[dev.cc] cmd/asm: final fixups for correct assembly of runtime, the last package to verify

- obj: add a missing setting of the context for a generated JMP instruction
- asm:  correct the encoding of mode (R)(R*scale)
- asm: fix a silly bug in the test for macro recursion.
- asm: accept address mode sym(R)(R*8); was an oversight

Change-Id: I27112eaaa1faa0d2ba97e414f0571b70733ea087
Reviewed-on: https://go-review.googlesource.com/4502
Reviewed-by: Russ Cox <rsc@golang.org>

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

@@ -235,6 +235,9 @@ func (p *Parser) operand(a *obj.Addr) bool {
 			break // Nothing can follow.
 		}
 		p.symbolReference(a, tok.String(), prefix)
+		if p.peek() == '(' {
+			p.registerIndirect(a, prefix)
+		}
 	case scanner.Int, scanner.Float, scanner.String, '+', '-', '~', '(':
 		if p.have(scanner.Float) {
 			if prefix != '$' {
@@ -276,39 +279,7 @@ func (p *Parser) operand(a *obj.Addr) bool {
 			}
 			break // Nothing can follow.
 		}
-		p.next()
+		p.registerIndirect(a, prefix)
-		tok := p.next()
-		r1, r2, scale, ok := p.register(tok.String(), 0)
-		if !ok {
-			p.errorf("indirect through non-register %s", tok)
-		}
-		if r2 != 0 {
-			p.errorf("indirect through register pair")
-		}
-		a.Type = obj.TYPE_MEM
-		if prefix == '$' {
-			a.Type = obj.TYPE_ADDR
-		}
-		a.Reg = r1
-		if r1 == arch.RPC && prefix != 0 {
-			p.errorf("illegal addressing mode for PC")
-		}
-		a.Scale = scale
-		p.get(')')
-		if scale == 0 && p.peek() == '(' {
-			p.next()
-			tok := p.next()
-			r1, r2, scale, ok = p.register(tok.String(), 0)
-			if !ok {
-				p.errorf("indirect through non-register %s", tok)
-			}
-			if r2 != 0 {
-				p.errorf("unimplemented two-register form")
-			}
-			a.Index = r1
-			a.Scale = scale
-			p.get(')')
-		}
 	}
 	p.expect(scanner.EOF)
 	return true
@@ -396,6 +367,51 @@ func (p *Parser) symbolReference(a *obj.Addr, name string, prefix rune) {
 	p.get(')')
 }
 
+// registerIndirect parses the general form of a register indirection.
+// It is can be (R1), (R2*scale), or (R1)(R2*scale) where R1 may be a simple
+// register or register pair R:R.
+// The opening parenthesis is known to be present.
+func (p *Parser) registerIndirect(a *obj.Addr, prefix rune) {
+	p.next()
+	tok := p.next()
+	r1, r2, scale, ok := p.register(tok.String(), 0)
+	if !ok {
+		p.errorf("indirect through non-register %s", tok)
+	}
+	if r2 != 0 {
+		p.errorf("indirect through register pair")
+	}
+	a.Type = obj.TYPE_MEM
+	if prefix == '$' {
+		a.Type = obj.TYPE_ADDR
+	}
+	a.Reg = r1
+	if r1 == arch.RPC && prefix != 0 {
+		p.errorf("illegal addressing mode for PC")
+	}
+	p.get(')')
+	if scale == 0 && p.peek() == '(' {
+		// General form (R)(R*scale).
+		p.next()
+		tok := p.next()
+		r1, r2, scale, ok = p.register(tok.String(), 0)
+		if !ok {
+			p.errorf("indirect through non-register %s", tok)
+		}
+		if r2 != 0 {
+			p.errorf("unimplemented two-register form")
+		}
+		a.Index = r1
+		a.Scale = scale
+		p.get(')')
+	} else if scale != 0 {
+		// First (R) was missing, all we have is (R*scale).
+		a.Reg = 0
+		a.Index = r1
+		a.Scale = scale
+	}
+}
+
 // Note: There are two changes in the expression handling here
 // compared to the old yacc/C implemenatations. Neither has
 // much practical consequence because the expressions we

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

@@ -93,9 +93,9 @@ func (in *Input) Next() ScanToken {
 		in.text = in.peekText
 		return tok
 	}
-	// If we cannot generate a token after 100 tries, we're in trouble.
+	// If we cannot generate a token after 100 macro invocations, we're in trouble.
 	// The usual case is caught by Push, below, but be safe.
-	for i := 0; i < 100; i++ {
+	for nesting := 0; nesting < 100; {
 		tok := in.Stack.Next()
 		switch tok {
 		case '#':
@@ -108,6 +108,7 @@ func (in *Input) Next() ScanToken {
 			name := in.Stack.Text()
 			macro := in.macros[name]
 			if macro != nil {
+				nesting++
 				in.invokeMacro(macro)
 				continue
 			}

src/cmd/dist/build.go

@@ -629,7 +629,7 @@ func install(dir string) {
 	}
 
 	isgo := true
-	ispkg := !strings.HasPrefix(dir, "cmd/") || strings.HasPrefix(dir, "cmd/internal/")
+	ispkg := !strings.HasPrefix(dir, "cmd/") || strings.HasPrefix(dir, "cmd/internal/") || strings.HasPrefix(dir, "cmd/asm/internal/")
 	islib := false
 
 	// Legacy C exceptions.

src/cmd/dist/buildtool.go

@@ -29,6 +29,11 @@ var bootstrapDirs = []string{
 	"internal/obj/i386",
 	"internal/obj/ppc64",
 	"internal/obj/x86",
+	"asm",
+	"asm/internal/arch",
+	"asm/internal/asm",
+	"asm/internal/flags",
+	"asm/internal/lex",
 	"new5a",
 	"new6a",
 	"new8a",
@@ -119,7 +124,7 @@ func bootstrapFixImports(text, srcFile string) string {
 		}
 		if strings.HasPrefix(line, `import "`) || strings.HasPrefix(line, `import . "`) ||
 			inBlock && (strings.HasPrefix(line, "\t\"") || strings.HasPrefix(line, "\t. \"")) {
-			lines[i] = strings.Replace(line, `"cmd/internal/`, `"bootstrap/internal/`, -1)
+			lines[i] = strings.Replace(line, `"cmd/`, `"bootstrap/`, -1)
 		}
 	}
 

src/cmd/internal/obj/x86/obj6.go

@@ -1063,6 +1063,7 @@ loop:
 		q.To.Type = obj.TYPE_BRANCH
 		q.To.Offset = p.Pc
 		q.Pcond = p
+		q.Ctxt = p.Ctxt
 		p = q
 	}