[dev.cc] cmd/asm: fix a few minor issues

Fix one place where semicolons were not recognized and fix the
pattern match for the syntax of some pseudo ops.
Also clean up a couple of unreachable code pieces.

There is still an undiagnosed bit difference betwen old and new .6
files. TBD.

With these fixes, asm can successfully compile and test the entire tree.
(Verified by
	turn off verifyAsm in cmd/go
	make.bash
	cp $GOROOT/bin/asm $GOROOT/pkg/tool/darwin_amd64/6a
	go test -short std
)

Change-Id: I91ea892098f76ef4f129fd2530e0c63ffd8745a9
Reviewed-on: https://go-review.googlesource.com/3688Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/asm/internal/addr/addr.go

@@ -71,7 +71,7 @@ func (a *Addr) Has(mask int) bool {
 	return false
 }
 
-// Is reports whether the address has exactly the specified elements.
+// Is reports whether the address has all the specified elements.
 // Indirect and immediate are checked.
 func (a *Addr) Is(mask int) bool {
 	if (mask&ImmediateConstant == 0) != !a.IsImmediateConstant {

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

@@ -302,7 +302,8 @@ func (p *Parser) asmGlobl(word string, operands [][]lex.Token) {
 
 	// Operand 0 has the general form foo<>+0x04(SB).
 	nameAddr := p.address(operands[0])
-	if !nameAddr.Is(addr.Symbol|addr.Register|addr.Indirect) || nameAddr.Register != arch.RSB {
+	ok := nameAddr.Is(addr.Symbol|addr.Register|addr.Indirect) || nameAddr.Is(addr.Symbol|addr.Register|addr.Indirect|addr.Offset)
+	if !ok || nameAddr.Register != arch.RSB {
 		p.errorf("GLOBL symbol %q must be an offset from SB", nameAddr.Symbol)
 	}
 	name := strings.Replace(nameAddr.Symbol, "·", ".", 1)
@@ -399,17 +400,19 @@ func (p *Parser) asmFuncData(word string, operands [][]lex.Token) {
 	if !valueAddr.Is(addr.ImmediateConstant | addr.Offset) {
 		p.errorf("FUNCDATA value must be an immediate constant")
 	}
-	value := valueAddr.Offset
+	value0 := valueAddr.Offset
 
 	// Operand 1 is a symbol name in the form foo(SB).
 	// That means symbol plus indirect on SB and no offset.
 	nameAddr := p.address(operands[1])
-	if !nameAddr.Is(addr.Symbol|addr.Register|addr.Indirect) || nameAddr.Register != arch.RSB {
+	ok := nameAddr.Is(addr.Symbol|addr.Register|addr.Indirect) || nameAddr.Is(addr.Symbol|addr.Register|addr.Indirect|addr.Offset)
+	if !ok || nameAddr.Register != arch.RSB {
 		p.errorf("FUNCDATA symbol %q must be an offset from SB", nameAddr.Symbol)
 	}
 	name := strings.Replace(nameAddr.Symbol, "·", ".", 1)
+	value1 := nameAddr.Offset
 
-	// log.Printf("FUNCDATA %s, $%d", name, value)
+	// log.Printf("FUNCDATA $%d, %d", value0, value1)
 	prog := &obj.Prog{
 		Ctxt:   p.linkCtxt,
 		As:     int16(p.arch.AFUNCDATA),
@@ -417,12 +420,13 @@ func (p *Parser) asmFuncData(word string, operands [][]lex.Token) {
 		From: obj.Addr{
 			Type:   int16(p.arch.D_CONST),
 			Index:  uint8(p.arch.D_NONE),
-			Offset: value,
+			Offset: value0,
 		},
 		To: obj.Addr{
 			Type:   int16(p.symbolType(&nameAddr)),
 			Index:  uint8(p.arch.D_NONE),
 			Sym:    obj.Linklookup(p.linkCtxt, name, 0),
+			Offset: value1,
 		},
 	}
 	p.append(prog, true)

src/cmd/asm/internal/asm/parse.go

@@ -92,7 +92,7 @@ func (p *Parser) line() bool {
 		p.lineNum = p.lex.Line()
 		p.histLineNum = lex.HistLine()
 		switch tok {
-		case '\n':
+		case '\n', ';':
 			continue
 		case scanner.EOF:
 			return false
@@ -438,8 +438,6 @@ func (p *Parser) term() uint64 {
 			return value
 		}
 	}
-	p.errorf("unexpected %s evaluating expression", p.peek())
-	return 0
 }
 
 // factor = const | '+' factor | '-' factor | '~' factor | '(' expr ')'

src/cmd/asm/internal/flags/flags.go

@@ -49,7 +49,7 @@ func Usage() {
 	os.Exit(2)
 }
 
-func Parse(goroot, goos, goarch string, theChar int) { // TODO: see below
+func Parse(theChar int) {
 	flag.Usage = Usage
 	flag.Parse()
 	if flag.NArg() != 1 {
@@ -64,8 +64,4 @@ func Parse(goroot, goos, goarch string, theChar int) { // TODO: see below
 		}
 		*OutputFile = fmt.Sprintf("%s.%c", input, theChar)
 	}
-	// Initialize to include $GOROOT/pkg/$GOOS_GOARCH/ so we find textflag.h
-	// TODO: Delete last line once asm is installed because the go command takes care of this.
-	// The arguments to Parse can be simplified then too.
-	I = append(I, filepath.Join(goroot, "pkg", fmt.Sprintf("%s_%s", goos, goarch)))
 }

src/cmd/asm/internal/lex/input.go

@@ -93,7 +93,9 @@ func (in *Input) Next() ScanToken {
 		in.text = in.peekText
 		return tok
 	}
-	for {
+	// If we cannot generate a token after 100 tries, we're in trouble.
+	// The usual case is caught by Push, below, but be safe.
+	for i := 0; i < 100; i++ {
 		tok := in.Stack.Next()
 		switch tok {
 		case '#':

src/cmd/asm/main.go

@@ -7,7 +7,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"go/build"
 	"log"
 	"os"
 
@@ -23,14 +22,14 @@ func main() {
 	log.SetFlags(0)
 	log.SetPrefix("asm: ")
 
-	GOARCH := build.Default.GOARCH
+	GOARCH := obj.Getgoarch()
 
 	architecture := arch.Set(GOARCH)
 	if architecture == nil {
 		log.Fatalf("asm: unrecognized architecture %s", GOARCH)
 	}
 
-	flags.Parse(obj.Getgoroot(), obj.Getgoos(), obj.Getgoarch(), architecture.Thechar)
+	flags.Parse(architecture.Thechar)
 
 	// Create object file, write header.
 	fd, err := os.Create(*flags.OutputFile)