compiler, libgo: Use //extern comments rather than __asm__.

From-SVN: r183981

gcc/go/ChangeLog

+2012-02-07  Ian Lance Taylor  <iant@google.com>
+
+	* gccgo.texi (Function Names): Document //extern instead of
+	__asm__.
+
 2012-02-01  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/52079

gcc/go/gccgo.texi

@@ -304,14 +304,20 @@ function is still using it.
 @node Function Names
 @section Function Names
 
-@cindex @code{__asm__}
+@cindex @code{extern}
+@cindex external names
 Go code can call C functions directly using a Go extension implemented
-in @command{gccgo}: a function declaration may be followed by
-@code{__asm__ ("@var{name}")}. For example, here is how the C function
-@code{open} can be declared in Go:
+in @command{gccgo}: a function declaration may be preceded by a
+comment giving the external name.  The comment must be at the
+beginning of the line and must start with @code{//extern}.  This must
+be followed by a space and then the external name of the function.
+The function declaration must be on the line immediately after the
+comment.  For example, here is how the C function @code{open} can be
+declared in Go:
 
 @smallexample
-func c_open(name *byte, mode int, perm int) int __asm__ ("open");
+//extern open
+func c_open(name *byte, mode int, perm int) int
 @end smallexample
 
 The C function naturally expects a nul terminated string, which in Go
@@ -333,7 +339,7 @@ present the name of a Go function that does not have a receiver is
 @option{-fgo-prefix} option used when the package is compiled; if the
 option is not used, the default is simply @code{go}.  To call the
 function from C you must set the name using the @command{gcc}
-extension similar to the @command{gccgo} extension.
+@code{__asm__} extension.
 
 @smallexample
 extern int go_function(int) __asm__ ("myprefix.mypackage.Function");

gcc/go/gofrontend/lex.cc

@@ -442,7 +442,7 @@ Token::print(FILE* file) const
 Lex::Lex(const char* input_file_name, FILE* input_file, Linemap* linemap)
   : input_file_name_(input_file_name), input_file_(input_file),
     linemap_(linemap), linebuf_(NULL), linebufsize_(120), linesize_(0),
-    lineoff_(0), lineno_(0), add_semi_at_eol_(false)
+    lineoff_(0), lineno_(0), add_semi_at_eol_(false), extern_()
 {
   this->linebuf_ = new char[this->linebufsize_];
   this->linemap_->start_file(input_file_name, 0);
@@ -541,6 +541,7 @@ Lex::earlier_location(int chars) const
 Token
 Lex::next_token()
 {
+  bool saw_cpp_comment = false;
   while (true)
     {
       if (!this->require_line())
@@ -552,6 +553,10 @@ Lex::next_token()
 	  return this->make_eof_token();
 	}
 
+      if (!saw_cpp_comment)
+	this->extern_.clear();
+      saw_cpp_comment = false;
+
       const char* p = this->linebuf_ + this->lineoff_;
       const char* pend = this->linebuf_ + this->linesize_;
 
@@ -588,6 +593,7 @@ Lex::next_token()
 		  p = pend;
 		  if (p[-1] == '\n' && this->add_semi_at_eol_)
 		    --p;
+		  saw_cpp_comment = true;
 		}
 	      else if (p[1] == '*')
 		{
@@ -1606,6 +1612,10 @@ Lex::skip_c_comment()
 void
 Lex::skip_cpp_comment()
 {
+  // Ensure that if EXTERN_ is set, it means that we just saw a
+  // //extern comment.
+  this->extern_.clear();
+
   const char* p = this->linebuf_ + this->lineoff_;
   const char* pend = this->linebuf_ + this->linesize_;
 
@@ -1648,12 +1658,35 @@ Lex::skip_cpp_comment()
 	}
     }
 
+  // As a special gccgo extension, a C++ comment at the start of the
+  // line of the form
+  //   //extern NAME
+  // which immediately precedes a function declaration means that the
+  // external name of the function declaration is NAME.  This is
+  // normally used to permit Go code to call a C function.
+  if (this->lineoff_ == 2
+      && pend - p > 7
+      && memcmp(p, "extern ", 7) == 0)
+    {
+      p += 7;
+      while (p < pend && (*p == ' ' || *p == '\t'))
+	++p;
+      const char* plend = pend;
+      while (plend > p
+	     && (plend[-1] == ' ' || plend[-1] == '\t' || plend[-1] == '\n'))
+	--plend;
+      if (plend > p)
+	this->extern_ = std::string(p, plend - p);
+    }
+
   while (p < pend)
     {
       this->lineoff_ = p - this->linebuf_;
       unsigned int c;
       bool issued_error;
       p = this->advance_one_utf8_char(p, &c, &issued_error);
+      if (issued_error)
+	this->extern_.clear();
     }
 }
 

gcc/go/gofrontend/lex.h

@@ -344,6 +344,11 @@ class Lex
   Token
   next_token();
 
+  // Return the contents of any current //extern comment.
+  const std::string&
+  extern_name() const
+  { return this->extern_; }
+
   // Return whether the identifier NAME should be exported.  NAME is a
   // mangled name which includes only ASCII characters.
   static bool
@@ -474,6 +479,9 @@ class Lex
   size_t lineno_;
   // Whether to add a semicolon if we see a newline now.
   bool add_semi_at_eol_;
+  // The external name to use for a function declaration, from a magic
+  // //extern comment.
+  std::string extern_;
 };
 
 #endif // !defined(GO_LEX_H)

gcc/go/gofrontend/parse.cc

@@ -2093,17 +2093,19 @@ Parse::simple_var_decl_or_assignment(const std::string& name,
 // FunctionDecl = "func" identifier Signature [ Block ] .
 // MethodDecl = "func" Receiver identifier Signature [ Block ] .
 
-// gcc extension:
+// Deprecated gcc extension:
 //   FunctionDecl = "func" identifier Signature
 //                    __asm__ "(" string_lit ")" .
 // This extension means a function whose real name is the identifier
-// inside the asm.
+// inside the asm.  This extension will be removed at some future
+// date.  It has been replaced with //extern comments.
 
 void
 Parse::function_decl()
 {
   go_assert(this->peek_token()->is_keyword(KEYWORD_FUNC));
   Location location = this->location();
+  std::string extern_name = this->lex_->extern_name();
   const Token* token = this->advance_token();
 
   Typed_identifier* rec = NULL;
@@ -2173,10 +2175,20 @@ Parse::function_decl()
     {
       if (named_object == NULL && !Gogo::is_sink_name(name))
 	{
-	  if (fntype != NULL)
-	    this->gogo_->declare_function(name, fntype, location);
-	  else
+	  if (fntype == NULL)
 	    this->gogo_->add_erroneous_name(name);
+	  else
+	    {
+	      named_object = this->gogo_->declare_function(name, fntype,
+							   location);
+	      if (!extern_name.empty()
+		  && named_object->is_function_declaration())
+		{
+		  Function_declaration* fd =
+		    named_object->func_declaration_value();
+		  fd->set_asm_name(extern_name);
+		}
+	    }
 	}
     }
   else

libgo/go/exp/terminal/util.go

@@ -60,7 +60,8 @@ func Restore(fd int, state *State) error {
 	return err
 }
 
-func ioctl(int, int, unsafe.Pointer) int __asm__("ioctl")
+//extern ioctl
+func ioctl(int, int, unsafe.Pointer) int
 
 // GetSize returns the dimensions of the given terminal.
 func GetSize(fd int) (width, height int, err error) {

libgo/go/math/abs.go

@@ -9,7 +9,10 @@ package math
 // Special cases are:
 //	Abs(±Inf) = +Inf
 //	Abs(NaN) = NaN
-func libc_fabs(float64) float64 __asm__("fabs")
+
+//extern fabs
+func libc_fabs(float64) float64
+
 func Abs(x float64) float64 {
 	return libc_fabs(x)
 }

libgo/go/math/asin.go

@@ -16,7 +16,10 @@ package math
 // Special cases are:
 //	Asin(±0) = ±0
 //	Asin(x) = NaN if x < -1 or x > 1
-func libc_asin(float64) float64 __asm__("asin")
+
+//extern asin
+func libc_asin(float64) float64
+
 func Asin(x float64) float64 {
 	return libc_asin(x)
 }
@@ -51,7 +54,10 @@ func asin(x float64) float64 {
 //
 // Special case is:
 //	Acos(x) = NaN if x < -1 or x > 1
-func libc_acos(float64) float64 __asm__("acos")
+
+//extern acos
+func libc_acos(float64) float64
+
 func Acos(x float64) float64 {
 	return libc_acos(x)
 }

libgo/go/math/atan.go

@@ -51,7 +51,10 @@ func satan(arg float64) float64 {
 // Special cases are:
 //	Atan(±0) = ±0
 //	Atan(±Inf) = ±Pi/2
-func libc_atan(float64) float64 __asm__("atan")
+
+//extern atan
+func libc_atan(float64) float64
+
 func Atan(x float64) float64 {
 	return libc_atan(x)
 }

libgo/go/math/atan2.go

@@ -26,7 +26,10 @@ package math
 //	Atan2(y<0, -Inf) = -Pi
 //	Atan2(+Inf, x) = +Pi/2
 //	Atan2(-Inf, x) = -Pi/2
-func libc_atan2(float64, float64) float64 __asm__("atan2")
+
+//extern atan2
+func libc_atan2(float64, float64) float64
+
 func Atan2(y, x float64) float64 {
 	return libc_atan2(y, x)
 }

libgo/go/math/exp.go

@@ -11,7 +11,10 @@ package math
 //	Exp(NaN) = NaN
 // Very large values overflow to 0 or +Inf.
 // Very small values underflow to 1.
-func libc_exp(float64) float64 __asm__("exp")
+
+//extern exp
+func libc_exp(float64) float64
+
 func Exp(x float64) float64 {
 	return libc_exp(x)
 }

libgo/go/math/expm1.go

@@ -121,7 +121,10 @@ package math
 //	Expm1(-Inf) = -1
 //	Expm1(NaN) = NaN
 // Very large values overflow to -1 or +Inf.
-func libc_expm1(float64) float64 __asm__("expm1")
+
+//extern expm1
+func libc_expm1(float64) float64
+
 func Expm1(x float64) float64 {
 	return libc_expm1(x)
 }

libgo/go/math/floor.go

@@ -10,7 +10,10 @@ package math
 //	Floor(±0) = ±0
 //	Floor(±Inf) = ±Inf
 //	Floor(NaN) = NaN
-func libc_floor(float64) float64 __asm__("floor")
+
+//extern floor
+func libc_floor(float64) float64
+
 func Floor(x float64) float64 {
 	return libc_floor(x)
 }
@@ -38,7 +41,10 @@ func floor(x float64) float64 {
 //	Ceil(±0) = ±0
 //	Ceil(±Inf) = ±Inf
 //	Ceil(NaN) = NaN
-func libc_ceil(float64) float64 __asm__("ceil")
+
+//extern ceil
+func libc_ceil(float64) float64
+
 func Ceil(x float64) float64 {
 	return libc_ceil(x)
 }
@@ -53,7 +59,10 @@ func ceil(x float64) float64 {
 //	Trunc(±0) = ±0
 //	Trunc(±Inf) = ±Inf
 //	Trunc(NaN) = NaN
-func libc_trunc(float64) float64 __asm__("trunc")
+
+//extern trunc
+func libc_trunc(float64) float64
+
 func Trunc(x float64) float64 {
 	return libc_trunc(x)
 }

libgo/go/math/ldexp.go

@@ -11,7 +11,10 @@ package math
 //	Ldexp(±0, exp) = ±0
 //	Ldexp(±Inf, exp) = ±Inf
 //	Ldexp(NaN, exp) = NaN
-func libc_ldexp(float64, int) float64 __asm__("ldexp")
+
+//extern ldexp
+func libc_ldexp(float64, int) float64
+
 func Ldexp(frac float64, exp int) float64 {
 	return libc_ldexp(frac, exp)
 }

libgo/go/math/log.go

@@ -77,7 +77,10 @@ package math
 //	Log(0) = -Inf
 //	Log(x < 0) = NaN
 //	Log(NaN) = NaN
-func libc_log(float64) float64 __asm__("log")
+
+//extern log
+func libc_log(float64) float64
+
 func Log(x float64) float64 {
 	return libc_log(x)
 }

libgo/go/math/log10.go

@@ -6,7 +6,10 @@ package math
 
 // Log10 returns the decimal logarithm of x.
 // The special cases are the same as for Log.
-func libc_log10(float64) float64 __asm__("log10")
+
+//extern log10
+func libc_log10(float64) float64
+
 func Log10(x float64) float64 {
 	return libc_log10(x)
 }
@@ -17,7 +20,10 @@ func log10(x float64) float64 {
 
 // Log2 returns the binary logarithm of x.
 // The special cases are the same as for Log.
-func libc_log2(float64) float64 __asm__("log2")
+
+//extern log2
+func libc_log2(float64) float64
+
 func Log2(x float64) float64 {
 	return libc_log2(x)
 }

libgo/go/math/log1p.go

@@ -92,7 +92,10 @@ package math
 //	Log1p(-1) = -Inf
 //	Log1p(x < -1) = NaN
 //	Log1p(NaN) = NaN
-func libc_log1p(float64) float64 __asm__("log1p")
+
+//extern log1p
+func libc_log1p(float64) float64
+
 func Log1p(x float64) float64 {
 	return libc_log1p(x)
 }

libgo/go/math/mod.go

@@ -18,7 +18,10 @@ package math
 //	Mod(x, 0) = NaN
 //	Mod(x, ±Inf) = x
 //	Mod(x, NaN) = NaN
-func libc_fmod(float64, float64) float64 __asm__("fmod")
+
+//extern fmod
+func libc_fmod(float64, float64) float64
+
 func Mod(x, y float64) float64 {
 	return libc_fmod(x, y)
 }

libgo/go/math/sin.go

@@ -114,7 +114,10 @@ var _cos = [...]float64{
 // Special cases are:
 //	Cos(±Inf) = NaN
 //	Cos(NaN) = NaN
-func libc_cos(float64) float64  __asm__("cos")
+
+//extern cos
+func libc_cos(float64) float64
+
 func Cos(x float64) float64 {
 	return libc_cos(x)
 }
@@ -176,7 +179,10 @@ func cos(x float64) float64 {
 //	Sin(±0) = ±0
 //	Sin(±Inf) = NaN
 //	Sin(NaN) = NaN
-func libc_sin(float64) float64 __asm__("sin")
+
+//extern sin
+func libc_sin(float64) float64
+
 func Sin(x float64) float64 {
 	return libc_sin(x)
 }

libgo/go/math/sqrt.go

@@ -11,7 +11,10 @@ package math
 //	Sqrt(±0) = ±0
 //	Sqrt(x < 0) = NaN
 //	Sqrt(NaN) = NaN
-func libc_sqrt(float64) float64 __asm__("sqrt")
+
+//extern sqrt
+func libc_sqrt(float64) float64
+
 func Sqrt(x float64) float64 {
 	return libc_sqrt(x)
 }

libgo/go/math/tan.go

@@ -79,7 +79,10 @@ var _tanQ = [...]float64{
 //	Tan(±0) = ±0
 //	Tan(±Inf) = NaN
 //	Tan(NaN) = NaN
-func libc_tan(float64) float64 __asm__("tan")
+
+//extern tan
+func libc_tan(float64) float64
+
 func Tan(x float64) float64 {
 	return libc_tan(x)
 }

libgo/go/net/cgo_unix.go

@@ -21,9 +21,14 @@ import (
 	"unsafe"
 )
 
-func libc_getaddrinfo(node *byte, service *byte, hints *syscall.Addrinfo, res **syscall.Addrinfo) int __asm__ ("getaddrinfo")
-func libc_freeaddrinfo(res *syscall.Addrinfo) __asm__ ("freeaddrinfo")
-func libc_gai_strerror(errcode int) *byte __asm__ ("gai_strerror")
+//extern getaddrinfo
+func libc_getaddrinfo(node *byte, service *byte, hints *syscall.Addrinfo, res **syscall.Addrinfo) int
+
+//extern freeaddrinfo
+func libc_freeaddrinfo(res *syscall.Addrinfo)
+
+//extern gai_strerror
+func libc_gai_strerror(errcode int) *byte
 
 // bytePtrToString takes a NUL-terminated array of bytes and convert
 // it to a Go string.

libgo/go/os/dir.go

@@ -10,12 +10,15 @@ import (
 	"unsafe"
 )
 
-func libc_dup(fd int) int __asm__ ("dup")
-func libc_opendir(*byte) *syscall.DIR __asm__ ("opendir")
-func libc_closedir(*syscall.DIR) int __asm__ ("closedir")
+//extern opendir
+func libc_opendir(*byte) *syscall.DIR
+
+//extern closedir
+func libc_closedir(*syscall.DIR) int
 
 // FIXME: pathconf returns long, not int.
-func libc_pathconf(*byte, int) int __asm__ ("pathconf")
+//extern pathconf
+func libc_pathconf(*byte, int) int
 
 func clen(n []byte) int {
 	for i := 0; i < len(n); i++ {
@@ -26,14 +29,14 @@ func clen(n []byte) int {
 	return len(n)
 }
 
-var elen int;
+var elen int
 
 func (file *File) readdirnames(n int) (names []string, err error) {
 	if elen == 0 {
-		var dummy syscall.Dirent;
+		var dummy syscall.Dirent
 		elen = (unsafe.Offsetof(dummy.Name) +
 			libc_pathconf(syscall.StringBytePtr(file.name), syscall.PC_NAME_MAX) +
-			1);
+			1)
 	}
 
 	if file.dirinfo == nil {

libgo/go/os/dir_largefile.go

@@ -9,4 +9,5 @@ package os
 
 import "syscall"
 
-func libc_readdir_r(*syscall.DIR, *syscall.Dirent, **syscall.Dirent) syscall.Errno __asm__ ("readdir64_r")
+//extern readdir64_r
+func libc_readdir_r(*syscall.DIR, *syscall.Dirent, **syscall.Dirent) syscall.Errno

libgo/go/os/dir_regfile.go

@@ -9,4 +9,5 @@ package os
 
 import "syscall"
 
-func libc_readdir_r(*syscall.DIR, *syscall.Dirent, **syscall.Dirent) syscall.Errno __asm__ ("readdir_r")
+// extern readdir_r
+func libc_readdir_r(*syscall.DIR, *syscall.Dirent, **syscall.Dirent) syscall.Errno

libgo/go/os/user/lookup_unix.go

@@ -26,8 +26,11 @@ static int mygetpwuid_r(int uid, struct passwd *pwd,
 }
 */
 
-func libc_getpwnam_r(name *byte, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int __asm__ ("getpwnam_r")
-func libc_getpwuid_r(uid syscall.Uid_t, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int __asm__ ("getpwuid_r")
+//extern getpwnam_r
+func libc_getpwnam_r(name *byte, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int
+
+//extern getpwuid_r
+func libc_getpwuid_r(uid syscall.Uid_t, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int
 
 // bytePtrToString takes a NUL-terminated array of bytes and convert
 // it to a Go string.

libgo/go/syscall/mksyscall.awk

@@ -96,8 +96,8 @@ BEGIN {
     cfnresult = line
 
     printf("// Automatically generated wrapper for %s/%s\n", gofnname, cfnname)
-    printf("func c_%s(%s) %s%s__asm__(\"%s\")\n",
-	   cfnname, cfnparams, cfnresult, cfnresult == "" ? "" : " ", cfnname)
+    printf("//extern %s\n", cfnname)
+    printf("func c_%s(%s) %s\n", cfnname, cfnparams, cfnresult)
     printf("func %s(%s) %s%s%s%s{\n",
 	   gofnname, gofnparams, gofnresults == "" ? "" : "(", gofnresults,
 	   gofnresults == "" ? "" : ")", gofnresults == "" ? "" : " ")

libgo/go/syscall/syscall_unix.go

@@ -18,8 +18,11 @@ var (
 	Stderr = 2
 )
 
-func c_syscall32(trap int32, a1, a2, a3, a4, a5, a6 int32) int32 __asm__ ("syscall");
-func c_syscall64(trap int64, a1, a2, a3, a4, a5, a6 int64) int64 __asm__ ("syscall");
+//extern syscall
+func c_syscall32(trap int32, a1, a2, a3, a4, a5, a6 int32) int32
+
+//extern syscall
+func c_syscall64(trap int64, a1, a2, a3, a4, a5, a6 int64) int64
 
 const darwinAMD64 = runtime.GOOS == "darwin" && runtime.GOARCH == "amd64"