dwarf2out: reset generation count in toplev::finalize [PR98751]

PR debug/98751 reports an issue in which most of libgccjit's tests
fails in DWARF 5 handling with
  `.Ldebug_loc2' is already defined"
asm errors.

The bogus label is being emitted at the 3rd in-process iteration, at:
  31673	      ASM_OUTPUT_LABEL (asm_out_file, loc_section_label);
which on the initial iteration emits:

 145   │ .Ldebug_loc0:

on the 2nd iteration:
 145   │ .Ldebug_loc1:

and on the 3rd iteration:
 145   │ .Ldebug_loc2:

which is a duplicate of a label emitted earlier:
 138   │     .section    .debug_loclists,"",@progbits
 139   │     .long   .Ldebug_loc3-.Ldebug_loc2
 140   │ .Ldebug_loc2:
 141   │     .value  0x5
 142   │     .byte   0x8
 143   │     .byte   0
 144   │     .long   0
 145   │ .Ldebug_loc2:

The issue seems to be that init_sections_and_labels creates the label
  ASM_GENERATE_INTERNAL_LABEL (loc_section_label, DEBUG_LOC_SECTION_LABEL,
			       generation);

where "generation" is a static local to init_sections_and_labels that
increments, and thus eventually hits the duplicate value.

It appears that this value is intended to be either 0 or 1, but in
the libgccjit case the compilation code can be invoked an arbitrary
number of times in-process, and hence can eventually lead to a
label name collision.

This patch adds code to dwarf2out_c_finalize (called by
toplev::finalize in libgccjit) to reset the generation counts,
fixing the issue.

gcc/ChangeLog:
	PR debug/98751
	* dwarf2out.c (output_line_info): Rename static variable
	"generation", moving it out of the function to...
	(output_line_info_generation): New.
	(init_sections_and_labels): Likewise, renaming the variable to...
	(init_sections_and_labels_generation): New.
	(dwarf2out_c_finalize): Reset the new variables.

1 files changed, 40 insertions, 26 deletions

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 8b6890a..93e5d15 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -12709,22 +12709,27 @@ output_one_line_info_table (dw_line_info_table *table)
   dw2_asm_output_data (1, DW_LNE_end_sequence, NULL);
 }
 
+static unsigned int output_line_info_generation;
+
 /* Output the source line number correspondence information.  This
    information goes into the .debug_line section.  */
 
 static void
 output_line_info (bool prologue_only)
 {
-  static unsigned int generation;
   char l1[MAX_ARTIFICIAL_LABEL_BYTES], l2[MAX_ARTIFICIAL_LABEL_BYTES];
   char p1[MAX_ARTIFICIAL_LABEL_BYTES], p2[MAX_ARTIFICIAL_LABEL_BYTES];
   bool saw_one = false;
   int opc;
 
-  ASM_GENERATE_INTERNAL_LABEL (l1, LINE_NUMBER_BEGIN_LABEL, generation);
-  ASM_GENERATE_INTERNAL_LABEL (l2, LINE_NUMBER_END_LABEL, generation);
-  ASM_GENERATE_INTERNAL_LABEL (p1, LN_PROLOG_AS_LABEL, generation);
-  ASM_GENERATE_INTERNAL_LABEL (p2, LN_PROLOG_END_LABEL, generation++);
+  ASM_GENERATE_INTERNAL_LABEL (l1, LINE_NUMBER_BEGIN_LABEL,
+			       output_line_info_generation);
+  ASM_GENERATE_INTERNAL_LABEL (l2, LINE_NUMBER_END_LABEL,
+			       output_line_info_generation);
+  ASM_GENERATE_INTERNAL_LABEL (p1, LN_PROLOG_AS_LABEL,
+			       output_line_info_generation);
+  ASM_GENERATE_INTERNAL_LABEL (p2, LN_PROLOG_END_LABEL,
+			       output_line_info_generation++);
 
   if (!XCOFF_DEBUGGING_INFO)
     {
@@ -28589,6 +28594,10 @@ output_macinfo (const char *debug_line_label, bool early_lto_debug)
   macinfo_label_base += macinfo_label_base_adj;
 }
 
+/* As init_sections_and_labels may get called multiple times, have a
+   generation count for labels.  */
+static unsigned init_sections_and_labels_generation;
+
 /* Initialize the various sections and labels for dwarf output and prefix
    them with PREFIX if non-NULL.  Returns the generation (zero based
    number of times function was called).  */
@@ -28596,10 +28605,6 @@ output_macinfo (const char *debug_line_label, bool early_lto_debug)
 static unsigned
 init_sections_and_labels (bool early_lto_debug)
 {
-  /* As we may get called multiple times have a generation count for
-     labels.  */
-  static unsigned generation = 0;
-
   if (early_lto_debug)
     {
       if (!dwarf_split_debug_info)
@@ -28634,7 +28639,7 @@ init_sections_and_labels (bool early_lto_debug)
 			   SECTION_DEBUG | SECTION_EXCLUDE, NULL);
 	  ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_abbrev_section_label,
 				       DEBUG_SKELETON_ABBREV_SECTION_LABEL,
-				       generation);
+				       init_sections_and_labels_generation);
 
 	  /* Somewhat confusing detail: The skeleton_[abbrev|info] sections
 	     stay in the main .o, but the skeleton_line goes into the split
@@ -28644,14 +28649,14 @@ init_sections_and_labels (bool early_lto_debug)
 			   SECTION_DEBUG | SECTION_EXCLUDE, NULL);
 	  ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_line_section_label,
 				       DEBUG_SKELETON_LINE_SECTION_LABEL,
-				       generation);
+				       init_sections_and_labels_generation);
 	  debug_str_offsets_section
 	    = get_section (DEBUG_LTO_DWO_STR_OFFSETS_SECTION,
 			   SECTION_DEBUG | SECTION_EXCLUDE,
 			   NULL);
 	  ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_info_section_label,
 				       DEBUG_SKELETON_INFO_SECTION_LABEL,
-				       generation);
+				       init_sections_and_labels_generation);
 	  debug_str_dwo_section = get_section (DEBUG_LTO_STR_DWO_SECTION,
 					       DEBUG_STR_DWO_SECTION_FLAGS,
 					       NULL);
@@ -28667,7 +28672,8 @@ init_sections_and_labels (bool early_lto_debug)
       debug_line_section = get_section (DEBUG_LTO_LINE_SECTION,
 					SECTION_DEBUG | SECTION_EXCLUDE, NULL);
       ASM_GENERATE_INTERNAL_LABEL (debug_line_section_label,
-				   DEBUG_LINE_SECTION_LABEL, generation);
+				   DEBUG_LINE_SECTION_LABEL,
+				   init_sections_and_labels_generation);
 
       debug_str_section = get_section (DEBUG_LTO_STR_SECTION,
 				       DEBUG_STR_SECTION_FLAGS
@@ -28711,7 +28717,7 @@ init_sections_and_labels (bool early_lto_debug)
 						       SECTION_DEBUG, NULL);
 	  ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_abbrev_section_label,
 				       DEBUG_SKELETON_ABBREV_SECTION_LABEL,
-				       generation);
+				       init_sections_and_labels_generation);
 
 	  /* Somewhat confusing detail: The skeleton_[abbrev|info] sections
 	     stay in the main .o, but the skeleton_line goes into the
@@ -28721,13 +28727,13 @@ init_sections_and_labels (bool early_lto_debug)
 			     SECTION_DEBUG | SECTION_EXCLUDE, NULL);
 	  ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_line_section_label,
 				       DEBUG_SKELETON_LINE_SECTION_LABEL,
-				       generation);
+				       init_sections_and_labels_generation);
 	  debug_str_offsets_section
 	    = get_section (DEBUG_DWO_STR_OFFSETS_SECTION,
 			   SECTION_DEBUG | SECTION_EXCLUDE, NULL);
 	  ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_info_section_label,
 				       DEBUG_SKELETON_INFO_SECTION_LABEL,
-				       generation);
+				       init_sections_and_labels_generation);
 	  debug_loc_section = get_section (dwarf_version >= 5
 					   ? DEBUG_DWO_LOCLISTS_SECTION
 					   : DEBUG_DWO_LOC_SECTION,
@@ -28767,31 +28773,37 @@ init_sections_and_labels (bool early_lto_debug)
     }
 
   ASM_GENERATE_INTERNAL_LABEL (abbrev_section_label,
-			       DEBUG_ABBREV_SECTION_LABEL, generation);
+			       DEBUG_ABBREV_SECTION_LABEL,
+			       init_sections_and_labels_generation);
   ASM_GENERATE_INTERNAL_LABEL (debug_info_section_label,
-			       DEBUG_INFO_SECTION_LABEL, generation);
+			       DEBUG_INFO_SECTION_LABEL,
+			       init_sections_and_labels_generation);
   info_section_emitted = false;
   ASM_GENERATE_INTERNAL_LABEL (debug_line_section_label,
-			       DEBUG_LINE_SECTION_LABEL, generation);
+			       DEBUG_LINE_SECTION_LABEL,
+			       init_sections_and_labels_generation);
   /* There are up to 4 unique ranges labels per generation.
      See also output_rnglists.  */
   ASM_GENERATE_INTERNAL_LABEL (ranges_section_label,
-			       DEBUG_RANGES_SECTION_LABEL, generation * 4);
+			       DEBUG_RANGES_SECTION_LABEL,
+			       init_sections_and_labels_generation * 4);
   if (dwarf_version >= 5 && dwarf_split_debug_info)
     ASM_GENERATE_INTERNAL_LABEL (ranges_base_label,
 				 DEBUG_RANGES_SECTION_LABEL,
-				 1 + generation * 4);
+				 1 + init_sections_and_labels_generation * 4);
   ASM_GENERATE_INTERNAL_LABEL (debug_addr_section_label,
-			       DEBUG_ADDR_SECTION_LABEL, generation);
+			       DEBUG_ADDR_SECTION_LABEL,
+			       init_sections_and_labels_generation);
   ASM_GENERATE_INTERNAL_LABEL (macinfo_section_label,
 			       (dwarf_strict && dwarf_version < 5)
 			       ? DEBUG_MACINFO_SECTION_LABEL
-			       : DEBUG_MACRO_SECTION_LABEL, generation);
+			       : DEBUG_MACRO_SECTION_LABEL,
+			       init_sections_and_labels_generation);
   ASM_GENERATE_INTERNAL_LABEL (loc_section_label, DEBUG_LOC_SECTION_LABEL,
-			       generation);
+			       init_sections_and_labels_generation);
 
-  ++generation;
-  return generation - 1;
+  ++init_sections_and_labels_generation;
+  return init_sections_and_labels_generation - 1;
 }
 
 /* Set up for Dwarf output at the start of compilation.  */
@@ -32379,6 +32391,8 @@ dwarf2out_c_finalize (void)
   base_types.release ();
   XDELETEVEC (producer_string);
   producer_string = NULL;
+  output_line_info_generation = 0;
+  init_sections_and_labels_generation = 0;
 }
 
 #include "gt-dwarf2out.h"