Patchwork C6X port 7/11: Cope with odd section names

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Submitter Bernd Schmidt
Date May 12, 2011, 4:30 p.m.
Message ID <4DCC0B2F.6050104@codesourcery.com>
Download mbox | patch
Permalink /patch/95341/
State New
Headers show

Comments

Bernd Schmidt - May 12, 2011, 4:30 p.m.
On 05/10/2011 06:55 PM, Joseph S. Myers wrote:
> 
> Unless the documentation is based on pre-existing GFDL-only documentation 
> in tm.texi.in, it's preferable for the documentation of a new hook to go 
> in the doc string in target.def and get to tm.texi that way, rather than 
> putting it directly in tm.texi.in.  (So you'd put the @hook in tm.texi.in, 
> but not the main body of the documentation for the hook.)

Changed.

> A default of ".rodata" instead of NULL would seem to simplify the rest of 
> the patch.

Changed.

>> -      char name[30];
>> +      char name[80];
> 
> There seems to be some undocumented requirement on the maximum length of 
> the string named by the hook, to avoid buffer overruns with these 
> fixed-size buffers.  Consider using alloca (or asprintf to avoid needing 
> to work out manually how much to add to the length of the string, but then 
> you need to free things before returning) to avoid such an undocumented 
> bound.

Changed.

New version below; tests running now on i686-linux after a bootstrap.


Bernd
* doc/tm.texi.in (TARGET_ASM_MERGEABLE_RODATA_PREFIX): Add hook.
	* doc/tm.texi: Regenerate.
	* target.def (mergeable_rodata_prefix: New defhookpod.
	* varasm.c (mergeable_string_section, mergeable_constant_section):
	Use it. Allocate name with alloca.

Patch

Index: gcc/doc/tm.texi
===================================================================
--- gcc/doc/tm.texi.orig
+++ gcc/doc/tm.texi
@@ -7030,6 +7030,12 @@  if function is in @code{.text.name}, and
 otherwise.
 @end deftypefn
 
+@deftypevr {Target Hook} {const char *} TARGET_ASM_MERGEABLE_RODATA_PREFIX
+Usually, the compiler uses the prefix @code{".rodata"} to construct
+section names for mergeable constant data.  Define this macro to override
+the string if a different section name should be used.
+@end deftypevr
+
 @deftypefn {Target Hook} {section *} TARGET_ASM_SELECT_RTX_SECTION (enum machine_mode @var{mode}, rtx @var{x}, unsigned HOST_WIDE_INT @var{align})
 Return the section into which a constant @var{x}, of mode @var{mode},
 should be placed.  You can assume that @var{x} is some kind of
Index: gcc/doc/tm.texi.in
===================================================================
--- gcc/doc/tm.texi.in.orig
+++ gcc/doc/tm.texi.in
@@ -6978,6 +6978,8 @@  if function is in @code{.text.name}, and
 otherwise.
 @end deftypefn
 
+@hook TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
 @hook TARGET_ASM_SELECT_RTX_SECTION
 Return the section into which a constant @var{x}, of mode @var{mode},
 should be placed.  You can assume that @var{x} is some kind of
Index: gcc/target.def
===================================================================
--- gcc/target.def.orig
+++ gcc/target.def
@@ -296,6 +296,15 @@  DEFHOOK
  section *, (tree decl),
  default_function_rodata_section)
 
+/* Nonnull if the target wants to override the default ".rodata" prefix
+   for mergeable data sections.  */
+DEFHOOKPOD
+(mergeable_rodata_prefix,
+ "Usually, the compiler uses the prefix @code{\".rodata\"} to construct\n\
+section names for mergeable constant data.  Define this macro to override\n\
+the string if a different section name should be used.",
+ const char *, ".rodata")
+
 /* Output a constructor for a symbol with a given priority.  */
 DEFHOOK
 (constructor,
Index: gcc/varasm.c
===================================================================
--- gcc/varasm.c.orig
+++ gcc/varasm.c
@@ -737,7 +737,8 @@  mergeable_string_section (tree decl ATTR
       const char *str;
       HOST_WIDE_INT i;
       int j, unit;
-      char name[30];
+      const char *prefix = targetm.asm_out.mergeable_rodata_prefix;
+      char *name = (char *) alloca (strlen (prefix) + 30);
 
       mode = TYPE_MODE (TREE_TYPE (TREE_TYPE (decl)));
       modesize = GET_MODE_BITSIZE (mode);
@@ -761,8 +762,8 @@  mergeable_string_section (tree decl ATTR
 	    }
 	  if (i == len - unit)
 	    {
-	      sprintf (name, ".rodata.str%d.%d", modesize / 8,
-		       (int) (align / 8));
+	      sprintf (name, "%s.str%d.%d", prefix,
+		       modesize / 8, (int) (align / 8));
 	      flags |= (modesize / 8) | SECTION_MERGE | SECTION_STRINGS;
 	      return get_section (name, flags, NULL);
 	    }
@@ -789,9 +790,10 @@  mergeable_constant_section (enum machine
       && align <= 256
       && (align & (align - 1)) == 0)
     {
-      char name[24];
+      const char *prefix = targetm.asm_out.mergeable_rodata_prefix;
+      char *name = (char *) alloca (strlen (prefix) + 30);
 
-      sprintf (name, ".rodata.cst%d", (int) (align / 8));
+      sprintf (name, "%s.cst%d", prefix, (int) (align / 8));
       flags |= (align / 8) | SECTION_MERGE;
       return get_section (name, flags, NULL);
     }