[google] Add libgcov interface for accessing profile directory (issue8726046)

[tejohnson at google dot com (Teresa Johnson)]

Patch to add interface for querying the profile directory prefix
specified to the -fprofile-generate= option.

Google ref b/8629045.

Tested with regression tests and internal test. Ok for google branches?

2013-04-17  Teresa Johnson  <tejohnson@google.com>

	* libgcc/libgcov.c (__gcov_get_profile_prefix): New function.
	* gcc/tree-profile.c (tree_init_instrumentation): New function.
	* gcc/coverage.c (get_const_string_type): Make non-static.
	(coverage_init): Invoke tree_init_instrumentation().
	* gcc/coverage.h (get_const_string_type): Declare.
        (tree_init_instrumentation): Ditto.

Index: libgcc/libgcov.c
===================================================================
--- libgcc/libgcov.c	(revision 197640)
+++ libgcc/libgcov.c	(working copy)
@@ -183,6 +183,14 @@ unsigned int __gcov_sampling_enabled ()
   return __gcov_has_sampling;
 }
 
+/* Profile directory prefix specified to -fprofile-generate=.  */
+extern char * __gcov_profile_prefix;
+
+char *__gcov_get_profile_prefix ()
+{
+  return __gcov_profile_prefix;
+}
+
 /* Per thread sample counter.  */
 THREAD_PREFIX gcov_unsigned_t __gcov_sample_counter = 0;
 
Index: gcc/tree-profile.c
===================================================================
--- gcc/tree-profile.c	(revision 197640)
+++ gcc/tree-profile.c	(working copy)
@@ -165,6 +165,9 @@ static struct pointer_set_t *instrumentation_to_be
 /* extern __thread gcov_unsigned_t __gcov_sample_counter  */
 static GTY(()) tree gcov_sample_counter_decl = NULL_TREE;
 
+/* extern gcov_unsigned_t __gcov_profile_prefix  */
+static tree GTY(()) gcov_profile_prefix_decl = NULL_TREE;
+
 /* extern gcov_unsigned_t __gcov_sampling_period  */
 static tree GTY(()) gcov_sampling_period_decl = NULL_TREE;
 
@@ -407,6 +410,41 @@ cleanup_instrumentation_sampling (void)
     }
 }
 
+/* Initialization function for FDO instrumentation.  */
+
+void
+tree_init_instrumentation (void)
+{
+  if (!gcov_profile_prefix_decl)
+    {
+      tree prefix_ptr;
+      int prefix_len;
+      tree prefix_string;
+
+      /* Construct an initializer for __gcov_profile_prefix.  */
+      gcov_profile_prefix_decl =
+        build_decl (UNKNOWN_LOCATION, VAR_DECL,
+                    get_identifier ("__gcov_profile_prefix"),
+                    get_const_string_type ());
+      TREE_PUBLIC (gcov_profile_prefix_decl) = 1;
+      DECL_ARTIFICIAL (gcov_profile_prefix_decl) = 1;
+      make_decl_one_only (gcov_profile_prefix_decl,
+                          DECL_ASSEMBLER_NAME (gcov_profile_prefix_decl));
+      TREE_STATIC (gcov_profile_prefix_decl) = 1;
+
+      prefix_len = strlen (profile_data_prefix);
+      prefix_string = build_string (prefix_len + 1, profile_data_prefix);
+      TREE_TYPE (prefix_string) = build_array_type
+          (char_type_node, build_index_type
+           (build_int_cst (NULL_TREE, prefix_len)));
+      prefix_ptr = build1 (ADDR_EXPR, get_const_string_type (),
+                           prefix_string);
+
+      DECL_INITIAL (gcov_profile_prefix_decl) = prefix_ptr;
+      varpool_finalize_decl (gcov_profile_prefix_decl);
+    }
+}
+
 /* Initialization function for FDO sampling.  */
 
 void
Index: gcc/coverage.c
===================================================================
--- gcc/coverage.c	(revision 197640)
+++ gcc/coverage.c	(working copy)
@@ -227,7 +227,7 @@ get_gcov_unsigned_t (void)
 
 /* Return the type node for const char *.  */
 
-static tree
+tree
 get_const_string_type (void)
 {
   return build_pointer_type
@@ -2879,6 +2879,7 @@ coverage_init (const char *filename, const char* s
   /* Define variables which are referenced at runtime by libgcov.  */
   if (profiling_enabled_p ())
     {
+      tree_init_instrumentation ();
       tree_init_dyn_ipa_parameters ();
       init_pmu_profiling ();
       tree_init_instrumentation_sampling ();
Index: gcc/coverage.h
===================================================================
--- gcc/coverage.h	(revision 197640)
+++ gcc/coverage.h	(working copy)
@@ -82,6 +82,7 @@ extern bool pmu_data_present (void);
 
 extern tree get_gcov_type (void);
 extern tree get_gcov_unsigned_t (void);
+extern tree get_const_string_type (void);
 
 /* Mark this module as containing asm statements.  */
 extern void coverage_has_asm_stmt (void);
@@ -89,5 +90,6 @@ extern void coverage_has_asm_stmt (void);
 /* Defined in tree-profile.c.  */
 extern void tree_init_instrumentation_sampling (void);
 extern void tree_init_dyn_ipa_parameters (void);
+extern void tree_init_instrumentation (void);
 
 #endif

--
This patch is available for review at http://codereview.appspot.com/8726046