[PATCH]: Fix PR debug/34249, [4.3 Regression] FAIL: gcc.dg/tree-prof/bb-reorg.c compilation, -fprofile-use -D_PROFILE_USE

[Uros Bizjak <ubizjak at gmail dot com>]

Hello!

The problem is with -freorder-blocks-and-partition flag, where start 
label of a function is put into text section and end label of a function 
is put into text.unlikely section. Assembler is not able to calculate 
the difference of these two sections, leading to assembly error.

It turns out, that the testcase works with -g, simply because we call 
switch_text_sections through debug_hooks for 
NOTE_INSN_SWITCH_TEXT_SECTIONS.  In this case, correct differences are 
output in the FDE.

So, the fix is simple -  for DWARF2_UNWIND_INFO targets, call 
dwarf2out_switch_text_section directly (depending on 
dwarf2out_do_frame). When called, this function sets 
fde->dw_fde_switched_sections flags that triggers specialized output for 
switched text sections.

BTW: I wonder, if we should set flag_inhibit_size_directive for 
-freorder-blocks-and-partition. .size is certainly not correct when half 
of the function is in some other section than start/end labels. The 
documentation says:

`-finhibit-size-directive'
    Don't output a `.size' assembler directive, or anything else that
    would cause trouble if the function is split in the middle, and the
    two halves are placed at locations far apart in memory.  This
    option is used when compiling `crtstuff.c'; you should not need to
    use it for anything else.

The patch was boostrapped on x86-pc-linux-gnu and regression tested for 
{,-m32}. The patch fixes bb-reorg.c failure.

OK for mainline?

2008-01-14  Uros Bizjak  <ubizjak@gmail.com>

       PR debug/34249
       * debug.h (dwarf2out_switch_text_section): Move declaration from ...
       * dwarf2out.c (dwarf2out_switch_text_section): ... here.  Make
       function global.
       * final.c (final_scan_insn) [NOTE_INSN_SWITCH_TEXT_SECTIONS]:
       Depending on dwarf2out_do_frame, call dwarf2out_switch_text_section
       for DWARF2_UNWIND_INFO targets.

Uros.
Index: final.c
===================================================================
--- final.c	(revision 131520)
+++ final.c	(working copy)
@@ -1777,7 +1777,13 @@ final_scan_insn (rtx insn, FILE *file, i
 
 	case NOTE_INSN_SWITCH_TEXT_SECTIONS:
 	  in_cold_section_p = !in_cold_section_p;
-	  (*debug_hooks->switch_text_section) ();
+#ifdef DWARF2_UNWIND_INFO
+	  if (dwarf2out_do_frame ())
+	    dwarf2out_switch_text_section ();
+	  else
+#endif
+	    (*debug_hooks->switch_text_section) ();
+
 	  switch_to_section (current_function_section ());
 	  break;
 
Index: debug.h
===================================================================
--- debug.h	(revision 131520)
+++ debug.h	(working copy)
@@ -160,6 +160,7 @@ extern void dwarf2out_frame_finish (void
 /* Decide whether we want to emit frame unwind information for the current
    translation unit.  */
 extern int dwarf2out_do_frame (void);
+extern void dwarf2out_switch_text_section (void);
 
 extern void debug_flush_symbol_queue (void);
 extern void debug_queue_symbol (tree);
Index: dwarf2out.c
===================================================================
--- dwarf2out.c	(revision 131520)
+++ dwarf2out.c	(working copy)
@@ -3659,7 +3659,6 @@ static void dwarf2out_imported_module_or
 static void dwarf2out_abstract_function (tree);
 static void dwarf2out_var_location (rtx);
 static void dwarf2out_begin_function (tree);
-static void dwarf2out_switch_text_section (void);
 
 /* The debug hooks structure.  */
 
@@ -7094,7 +7093,7 @@ dwarf2out_note_section_used (void)
     cold_text_section_used = true;
 }
 
-static void
+void
 dwarf2out_switch_text_section (void)
 {
   dw_fde_ref fde;