RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Zack Weinberg]

This patch makes some improvements to the definition of
ASM_OUTPUT_MEASURED_SIZE and to the code that uses it.  The motivation
is convoluted - please bear with me.

All but two of the current uses of ASM_OUTPUT_MEASURED_SIZE follow the
pattern

  { char label[256];
    static int labelno;
    ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno)
    ASM_OUTPUT_INTERNAL_LABEL (file, "Lfe", labelno)
    ASM_OUTPUT_MEASURED_SIZE (file, fname, label)
  }

which produces assembly output of the form

foo:
   /* ... */
.Lfe23:
   .size foo, .Lfe23-foo

The other two uses simply say

  ASM_OUTPUT_MEASURED_SIZE (file, fname, ".")

which produces

foo:
  /* ... */
  .size foo, .-foo

Or, it's supposed to do that.  ASM_OUTPUT_MEASURED_SIZE uses
assemble_name() to emit the dot, and on targets that prepend
underscores to user visible identifiers, we get

_foo:
  /* ... */
  .size _foo, _.-_foo

which the assembler naturally objects to.  So those targets are
broken by my change, and a fix is needed.

Now, note that ASM_OUTPUT_MEASURED_SIZE is never used other than to
calculate the difference between a symbol and the current address; we
just have two idioms for that operation.  One is substantially more
complicated than the other.  It seems to me that any assembler with a
.size directive ought to be modern enough to accept the expression
".-foo".  Therefore I propose to use that idiom universally, which
permits me to eliminate the third argument to ASM_OUTPUT_MEASURED_SIZE, 
and write out the dot with puts(), solving the problem currently
experienced by OpenBSD.  Eliminating a whole bunch of duplicate code
is a nice side effect.

I have built cross compilers as before, but it is impossible for me to
test it properly.  GAS from binutils CVS of course accepts ".-foo" -
the question is whether there exists a vendor assembler, or an old
version of GAS, that doesn't.  Reactions from the maintainers of the
affected targets would be appreciated.

Header			Tested with target
------			------------------
elfos.h			i386-linux
netbsd-aout.h		i386-netbsd
openbsd.h		i386-openbsd
arm/elf.h		arm-elf
avr/avr.h		avr-none
cris/aout.h		cris-aout
i386/freebsd-aout.h	i386-freebsd2
i386/sco5.h		i386-sco3.2v5
ip2k/ip2k.h		ip2k-elf (*)
m88k/m88k.h		m88k-aout
xtensa/elf.h		xtensa-elf
xtensa/linux.h		xtensa-linux

(*) This target does not build due to unrelated bugs.

A great many other targets are affected, since the change touches
shared headers such as elfos.h.

zw

	* defaults.h (ASM_OUTPUT_MEASURED_SIZE): Take only two
	arguments.  Always use ".-symbol" as expression argument.
	* doc/tm.texi: Update to match.  Document requirement for
	".size symbol, .-symbol" to be acceptable to assembler.

	* config/elfos.h, config/netbsd-aout.h, config/openbsd.h,
	config/arm/elf.h, config/avr/avr.h, config/cris/aout.h,
	config/i386/freebsd-aout.h, config/i386/sco5.h,
	config/ip2k/ip2k.h, config/m88k/m88k.h, config/xtensa/elf.h,
	config/xtensa/linux.h:  Update uses of ASM_OUTPUT_MEASURED_SIZE.

===================================================================
Index: defaults.h
--- defaults.h	25 Jul 2002 05:14:17 -0000	1.84
+++ defaults.h	25 Jul 2002 23:48:46 -0000
@@ -200,15 +200,13 @@ do { fputs (integer_asm_op (POINTER_SIZE
     }							\
   while (0)
 
-#define ASM_OUTPUT_MEASURED_SIZE(STREAM, BEG, END)	\
+#define ASM_OUTPUT_MEASURED_SIZE(STREAM, NAME)		\
   do							\
     {							\
       fputs (SIZE_ASM_OP, STREAM);			\
-      assemble_name (STREAM, BEG);			\
-      fputs (", ", STREAM);				\
-      assemble_name (STREAM, END);			\
-      putc ('-', STREAM);				\
-      assemble_name (STREAM, BEG);			\
+      assemble_name (STREAM, NAME);			\
+      fputs (", .-", STREAM);				\
+      assemble_name (STREAM, NAME);			\
       putc ('\n', STREAM);				\
     }							\
   while (0)
===================================================================
Index: config/elfos.h
--- config/elfos.h	25 Jul 2002 05:14:17 -0000	1.49
+++ config/elfos.h	25 Jul 2002 23:48:47 -0000
@@ -354,16 +354,7 @@ Boston, MA 02111-1307, USA.  */
   do								\
     {								\
       if (!flag_inhibit_size_directive)				\
-	{							\
-	  char label[256];					\
-	  static int labelno;					\
-	  							\
-	  labelno++;						\
-	  							\
-	  ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);	\
-	  ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);	\
-	  ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), label);	\
-	}							\
+	ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);			\
     }								\
   while (0)
 #endif
===================================================================
Index: config/netbsd-aout.h
--- config/netbsd-aout.h	25 Jul 2002 05:14:17 -0000	1.5
+++ config/netbsd-aout.h	25 Jul 2002 23:48:47 -0000
@@ -196,13 +196,6 @@ Boston, MA 02111-1307, USA.  */
   do									\
     {									\
       if (!flag_inhibit_size_directive)					\
-	{								\
-	  char label[256];						\
-	  static int labelno;						\
-	  labelno++;							\
-	  ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);		\
-	  ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);		\
-	  ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME, label);		\
-	}								\
+	ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);				\
     }									\
   while (0)
===================================================================
Index: config/openbsd.h
--- config/openbsd.h	25 Jul 2002 05:14:17 -0000	1.12
+++ config/openbsd.h	25 Jul 2002 23:48:47 -0000
@@ -212,10 +212,10 @@ Boston, MA 02111-1307, USA.  */
 #ifndef OBSD_HAS_DECLARE_FUNCTION_SIZE
 /* Declare the size of a function.  */
 #undef ASM_DECLARE_FUNCTION_SIZE
-#define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)			\
-  do {									\
-    if (!flag_inhibit_size_directive)					\
-      ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME, ".");			\
+#define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)		\
+  do {								\
+    if (!flag_inhibit_size_directive)				\
+      ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);			\
   } while (0)
 #endif
 
===================================================================
Index: config/arm/elf.h
--- config/arm/elf.h	25 Jul 2002 05:14:18 -0000	1.35
+++ config/arm/elf.h	25 Jul 2002 23:48:47 -0000
@@ -79,14 +79,7 @@ Boston, MA 02111-1307, USA.  */
     {								\
       ARM_DECLARE_FUNCTION_SIZE (FILE, FNAME, DECL);		\
       if (!flag_inhibit_size_directive)				\
-        {							\
-          char label[256];					\
-	  static int labelno;					\
-	  labelno ++;						\
-	  ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);	\
-	  ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);	\
-	  ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), label);	\
-        }							\
+	ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);			\
     }								\
   while (0)
 
===================================================================
Index: config/avr/avr.h
--- config/avr/avr.h	25 Jul 2002 05:14:18 -0000	1.61
+++ config/avr/avr.h	25 Jul 2002 23:48:48 -0000
@@ -1969,14 +1969,7 @@ do {								\
 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)			\
   do {									\
     if (!flag_inhibit_size_directive)					\
-      {									\
-        char label[256];						\
-	static int labelno;						\
-	labelno++;							\
-	ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);		\
-	ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);		\
-	ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), label);		\
-      }									\
+      ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);				\
   } while (0)
 /* A C statement (sans semicolon) to output to the stdio stream
    STREAM any text necessary for declaring the size of a function
===================================================================
Index: config/cris/aout.h
--- config/cris/aout.h	25 Jul 2002 05:14:18 -0000	1.3
+++ config/cris/aout.h	25 Jul 2002 23:48:48 -0000
@@ -339,16 +339,7 @@ Boston, MA 02111-1307, USA.  */
   do								\
     {								\
       if (!flag_inhibit_size_directive)				\
-	{							\
-	  char label[256];					\
-	  static int labelno;					\
-	  							\
-	  labelno++;						\
-	  							\
-	  ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);	\
-	  ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);	\
-	  ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), label);	\
-	}							\
+	ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);			\
     }								\
   while (0)
 
===================================================================
Index: config/i386/freebsd-aout.h
--- config/i386/freebsd-aout.h	25 Jul 2002 05:14:19 -0000	1.12
+++ config/i386/freebsd-aout.h	25 Jul 2002 23:48:48 -0000
@@ -207,14 +207,7 @@ do {                                    
 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)			\
   do {									\
     if (!flag_inhibit_size_directive)					\
-      {									\
-        char label[256];						\
-	static int labelno;						\
-	labelno++;							\
-	ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);		\
-	ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);		\
-	ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), label);		\
-      }									\
+      ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);				\
   } while (0)
 
 #define ASM_SPEC   " %| %{fpic:-k} %{fPIC:-k}"
===================================================================
Index: config/i386/sco5.h
--- config/i386/sco5.h	25 Jul 2002 05:14:19 -0000	1.69
+++ config/i386/sco5.h	25 Jul 2002 23:48:49 -0000
@@ -150,7 +150,7 @@ do {									\
 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)			\
   do {									\
     if (TARGET_ELF && !flag_inhibit_size_directive)			\
-      ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), ".");			\
+      ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);				\
   } while (0)
 
 #undef ASM_DECLARE_OBJECT_NAME
===================================================================
Index: config/ip2k/ip2k.h
--- config/ip2k/ip2k.h	25 Jul 2002 05:14:20 -0000	1.2
+++ config/ip2k/ip2k.h	25 Jul 2002 23:48:49 -0000
@@ -2139,14 +2139,7 @@ do {						\
 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)		\
   do {								\
     if (!flag_inhibit_size_directive)				\
-      {								\
-        char label[256];					\
-	static int labelno;					\
-	labelno++;						\
-	ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);	\
-	ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);	\
-	ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), label);	\
-      }								\
+      ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);			\
   } while (0)
 /* A C statement (sans semicolon) to output to the stdio stream
    STREAM any text necessary for declaring the size of a function
===================================================================
Index: config/m88k/m88k.h
--- config/m88k/m88k.h	25 Jul 2002 05:14:21 -0000	1.66
+++ config/m88k/m88k.h	25 Jul 2002 23:48:50 -0000
@@ -1866,18 +1866,8 @@ do {									 \
 #undef	ASM_DECLARE_FUNCTION_SIZE
 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)			\
   do {									\
-    if (DECLARE_ASM_NAME)						\
-      {									\
-	if (!flag_inhibit_size_directive)				\
-	  {								\
-	    char label[256];						\
-	    static int labelno = 0;					\
-	    labelno++;							\
-	    ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);	\
-	    ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);		\
-	    ASM_OUTPUT_MEASURED_SIZE (FILE, (FNAME), label);		\
-	  }								\
-      }									\
+    if (DECLARE_ASM_NAME && !flag_inhibit_size_directive)		\
+      ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);				\
   } while (0)
 
 /* This is how to output the definition of a user-level label named NAME,
===================================================================
Index: config/xtensa/elf.h
--- config/xtensa/elf.h	25 Jul 2002 05:14:22 -0000	1.3
+++ config/xtensa/elf.h	25 Jul 2002 23:48:50 -0000
@@ -112,16 +112,7 @@ Software Foundation, 59 Temple Place - S
   do								\
     {								\
       if (!flag_inhibit_size_directive)				\
-	{							\
-	  char label[256];					\
-	  static int labelno;					\
-	  							\
-	  labelno++;						\
-	  							\
-	  ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);	\
-	  ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);	\
-	  ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME, label);	\
-	}							\
+	ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);			\
       XTENSA_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL);		\
     }								\
   while (0)
===================================================================
Index: config/xtensa/linux.h
--- config/xtensa/linux.h	25 Jul 2002 05:14:22 -0000	1.5
+++ config/xtensa/linux.h	25 Jul 2002 23:48:50 -0000
@@ -68,16 +68,7 @@ Software Foundation, 59 Temple Place - S
   do								\
     {								\
       if (!flag_inhibit_size_directive)				\
-	{							\
-	  char label[256];					\
-	  static int labelno;					\
-	  							\
-	  labelno++;						\
-	  							\
-	  ASM_GENERATE_INTERNAL_LABEL (label, "Lfe", labelno);	\
-	  ASM_OUTPUT_INTERNAL_LABEL (FILE, "Lfe", labelno);	\
-	  ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME, label);	\
-	}							\
+	ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);			\
       XTENSA_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL);		\
     }								\
   while (0)
===================================================================
Index: doc/tm.texi
--- doc/tm.texi	25 Jul 2002 05:14:23 -0000	1.150
+++ doc/tm.texi	25 Jul 2002 23:48:54 -0000
@@ -6421,12 +6421,18 @@ If you define @code{SIZE_ASM_OP}, a defa
 provided.
 
 @findex ASM_OUTPUT_MEASURED_SIZE
-@item ASM_OUTPUT_MEASURED_SIZE (@var{stream}, @var{beg}, @var{end})
+@item ASM_OUTPUT_MEASURED_SIZE (@var{stream}, @var{name})
 A C statement (sans semicolon) to output to the stdio stream
 @var{stream} a directive telling the assembler to calculate the size of
-the symbol @var{beg} by subtracting its address from that of the symbol
-@var{end}.  If you define @code{SIZE_ASM_OP}, a default definition of
-this macro is provided.
+the symbol @var{name} by subtracting its address from the current
+address.  
+
+If you define @code{SIZE_ASM_OP}, a default definition of this macro is
+provided.  The default assumes that the assembler recognizes a special
+@samp{.} symbol as referring to the current address, and can calculate
+the difference between this and another symbol.  If your assembler does
+not recognize @samp{.} or cannot do calculations with it, you will need
+to redefine @code{ASM_OUTPUT_MEASURED_SIZE} to use some other technique.
 
 @findex TYPE_ASM_OP
 @item TYPE_ASM_OP

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Richard Henderson]

On Thu, Jul 25, 2002 at 05:20:49PM -0700, Zack Weinberg wrote:
> It seems to me that any assembler with a
> .size directive ought to be modern enough to accept the expression
> ".-foo".

I don't think this is actually true.  Better try this
on Solaris, Irix, and SCO.

I'd be willing to go the other way and always use the
intermediate symbol though.


r~

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Zack Weinberg]

On Thu, Jul 25, 2002 at 06:53:39PM -0700, Richard Henderson wrote:
> On Thu, Jul 25, 2002 at 05:20:49PM -0700, Zack Weinberg wrote:
> > It seems to me that any assembler with a
> > .size directive ought to be modern enough to accept the expression
> > ".-foo".
> 
> I don't think this is actually true.  Better try this
> on Solaris, Irix, and SCO.

Robert Lipe has reported it works on SCO.

On Solaris,

$ cat test.s
        .section ".text"
        .global foo
        .type    foo,#function
foo:
        retl
        sll     %o0, 1, %o0
        .size    foo, .-foo
$ /usr/ccs/bin/as -V test.s
as: Sun WorkShop 6 99/08/18
$ nm test.o
[Index]   Value      Size    Type  Bind  Other Shndx   Name
[1]     |         0|       0|SECT |LOCL |0    |2      |
[2]     |         0|       8|FUNC |GLOB |0    |2      |foo
$ uname -a
SunOS chili 5.8 Generic_108528-10 sun4u sparc SUNW,Ultra-5_10

2.8 is recent, yes, but the datestamp on that assembler is quite old.
(I no longer remember how to find out what patches have been applied
to a specific file.)

I have no access to IRIX.

> I'd be willing to go the other way and always use the intermediate
> symbol though.

I'd be willing to do that if we have to, but if we can make .-sym
work on all or even most of these systems I think that's a cleaner
solution.

zw

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Richard Sandiford]

Zack Weinberg <zack@codesourcery.com> writes:
> I have no access to IRIX.

The irix headers define their own ASM_DECLARE_FUNCTION_SIZE,
probably because it doesn't seem to like the old form either:

        .globl  s
        .data
s:
        .word   1
        .word   2
t:
        .size   s,t-s

gave me:

as: Error: /foo.s, line 7: Symbol must have absolute value: t
      .size s, t - s
as: Error: /foo.s, line 7: Symbol must have absolute value: s

(works if you replace "t-s" with "8").

Richard

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Mark Mitchell]

> I'd be willing to do that if we have to, but if we can make .-sym
> work on all or even most of these systems I think that's a cleaner
> solution.

I think there's more to be gained by using the same technique everywhere
than by using either of the two techniques.

I suggest we use the intermediate symbol technique since we're all
pretty sure that will work.  That will let us eliminate the code
duplication.  Then, if we are fully convinced that there's no risk
in using the '.-sym' approach we can always change that later.

On the other hand, if we are already confident of that, we can do it
now.

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Richard Henderson]

On Fri, Jul 26, 2002 at 11:46:37AM +0100, Richard Sandiford wrote:
> The irix headers define their own ASM_DECLARE_FUNCTION_SIZE,
> probably because it doesn't seem to like the old form either:

Ah, right.  The function size gets set via the ".end" directive.

> as: Error: /foo.s, line 7: Symbol must have absolute value: s

Since neither form works on Irix, I guess defaulting to .-foo
is fine, since Irix won't be using the macro at all.


r~

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Zack Weinberg]

On Fri, Jul 26, 2002 at 11:07:54AM -0700, Richard Henderson wrote:
> On Fri, Jul 26, 2002 at 11:46:37AM +0100, Richard Sandiford wrote:
> > The irix headers define their own ASM_DECLARE_FUNCTION_SIZE,
> > probably because it doesn't seem to like the old form either:
> 
> Ah, right.  The function size gets set via the ".end" directive.
> 
> > as: Error: /foo.s, line 7: Symbol must have absolute value: s
> 
> Since neither form works on Irix, I guess defaulting to .-foo
> is fine, since Irix won't be using the macro at all.

Are there any other potentially problematic platforms, or can I go
ahead and check the patch in?

zw

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Richard Henderson]

On Fri, Jul 26, 2002 at 02:56:58PM -0700, Zack Weinberg wrote:
> Are there any other potentially problematic platforms, or can I go
> ahead and check the patch in?

Not that I'm aware of.  Go ahead and check in the patch.


r~

Re: RFC/RFA: Improve definition of ASM_OUTPUT_MEASURED_SIZE

[Mark Mitchell]

--On Friday, July 26, 2002 11:07:54 AM -0700 Richard Henderson 
<rth@redhat.com> wrote:

> On Fri, Jul 26, 2002 at 11:46:37AM +0100, Richard Sandiford wrote:
>> The irix headers define their own ASM_DECLARE_FUNCTION_SIZE,
>> probably because it doesn't seem to like the old form either:
>
> Ah, right.  The function size gets set via the ".end" directive.
>
>> as: Error: /foo.s, line 7: Symbol must have absolute value: s
>
> Since neither form works on Irix, I guess defaulting to .-foo
> is fine, since Irix won't be using the macro at all.

OK; Zack, please put in the patch.

Thanks!

-- 
Mark Mitchell                mark@codesourcery.com
CodeSourcery, LLC            http://www.codesourcery.com