v.Block
+	_ = b
+	typ := &b.Func.Config.Types
+	_ = typ
+	// match: (Select0 (Mul32uover x y))
+	// cond:
+	// result: (Select0 <typ.UInt32> (MULLU x y))
+	for {
+		v_0 := v.Args[0]
+		if v_0.Op != OpMul32uover {
+			break
+		}
+		_ = v_0.Args[1]
+		x := v_0.Args[0]
+		y := v_0.Args[1]
+		v.reset(OpSelect0)
+		v.Type = typ.UInt32
+		v0 := b.NewValue0(v.Pos, Op386MULLU, types.NewTuple(typ.UInt32, types.TypeFlags))
+		v0.AddArg(x)
+		v0.AddArg(y)
+		v.AddArg(v0)
+		return true
+	}
+	return false
+}
+func rewriteValue386_OpSelect1_0(v *Value) bool {
+	b := v.Block
+	_ = b
+	typ := &b.Func.Config.Types
+	_ = typ
+	// match: (Select1 (Mul32uover x y))
+	// cond:
+	// result: (SETO (Select1 <types.TypeFlags> (MULLU x y)))
+	for {
+		v_0 := v.Args[0]
+		if v_0.Op != OpMul32uover {
+			break
+		}
+		_ = v_0.Args[1]
+		x := v_0.Args[0]
+		y := v_0.Args[1]
+		v.reset(Op386SETO)
+		v0 := b.NewValue0(v.Pos, OpSelect1, types.TypeFlags)
+		v1 := b.NewValue0(v.Pos, Op386MULLU, types.NewTuple(typ.UInt32, types.TypeFlags))
+		v1.AddArg(x)
+		v1.AddArg(y)
+		v0.AddArg(v1)
+		v.AddArg(v0)
+		return true
+	}
+	return false
+}
 func rewriteValue386_OpSignExt16to32_0(v *Value) bool {
 	// match: (SignExt16to32 x)
 	// cond:
@@ -24845,6 +24902,20 @@ func rewriteBlock386(b *Block) bool {
 			b.Aux = nil
 			return true
 		}
+		// match: (If (SETO cmp) yes no)
+		// cond:
+		// result: (OS cmp yes no)
+		for {
+			v := b.Control
+			if v.Op != Op386SETO {
+				break
+			}
+			cmp := v.Args[0]
+			b.Kind = Block386OS
+			b.SetControl(cmp)
+			b.Aux = nil
+			return true
+		}
 		// match: (If (SETGF cmp) yes no)
 		// cond:
 		// result: (UGT cmp yes no)
@@ -25602,6 +25673,58 @@ func rewriteBlock386(b *Block) bool {
 			b.Aux = nil
 			return true
 		}
+		// match: (NE (TESTB (SETO cmp) (SETO cmp)) yes no)
+		// cond:
+		// result: (OS cmp yes no)
+		for {
+			v := b.Control
+			if v.Op != Op386TESTB {
+				break
+			}
+			_ = v.Args[1]
+			v_0 := v.Args[0]
+			if v_0.Op != Op386SETO {
+				break
+			}
+			cmp := v_0.Args[0]
+			v_1 := v.Args[1]
+			if v_1.Op != Op386SETO {
+				break
+			}
+			if cmp != v_1.Args[0] {
+				break
+			}
+			b.Kind = Block386OS
+			b.SetControl(cmp)
+			b.Aux = nil
+			return true
+		}
+		// match: (NE (TESTB (SETO cmp) (SETO cmp)) yes no)
+		// cond:
+		// result: (OS cmp yes no)
+		for {
+			v := b.Control
+			if v.Op != Op386TESTB {
+				break
+			}
+			_ = v.Args[1]
+			v_0 := v.Args[0]
+			if v_0.Op != Op386SETO {
+				break
+			}
+			cmp := v_0.Args[0]
+			v_1 := v.Args[1]
+			if v_1.Op != Op386SETO {
+				break
+			}
+			if cmp != v_1.Args[0] {
+				break
+			}
+			b.Kind = Block386OS
+			b.SetControl(cmp)
+			b.Aux = nil
+			return true
+		}
 		// match: (NE (TESTB (SETGF cmp) (SETGF cmp)) yes no)
 		// cond:
 		// result: (UGT cmp yes no)

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

@@ -64552,6 +64552,46 @@ func rewriteValueAMD64_OpRsh8x8_0(v *Value) bool {
 func rewriteValueAMD64_OpSelect0_0(v *Value) bool {
 	b := v.Block
 	_ = b
+	typ := &b.Func.Config.Types
+	_ = typ
+	// match: (Select0 (Mul64uover x y))
+	// cond:
+	// result: (Select0 <typ.UInt64> (MULQU x y))
+	for {
+		v_0 := v.Args[0]
+		if v_0.Op != OpMul64uover {
+			break
+		}
+		_ = v_0.Args[1]
+		x := v_0.Args[0]
+		y := v_0.Args[1]
+		v.reset(OpSelect0)
+		v.Type = typ.UInt64
+		v0 := b.NewValue0(v.Pos, OpAMD64MULQU, types.NewTuple(typ.UInt64, types.TypeFlags))
+		v0.AddArg(x)
+		v0.AddArg(y)
+		v.AddArg(v0)
+		return true
+	}
+	// match: (Select0 (Mul32uover x y))
+	// cond:
+	// result: (Select0 <typ.UInt32> (MULLU x y))
+	for {
+		v_0 := v.Args[0]
+		if v_0.Op != OpMul32uover {
+			break
+		}
+		_ = v_0.Args[1]
+		x := v_0.Args[0]
+		y := v_0.Args[1]
+		v.reset(OpSelect0)
+		v.Type = typ.UInt32
+		v0 := b.NewValue0(v.Pos, OpAMD64MULLU, types.NewTuple(typ.UInt32, types.TypeFlags))
+		v0.AddArg(x)
+		v0.AddArg(y)
+		v.AddArg(v0)
+		return true
+	}
 	// match: (Select0 <t> (AddTupleFirst32 val tuple))
 	// cond:
 	// result: (ADDL val (Select0 <t> tuple))
@@ -64593,6 +64633,50 @@ func rewriteValueAMD64_OpSelect0_0(v *Value) bool {
 	return false
 }
 func rewriteValueAMD64_OpSelect1_0(v *Value) bool {
+	b := v.Block
+	_ = b
+	typ := &b.Func.Config.Types
+	_ = typ
+	// match: (Select1 (Mul64uover x y))
+	// cond:
+	// result: (SETO (Select1 <types.TypeFlags> (MULQU x y)))
+	for {
+		v_0 := v.Args[0]
+		if v_0.Op != OpMul64uover {
+			break
+		}
+		_ = v_0.Args[1]
+		x := v_0.Args[0]
+		y := v_0.Args[1]
+		v.reset(OpAMD64SETO)
+		v0 := b.NewValue0(v.Pos, OpSelect1, types.TypeFlags)
+		v1 := b.NewValue0(v.Pos, OpAMD64MULQU, types.NewTuple(typ.UInt64, types.TypeFlags))
+		v1.AddArg(x)
+		v1.AddArg(y)
+		v0.AddArg(v1)
+		v.AddArg(v0)
+		return true
+	}
+	// match: (Select1 (Mul32uover x y))
+	// cond:
+	// result: (SETO (Select1 <types.TypeFlags> (MULLU x y)))
+	for {
+		v_0 := v.Args[0]
+		if v_0.Op != OpMul32uover {
+			break
+		}
+		_ = v_0.Args[1]
+		x := v_0.Args[0]
+		y := v_0.Args[1]
+		v.reset(OpAMD64SETO)
+		v0 := b.NewValue0(v.Pos, OpSelect1, types.TypeFlags)
+		v1 := b.NewValue0(v.Pos, OpAMD64MULLU, types.NewTuple(typ.UInt32, types.TypeFlags))
+		v1.AddArg(x)
+		v1.AddArg(y)
+		v0.AddArg(v1)
+		v.AddArg(v0)
+		return true
+	}
 	// match: (Select1 (AddTupleFirst32 _ tuple))
 	// cond:
 	// result: (Select1 tuple)
@@ -66757,6 +66841,20 @@ func rewriteBlockAMD64(b *Block) bool {
 			b.Aux = nil
 			return true
 		}
+		// match: (If (SETO cmp) yes no)
+		// cond:
+		// result: (OS cmp yes no)
+		for {
+			v := b.Control
+			if v.Op != OpAMD64SETO {
+				break
+			}
+			cmp := v.Args[0]
+			b.Kind = BlockAMD64OS
+			b.SetControl(cmp)
+			b.Aux = nil
+			return true
+		}
 		// match: (If (SETGF cmp) yes no)
 		// cond:
 		// result: (UGT cmp yes no)
@@ -67514,6 +67612,58 @@ func rewriteBlockAMD64(b *Block) bool {
 			b.Aux = nil
 			return true
 		}
+		// match: (NE (TESTB (SETO cmp) (SETO cmp)) yes no)
+		// cond:
+		// result: (OS cmp yes no)
+		for {
+			v := b.Control
+			if v.Op != OpAMD64TESTB {
+				break
+			}
+			_ = v.Args[1]
+			v_0 := v.Args[0]
+			if v_0.Op != OpAMD64SETO {
+				break
+			}
+			cmp := v_0.Args[0]
+			v_1 := v.Args[1]
+			if v_1.Op != OpAMD64SETO {
+				break
+			}
+			if cmp != v_1.Args[0] {
+				break
+			}
+			b.Kind = BlockAMD64OS
+			b.SetControl(cmp)
+			b.Aux = nil
+			return true
+		}
+		// match: (NE (TESTB (SETO cmp) (SETO cmp)) yes no)
+		// cond:
+		// result: (OS cmp yes no)
+		for {
+			v := b.Control
+			if v.Op != OpAMD64TESTB {
+				break
+			}
+			_ = v.Args[1]
+			v_0 := v.Args[0]
+			if v_0.Op != OpAMD64SETO {
+				break
+			}
+			cmp := v_0.Args[0]
+			v_1 := v.Args[1]
+			if v_1.Op != OpAMD64SETO {
+				break
+			}
+			if cmp != v_1.Args[0] {
+				break
+			}
+			b.Kind = BlockAMD64OS
+			b.SetControl(cmp)
+			b.Aux = nil
+			return true
+		}
 		// match: (NE (TESTL (SHLL (MOVLconst [1]) x) y))
 		// cond: !config.nacl
 		// result: (ULT (BTL x y))

src/cmd/compile/internal/x86/ssa.go

@@ -278,6 +278,13 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 			m.To.Reg = x86.REG_DX
 		}
 
+	case ssa.Op386MULLU:
+		// Arg[0] is already in AX as it's the only register we allow
+		// results lo in AX
+		p := s.Prog(v.Op.Asm())
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = v.Args[1].Reg()
+
 	case ssa.Op386MULLQU:
 		// AX * args[1], high 32 bits in DX (result[0]), low 32 bits in AX (result[1]).
 		p := s.Prog(v.Op.Asm())
@@ -770,7 +777,8 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		ssa.Op386SETGF, ssa.Op386SETGEF,
 		ssa.Op386SETB, ssa.Op386SETBE,
 		ssa.Op386SETORD, ssa.Op386SETNAN,
-		ssa.Op386SETA, ssa.Op386SETAE:
+		ssa.Op386SETA, ssa.Op386SETAE,
+		ssa.Op386SETO:
 		p := s.Prog(v.Op.Asm())
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = v.Reg()
@@ -842,6 +850,8 @@ var blockJump = [...]struct {
 	ssa.Block386GE:  {x86.AJGE, x86.AJLT},
 	ssa.Block386LE:  {x86.AJLE, x86.AJGT},
 	ssa.Block386GT:  {x86.AJGT, x86.AJLE},
+	ssa.Block386OS:  {x86.AJOS, x86.AJOC},
+	ssa.Block386OC:  {x86.AJOC, x86.AJOS},
 	ssa.Block386ULT: {x86.AJCS, x86.AJCC},
 	ssa.Block386UGE: {x86.AJCC, x86.AJCS},
 	ssa.Block386UGT: {x86.AJHI, x86.AJLS},
@@ -903,6 +913,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
 	case ssa.Block386EQ, ssa.Block386NE,
 		ssa.Block386LT, ssa.Block386GE,
 		ssa.Block386LE, ssa.Block386GT,
+		ssa.Block386OS, ssa.Block386OC,
 		ssa.Block386ULT, ssa.Block386UGT,
 		ssa.Block386ULE, ssa.Block386UGE:
 		jmp := blockJump[b.Kind]

src/runtime/internal/math/math_test.go

@@ -49,3 +49,31 @@ func TestMulUintptr(t *testing.T) {
 		}
 	}
 }
+
+var SinkUintptr uintptr
+var SinkBool bool
+
+var x, y uintptr
+
+func BenchmarkMulUintptr(b *testing.B) {
+	x, y = 1, 2
+	b.Run("small", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			var overflow bool
+			SinkUintptr, overflow = MulUintptr(x, y)
+			if overflow {
+				SinkUintptr = 0
+			}
+		}
+	})
+	x, y = MaxUintptr, MaxUintptr-1
+	b.Run("large", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			var overflow bool
+			SinkUintptr, overflow = MulUintptr(x, y)
+			if overflow {
+				SinkUintptr = 0
+			}
+		}
+	})
+}