asm: give error message for unadorned symbol reference

On amd64, the program

TEXT    foo0(SB),7,$-8
    ADDQ R520, R1
    RET

used to trigger this error because R520 was being passed through to obj:

asm: doasm: notfound ft=23 tt=23 00000 (x.s:2)	ADDQ	0, 0 23 23

Now it gets this one, as it is indeed a parse error:

x.s:2: illegal addressing mode for symbol R520

This couldn't be fixed until #12632 had been fixed for arm64.

Fixes #12470.

Change-Id: I19830c4ae9337887b93f85d9a239e2b89dbb2219
Reviewed-on: https://go-review.googlesource.com/14691
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>

diff --git a/src/cmd/asm/internal/asm/parse.go b/src/cmd/asm/internal/asm/parse.go
index b38b53db708be3a756a4ff60e89789219dd9898c..9a42838be90acbd73c41eadcbcfeebbc470d995e 100644 (file)
--- a/src/cmd/asm/internal/asm/parse.go
+++ b/src/cmd/asm/internal/asm/parse.go
@@ -38,6 +38,7 @@ type Parser struct {
        firstProg     *obj.Prog
        lastProg      *obj.Prog
        dataAddr      map[string]int64 // Most recent address for DATA for this symbol.
+       isJump        bool             // Instruction being assembled is a jump.
        errorWriter   io.Writer
 }
 
@@ -197,15 +198,15 @@ func (p *Parser) line() bool {
 
 func (p *Parser) instruction(op int, word, cond string, operands [][]lex.Token) {
        p.addr = p.addr[0:0]
-       isJump := p.arch.IsJump(word)
+       p.isJump = p.arch.IsJump(word)
        for _, op := range operands {
                addr := p.address(op)
-               if !isJump && addr.Reg < 0 { // Jumps refer to PC, a pseudo.
+               if !p.isJump && addr.Reg < 0 { // Jumps refer to PC, a pseudo.
                        p.errorf("illegal use of pseudo-register in %s", word)
                }
                p.addr = append(p.addr, addr)
        }
-       if isJump {
+       if p.isJump {
                p.asmJump(op, cond, p.addr)
                return
        }
@@ -575,12 +576,14 @@ func (p *Parser) symbolReference(a *obj.Addr, name string, prefix rune) {
        }
        a.Sym = obj.Linklookup(p.ctxt, name, isStatic)
        if p.peek() == scanner.EOF {
-               if prefix != 0 {
-                       p.errorf("illegal addressing mode for symbol %s", name)
+               if prefix == 0 && p.isJump {
+                       // Symbols without prefix or suffix are jump labels.
+                       return
                }
+               p.errorf("illegal or missing addressing mode for symbol %s", name)
                return
        }
-       // Expect (SB) or (FP), (PC), (SB), or (SP)
+       // Expect (SB), (FP), (PC), or (SP)
        p.get('(')
        reg := p.get(scanner.Ident).String()
        p.get(')')