Add support for debugging with ICF (Identical Code Folding).

gcc/ChangeLog:
	Add support for debugging with ICF (Identical Code Folding).
	* calls.c (debug.h): New #include.
	(emit_call_1): Call virtual_call_token debug hook.
	* common.opt (-fenable-icf-debug): New option.
	* dwarf2out.c (dwarf2_debug_hooks): Add entries for new hooks (two
	locations in the source).
	(poc_label_num): New variable.
	(dcall_entry, vcall_entry): New typedefs.
	(dcall_table, vcall_table): New variables.
	(struct vcall_insn): New type.
	(vcall_insn_table): New variable.
	(DEBUG_DCALL_SECTION, DEBUG_VCALL_SECTION): New macros.
	(size_of_dcall_table): New function.
	(output_dcall_table): New function.
	(size_of_vcall_table): New function.
	(output_vcall_table): New function.
	(dwarf2out_direct_call): New function.
	(vcall_insn_table_hash): New function.
	(vcall_insn_table_eq): New function.
	(dwarf2out_virtual_call_token): New function.
	(dwarf2out_virtual_call): New function.
	(dwarf2out_init): Allocate new tables and sections.
	(prune_unused_types): Mark DIEs referenced from direct call table.
	(dwarf2out_finish): Output direct and virtual call tables.
	* final.c (final_scan_insn): Call direct_call and virtual_call
	debug hooks.
	* debug.h (struct gcc_debug_hooks): Add direct_call,
	virtual_call_token, virtual_call hooks.
	(debug_nothing_uid): New function.
	* debug.c (do_nothing_debug_hooks): Add dummy entries for new hooks.
	(debug_nothing_uid): New function.
	* dbxout.c (dbx_debug_hooks): Add dummy entries for new hooks.
	* sdbout.c (sdb_debug_hooks): Likewise.
	* vmsdbgout.c (vmsdbg_debug_hooks): Likewise.
	* doc/invoke.texi (-fenable-icf-debug): New option.

gcc/testsuite/ChangeLog:
	Add support for debugging with ICF (Identical Code Folding).
	* g++.dg/debug/dwarf2/icf.C: New test.

From-SVN: r152577

gcc/ChangeLog

+2009-10-08  Cary Coutant  <ccoutant@google.com>
+
+	Add support for debugging with ICF (Identical Code Folding).
+	* calls.c (debug.h): New #include.
+	(emit_call_1): Call virtual_call_token debug hook.
+	* common.opt (-fenable-icf-debug): New option.
+	* dwarf2out.c (dwarf2_debug_hooks): Add entries for new hooks (two
+	locations in the source).
+	(poc_label_num): New variable.
+	(dcall_entry, vcall_entry): New typedefs.
+	(dcall_table, vcall_table): New variables.
+	(struct vcall_insn): New type.
+	(vcall_insn_table): New variable.
+	(DEBUG_DCALL_SECTION, DEBUG_VCALL_SECTION): New macros.
+	(size_of_dcall_table): New function.
+	(output_dcall_table): New function.
+	(size_of_vcall_table): New function.
+	(output_vcall_table): New function.
+	(dwarf2out_direct_call): New function.
+	(vcall_insn_table_hash): New function.
+	(vcall_insn_table_eq): New function.
+	(dwarf2out_virtual_call_token): New function.
+	(dwarf2out_virtual_call): New function.
+	(dwarf2out_init): Allocate new tables and sections.
+	(prune_unused_types): Mark DIEs referenced from direct call table.
+	(dwarf2out_finish): Output direct and virtual call tables.
+	* final.c (final_scan_insn): Call direct_call and virtual_call
+	debug hooks.
+	* debug.h (struct gcc_debug_hooks): Add direct_call,
+	virtual_call_token, virtual_call hooks.
+	(debug_nothing_uid): New function.
+	* debug.c (do_nothing_debug_hooks): Add dummy entries for new hooks.
+	(debug_nothing_uid): New function.
+	* dbxout.c (dbx_debug_hooks): Add dummy entries for new hooks.
+	* sdbout.c (sdb_debug_hooks): Likewise.
+	* vmsdbgout.c (vmsdbg_debug_hooks): Likewise.
+	* doc/invoke.texi (-fenable-icf-debug): New option.
+
 2009-10-08  Alexandre Oliva  <aoliva@redhat.com>
 
 	PR debug/41353

gcc/calls.c

@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "sbitmap.h"
 #include "langhooks.h"
 #include "target.h"
+#include "debug.h"
 #include "cgraph.h"
 #include "except.h"
 #include "dbgcnt.h"
@@ -394,6 +395,11 @@ emit_call_1 (rtx funexp, tree fntree ATTRIBUTE_UNUSED, tree fndecl ATTRIBUTE_UNU
 
   SIBLING_CALL_P (call_insn) = ((ecf_flags & ECF_SIBCALL) != 0);
 
+  /* Record debug information for virtual calls.  */
+  if (flag_enable_icf_debug && fndecl == NULL)
+    (*debug_hooks->virtual_call_token) (CALL_EXPR_FN (fntree),
+                                        INSN_UID (call_insn));
+
   /* Restore this now, so that we do defer pops for this call's args
      if the context of the call as a whole permits.  */
   inhibit_defer_pop = old_inhibit_defer_pop;

gcc/common.opt

@@ -502,6 +502,10 @@ femit-class-debug-always
 Common Report Var(flag_emit_class_debug_always) Init(0)
 Do not suppress C++ class debug information.
 
+fenable-icf-debug
+Common Report Var(flag_enable_icf_debug)
+Generate debug information to support Identical Code Folding (ICF)
+
 fexceptions
 Common Report Var(flag_exceptions) Optimization
 Enable exception handling

gcc/dbxout.c

@@ -373,6 +373,9 @@ const struct gcc_debug_hooks dbx_debug_hooks =
   dbxout_handle_pch,		         /* handle_pch */
   debug_nothing_rtx,		         /* var_location */
   debug_nothing_void,                    /* switch_text_section */
+  debug_nothing_tree,		         /* direct_call */
+  debug_nothing_tree_int,		 /* virtual_call_token */
+  debug_nothing_uid,		         /* virtual_call */
   debug_nothing_tree_tree,		 /* set_name */
   0                                      /* start_end_main_source_file */
 };
@@ -406,6 +409,9 @@ const struct gcc_debug_hooks xcoff_debug_hooks =
   dbxout_handle_pch,		         /* handle_pch */
   debug_nothing_rtx,		         /* var_location */
   debug_nothing_void,                    /* switch_text_section */
+  debug_nothing_tree,		         /* direct_call */
+  debug_nothing_tree_int,		 /* virtual_call_token */
+  debug_nothing_uid,		         /* virtual_call */
   debug_nothing_tree_tree,	         /* set_name */
   0                                      /* start_end_main_source_file */
 };

gcc/debug.c

@@ -50,6 +50,9 @@ const struct gcc_debug_hooks do_nothing_debug_hooks =
   debug_nothing_int,		         /* handle_pch */
   debug_nothing_rtx,		         /* var_location */
   debug_nothing_void,                    /* switch_text_section */
+  debug_nothing_tree,		         /* direct_call */
+  debug_nothing_tree_int,	         /* virtual_call_token */
+  debug_nothing_uid,		         /* virtual_call */
   debug_nothing_tree_tree,		 /* set_name */
   0                                      /* start_end_main_source_file */
 };
@@ -127,3 +130,8 @@ debug_nothing_tree_int (tree decl ATTRIBUTE_UNUSED,
 			int local ATTRIBUTE_UNUSED)
 {
 }
+
+void
+debug_nothing_uid (int uid ATTRIBUTE_UNUSED)
+{
+}

gcc/debug.h

@@ -126,6 +126,25 @@ struct gcc_debug_hooks
      text sections.  */
   void (* switch_text_section) (void);
 
+  /* Records a direct call to the function DECL, noting the point of call
+     and the debug info for the function.  Called from final_scan_insn
+     when ICF debugging is enabled.  */
+  void (* direct_call) (tree decl);
+
+  /* Records the OBJ_TYPE_REF_TOKEN for a virtual call through ADDR, which
+     for C++ is the vtable slot index, noting the INSN_UID for the call
+     instruction.  Called from calls.c:emit_call_1 when ICF debugging is
+     enabled.  It's necessary to do this during lowering because the
+     call instruction and the OBJ_TYPE_REF become separated after that
+     point.  */
+  void (* virtual_call_token) (tree addr, int insn_uid);
+
+  /* Records a virtual call given INSN_UID, which is the UID of the call
+     instruction.  The UID is then mapped to the vtable slot index noted
+     during the lowering phase.  Called from final_scan_insn when ICF
+     debugging is enabled.  */
+  void (* virtual_call) (int insn_uid);
+
   /* Called from grokdeclarator.  Replaces the anonymous name with the
      type name.  */
   void (* set_name) (tree, tree);
@@ -151,6 +170,7 @@ extern void debug_nothing_tree_int (tree, int);
 extern void debug_nothing_tree_tree_tree_bool (tree, tree, tree, bool);
 extern bool debug_true_const_tree (const_tree);
 extern void debug_nothing_rtx (rtx);
+extern void debug_nothing_uid (int);
 
 /* Hooks for various debug formats.  */
 extern const struct gcc_debug_hooks do_nothing_debug_hooks;

gcc/doc/invoke.texi

@@ -307,6 +307,7 @@ Objective-C and Objective-C++ Dialects}.
 -fcompare-debug@r{[}=@var{opts}@r{]}  -fcompare-debug-second @gol
 -feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
 -feliminate-unused-debug-symbols -femit-class-debug-always @gol
+-fenable-icf-debug @gol
 -fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report -fprofile-arcs @gol
 -frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
 -fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose @gol
@@ -4609,6 +4610,11 @@ The default is @samp{-femit-struct-debug-detailed=all}.
 
 This option works only with DWARF 2.
 
+@item -fenable-icf-debug
+@opindex fenable-icf-debug
+Generate additional debug information to support identical code folding (ICF).
+This option only works with DWARF version 2 or higher.
+
 @item -fno-merge-debug-strings
 @opindex fmerge-debug-strings
 @opindex fno-merge-debug-strings

gcc/final.c

@@ -2684,6 +2684,26 @@ final_scan_insn (rtx insn, FILE *file, int optimize ATTRIBUTE_UNUSED,
 	/* Output assembler code from the template.  */
 	output_asm_insn (templ, recog_data.operand);
 
+	/* Record point-of-call information for ICF debugging.  */
+	if (flag_enable_icf_debug && CALL_P (insn))
+	  {
+	    rtx x = call_from_call_insn (insn);
+	    x = XEXP (x, 0);
+	    if (x && MEM_P (x))
+	      {
+	        if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF)
+	          {
+		    tree t;
+		    x = XEXP (x, 0);
+		    t = SYMBOL_REF_DECL (x);
+		    if (t)
+		      (*debug_hooks->direct_call) (t);
+	          }
+	        else
+	          (*debug_hooks->virtual_call) (INSN_UID (insn));
+	      }
+	  }
+
 	/* Some target machines need to postscan each insn after
 	   it is output.  */
 	if (targetm.asm_out.final_postscan_insn)

gcc/sdbout.c

@@ -337,6 +337,9 @@ const struct gcc_debug_hooks sdb_debug_hooks =
   debug_nothing_int,		         /* handle_pch */
   debug_nothing_rtx,		         /* var_location */
   debug_nothing_void,                    /* switch_text_section */
+  debug_nothing_tree,		         /* direct_call */
+  debug_nothing_tree_int,		 /* virtual_call_token */
+  debug_nothing_uid,		         /* virtual_call */
   debug_nothing_tree_tree,		 /* set_name */
   0                                      /* start_end_main_source_file */
 };
@@ -1725,6 +1728,9 @@ const struct gcc_debug_hooks sdb_debug_hooks =
   0,		/* handle_pch */
   0,		/* var_location */
   0,		/* switch_text_section */
+  0,		/* direct_call */
+  0,		/* virtual_call_token */
+  0,		/* virtual_call */
   0,		/* set_name */
   0		/* start_end_main_source_file */
 };

gcc/testsuite/ChangeLog

+2009-10-08  Cary Coutant  <ccoutant@google.com>
+
+	Add support for debugging with ICF (Identical Code Folding).
+	* g++.dg/debug/dwarf2/icf.C: New test.
+
 2009-10-08  Adam Nemet  <anemet@caviumnetworks.com>
 
 	* gcc.target/mips/truncate-6.c: New test.

gcc/testsuite/g++.dg/debug/dwarf2/icf.C

+// Test support for ICF debugging. 
+// { dg-do compile }
+// { dg-options "-O0 -gdwarf-2 -fenable-icf-debug -dA" }
+
+class A
+{
+ public:
+  A();
+  virtual void work();
+  virtual int p();
+ private:
+  int i;
+};
+
+class B
+{
+ public:
+  B();
+  ~B();
+  void work(const A* a);
+ private:
+  int j;
+};
+
+int
+test1(A* a)
+{
+  a->work();
+}
+
+int
+test2(A* a)
+{
+  if (a->p())
+    {
+      B b;
+      b.work(a);
+    }
+}
+
+// Verify that we get .debug_dcall and .debug_vcall tables generated
+// and that we see entries for both virtual calls. 
+// { dg-final { scan-assembler "\\.section.*\.debug_dcall" } }
+// { dg-final { scan-assembler "\\.section.*\.debug_vcall" } }
+// { dg-final { scan-assembler "New caller" } }
+// { dg-final { scan-assembler "Caller DIE offset" } }
+// { dg-final { scan-assembler "Point of call" } }
+// { dg-final { scan-assembler "Callee DIE offset" } }
+// { dg-final { scan-assembler "0x0.*Vtable slot" } }
+// { dg-final { scan-assembler "0x1.*Vtable slot" } }

gcc/vmsdbgout.c

@@ -213,6 +213,9 @@ const struct gcc_debug_hooks vmsdbg_debug_hooks
    debug_nothing_int,		  /* handle_pch */
    debug_nothing_rtx,		  /* var_location */
    debug_nothing_void,            /* switch_text_section */
+   debug_nothing_tree,		  /* direct_call */
+   debug_nothing_tree_int,	  /* virtual_call_token */
+   debug_nothing_uid,		  /* virtual_call */
    debug_nothing_tree_tree,	  /* set_name */
    0                              /* start_end_main_source_file */
 };