cmd/compile: clean up getlinepragma

Passes toolstash -cmp.

Change-Id: Ia497b51c74a9c760a873e1ed690e4408fd0fe596
Reviewed-on: https://go-review.googlesource.com/19844
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/compile/internal/gc/lex.go b/src/cmd/compile/internal/gc/lex.go
index cbd435b49ef6dda548a9dcf9b4545cf560000766..09b233548b3c30730b58df43435c92273f2bbc31 100644 (file)
--- a/src/cmd/compile/internal/gc/lex.go
+++ b/src/cmd/compile/internal/gc/lex.go
@@ -1569,10 +1569,8 @@ func more(pp *string) bool {
 // as a discontinuity in sequential line numbers.
 // the next line of input comes from parse.y:15
 func (l *lexer) getlinepragma() rune {
-       var cmd, verb, name string
-
        c := l.getr()
-       if c == 'g' {
+       if c == 'g' { // check for //go: directive
                cp := &lexbuf
                cp.Reset()
                cp.WriteByte('g') // already read
@@ -1594,77 +1592,55 @@ func (l *lexer) getlinepragma() rune {
                        pragcgo(text)
                }
 
-               cmd = text
-               verb = cmd
-               if i := strings.Index(verb, " "); i >= 0 {
+               verb := text
+               if i := strings.Index(text, " "); i >= 0 {
                        verb = verb[:i]
                }
 
-               if verb == "go:linkname" {
+               switch verb {
+               case "go:linkname":
                        if !imported_unsafe {
                                Yyerror("//go:linkname only allowed in Go files that import \"unsafe\"")
                        }
-                       f := strings.Fields(cmd)
+                       f := strings.Fields(text)
                        if len(f) != 3 {
                                Yyerror("usage: //go:linkname localname linkname")
-                               return c
+                               break
                        }
-
                        Lookup(f[1]).Linkname = f[2]
-                       return c
-               }
-
-               if verb == "go:nointerface" && obj.Fieldtrack_enabled != 0 {
-                       nointerface = true
-                       return c
-               }
-
-               if verb == "go:noescape" {
+               case "go:nointerface":
+                       if obj.Fieldtrack_enabled != 0 {
+                               nointerface = true
+                       }
+               case "go:noescape":
                        noescape = true
-                       return c
-               }
-
-               if verb == "go:norace" {
+               case "go:norace":
                        norace = true
-                       return c
-               }
-
-               if verb == "go:nosplit" {
+               case "go:nosplit":
                        nosplit = true
-                       return c
-               }
-
-               if verb == "go:noinline" {
+               case "go:noinline":
                        noinline = true
-                       return c
-               }
-
-               if verb == "go:systemstack" {
+               case "go:systemstack":
                        if compiling_runtime == 0 {
                                Yyerror("//go:systemstack only allowed in runtime")
                        }
                        systemstack = true
-                       return c
-               }
-
-               if verb == "go:nowritebarrier" {
+               case "go:nowritebarrier":
                        if compiling_runtime == 0 {
                                Yyerror("//go:nowritebarrier only allowed in runtime")
                        }
                        nowritebarrier = true
-                       return c
-               }
-
-               if verb == "go:nowritebarrierrec" {
+               case "go:nowritebarrierrec":
                        if compiling_runtime == 0 {
                                Yyerror("//go:nowritebarrierrec only allowed in runtime")
                        }
                        nowritebarrierrec = true
                        nowritebarrier = true // Implies nowritebarrier
-                       return c
                }
                return c
        }
+
+       // check for //line directive
        if c != 'l' {
                return c
        }
@@ -1694,34 +1670,25 @@ func (l *lexer) getlinepragma() rune {
                }
                cp.WriteByte(byte(c))
        }
-
        cp = nil
 
        if linep == 0 {
                return c
        }
        text := strings.TrimSuffix(lexbuf.String(), "\r")
-       n := 0
-       for _, c := range text[linep:] {
-               if c < '0' || c > '9' {
-                       goto out
-               }
-               n = n*10 + int(c) - '0'
-               if n > 1e8 {
-                       Yyerror("line number out of range")
-                       errorexit()
-               }
+       n, err := strconv.Atoi(text[linep:])
+       if err != nil {
+               return c // todo: make this an error instead? it is almost certainly a bug.
+       }
+       if n > 1e8 {
+               Yyerror("line number out of range")
+               errorexit()
        }
-
        if n <= 0 {
                return c
        }
 
-       name = text[:linep-1]
-       linehistupdate(name, n)
-       return c
-
-out:
+       linehistupdate(text[:linep-1], n)
        return c
 }