collect2.c (DO_COLLECT_EXPORT_LIST): New internal macro, always defined.

        * collect2.c (DO_COLLECT_EXPORT_LIST): New internal macro,
        always defined.  Reflect definition or absence of such for
        COLLECT_EXPORT_LIST.  Readability helper.
        (scanfilter): New enum, to help control what symbols
        are to be considered or ignored by scan_prog_file.
        (enum pass): Rename as "scanpass", moved together with scanfilter
        prior to scan_prog_file's prototype.
        (scan_prog_file): Accept and honor scanpass and scanfilter arguments.
        Group prototype with the scanpass/scanfilter definitions, factorize
        head comments for the several implementations at the prototype.
        (main): Reorganize the first pass link control to let AIX
        drag only the needed frame tables in executables.  Prevent
        frame tables collection during the scan aimed at static ctors.
        Pre-link and scan for frame tables later to compensate.
        * doc/tm.texi (ASM_OUTPUT_DWARF_TABLE_REF): New macro.
        A C statement to issue assembly directives that create a reference
        to the given DWARF table identifier label from the current function
        section.
        * dwarf2out.c (switch_to_eh_frame_section): Add a BACK argument
        to differentiate first time section entry.  Only emit a .data
        tables start identifier label the first time around.
        (switch_to_frame_table_section): New function.  Helper for
        output_call_frame_info to switch possibly BACK into the eh_frame
        or the debug_frame section depending on FOR_EH.
        (output_call_frame_info): Use helper to first enter the proper
        frame section.
        (output_fde): Use ASM_OUTPUT_DWARF_TABLE_REF when defined to
        emit a link to the frame table start label from each function
        section.
        * config/rs6000/rs6000.c (rs6000_aix_asm_output_dwarf_table_ref):
        New function.  Implementation of ASM_OUTPUT_DWARF_TABLE_REF.
        * config/rs6000/rs6000-protos.h: Declare it.
        * config/rs6000/aix.h (ASM_OUTPUT_DWARF_TABLE_REF): Define.

From-SVN: r151157

gcc/ChangeLog

+2009-08-28  Olivier Hainque  <hainque@adacore.com>
+
+	* collect2.c (DO_COLLECT_EXPORT_LIST): New internal macro,
+	always defined.  Reflect definition or absence of such for
+	COLLECT_EXPORT_LIST.  Readability helper.
+	(scanfilter): New enum, to help control what symbols
+	are to be considered or ignored by scan_prog_file.
+	(enum pass): Rename as "scanpass", moved together with scanfilter
+	prior to scan_prog_file's prototype.
+	(scan_prog_file): Accept and honor scanpass and scanfilter arguments.
+	Group prototype with the scanpass/scanfilter definitions, factorize
+	head comments for the several implementations at the prototype.
+	(main): Reorganize the first pass link control to let AIX
+	drag only the needed frame tables in executables.  Prevent
+	frame tables collection during the scan aimed at static ctors.
+	Pre-link and scan for frame tables later to compensate.
+	* doc/tm.texi (ASM_OUTPUT_DWARF_TABLE_REF): New macro.
+	A C statement to issue assembly directives that create a reference
+	to the given DWARF table identifier label from the current function
+	section.
+	* dwarf2out.c (switch_to_eh_frame_section): Add a BACK argument
+	to differentiate first time section entry.  Only emit a .data
+	tables start identifier label the first time around.
+	(switch_to_frame_table_section): New function.  Helper for
+	output_call_frame_info to switch possibly BACK into the eh_frame
+	or the debug_frame section depending on FOR_EH.
+	(output_call_frame_info): Use helper to first enter the proper
+	frame section.
+	(output_fde): Use ASM_OUTPUT_DWARF_TABLE_REF when defined to
+	emit a link to the frame table start label from each function
+	section.
+	* config/rs6000/rs6000.c (rs6000_aix_asm_output_dwarf_table_ref):
+	New function.  Implementation of ASM_OUTPUT_DWARF_TABLE_REF.
+	* config/rs6000/rs6000-protos.h: Declare it.
+	* config/rs6000/aix.h (ASM_OUTPUT_DWARF_TABLE_REF): Define.
+
 2009-08-27  Kaz Kojima  <kkojima@gcc.gnu.org>
 
 	* config/sh/sh.c (split_branches): Check the result of

gcc/config/rs6000/aix.h

@@ -43,6 +43,12 @@
    collect has a chance to see them, so scan the object files directly.  */
 #define COLLECT_EXPORT_LIST
 
+/* Issue assembly directives that create a reference to the given DWARF table
+   identifier label from the current function section.  This is defined to
+   ensure we drag frame frame tables associated with needed function bodies in
+   a link with garbage collection activated.  */
+#define ASM_OUTPUT_DWARF_TABLE_REF rs6000_aix_asm_output_dwarf_table_ref
+
 /* Handle #pragma weak and #pragma pack.  */
 #define HANDLE_SYSV_PRAGMA 1
 

gcc/config/rs6000/rs6000-protos.h

@@ -179,6 +179,8 @@ extern int rs6000_memory_move_cost (enum machine_mode, enum reg_class, int);
 extern bool rs6000_tls_referenced_p (rtx);
 extern void rs6000_conditional_register_usage (void);
 
+extern void rs6000_aix_asm_output_dwarf_table_ref (char *);
+
 /* Declare functions in rs6000-c.c */
 
 extern void rs6000_pragma_longcall (struct cpp_reader *);

gcc/config/rs6000/rs6000.c

@@ -17612,6 +17612,15 @@ create_TOC_reference (rtx symbol)
 	       gen_rtx_UNSPEC (Pmode, gen_rtvec (1, symbol), UNSPEC_TOCREL)));
 }
 
+/* Issue assembly directives that create a reference to the given DWARF
+   FRAME_TABLE_LABEL from the current function section.  */
+void
+rs6000_aix_asm_output_dwarf_table_ref (char * frame_table_label)
+{
+  fprintf (asm_out_file, "\t.ref %s\n",
+	   TARGET_STRIP_NAME_ENCODING (frame_table_label));
+}
+
 /* If _Unwind_* has been called from within the same module,
    toc register is not guaranteed to be saved to 40(1) on function
    entry.  Save it there in that case.  */

gcc/doc/tm.texi

@@ -9159,6 +9159,13 @@ A C statement to issue assembly directives that create a self-relative
 reference to the given @var{label}, using an integer of the given @var{size}.
 @end defmac
 
+@defmac ASM_OUTPUT_DWARF_TABLE_REF (@var{label})
+A C statement to issue assembly directives that create a reference to
+the DWARF table identifier @var{label} from the current section.  This
+is used on some systems to avoid garbage collecting a DWARF table which
+is referenced by a function.
+@end defmac
+
 @deftypefn {Target Hook} void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *@var{FILE}, int @var{size}, rtx @var{x})
 If defined, this target hook is a function which outputs a DTP-relative
 reference to the given TLS symbol of the specified size.

gcc/dwarf2out.c

@@ -2932,12 +2932,12 @@ dw_cfi_oprnd2_desc (enum dwarf_call_frame_info cfi)
 
 #if defined (DWARF2_DEBUGGING_INFO) || defined (DWARF2_UNWIND_INFO)
 
-/* Switch to eh_frame_section.  If we don't have an eh_frame_section,
-   switch to the data section instead, and write out a synthetic label
-   for collect2.  */
+/* Switch [BACK] to eh_frame_section.  If we don't have an eh_frame_section,
+   switch to the data section instead, and write out a synthetic start label
+   for collect2 the first time around.  */
 
 static void
-switch_to_eh_frame_section (void)
+switch_to_eh_frame_section (bool back)
 {
   tree label;
 
@@ -2980,11 +2980,15 @@ switch_to_eh_frame_section (void)
       /* We have no special eh_frame section.  Put the information in
 	 the data section and emit special labels to guide collect2.  */
       switch_to_section (data_section);
-      label = get_file_function_name ("F");
-      ASM_OUTPUT_ALIGN (asm_out_file, floor_log2 (PTR_SIZE));
-      targetm.asm_out.globalize_label (asm_out_file,
-				       IDENTIFIER_POINTER (label));
-      ASM_OUTPUT_LABEL (asm_out_file, IDENTIFIER_POINTER (label));
+
+      if (!back)
+	{
+	  label = get_file_function_name ("F");
+	  ASM_OUTPUT_ALIGN (asm_out_file, floor_log2 (PTR_SIZE));
+	  targetm.asm_out.globalize_label (asm_out_file,
+					   IDENTIFIER_POINTER (label));
+	  ASM_OUTPUT_LABEL (asm_out_file, IDENTIFIER_POINTER (label));
+	}
     }
 }
 
@@ -3534,6 +3538,20 @@ output_fde (dw_fde_ref fde, bool for_eh, bool second,
 	output_cfi (cfi, fde, for_eh);
     }
 
+  /* If we are to emit a ref/link from function bodies to their frame tables,
+     do it now.  This is typically performed to make sure that tables
+     associated with functions are dragged with them and not discarded in
+     garbage collecting links. We need to do this on a per function basis to
+     cope with -ffunction-sections.  */
+
+#ifdef ASM_OUTPUT_DWARF_TABLE_REF
+  /* Switch to the function section, emit the ref to the tables, and
+     switch *back* into the table section.  */
+  switch_to_section (function_section (fde->decl));
+  ASM_OUTPUT_DWARF_TABLE_REF (section_start_label);
+  switch_to_frame_table_section (for_eh, true);
+#endif
+
   /* Pad the FDE out to an address sized boundary.  */
   ASM_OUTPUT_ALIGN (asm_out_file,
 		    floor_log2 ((for_eh ? PTR_SIZE : DWARF2_ADDR_SIZE)));
@@ -3543,6 +3561,22 @@ output_fde (dw_fde_ref fde, bool for_eh, bool second,
 }
 
 
+/* Switch [BACK] to the eh or debug frame table section, depending on
+   FOR_EH.  */
+static void
+switch_to_frame_table_section (int for_eh, bool back)
+{
+  if (for_eh)
+    switch_to_eh_frame_section (back);
+  else
+    {
+      if (!debug_frame_section)
+	debug_frame_section = get_section (DEBUG_FRAME_SECTION,
+					   SECTION_DEBUG, NULL);
+      switch_to_section (debug_frame_section);
+    }
+}
+
 /* Output the call frame information used to record information
    that relates to calculating the frame pointer, and records the
    location of saved registers.  */
@@ -3613,15 +3647,8 @@ output_call_frame_info (int for_eh)
   if (flag_debug_asm)
     app_enable ();
 
-  if (for_eh)
-    switch_to_eh_frame_section ();
-  else
-    {
-      if (!debug_frame_section)
-	debug_frame_section = get_section (DEBUG_FRAME_SECTION,
-					   SECTION_DEBUG, NULL);
-      switch_to_section (debug_frame_section);
-    }
+  /* Switch to the proper frame section, first time.  */
+  switch_to_frame_table_section (for_eh, false);
 
   ASM_GENERATE_INTERNAL_LABEL (section_start_label, FRAME_BEGIN_LABEL, for_eh);
   ASM_OUTPUT_LABEL (asm_out_file, section_start_label);