Add ability to track uninitialized variables, and mark uninitialized variables…

Add ability to track uninitialized variables, and mark uninitialized variables in the Dwarf debug info.

Add ability to track uninitialized variables, and mark uninitialized
variables in the Dwarf debug info.  Controlled by compile option
-fvar-tracking-uninit

From-SVN: r126630

gcc/ChangeLog

+2007-07-13  Caroline Tice  <ctice@apple.com>
+	
+	* toplev.c (process_options): Turn flag_var_tracking_uninit off when
+	flag_var_tracking is explicitly turned off (i.e. when variable
+	tracking is not feasible); otherwise, turn flag_var_tracking on when
+	flag_var_tracking_uninit is on.
+	* rtl.def (VAR_LOCATION): Add a new integer subfield to VAR_LOCATION
+	note definitions, to allow recording of initialization status in the
+	notes.
+	* dwarf2out.c (dwarf_stack_op_name): Add case for DW_OP_GNU_uninit.
+	(add_var_loc_to_decl): Add comparison of NOTE_VAR_LOCATION_STATUS to
+	determine if two note locations are equal.
+	(output_loc_list): Don't output list entries whose start & end labels
+	are the same.
+	(reg_loc_descriptor): Add parameter for initialization status; pass it
+	to other loc descriptor functions.
+	(one_reg_loc_descriptor): Add parameter for initialization status;
+	check its value and add DW_OP_GNU_uninit to returned loc descr if
+	appropriate.
+	(multiple_reg_loc_descriptor): Add parameter for initialization
+	status;
+	pass init status argument to other loc descriptor functions; check
+	value of intialization parameter and add DW_OP_GNU_uninit to returned
+	loc descr if appropriate.
+	(based_loc_descr): Add parameter for initialization status; add new
+	variable for return value; check value of initialization parameter and
+	add DW_OP_GNU_uninit to returned loc descr if appropriate.
+	(concatn_mem_loc_descriptor): Add parameter for initialization status;
+	pass init status argument to other loc descriptor functions; check
+	value of intialization parameter and add DW_OP_GNU_uninit to returned
+	loc descr if appropriate.
+	(mem_loc_descriptor): Likewise.
+	(concat_loc_descriptor): Likewise.
+	(concatn_loc_descriptor): Likewise.
+	(loc_descriptor): Add parameter for initialization status; pass it as
+	argument to other loc descriptor function calls.
+	(loc_descriptor_from_tree_1): Add appropriate initialization status
+	to loc descriptor function calls.
+	(add_location_or_const_value_attribute): Get initialization status
+	from VAR_LOCATION note; add initialization status to loc descriptor
+	function calls.
+	* dwarf2.h (enum dwarf_location_atom): New op, DW_OP_GNU_uninit.
+	* print-rtl.c (print_rtx): When printing a VAR_LOCATION note, if
+	status is uninitialized, add "[uninint]" to output.
+	* common.opt (fvar-tracking-uninit): New option, similar to
+	fvar-tracking, to turn on tracking of uninitialized variables; creates
+	a new global flag, flag_var_tracking_uninit.
+	* rtl.h (NOTE_VAR_LOCATION_STATUS): New macro for accessing new field.
+	(enum var_init_status): New type, for var initialization status field.
+	* var-tracking.c (struct location_chain_def): Two new fields, init,
+	for initialization status, and set_src for the assignment value expr.
+	(unshare_variable): New parameter for initialization status;
+	initialize new init and set_src fields.
+	(var_reg_set): New parameters for initialization status and value;
+	pass them to set_variable_part.
+	(var_mem_set): Likewise.
+	(get_init_value): New function.
+	(var_reg_delete_and_set): New initialization status & value
+	parameters; add call to get_init_value if status is unknown; pass new
+	parameters to clobber_variable_part and var_reg_set.
+	(var_mem_delete_and_set): Likewise.
+	(var_reg_delete): Pass null set_src value to clobber_variable_part.
+	(var_mem_delete): Likewise.
+	(variable_union): Pass status to unshare_variable; initialize new init
+	and set_src fields. If flag_var_tracking_uninit is not set, force
+	status to initialized.
+	(add_stores): Store insn, rather than NEXT_INSN(insn), so it can be
+	used later to get the set_src value.
+	(find_src_status): New function.
+	(find_src_set_src): New function.
+	(compute_bb_dataflow): Pass init status to calls to var_reg_set,
+	var_mem_set, var_reg_delete_and_set and var_mem_delete_and_set; for
+	MO_SET, get set_src value and pass it to var_reg_delete_and_set
+	and var_mem_delete_and_set.
+	(dump_variable): Print out "[uninit]" if appropriate.
+	(set_variable_part): Add new initialization and set_src parameters;
+	pass status to unshare_variable; set node->init and node- >set_src
+	fields and modify slot in hash table appropriately; save the init and
+	set_src values if appropriate and assign to the new node.
+	(clobber_variable_part): New set_src parameter; if two nodes have
+	same variable and same location but different set_src (assignment)
+	values, clobber old node.
+	(delete_variable_part): Pass init status to unshare_variable.
+	(emit_note_insn_var_location): Add initialized var; assign var's init
+	status to new 'initialized'; pass new init status field to calls to
+	gen_rtx_VAR_LOCATION. If flag_var_tracking_uninit is not set, force
+	status to initialized.
+	(emit_notes_in_bb): Pass initialization status to calls to
+	var_reg_set, var_mem_set, var_reg_delete_and_set and
+	var_mem_delete_and_set; for MO_SET, get set_src value and pass it to
+	var_reg_delete_and_set and var_mem_delete_and_set; call
+	emit_notes_for_changes on NEXT_INSN(insn) rather than on insn, to
+	make up for change in add_stores.
+	(vt_add_function_parameters): Add status to calls to
+	set_variable_part.
+	* config/darwin.c (darwin_override_options): Turn on uninitialized
+	tracking automatically, if var_tracking is on and the system is
+	10.5 or higher.
+	
 2007-07-13  Sa Liu  <saliu@de.ibm.com>
 
 	* config.gcc: Add options for arch and tune on SPU.

gcc/common.opt

@@ -1130,6 +1130,10 @@ fvar-tracking
 Common Report Var(flag_var_tracking) VarExists Optimization
 Perform variable tracking
 
+fvar-tracking-uninit
+Common Report Var(flag_var_tracking_uninit) Optimization
+Perform variable tracking and also tag variables that are uninitialized
+
 ftree-vectorize
 Common Report Var(flag_tree_vectorize) Optimization
 Enable loop vectorization on trees

gcc/config/darwin.c

@@ -1728,6 +1728,9 @@ darwin_override_options (void)
       /* No -fnon-call-exceptions data in kexts.  */
       flag_non_call_exceptions = 0;
     }
+  if (flag_var_tracking
+      && strverscmp (darwin_macosx_version_min, "10.5") >= 0)
+    flag_var_tracking_uninit = 1;
 }
 
 #include "gt-darwin.h"

gcc/dwarf2.h

@@ -540,6 +540,8 @@ enum dwarf_location_atom
     DW_OP_bit_piece = 0x9d,
     /* GNU extensions.  */
     DW_OP_GNU_push_tls_address = 0xe0,
+    /* The following is for marking variables that are uninitialized.  */
+    DW_OP_GNU_uninit     = 0xf0,
     /* HP extensions.  */
     DW_OP_HP_unknown     = 0xe0, /* Ouch, the same as GNU_push_tls_address.  */
     DW_OP_HP_is_value    = 0xe1,

gcc/print-rtl.c

@@ -325,6 +325,9 @@ print_rtx (rtx in_rtx)
 		print_mem_expr (outfile, NOTE_VAR_LOCATION_DECL (in_rtx));
 		fprintf (outfile, " ");
 		print_rtx (NOTE_VAR_LOCATION_LOC (in_rtx));
+		if (NOTE_VAR_LOCATION_STATUS (in_rtx) == 
+		                                 VAR_INIT_STATUS_UNINITIALIZED)
+		  fprintf (outfile, " [uninit]");
 		fprintf (outfile, ")");
 #endif
 		break;

gcc/rtl.def

@@ -680,7 +680,9 @@ DEF_RTL_EXPR(SS_TRUNCATE, "ss_truncate", "e", RTX_UNARY)
 DEF_RTL_EXPR(US_TRUNCATE, "us_truncate", "e", RTX_UNARY)
 
 /* Information about the variable and its location.  */
-DEF_RTL_EXPR(VAR_LOCATION, "var_location", "te", RTX_EXTRA)
+/* Changed 'te' to 'tei'; the 'i' field is for recording
+   initialization status of variables.  */
+DEF_RTL_EXPR(VAR_LOCATION, "var_location", "tei", RTX_EXTRA)
 
 /* All expressions from this point forward appear only in machine
    descriptions.  */

gcc/rtl.h

@@ -847,6 +847,22 @@ extern const char * const reg_note_name[];
 #define NOTE_VAR_LOCATION_LOC(INSN)	(XCEXP (XCEXP (INSN, 4, NOTE),  \
 						1, VAR_LOCATION))
 
+/* Initialization status of the variable in the location.  Status
+   can be unknown, uninitialized or initialized.  See enumeration
+   type below.  */
+#define NOTE_VAR_LOCATION_STATUS(INSN)  (XCINT (XCEXP (INSN, 4, NOTE), \
+						2, VAR_LOCATION))
+
+/* Possible initialization status of a variable.   When requested
+   by the user, this information is tracked and recorded in the DWARF
+   debug information, along with the variable's location.  */
+enum var_init_status
+{
+  VAR_INIT_STATUS_UNKNOWN,
+  VAR_INIT_STATUS_UNINITIALIZED,
+  VAR_INIT_STATUS_INITIALIZED
+};
+
 /* Codes that appear in the NOTE_KIND field for kinds of notes
    that are not line numbers.  These codes are all negative.
    

gcc/toplev.c

@@ -1874,7 +1874,8 @@ process_options (void)
   if (debug_info_level < DINFO_LEVEL_NORMAL
       || debug_hooks->var_location == do_nothing_debug_hooks.var_location)
     {
-      if (flag_var_tracking == 1)
+      if (flag_var_tracking == 1
+	  || flag_var_tracking_uninit == 1)
         {
 	  if (debug_info_level < DINFO_LEVEL_NORMAL)
 	    warning (0, "variable tracking requested, but useless unless "
@@ -1884,6 +1885,7 @@ process_options (void)
 		     "by this debug format");
 	}
       flag_var_tracking = 0;
+      flag_var_tracking_uninit = 0;
     }
 
   if (flag_rename_registers == AUTODETECT_VALUE)
@@ -1893,6 +1895,12 @@ process_options (void)
   if (flag_var_tracking == AUTODETECT_VALUE)
     flag_var_tracking = optimize >= 1;
 
+  /* If the user specifically requested variable tracking with tagging
+     uninitialized variables, we need to turn on variable tracking.
+     (We already determined above that variable tracking is feasible.)  */
+  if (flag_var_tracking_uninit)
+    flag_var_tracking = 1;
+
   /* 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.  */