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

1 files changed, 45 insertions, 18 deletions

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index ad956f8..04f8758 100644
--- a/gcc/dwarf2out.c
+++ b/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);