cmd/internal/obj/mips: add support for GOARCH=mips{,le}

Implements subset of MIPS32(r1) instruction set.

Change-Id: Iba017350f6c2763de05d4d1bc2f123e8eb76d0ff
Reviewed-on: https://go-review.googlesource.com/31475
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/asm/internal/arch/arch.go

@@ -415,7 +415,7 @@ func archMips64() *Arch {
 	}
 	for i, s := range mips.Anames {
 		if obj.As(i) >= obj.A_ARCHSPECIFIC {
-			instructions[s] = obj.As(i) + obj.ABaseMIPS64
+			instructions[s] = obj.As(i) + obj.ABaseMIPS
 		}
 	}
 	// Annoying alias.

src/cmd/internal/obj/link.go

@@ -311,7 +311,7 @@ const (
 	ABaseAMD64
 	ABasePPC64
 	ABaseARM64
-	ABaseMIPS64
+	ABaseMIPS
 	ABaseS390X
 
 	AllowedOpCodes = 1 << 10            // The number of opcodes available for any given architecture.
@@ -532,7 +532,7 @@ const (
 	// R_ADDRARM64 relocates an adrp, add pair to compute the address of the
 	// referenced symbol.
 	R_ADDRARM64
-	// R_ADDRMIPS (only used on mips64) resolves to the low 16 bits of an external
+	// R_ADDRMIPS (only used on mips/mips64) resolves to the low 16 bits of an external
 	// address, by encoding it into the instruction.
 	R_ADDRMIPS
 	// R_ADDROFF resolves to a 32-bit offset from the beginning of the section
@@ -660,7 +660,7 @@ const (
 	// TODO(mundaym): remove once variants can be serialized - see issue 14218.
 	R_PCRELDBL
 
-	// R_ADDRMIPSU (only used on mips64) resolves to the sign-adjusted "upper" 16
+	// R_ADDRMIPSU (only used on mips/mips64) resolves to the sign-adjusted "upper" 16
 	// bits (bit 16-31) of an external address, by encoding it into the instruction.
 	R_ADDRMIPSU
 	// R_ADDRMIPSTLS (only used on mips64) resolves to the low 16 bits of a TLS

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

@@ -44,7 +44,7 @@ const (
 )
 
 const (
-	REG_R0 = obj.RBaseMIPS64 + iota
+	REG_R0 = obj.RBaseMIPS + iota
 	REG_R1
 	REG_R2
 	REG_R3
@@ -217,6 +217,11 @@ const (
 	NSCHED = 20
 )
 
+const (
+	Mips32 = 32
+	Mips64 = 64
+)
+
 const (
 	C_NONE = iota
 	C_REG
@@ -258,7 +263,7 @@ const (
 )
 
 const (
-	AABSD = obj.ABaseMIPS64 + obj.A_ARCHSPECIFIC + iota
+	AABSD = obj.ABaseMIPS + obj.A_ARCHSPECIFIC + iota
 	AABSF
 	AABSW
 	AADD
@@ -278,6 +283,12 @@ const (
 	ABLTZAL
 	ABNE
 	ABREAK
+	ACLO
+	ACLZ
+	ACMOVF
+	ACMOVN
+	ACMOVT
+	ACMOVZ
 	ACMPEQD
 	ACMPEQF
 	ACMPGED
@@ -290,6 +301,7 @@ const (
 	ADIVU
 	ADIVW
 	AGOK
+	ALL
 	ALUI
 	AMOVB
 	AMOVBU
@@ -319,9 +331,12 @@ const (
 	AREM
 	AREMU
 	ARFE
+	ASC
 	ASGT
 	ASGTU
 	ASLL
+	ASQRTD
+	ASQRTF
 	ASRA
 	ASRL
 	ASUB
@@ -329,11 +344,14 @@ const (
 	ASUBF
 	ASUBU
 	ASUBW
+	ASYNC
 	ASYSCALL
+	ATEQ
 	ATLBP
 	ATLBR
 	ATLBWI
 	ATLBWR
+	ATNE
 	AWORD
 	AXOR
 

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

@@ -26,6 +26,12 @@ var Anames = []string{
 	"BLTZAL",
 	"BNE",
 	"BREAK",
+	"CLO",
+	"CLZ",
+	"CMOVF",
+	"CMOVN",
+	"CMOVT",
+	"CMOVZ",
 	"CMPEQD",
 	"CMPEQF",
 	"CMPGED",
@@ -38,6 +44,7 @@ var Anames = []string{
 	"DIVU",
 	"DIVW",
 	"GOK",
+	"LL",
 	"LUI",
 	"MOVB",
 	"MOVBU",
@@ -67,9 +74,12 @@ var Anames = []string{
 	"REM",
 	"REMU",
 	"RFE",
+	"SC",
 	"SGT",
 	"SGTU",
 	"SLL",
+	"SQRTD",
+	"SQRTF",
 	"SRA",
 	"SRL",
 	"SUB",
@@ -77,11 +87,14 @@ var Anames = []string{
 	"SUBF",
 	"SUBU",
 	"SUBW",
+	"SYNC",
 	"SYSCALL",
+	"TEQ",
 	"TLBP",
 	"TLBR",
 	"TLBWI",
 	"TLBWR",
+	"TNE",
 	"WORD",
 	"XOR",
 	"MOVV",

src/cmd/internal/obj/mips/list0.go

@@ -35,8 +35,8 @@ import (
 )
 
 func init() {
-	obj.RegisterRegister(obj.RBaseMIPS64, REG_LAST&^1023+1024, Rconv)
-	obj.RegisterOpcode(obj.ABaseMIPS64, Anames)
+	obj.RegisterRegister(obj.RBaseMIPS, REG_LAST+1, Rconv)
+	obj.RegisterOpcode(obj.ABaseMIPS, Anames)
 }
 
 func Rconv(r int) string {
@@ -70,7 +70,7 @@ func Rconv(r int) string {
 		return "LO"
 	}
 
-	return fmt.Sprintf("Rgok(%d)", r-obj.RBaseMIPS64)
+	return fmt.Sprintf("Rgok(%d)", r-obj.RBaseMIPS)
 }
 
 func DRconv(a int) string {

src/cmd/internal/obj/mips/obj0.go

@@ -37,6 +37,18 @@ import (
 )
 
 func progedit(ctxt *obj.Link, p *obj.Prog) {
+	// Maintain information about code generation mode.
+	if ctxt.Mode == 0 {
+		switch ctxt.Arch.Family {
+		default:
+			ctxt.Diag("unsupported arch family")
+		case sys.MIPS:
+			ctxt.Mode = Mips32
+		case sys.MIPS64:
+			ctxt.Mode = Mips64
+		}
+	}
+
 	p.From.Class = 0
 	p.To.Class = 0
 
@@ -59,7 +71,7 @@ func progedit(ctxt *obj.Link, p *obj.Prog) {
 			f32 := float32(p.From.Val.(float64))
 			i32 := math.Float32bits(f32)
 			if i32 == 0 {
-				p.As = AMOVV
+				p.As = AMOVW
 				p.From.Type = obj.TYPE_REG
 				p.From.Reg = REGZERO
 				break
@@ -76,7 +88,7 @@ func progedit(ctxt *obj.Link, p *obj.Prog) {
 	case AMOVD:
 		if p.From.Type == obj.TYPE_FCONST {
 			i64 := math.Float64bits(p.From.Val.(float64))
-			if i64 == 0 {
+			if i64 == 0 && ctxt.Mode&Mips64 != 0 {
 				p.As = AMOVV
 				p.From.Type = obj.TYPE_REG
 				p.From.Reg = REGZERO
@@ -271,6 +283,15 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 		}
 	}
 
+	var mov, add obj.As
+	if ctxt.Mode&Mips64 != 0 {
+		add = AADDV
+		mov = AMOVV
+	} else {
+		add = AADDU
+		mov = AMOVW
+	}
+
 	autosize := int32(0)
 	var p1 *obj.Prog
 	var p2 *obj.Prog
@@ -278,13 +299,14 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 		o := p.As
 		switch o {
 		case obj.ATEXT:
-			autosize = int32(textstksiz + 8)
-			if (p.Mark&LEAF != 0) && autosize <= 8 {
+			autosize = int32(textstksiz + ctxt.FixedFrameSize())
+			if (p.Mark&LEAF != 0) && autosize <= int32(ctxt.FixedFrameSize()) {
 				autosize = 0
-			} else if autosize&4 != 0 {
+			} else if autosize&4 != 0 && ctxt.Mode&Mips64 != 0 {
 				autosize += 4
 			}
-			p.To.Offset = int64(autosize) - 8
+
+			p.To.Offset = int64(autosize) - ctxt.FixedFrameSize()
 
 			if p.From3.Offset&obj.NOSPLIT == 0 {
 				p = stacksplit(ctxt, p, autosize) // emit split check
@@ -299,7 +321,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				// during the execution of the function prologue, the traceback
 				// code will not see a half-updated stack frame.
 				q = obj.Appendp(ctxt, q)
-				q.As = AMOVV
+				q.As = mov
 				q.Lineno = p.Lineno
 				q.From.Type = obj.TYPE_REG
 				q.From.Reg = REGLINK
@@ -308,7 +330,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				q.To.Reg = REGSP
 
 				q = obj.Appendp(ctxt, q)
-				q.As = AADDV
+				q.As = add
 				q.Lineno = p.Lineno
 				q.From.Type = obj.TYPE_CONST
 				q.From.Offset = int64(-autosize)
@@ -333,13 +355,13 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 			if cursym.Text.From3.Offset&obj.WRAPPER != 0 {
 				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
 				//
-				//	MOVV	g_panic(g), R1
-				//	BEQ		R1, end
-				//	MOVV	panic_argp(R1), R2
-				//	ADDV	$(autosize+8), R29, R3
-				//	BNE		R2, R3, end
-				//	ADDV	$8, R29, R2
-				//	MOVV	R2, panic_argp(R1)
+				//	MOV	g_panic(g), R1
+				//	BEQ	R1, end
+				//	MOV	panic_argp(R1), R2
+				//	ADD	$(autosize+FIXED_FRAME), R29, R3
+				//	BNE	R2, R3, end
+				//	ADD	$FIXED_FRAME, R29, R2
+				//	MOV	R2, panic_argp(R1)
 				// end:
 				//	NOP
 				//
@@ -348,7 +370,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 
 				q = obj.Appendp(ctxt, q)
 
-				q.As = AMOVV
+				q.As = mov
 				q.From.Type = obj.TYPE_MEM
 				q.From.Reg = REGG
 				q.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
@@ -364,7 +386,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				p1 = q
 
 				q = obj.Appendp(ctxt, q)
-				q.As = AMOVV
+				q.As = mov
 				q.From.Type = obj.TYPE_MEM
 				q.From.Reg = REG_R1
 				q.From.Offset = 0 // Panic.argp
@@ -372,9 +394,9 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				q.To.Reg = REG_R2
 
 				q = obj.Appendp(ctxt, q)
-				q.As = AADDV
+				q.As = add
 				q.From.Type = obj.TYPE_CONST
-				q.From.Offset = int64(autosize) + 8
+				q.From.Offset = int64(autosize) + ctxt.FixedFrameSize()
 				q.Reg = REGSP
 				q.To.Type = obj.TYPE_REG
 				q.To.Reg = REG_R3
@@ -389,15 +411,15 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				p2 = q
 
 				q = obj.Appendp(ctxt, q)
-				q.As = AADDV
+				q.As = add
 				q.From.Type = obj.TYPE_CONST
-				q.From.Offset = 8
+				q.From.Offset = ctxt.FixedFrameSize()
 				q.Reg = REGSP
 				q.To.Type = obj.TYPE_REG
 				q.To.Reg = REG_R2
 
 				q = obj.Appendp(ctxt, q)
-				q.As = AMOVV
+				q.As = mov
 				q.From.Type = obj.TYPE_REG
 				q.From.Reg = REG_R2
 				q.To.Type = obj.TYPE_MEM
@@ -438,7 +460,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 					break
 				}
 
-				p.As = AADDV
+				p.As = add
 				p.From.Type = obj.TYPE_CONST
 				p.From.Offset = int64(autosize)
 				p.To.Type = obj.TYPE_REG
@@ -459,7 +481,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				break
 			}
 
-			p.As = AMOVV
+			p.As = mov
 			p.From.Type = obj.TYPE_MEM
 			p.From.Offset = 0
 			p.From.Reg = REGSP
@@ -471,7 +493,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 
 			if autosize != 0 {
 				q = ctxt.NewProg()
-				q.As = AADDV
+				q.As = add
 				q.Lineno = p.Lineno
 				q.From.Type = obj.TYPE_CONST
 				q.From.Offset = int64(autosize)
@@ -501,7 +523,9 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 			q1.Link = q.Link
 			q.Link = q1
 
-		case AADDV,
+		case AADD,
+			AADDU,
+			AADDV,
 			AADDVU:
 			if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.From.Type == obj.TYPE_CONST {
 				p.Spadj = int32(-p.From.Offset)
@@ -564,10 +588,27 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 }
 
 func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
-	// MOVV	g_stackguard(g), R1
+	// Leaf function with no frame is effectively NOSPLIT.
+	if framesize == 0 {
+		return p
+	}
+
+	var mov, add, sub obj.As
+
+	if ctxt.Mode&Mips64 != 0 {
+		add = AADDV
+		mov = AMOVV
+		sub = ASUBVU
+	} else {
+		add = AADDU
+		mov = AMOVW
+		sub = ASUBU
+	}
+
+	// MOV	g_stackguard(g), R1
 	p = obj.Appendp(ctxt, p)
 
-	p.As = AMOVV
+	p.As = mov
 	p.From.Type = obj.TYPE_MEM
 	p.From.Reg = REGG
 	p.From.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
@@ -591,11 +632,11 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 		p.To.Reg = REG_R1
 	} else if framesize <= obj.StackBig {
 		// large stack: SP-framesize < stackguard-StackSmall
-		//	ADDV	$-framesize, SP, R2
+		//	ADD	$-framesize, SP, R2
 		//	SGTU	R2, stackguard, R1
 		p = obj.Appendp(ctxt, p)
 
-		p.As = AADDV
+		p.As = add
 		p.From.Type = obj.TYPE_CONST
 		p.From.Offset = int64(-framesize)
 		p.Reg = REGSP
@@ -619,15 +660,15 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 		// Preemption sets stackguard to StackPreempt, a very large value.
 		// That breaks the math above, so we have to check for that explicitly.
 		//	// stackguard is R1
-		//	MOVV	$StackPreempt, R2
+		//	MOV	$StackPreempt, R2
 		//	BEQ	R1, R2, label-of-call-to-morestack
-		//	ADDV	$StackGuard, SP, R2
-		//	SUBVU	R1, R2
-		//	MOVV	$(framesize+(StackGuard-StackSmall)), R1
+		//	ADD	$StackGuard, SP, R2
+		//	SUB	R1, R2
+		//	MOV	$(framesize+(StackGuard-StackSmall)), R1
 		//	SGTU	R2, R1, R1
 		p = obj.Appendp(ctxt, p)
 
-		p.As = AMOVV
+		p.As = mov
 		p.From.Type = obj.TYPE_CONST
 		p.From.Offset = obj.StackPreempt
 		p.To.Type = obj.TYPE_REG
@@ -643,7 +684,7 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 		p.Mark |= BRANCH
 
 		p = obj.Appendp(ctxt, p)
-		p.As = AADDV
+		p.As = add
 		p.From.Type = obj.TYPE_CONST
 		p.From.Offset = obj.StackGuard
 		p.Reg = REGSP
@@ -651,14 +692,14 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 		p.To.Reg = REG_R2
 
 		p = obj.Appendp(ctxt, p)
-		p.As = ASUBVU
+		p.As = sub
 		p.From.Type = obj.TYPE_REG
 		p.From.Reg = REG_R1
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = REG_R2
 
 		p = obj.Appendp(ctxt, p)
-		p.As = AMOVV
+		p.As = mov
 		p.From.Type = obj.TYPE_CONST
 		p.From.Offset = int64(framesize) + obj.StackGuard - obj.StackSmall
 		p.To.Type = obj.TYPE_REG
@@ -683,10 +724,10 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 	p.To.Type = obj.TYPE_BRANCH
 	p.Mark |= BRANCH
 
-	// MOVV	LINK, R3
+	// MOV	LINK, R3
 	p = obj.Appendp(ctxt, p)
 
-	p.As = AMOVV
+	p.As = mov
 	p.From.Type = obj.TYPE_REG
 	p.From.Reg = REGLINK
 	p.To.Type = obj.TYPE_REG
@@ -1494,3 +1535,19 @@ var Linkmips64le = obj.LinkArch{
 	Follow:     follow,
 	Progedit:   progedit,
 }
+
+var Linkmips = obj.LinkArch{
+	Arch:       sys.ArchMIPS,
+	Preprocess: preprocess,
+	Assemble:   span0,
+	Follow:     follow,
+	Progedit:   progedit,
+}
+
+var Linkmipsle = obj.LinkArch{
+	Arch:       sys.ArchMIPSLE,
+	Preprocess: preprocess,
+	Assemble:   span0,
+	Follow:     follow,
+	Progedit:   progedit,
+}

src/cmd/internal/obj/util.go

@@ -384,13 +384,13 @@ var regSpace []regSet
 const (
 	// Because of masking operations in the encodings, each register
 	// space should start at 0 modulo some power of 2.
-	RBase386    = 1 * 1024
-	RBaseAMD64  = 2 * 1024
-	RBaseARM    = 3 * 1024
-	RBasePPC64  = 4 * 1024  // range [4k, 8k)
-	RBaseARM64  = 8 * 1024  // range [8k, 13k)
-	RBaseMIPS64 = 13 * 1024 // range [13k, 14k)
-	RBaseS390X  = 14 * 1024 // range [14k, 15k)
+	RBase386   = 1 * 1024
+	RBaseAMD64 = 2 * 1024
+	RBaseARM   = 3 * 1024
+	RBasePPC64 = 4 * 1024  // range [4k, 8k)
+	RBaseARM64 = 8 * 1024  // range [8k, 13k)
+	RBaseMIPS  = 13 * 1024 // range [13k, 14k)
+	RBaseS390X = 14 * 1024 // range [14k, 15k)
 )
 
 // RegisterRegister binds a pretty-printer (Rconv) for register