[dev.cc] cmd/asm: the text flag argument to TEXT psudo-op is optional

Allow TEXT to have two or three operands.
In
	TEXT foo(SB),flag,$0
the flag can be missing, in which case we take it to be zero.

Change-Id: I7b88543b52019f7890baac4b95f9e63884d43c83
Reviewed-on: https://go-review.googlesource.com/3440
Reviewed-by: Russ Cox <rsc@golang.org>

diff --git a/src/cmd/asm/internal/asm/asm.go b/src/cmd/asm/internal/asm/asm.go
index 82846d0309cfa2a5e5484e61820ff3844e9738d6..dfb7ad19cce0fef195b5c89bb0a786a2d0834d08 100644 (file)
--- a/src/cmd/asm/internal/asm/asm.go
+++ b/src/cmd/asm/internal/asm/asm.go
@@ -146,8 +146,8 @@ func (p *Parser) append(prog *obj.Prog, doLabel bool) {
 // asmText assembles a TEXT pseudo-op.
 // TEXT runtime·sigtramp(SB),4,$0-0
 func (p *Parser) asmText(word string, operands [][]lex.Token) {
-       if len(operands) != 3 {
-               p.errorf("expect three operands for TEXT")
+       if len(operands) != 2 && len(operands) != 3 {
+               p.errorf("expect two or three operands for TEXT")
        }
 
        // Operand 0 is the symbol name in the form foo(SB).
@@ -157,22 +157,26 @@ func (p *Parser) asmText(word string, operands [][]lex.Token) {
                p.errorf("TEXT symbol %q must be an offset from SB", nameAddr.Symbol)
        }
        name := nameAddr.Symbol
+       next := 1
 
-       // Operand 1 is the text flag, a literal integer.
-       // TODO: This is optional but this parser takes it as required.
-       flagAddr := p.address(operands[1])
-       if !flagAddr.Is(addr.Offset) {
-               p.errorf("TEXT flag for %s must be an integer", name)
+       // Next operand is the optional text flag, a literal integer.
+       flag := int8(0)
+       if len(operands) == 3 {
+               flagAddr := p.address(operands[next])
+               if !flagAddr.Is(addr.Offset) {
+                       p.errorf("TEXT flag for %s must be an integer", name)
+               }
+               flag = int8(flagAddr.Offset)
+               next++
        }
-       flag := int8(flagAddr.Offset)
 
-       // Operand 2 is the frame and arg size.
+       // Next operand is the frame and arg size.
        // Bizarre syntax: $frameSize-argSize is two words, not subtraction.
        // Both frameSize and argSize must be simple integers; only frameSize
        // can be negative.
        // The "-argSize" may be missing; if so, set it to obj.ArgsSizeUnknown.
        // Parse left to right.
-       op := operands[2]
+       op := operands[next]
        if len(op) < 2 || op[0].ScanToken != '$' {
                p.errorf("TEXT %s: frame size must be an immediate constant", name)
        }