Josef Zlomek <zlomekj@suse.cz>

Josef Zlomek <zlomekj@suse.cz> * Makefile.in (var-tracking.o): New. * common.opt (fvar-tracking): New. * flags.h (flag_var_tracking): New. * gengtype.c (adjust_field_rtx_def): NOTE_INSN_VAR_LOCATION was added. * opts.c (common_handle_option): Add OPT_fvar_tracking. * print-rtl.c (print_rtx): NOTE_INSN_VAR_LOCATION was added. * rtl.c (note_insn_name): Likewise. * rtl.def (VAR_LOCATION): New. * rtl.h (NOTE_VAR_LOCATION): New. (NOTE_VAR_LOCATION_DECL): New. (NOTE_VAR_LOCATION_LOC): New. (enum insn_note): NOTE_INSN_VAR_LOCATION was added. (variable_tracking_main): New exported function. * timevar.def (TV_VAR_TRACKING): New. * toplev.c (enum dump_file_index): Added DFI_vartrack. (dump_file): "vartrack" was added (-dV). (flag_var_tracking): New. (f_options): "var-tracking" was added. (rest_of_handle_variable_tracking): New function. (rest_of_compilation): Run variable tracking. (process_options): If user has not specified flag_var_tracking set it according to optimize, debug_info_level and debug_hooks. * tree.h (frame_base_decl): New. * var-tracking.c: New file. * config/ia64/ia64.c (ia64_flag_var_tracking): New variable. (ia64_override_options): Set flags to run variable tracking in machine dependent reorg instead of toplev.c. (ia64_reorg): Run variable tracking if wanted. * doc/invoke.texi: Mention variable tracking in -dV, add and -fvar-tracking. * doc/passes.texi: Added variable tracking pass. Daniel Berlin <dberlin@dberlin.org> * debug.h (struct gcc_debug_hooks): Added var_location debug hook. * dbxout.c (dbx_debug_hooks): Likewise. (xcoff_debug): Likewise. * debug.c (do_nothing_debug_hooks): Likewise. * dwarf2out.c (dwarf2_debug_hooks): Likewise. * dwarfout.c (dwarf_debug_hooks): Likewise. * sdbout.c (sdb_debug_hooks): Likewise. * vmsdbgout.c (vmsdbg_debug_hooks): Likewise. * final.c (final_scan_insn): Call var_location debug hook for each NOTE_INSN_VAR_LOCATION. Co-Authored-By: Daniel Berlin <dberlin@dberlin.org> From-SVN: r77418
2004-02-06 21:03:45 +01:00 · 2004-02-06 21:03:45 +01:00 · 014a1138d6
commit 014a1138d6
parent 298c28a8f4
24 changed files with 2820 additions and 10 deletions
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@ -1,3 +1,51 @@
+2004-02-06  Josef Zlomek  <zlomekj@suse.cz>
+            Daniel Berlin <dberlin@dberlin.org>
+
+	Josef Zlomek  <zlomekj@suse.cz>
+	* Makefile.in (var-tracking.o): New.
+	* common.opt (fvar-tracking): New.
+	* flags.h (flag_var_tracking): New.
+	* gengtype.c (adjust_field_rtx_def): NOTE_INSN_VAR_LOCATION was added.
+	* opts.c (common_handle_option): Add OPT_fvar_tracking.
+	* print-rtl.c (print_rtx): NOTE_INSN_VAR_LOCATION was added.
+        * rtl.c (note_insn_name): Likewise.
+        * rtl.def (VAR_LOCATION): New.
+        * rtl.h (NOTE_VAR_LOCATION): New.
+        (NOTE_VAR_LOCATION_DECL): New.
+        (NOTE_VAR_LOCATION_LOC): New.
+        (enum insn_note): NOTE_INSN_VAR_LOCATION was added.
+        (variable_tracking_main): New exported function.
+        * timevar.def (TV_VAR_TRACKING): New.
+        * toplev.c (enum dump_file_index): Added DFI_vartrack.
+        (dump_file): "vartrack" was added (-dV).
+        (flag_var_tracking): New.
+        (f_options): "var-tracking" was added.
+	(rest_of_handle_variable_tracking): New function.
+        (rest_of_compilation): Run variable tracking.
+	(process_options): If user has not specified flag_var_tracking set it
+	according to optimize, debug_info_level and debug_hooks.
+	* tree.h (frame_base_decl): New.
+        * var-tracking.c: New file.
+	* config/ia64/ia64.c (ia64_flag_var_tracking): New variable.
+	(ia64_override_options): Set flags to run variable tracking in machine
+	dependent reorg instead of toplev.c.
+	(ia64_reorg): Run variable tracking if wanted.
+        * doc/invoke.texi: Mention variable tracking in -dV,
+	add and -fvar-tracking.
+        * doc/passes.texi: Added variable tracking pass.
+
+	Daniel Berlin <dberlin@dberlin.org>
+	* debug.h (struct gcc_debug_hooks): Added var_location debug hook.
+	* dbxout.c (dbx_debug_hooks): Likewise.
+	(xcoff_debug): Likewise.
+	* debug.c (do_nothing_debug_hooks): Likewise.
+	* dwarf2out.c (dwarf2_debug_hooks): Likewise.
+	* dwarfout.c (dwarf_debug_hooks): Likewise.
+	* sdbout.c (sdb_debug_hooks): Likewise.
+	* vmsdbgout.c (vmsdbg_debug_hooks): Likewise.
+	* final.c (final_scan_insn): Call var_location debug hook for each 
+	NOTE_INSN_VAR_LOCATION. 
+
 2004-02-06  Jan Hubicka  <jh@suse.cz>

 	* flow.c (update_life_info): Allocate reg_deaths when called from
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@ -852,7 +852,7 @@ OBJS-common = \
 insn-extract.o insn-opinit.o insn-output.o insn-peep.o insn-recog.o	   \
 integrate.o intl.o jump.o  langhooks.o lcm.o lists.o local-alloc.o  	   \
 loop.o optabs.o options.o opts.o params.o postreload.o predict.o	   \
- print-rtl.o print-tree.o value-prof.o					   \
+ print-rtl.o print-tree.o value-prof.o var-tracking.o			   \
 profile.o ra.o ra-build.o ra-colorize.o ra-debug.o ra-rewrite.o	   \
 real.o recog.o reg-stack.o regclass.o regmove.o regrename.o		   \
 reload.o reload1.o reorg.o resource.o rtl.o rtlanal.o rtl-error.o	   \
@ -1669,6 +1669,9 @@ lcm.o : lcm.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) $(REGS_H) \
 df.o : df.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
   insn-config.h $(RECOG_H) function.h $(REGS_H) alloc-pool.h hard-reg-set.h \
   $(BASIC_BLOCK_H) df.h $(FIBHEAP_H)
+var-tracking.o : var-tracking.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
+   $(RTL_H) $(TREE_H) hard-reg-set.h insn-config.h reload.h flags.h \
+   $(BASIC_BLOCK_H) output.h sbitmap.h alloc-pool.h $(FIBHEAP_H) $(HASHTAB_H)
 conflict.o : conflict.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(OBSTACK_H) \
   $(HASHTAB_H) $(RTL_H) hard-reg-set.h $(BASIC_BLOCK_H)
 profile.o : profile.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
--- a/gcc/common.opt
+++ b/gcc/common.opt
@ -715,6 +715,10 @@ funwind-tables
 Common
 Just generate unwind tables for exception handling

+fvar-tracking
+Common
+Perform variable tracking
+
 fverbose-asm
 Common
 Add extra commentary to assembler output
--- a/gcc/config/ia64/ia64.c
+++ b/gcc/config/ia64/ia64.c
@ -117,6 +117,10 @@ const char *ia64_tune_string;
   avoid the normal second scheduling pass.  */
 static int ia64_flag_schedule_insns2;

+/* Determines whether we run variable tracking in machine dependent
+   reorganization.  */
+static int ia64_flag_var_tracking;
+
 /* Variables which are this size or smaller are put in the sdata/sbss
   sections.  */

@ -4785,6 +4789,11 @@ ia64_override_options (void)
  ia64_flag_schedule_insns2 = flag_schedule_insns_after_reload;
  flag_schedule_insns_after_reload = 0;

+  /* Variable tracking should be run after all optimizations which change order
+     of insns.  It also needs a valid CFG.  */
+  ia64_flag_var_tracking = flag_var_tracking;
+  flag_var_tracking = 0;
+
  ia64_section_threshold = g_switch_set ? g_switch_value : IA64_DEFAULT_GVALUE;

  init_machine_status = ia64_init_machine_status;
@ -7630,6 +7639,13 @@ ia64_reorg (void)

  fixup_errata ();
  emit_predicate_relation_info ();
+
+  if (ia64_flag_var_tracking)
+    {
+      timevar_push (TV_VAR_TRACKING);
+      variable_tracking_main ();
+      timevar_pop (TV_VAR_TRACKING);
+    }
 }

 /* Return true if REGNO is used by the epilogue.  */
--- a/gcc/dbxout.c
+++ b/gcc/dbxout.c
@ -400,7 +400,8 @@ const struct gcc_debug_hooks dbx_debug_hooks =
  debug_nothing_tree,		         /* deferred_inline_function */
  debug_nothing_tree,		         /* outlining_inline_function */
  debug_nothing_rtx,		         /* label */
-  dbxout_handle_pch		         /* handle_pch */
+  dbxout_handle_pch,		         /* handle_pch */
+  debug_nothing_rtx		         /* var_location */
 };
 #endif /* DBX_DEBUGGING_INFO  */

@ -428,7 +429,8 @@ const struct gcc_debug_hooks xcoff_debug_hooks =
  debug_nothing_tree,		         /* deferred_inline_function */
  debug_nothing_tree,		         /* outlining_inline_function */
  debug_nothing_rtx,		         /* label */
-  dbxout_handle_pch		         /* handle_pch */
+  dbxout_handle_pch,		         /* handle_pch */
+  debug_nothing_rtx		         /* var_location */
 };
 #endif /* XCOFF_DEBUGGING_INFO  */

--- a/gcc/debug.c
+++ b/gcc/debug.c
@ -45,7 +45,8 @@ const struct gcc_debug_hooks do_nothing_debug_hooks =
  debug_nothing_tree,		         /* deferred_inline_function */
  debug_nothing_tree,		         /* outlining_inline_function */
  debug_nothing_rtx,		         /* label */
-  debug_nothing_int		         /* handle_pch */
+  debug_nothing_int,		         /* handle_pch */
+  debug_nothing_rtx		         /* var_location */
 };

 /* This file contains implementations of each debug hook that do
--- a/gcc/debug.h
+++ b/gcc/debug.h
@ -108,6 +108,9 @@ struct gcc_debug_hooks
  /* Called after the start and before the end of writing a PCH file.
     The parameter is 0 if after the start, 1 if before the end.  */
  void (* handle_pch) (unsigned int);
+
+  /* Called from final_scan_insn for any NOTE_INSN_VAR_LOCATION note.  */
+  void (* var_location) (rtx);
 };

 extern const struct gcc_debug_hooks *debug_hooks;
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@ -251,7 +251,7 @@ in the following sections.
 -feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
 -feliminate-unused-debug-symbols -fmem-report -fprofile-arcs @gol
 -frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
-ftest-coverage  -ftime-report @gol
+-ftest-coverage  -ftime-report -fvar-tracking @gol
 -g  -g@var{level}  -gcoff -gdwarf-2 @gol
 -ggdb  -gstabs  -gstabs+  -gvms  -gxcoff  -gxcoff+ @gol
 -p  -pg  -print-file-name=@var{library}  -print-libgcc-file-name @gol
@ -3313,6 +3313,7 @@ Dump callgraph and unit-at-a-time optimization @file{@var{file}.00.unit}.
@item V
@opindex dV
 Dump after the value profile transformations, to @file{@var{file}.13.vpt}.
+Also dump after variable tracking, to @file{@var{file}.35.vartrack}.
@item w
@opindex dw
 Dump after the second flow pass, to @file{@var{file}.27.flow2}.
@ -3467,6 +3468,16 @@ executing the program itself.  The second number is ``system time,''
 time spent executing operating system routines on behalf of the program.
 Both numbers are in seconds.

+@item -fvar-tracking
+@opindex fvar-tracking
+Run variable tracking pass. It computes where variables are stored at each
+position in code. Better debugging information is then generated
+(if the debugging information format supports this information).
+
+It is enabled by default when compiling with optimization (@option{-Os},
+@option{-O}, @option{-O2}, ...), debugging information (@option{-g}) and
+the debug info format supports it.
+
@item -print-file-name=@var{library}
@opindex print-file-name
 Print the full absolute name of the library file @var{library} that
--- a/gcc/doc/passes.texi
+++ b/gcc/doc/passes.texi
@ -507,6 +507,19 @@ The option @option{-dB} causes a debugging dump of the RTL code after
 this pass.  This dump file's name is made by appending @samp{.bbro} to
 the input file name.

+@cindex variable tracking
+@item
+Variable tracking.  This pass computes where the variables are stored at each
+position in code and generates notes describing the variable locations
+to RTL code.  The location lists are then generated according to these
+notes to debug information if the debugging information format supports
+location lists.
+
+@opindex dV
+The option @option{-dV} causes a debugging dump of the RTL code after
+this pass.  This dump file's name is made by appending @samp{.vartrack}
+to the input file name.
+
@cindex delayed branch scheduling
@cindex scheduling, delayed branch
@item
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@ -3280,7 +3280,8 @@ const struct gcc_debug_hooks dwarf2_debug_hooks =
     something tries to reference them.  */
  dwarf2out_abstract_function,	/* outlining_inline_function */
  debug_nothing_rtx,		/* label */
-  debug_nothing_int		/* handle_pch */
+  debug_nothing_int,		/* handle_pch */
+  debug_nothing_rtx		/* var_location */
 };
 #endif

--- a/gcc/final.c
+++ b/gcc/final.c
@ -1782,6 +1782,10 @@ final_scan_insn (rtx insn, FILE *file, int optimize ATTRIBUTE_UNUSED,
 	  ASM_OUTPUT_DEBUG_LABEL (file, "L", CODE_LABEL_NUMBER (insn));
 	  break;

+	case NOTE_INSN_VAR_LOCATION:
+	  (*debug_hooks->var_location) (insn);
+	  break;
+
 	case 0:
 	  break;

--- a/gcc/flags.h
+++ b/gcc/flags.h
@ -723,6 +723,9 @@ extern int flag_web;
   used.  */
 extern int flag_remove_unreachable_functions;

+/* Nonzero if we should track variables.  */
+extern int flag_var_tracking;
+
 /* A string that's used when a random name is required.  NULL means
   to make it really random.  */

--- a/gcc/gengtype.c
+++ b/gcc/gengtype.c
@ -450,6 +450,7 @@ adjust_field_rtx_def (type_p t, options_p opt ATTRIBUTE_UNUSED)
 	    break;

 	  case NOTE_INSN_EXPECTED_VALUE:
+	  case NOTE_INSN_VAR_LOCATION:
 	    note_flds->name = "rtx";
 	    note_flds->type = rtx_tp;
 	    break;
--- a/gcc/opts.c
+++ b/gcc/opts.c
@ -1436,6 +1436,10 @@ common_handle_option (size_t scode, const char *arg,
      flag_unwind_tables = value;
      break;

+    case OPT_fvar_tracking:
+      flag_var_tracking = value;
+      break;
+
    case OPT_fverbose_asm:
      flag_verbose_asm = value;
      break;
--- a/gcc/print-rtl.c
+++ b/gcc/print-rtl.c
@ -291,6 +291,14 @@ print_rtx (rtx in_rtx)
 		  fprintf (outfile, " [ ERROR ]");
 		break;

+	      case NOTE_INSN_VAR_LOCATION:
+		fprintf (outfile, " (");
+		print_mem_expr (outfile, NOTE_VAR_LOCATION_DECL (in_rtx));
+		fprintf (outfile, " ");
+		print_rtx (NOTE_VAR_LOCATION_LOC (in_rtx));
+		fprintf (outfile, ")");
+		break;
+
 	      default:
 		{
 		  const char * const str = X0STR (in_rtx, i);
--- a/gcc/rtl.c
+++ b/gcc/rtl.c
@ -122,7 +122,7 @@ const char * const note_insn_name[NOTE_INSN_MAX - NOTE_INSN_BIAS] =
  "NOTE_INSN_EH_REGION_BEG", "NOTE_INSN_EH_REGION_END",
  "NOTE_INSN_REPEATED_LINE_NUMBER",
  "NOTE_INSN_BASIC_BLOCK", "NOTE_INSN_EXPECTED_VALUE",
-  "NOTE_INSN_PREDICTION"
+  "NOTE_INSN_PREDICTION", "NOTE_INSN_VAR_LOCATION"
 };

 const char * const reg_note_name[] =
--- a/gcc/rtl.def
+++ b/gcc/rtl.def
@ -1215,6 +1215,8 @@ DEF_RTL_EXPR(SS_TRUNCATE, "ss_truncate", "e", '1')
 /* Unsigned saturating truncate.  */
 DEF_RTL_EXPR(US_TRUNCATE, "us_truncate", "e", '1')

+/* Information about the variable and its location.  */
+DEF_RTL_EXPR(VAR_LOCATION, "var_location", "te", 'x')

 /*
 Local variables:
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@ -819,6 +819,7 @@ extern const char * const reg_note_name[];
 #define NOTE_EXPECTED_VALUE(INSN) XCEXP (INSN, 4, NOTE)
 #define NOTE_PREDICTION(INSN)   XCINT (INSN, 4, NOTE)
 #define NOTE_PRECONDITIONED(INSN)   XCINT (INSN, 4, NOTE)
+#define NOTE_VAR_LOCATION(INSN)	XCEXP (INSN, 4, NOTE)

 /* In a NOTE that is a line number, this is the line number.
   Other kinds of NOTEs are identified by negative numbers here.  */
@ -834,6 +835,12 @@ extern const char * const reg_note_name[];
 #define NOTE_PREDICTION_FLAGS(INSN) (XCINT(INSN, 4, NOTE)&0xff)
 #define NOTE_PREDICT(ALG,FLAGS)     ((ALG<<8)+(FLAGS))

+/* Variable declaration and the location of a variable.  */
+#define NOTE_VAR_LOCATION_DECL(INSN)	(XCTREE (XCEXP (INSN, 4, NOTE), \
+						 0, VAR_LOCATION))
+#define NOTE_VAR_LOCATION_LOC(INSN)	(XCEXP (XCEXP (INSN, 4, NOTE),  \
+						1, VAR_LOCATION))
+  
 /* Codes that appear in the NOTE_LINE_NUMBER field
   for kinds of notes that are not line numbers.

@ -917,6 +924,9 @@ enum insn_note
  /* Record a prediction.  Uses NOTE_PREDICTION.  */
  NOTE_INSN_PREDICTION,

+  /* The location of a variable.  */
+  NOTE_INSN_VAR_LOCATION,
+
  NOTE_INSN_MAX
 };

@ -2343,4 +2353,7 @@ extern bool expensive_function_p (int);
 /* In tracer.c */
 extern void tracer (void);

+/* In var-tracking.c */
+extern void variable_tracking_main (void);
+
 #endif /* ! GCC_RTL_H */
--- a/gcc/sdbout.c
+++ b/gcc/sdbout.c
@ -335,7 +335,8 @@ const struct gcc_debug_hooks sdb_debug_hooks =
  debug_nothing_tree,		         /* deferred_inline_function */
  debug_nothing_tree,		         /* outlining_inline_function */
  sdbout_label,			         /* label */
-  debug_nothing_int		         /* handle_pch */
+  debug_nothing_int,		         /* handle_pch */
+  debug_nothing_rtx		         /* var_location */
 };

 /* Return a unique string to name an anonymous type.  */
--- a/gcc/timevar.def
+++ b/gcc/timevar.def
@ -95,6 +95,7 @@ DEFTIMEVAR (TV_SHORTEN_BRANCH        , "shorten branches")
 DEFTIMEVAR (TV_REG_STACK             , "reg stack")
 DEFTIMEVAR (TV_FINAL                 , "final")
 DEFTIMEVAR (TV_SYMOUT                , "symout")
+DEFTIMEVAR (TV_VAR_TRACKING          , "variable tracking")

 /* Everything else in rest_of_compilation not included above.  */
 DEFTIMEVAR (TV_REST_OF_COMPILATION   , "rest of compilation")
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@ -158,6 +158,7 @@ static void rest_of_handle_reorder_blocks (tree, rtx);
 #ifdef STACK_REGS
 static void rest_of_handle_stack_regs (tree, rtx);
 #endif
+static void rest_of_handle_variable_tracking (tree, rtx);
 static void rest_of_handle_machine_reorg (tree, rtx);
 #ifdef DELAY_SLOTS
 static void rest_of_handle_delay_slots (tree, rtx);
@ -289,6 +290,7 @@ enum dump_file_index
  DFI_branch_target_load,
  DFI_sched2,
  DFI_stack,
+  DFI_vartrack,
  DFI_mach,
  DFI_dbr,
  DFI_MAX
@ -340,6 +342,7 @@ static struct dump_file_info dump_file[DFI_MAX] =
  { "btl",	'd', 1, 0, 0 }, /* Yes, duplicate enable switch.  */
  { "sched2",	'R', 1, 0, 0 },
  { "stack",	'k', 1, 0, 0 },
+  { "vartrack",	'V', 1, 0, 0 }, /* Yes, duplicate enable switch.  */
  { "mach",	'M', 1, 0, 0 },
  { "dbr",	'd', 0, 0, 0 },
 };
@ -965,6 +968,13 @@ int flag_tracer = 0;

 int flag_unit_at_a_time = 0;

+/* Nonzero if we should track variables.  When
+   flag_var_tracking == AUTODETECT_FLAG_VAR_TRACKING it will be set according
+   to optimize, debug_info_level and debug_hooks in process_options ().  */
+ 
+#define AUTODETECT_FLAG_VAR_TRACKING 2
+int flag_var_tracking = AUTODETECT_FLAG_VAR_TRACKING;
+
 /* Values of the -falign-* flags: how much to align labels in code.
   0 means `use default', 1 means `don't align'.
   For each variable, there is an _log variant which is the power
@ -1145,7 +1155,8 @@ static const lang_independent_options f_options[] =
  {"mem-report", &mem_report, 1 },
  { "trapv", &flag_trapv, 1 },
  { "wrapv", &flag_wrapv, 1 },
-  { "new-ra", &flag_new_regalloc, 1 }
+  { "new-ra", &flag_new_regalloc, 1 },
+  { "var-tracking", &flag_var_tracking, 1}
 };

 /* Here is a table, controlled by the tm.h file, listing each -m switch
@ -2148,6 +2159,18 @@ rest_of_handle_stack_regs (tree decl, rtx insns)
 }
 #endif

+/* Track the variables, ie. compute where the variable is stored at each position in function.  */
+static void
+rest_of_handle_variable_tracking (tree decl, rtx insns)
+{
+  timevar_push (TV_VAR_TRACKING);
+  open_dump_file (DFI_vartrack, decl);
+
+  variable_tracking_main ();
+
+  close_dump_file (DFI_vartrack, print_rtl_with_bb, insns);
+  timevar_pop (TV_VAR_TRACKING);
+}

 /* Machine independent reorg pass.  */
 static void
@ -3562,6 +3585,9 @@ rest_of_compilation (tree decl)

  compute_alignments ();

+  if (flag_var_tracking)
+    rest_of_handle_variable_tracking (decl, insns);
+
  /* CFG is no longer maintained up-to-date.  */
  free_bb_for_insn ();

@ -4414,6 +4440,16 @@ process_options (void)
    error ("target system does not support the \"%s\" debug format",
 	   debug_type_names[write_symbols]);

+  /* Now we know which debug output will be used so we can set
+     flag_var_tracking if user has not specified it.  */
+  if (flag_var_tracking == AUTODETECT_FLAG_VAR_TRACKING)
+    {
+      /* User has not specified -f(no-)var-tracking so autodetect it.  */
+      flag_var_tracking
+	= (optimize >= 1 && debug_info_level >= DINFO_LEVEL_NORMAL
+	   && debug_hooks->var_location != do_nothing_debug_hooks.var_location);
+    }
+
  /* If auxiliary info generation is desired, open the output file.
     This goes in the same directory as the source file--unlike
     all the other output files.  */
--- a/gcc/tree.h
+++ b/gcc/tree.h
@ -2060,6 +2060,7 @@ enum ptrmemfunc_vbit_where_t

 #define NULL_TREE (tree) NULL

+extern tree frame_base_decl;
 extern tree decl_assembler_name (tree);

 /* Compute the number of bytes occupied by 'node'.  This routine only
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
--- a/gcc/vmsdbgout.c
+++ b/gcc/vmsdbgout.c
@ -190,7 +190,8 @@ const struct gcc_debug_hooks vmsdbg_debug_hooks
   debug_nothing_tree,		  /* deferred_inline_function */
   vmsdbgout_abstract_function,
   debug_nothing_rtx,		  /* label */
-   debug_nothing_int		  /* handle_pch */
+   debug_nothing_int,		  /* handle_pch */
+   debug_nothing_rtx		  /* var_location */
 };

 /* Definitions of defaults for assembler-dependent names of various