cmd/compile: intrinsify Ctz{32,64} and Bswap{32,64} on s390x

Also adds the 'find leftmost one' instruction (FLOGR) and replaces the
WORD-encoded use of FLOGR in math/big with it.

Change-Id: I18e7cd19e75b8501a6ae8bd925471f7e37ded206
Reviewed-on: https://go-review.googlesource.com/29372Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/asm/internal/asm/testdata/s390x.s

@@ -104,6 +104,7 @@ TEXT main·foo(SB),7,$16-0 // TEXT main.foo(SB), 7, $16-0
 	NEG	R1, R2                // b9030021
 	NEGW	R1                    // b9130011
 	NEGW	R1, R2                // b9130021
+	FLOGR	R2, R2                // b9830022
 
 	LAA	R1, R2, 524287(R3)    // eb213fff7ff8
 	LAAG	R4, R5, -524288(R6)   // eb54600080e8

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

@@ -2519,16 +2519,16 @@ func intrinsicInit() {
 		/******** runtime/internal/sys ********/
 		intrinsicKey{"runtime/internal/sys", "Ctz32"}: enableOnArch(func(s *state, n *Node) *ssa.Value {
 			return s.newValue1(ssa.OpCtz32, Types[TUINT32], s.intrinsicFirstArg(n))
-		}, sys.AMD64, sys.ARM64, sys.ARM),
+		}, sys.AMD64, sys.ARM64, sys.ARM, sys.S390X),
 		intrinsicKey{"runtime/internal/sys", "Ctz64"}: enableOnArch(func(s *state, n *Node) *ssa.Value {
 			return s.newValue1(ssa.OpCtz64, Types[TUINT64], s.intrinsicFirstArg(n))
-		}, sys.AMD64, sys.ARM64, sys.ARM),
+		}, sys.AMD64, sys.ARM64, sys.ARM, sys.S390X),
 		intrinsicKey{"runtime/internal/sys", "Bswap32"}: enableOnArch(func(s *state, n *Node) *ssa.Value {
 			return s.newValue1(ssa.OpBswap32, Types[TUINT32], s.intrinsicFirstArg(n))
-		}, sys.AMD64, sys.ARM64, sys.ARM),
+		}, sys.AMD64, sys.ARM64, sys.ARM, sys.S390X),
 		intrinsicKey{"runtime/internal/sys", "Bswap64"}: enableOnArch(func(s *state, n *Node) *ssa.Value {
 			return s.newValue1(ssa.OpBswap64, Types[TUINT64], s.intrinsicFirstArg(n))
-		}, sys.AMD64, sys.ARM64, sys.ARM),
+		}, sys.AMD64, sys.ARM64, sys.ARM, sys.S390X),
 
 		/******** runtime/internal/atomic ********/
 		intrinsicKey{"runtime/internal/atomic", "Load"}: enableOnArch(func(s *state, n *Node) *ssa.Value {

src/cmd/compile/internal/s390x/prog.go

@@ -67,6 +67,7 @@ var progtable = [s390x.ALAST & obj.AMask]obj.ProgInfo{
 	s390x.AMODDU & obj.AMask:  {Flags: gc.SizeQ | gc.LeftRead | gc.RegRead | gc.RightWrite},
 	s390x.AMODW & obj.AMask:   {Flags: gc.SizeL | gc.LeftRead | gc.RegRead | gc.RightWrite},
 	s390x.AMODWU & obj.AMask:  {Flags: gc.SizeL | gc.LeftRead | gc.RegRead | gc.RightWrite},
+	s390x.AFLOGR & obj.AMask:  {Flags: gc.SizeQ | gc.LeftRead | gc.RightWrite},
 
 	// Floating point.
 	s390x.AFADD & obj.AMask:  {Flags: gc.SizeD | gc.LeftRead | gc.RegRead | gc.RightWrite},

src/cmd/compile/internal/s390x/ssa.go

@@ -525,16 +525,13 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		if gc.Maxarg < v.AuxInt {
 			gc.Maxarg = v.AuxInt
 		}
-	case ssa.OpS390XNEG, ssa.OpS390XNEGW:
-		r := v.Reg()
+	case ssa.OpS390XFLOGR, ssa.OpS390XNEG, ssa.OpS390XNEGW,
+		ssa.OpS390XMOVWBR, ssa.OpS390XMOVDBR:
 		p := gc.Prog(v.Op.Asm())
-		r1 := v.Args[0].Reg()
-		if r != r1 {
-			p.From.Type = obj.TYPE_REG
-			p.From.Reg = r1
-		}
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = v.Args[0].Reg()
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = r
+		p.To.Reg = v.Reg()
 	case ssa.OpS390XNOT, ssa.OpS390XNOTW:
 		v.Fatalf("NOT/NOTW generated %s", v.LongString())
 	case ssa.OpS390XMOVDEQ, ssa.OpS390XMOVDNE,

src/cmd/compile/internal/ssa/gen/S390X.rules

@@ -101,6 +101,13 @@
 (OffPtr [off] ptr) && is32Bit(off) -> (ADDconst [off] ptr)
 (OffPtr [off] ptr) -> (ADD (MOVDconst [off]) ptr)
 
+// Ctz(x) = 64 - findLeftmostOne((x-1)&^x)
+(Ctz64 <t> x) -> (SUB (MOVDconst [64]) (FLOGR (AND <t> (SUBconst <t> [1] x) (NOT <t> x))))
+(Ctz32 <t> x) -> (SUB (MOVDconst [64]) (FLOGR (MOVWZreg (ANDW <t> (SUBWconst <t> [1] x) (NOTW <t> x)))))
+
+(Bswap64 x) -> (MOVDBR x)
+(Bswap32 x) -> (MOVWBR x)
+
 (Sqrt x) -> (FSQRT x)
 
 // Lowering extension

src/cmd/compile/internal/ssa/gen/S390XOps.go

@@ -315,6 +315,9 @@ func init() {
 		{name: "MOVWload", argLength: 2, reg: gpload, asm: "MOVW", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true},                  // ditto, sign extend to int64
 		{name: "MOVDload", argLength: 2, reg: gpload, asm: "MOVD", aux: "SymOff", typ: "UInt64", clobberFlags: true, faultOnNilArg0: true},   // load 8 bytes from arg0+auxint+aux. arg1=mem
 
+		{name: "MOVWBR", argLength: 1, reg: gp11, asm: "MOVWBR"}, // arg0 swap bytes
+		{name: "MOVDBR", argLength: 1, reg: gp11, asm: "MOVDBR"}, // arg0 swap bytes
+
 		{name: "MOVHBRload", argLength: 2, reg: gpload, asm: "MOVHBR", aux: "SymOff", typ: "UInt16", clobberFlags: true, faultOnNilArg0: true}, // load 2 bytes from arg0+auxint+aux. arg1=mem. Reverse bytes.
 		{name: "MOVWBRload", argLength: 2, reg: gpload, asm: "MOVWBR", aux: "SymOff", typ: "UInt32", clobberFlags: true, faultOnNilArg0: true}, // load 4 bytes from arg0+auxint+aux. arg1=mem. Reverse bytes.
 		{name: "MOVDBRload", argLength: 2, reg: gpload, asm: "MOVDBR", aux: "SymOff", typ: "UInt64", clobberFlags: true, faultOnNilArg0: true}, // load 8 bytes from arg0+auxint+aux. arg1=mem. Reverse bytes.
@@ -387,6 +390,16 @@ func init() {
 		{name: "FlagLT"}, // <
 		{name: "FlagGT"}, // >
 
+		// find leftmost one
+		{
+			name:         "FLOGR",
+			argLength:    1,
+			reg:          regInfo{inputs: gponly, outputs: []regMask{buildReg("R0")}, clobbers: buildReg("R1")},
+			asm:          "FLOGR",
+			typ:          "UInt64",
+			clobberFlags: true,
+		},
+
 		// store multiple
 		{
 			name:           "STMG2",

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

@@ -1354,6 +1354,8 @@ const (
 	OpS390XMOVWZload
 	OpS390XMOVWload
 	OpS390XMOVDload
+	OpS390XMOVWBR
+	OpS390XMOVDBR
 	OpS390XMOVHBRload
 	OpS390XMOVWBRload
 	OpS390XMOVDBRload
@@ -1391,6 +1393,7 @@ const (
 	OpS390XFlagEQ
 	OpS390XFlagLT
 	OpS390XFlagGT
+	OpS390XFLOGR
 	OpS390XSTMG2
 	OpS390XSTMG3
 	OpS390XSTMG4
@@ -17110,6 +17113,32 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name:   "MOVWBR",
+		argLen: 1,
+		asm:    s390x.AMOVWBR,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 5119}, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R12
+			},
+			outputs: []outputInfo{
+				{0, 5119}, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R12
+			},
+		},
+	},
+	{
+		name:   "MOVDBR",
+		argLen: 1,
+		asm:    s390x.AMOVDBR,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 5119}, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R12
+			},
+			outputs: []outputInfo{
+				{0, 5119}, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R12
+			},
+		},
+	},
 	{
 		name:           "MOVHBRload",
 		auxType:        auxSymOff,
@@ -17581,6 +17610,21 @@ var opcodeTable = [...]opInfo{
 		argLen: 0,
 		reg:    regInfo{},
 	},
+	{
+		name:         "FLOGR",
+		argLen:       1,
+		clobberFlags: true,
+		asm:          s390x.AFLOGR,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 5119}, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R12
+			},
+			clobbers: 2, // R1
+			outputs: []outputInfo{
+				{0, 1}, // R0
+			},
+		},
+	},
 	{
 		name:           "STMG2",
 		auxType:        auxSymOff,

src/cmd/compile/internal/ssa/rewriteS390X.go

@@ -36,6 +36,10 @@ func rewriteValueS390X(v *Value, config *Config) bool {
 		return rewriteValueS390X_OpAndB(v, config)
 	case OpAvg64u:
 		return rewriteValueS390X_OpAvg64u(v, config)
+	case OpBswap32:
+		return rewriteValueS390X_OpBswap32(v, config)
+	case OpBswap64:
+		return rewriteValueS390X_OpBswap64(v, config)
 	case OpClosureCall:
 		return rewriteValueS390X_OpClosureCall(v, config)
 	case OpCom16:
@@ -64,6 +68,10 @@ func rewriteValueS390X(v *Value, config *Config) bool {
 		return rewriteValueS390X_OpConstNil(v, config)
 	case OpConvert:
 		return rewriteValueS390X_OpConvert(v, config)
+	case OpCtz32:
+		return rewriteValueS390X_OpCtz32(v, config)
+	case OpCtz64:
+		return rewriteValueS390X_OpCtz64(v, config)
 	case OpCvt32Fto32:
 		return rewriteValueS390X_OpCvt32Fto32(v, config)
 	case OpCvt32Fto64:
@@ -887,6 +895,32 @@ func rewriteValueS390X_OpAvg64u(v *Value, config *Config) bool {
 		return true
 	}
 }
+func rewriteValueS390X_OpBswap32(v *Value, config *Config) bool {
+	b := v.Block
+	_ = b
+	// match: (Bswap32 x)
+	// cond:
+	// result: (MOVWBR x)
+	for {
+		x := v.Args[0]
+		v.reset(OpS390XMOVWBR)
+		v.AddArg(x)
+		return true
+	}
+}
+func rewriteValueS390X_OpBswap64(v *Value, config *Config) bool {
+	b := v.Block
+	_ = b
+	// match: (Bswap64 x)
+	// cond:
+	// result: (MOVDBR x)
+	for {
+		x := v.Args[0]
+		v.reset(OpS390XMOVDBR)
+		v.AddArg(x)
+		return true
+	}
+}
 func rewriteValueS390X_OpClosureCall(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
@@ -1078,6 +1112,62 @@ func rewriteValueS390X_OpConvert(v *Value, config *Config) bool {
 		return true
 	}
 }
+func rewriteValueS390X_OpCtz32(v *Value, config *Config) bool {
+	b := v.Block
+	_ = b
+	// match: (Ctz32 <t> x)
+	// cond:
+	// result: (SUB (MOVDconst [64]) (FLOGR (MOVWZreg (ANDW <t> (SUBWconst <t> [1] x) (NOTW <t> x)))))
+	for {
+		t := v.Type
+		x := v.Args[0]
+		v.reset(OpS390XSUB)
+		v0 := b.NewValue0(v.Line, OpS390XMOVDconst, config.fe.TypeUInt64())
+		v0.AuxInt = 64
+		v.AddArg(v0)
+		v1 := b.NewValue0(v.Line, OpS390XFLOGR, config.fe.TypeUInt64())
+		v2 := b.NewValue0(v.Line, OpS390XMOVWZreg, config.fe.TypeUInt64())
+		v3 := b.NewValue0(v.Line, OpS390XANDW, t)
+		v4 := b.NewValue0(v.Line, OpS390XSUBWconst, t)
+		v4.AuxInt = 1
+		v4.AddArg(x)
+		v3.AddArg(v4)
+		v5 := b.NewValue0(v.Line, OpS390XNOTW, t)
+		v5.AddArg(x)
+		v3.AddArg(v5)
+		v2.AddArg(v3)
+		v1.AddArg(v2)
+		v.AddArg(v1)
+		return true
+	}
+}
+func rewriteValueS390X_OpCtz64(v *Value, config *Config) bool {
+	b := v.Block
+	_ = b
+	// match: (Ctz64 <t> x)
+	// cond:
+	// result: (SUB (MOVDconst [64]) (FLOGR (AND <t> (SUBconst <t> [1] x) (NOT <t> x))))
+	for {
+		t := v.Type
+		x := v.Args[0]
+		v.reset(OpS390XSUB)
+		v0 := b.NewValue0(v.Line, OpS390XMOVDconst, config.fe.TypeUInt64())
+		v0.AuxInt = 64
+		v.AddArg(v0)
+		v1 := b.NewValue0(v.Line, OpS390XFLOGR, config.fe.TypeUInt64())
+		v2 := b.NewValue0(v.Line, OpS390XAND, t)
+		v3 := b.NewValue0(v.Line, OpS390XSUBconst, t)
+		v3.AuxInt = 1
+		v3.AddArg(x)
+		v2.AddArg(v3)
+		v4 := b.NewValue0(v.Line, OpS390XNOT, t)
+		v4.AddArg(x)
+		v2.AddArg(v4)
+		v1.AddArg(v2)
+		v.AddArg(v1)
+		return true
+	}
+}
 func rewriteValueS390X_OpCvt32Fto32(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b

src/cmd/internal/obj/s390x/a.out.go

@@ -255,6 +255,9 @@ const (
 	AMOVDLT
 	AMOVDNE
 
+	// find leftmost one
+	AFLOGR
+
 	// integer bitwise
 	AAND
 	AANDN

src/cmd/internal/obj/s390x/anames.go

@@ -49,6 +49,7 @@ var Anames = []string{
 	"MOVDLE",
 	"MOVDLT",
 	"MOVDNE",
+	"FLOGR",
 	"AND",
 	"ANDN",
 	"NAND",

src/cmd/internal/obj/s390x/asmz.go

@@ -220,6 +220,9 @@ var optab = []Optab{
 	// move on condition
 	Optab{AMOVDEQ, C_REG, C_NONE, C_NONE, C_REG, 17, 0},
 
+	// find leftmost one
+	Optab{AFLOGR, C_REG, C_NONE, C_NONE, C_REG, 8, 0},
+
 	// compare
 	Optab{ACMP, C_REG, C_NONE, C_NONE, C_REG, 70, 0},
 	Optab{ACMP, C_REG, C_NONE, C_NONE, C_LCON, 71, 0},
@@ -2864,6 +2867,13 @@ func asmout(ctxt *obj.Link, asm *[]byte) {
 		}
 		zRSY(opcode, uint32(r1), uint32(r3), uint32(b2), uint32(d2), asm)
 
+	case 8: // find leftmost one
+		if p.To.Reg&1 != 0 {
+			ctxt.Diag("target must be an even-numbered register")
+		}
+		// FLOGR also writes a mask to p.To.Reg+1.
+		zRRE(op_FLOGR, uint32(p.To.Reg), uint32(p.From.Reg), asm)
+
 	case 10: // subtract reg [reg] reg
 		r := int(p.Reg)
 

src/math/big/arith_s390x.s

@@ -559,9 +559,9 @@ E7:	SUB  $1, R7		// i--
 
 // func bitLen(x Word) (n int)
 TEXT ·bitLen(SB),NOSPLIT,$0
-	MOVD x+0(FP), R2
-	WORD $0xb9830022 // FLOGR R2,R2
-	MOVD $64, R3
-	SUB  R2, R3
-	MOVD R3, n+8(FP)
+	MOVD  x+0(FP), R2
+	FLOGR R2, R2 // clobbers R3
+	MOVD  $64, R3
+	SUB   R2, R3
+	MOVD  R3, n+8(FP)
 	RET

test/intrinsic.go

 // errorcheckandrundir -0 -d=ssa/intrinsics/debug
-// +build amd64 arm64 arm
+// +build amd64 arm64 arm s390x
 
 // Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style