[PATCH 7/7] Libsanitizer merge from upstream r285547.

[Maxim Ostapenko <m dot ostapenko at samsung dot com>]

This patch tries to implement odr indicators functionality at compiler 
side.
We emit new __odr_asan_XXX symbol for each instrumented global that 
indicates whether this global was already registered and the library 
checks this indicator symbol at runtime. For some globals (e.g. static 
or hidden) the odr indicator is not needed, thus we can skip the 
indicator for them and pass zero to runtime.
If this patch is undesirable at this stage, we can probably postpone it 
until GCC 8 though.

From 137f139972a89259b9d8521e13ecb76fd2cef433 Mon Sep 17 00:00:00 2001
From: Maxim Ostapenko <m.ostapenko@samsung.com>
Date: Fri, 28 Oct 2016 10:22:03 +0300
Subject: [PATCH 7/7] Add support for ASan odr_indicator.

config/

	* bootstrap-asan.mk: Replace LSAN_OPTIONS=detect_leaks=0 with
	ASAN_OPTIONS=detect_leaks=0:use_odr_indicator=1.

gcc/

	* asan.c (asan_global_struct): Refactor.
	(create_odr_indicator): New function.
	(asan_needs_odr_indicator_p): Likewise.
	(is_odr_indicator): Likewise.
	(asan_add_global): Introduce odr_indicator_ptr. Pass it into global's
	constructor.
	(asan_protect_global): Do not protect odr indicators.

gcc/testsuite/

	* c-c++-common/asan/no-redundant-odr-indicators-1.c: New test.
---
 config/ChangeLog                                   |  5 ++
 config/bootstrap-asan.mk                           |  2 +-
 gcc/ChangeLog                                      | 10 +++
 gcc/asan.c                                         | 76 +++++++++++++++++++---
 gcc/testsuite/ChangeLog                            |  4 ++
 .../asan/no-redundant-odr-indicators-1.c           | 17 +++++
 6 files changed, 105 insertions(+), 9 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/asan/no-redundant-odr-indicators-1.c

diff --git a/config/ChangeLog b/config/ChangeLog
index 3b0092b..0c75185 100644
--- a/config/ChangeLog
+++ b/config/ChangeLog
@@ -1,3 +1,8 @@
+2016-11-07  Maxim Ostapenko  <m.ostapenko@samsung.com>
+
+	* bootstrap-asan.mk: Replace LSAN_OPTIONS=detect_leaks=0 with
+	ASAN_OPTIONS=detect_leaks=0:use_odr_indicator=1.
+
 2016-06-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>
 
 	* elf.m4: Remove interix support.
diff --git a/config/bootstrap-asan.mk b/config/bootstrap-asan.mk
index 70baaf9..e73d4c2 100644
--- a/config/bootstrap-asan.mk
+++ b/config/bootstrap-asan.mk
@@ -1,7 +1,7 @@
 # This option enables -fsanitize=address for stage2 and stage3.
 
 # Suppress LeakSanitizer in bootstrap.
-export LSAN_OPTIONS="detect_leaks=0"
+export ASAN_OPTIONS=detect_leaks=0:use_odr_indicator=1
 
 STAGE2_CFLAGS += -fsanitize=address
 STAGE3_CFLAGS += -fsanitize=address
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1da0ef9..527cafa 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,15 @@
 2016-11-07  Maxim Ostapenko  <m.ostapenko@samsung.com>
 
+	* asan.c (asan_global_struct): Refactor.
+	(create_odr_indicator): New function.
+	(asan_needs_odr_indicator_p): Likewise.
+	(is_odr_indicator): Likewise.
+	(asan_add_global): Introduce odr_indicator_ptr. Pass it into global's
+	constructor.
+	(asan_protect_global): Do not protect odr indicators.
+
+2016-11-07  Maxim Ostapenko  <m.ostapenko@samsung.com>
+
 	* asan.h (asan_intercepted_p): Handle BUILT_IN_STRCSPN,
 	BUILT_IN_STRPBRK, BUILT_IN_STRSPN and BUILT_IN_STRSTR.
 
diff --git a/gcc/asan.c b/gcc/asan.c
index fdc84bd..b54110a 100644
--- a/gcc/asan.c
+++ b/gcc/asan.c
@@ -1329,6 +1329,16 @@ asan_needs_local_alias (tree decl)
   return DECL_WEAK (decl) || !targetm.binds_local_p (decl);
 }
 
+/* Return true if DECL, a global var, is an artificial ODR indicator symbol
+   therefore doesn't need protection.  */
+
+static bool
+is_odr_indicator (tree decl)
+{
+  const char *sym_name = IDENTIFIER_POINTER (DECL_NAME (decl));
+  return strstr(sym_name, "_.__odr_asan_") == sym_name;
+}
+
 /* Return true if DECL is a VAR_DECL that should be protected
    by Address Sanitizer, by appending a red zone with protected
    shadow memory after it and aligning it to at least
@@ -1377,7 +1387,8 @@ asan_protect_global (tree decl)
       || ASAN_RED_ZONE_SIZE * BITS_PER_UNIT > MAX_OFILE_ALIGNMENT
       || !valid_constant_size_p (DECL_SIZE_UNIT (decl))
       || DECL_ALIGN_UNIT (decl) > 2 * ASAN_RED_ZONE_SIZE
-      || TREE_TYPE (decl) == ubsan_get_source_location_type ())
+      || TREE_TYPE (decl) == ubsan_get_source_location_type ()
+      || is_odr_indicator (decl))
     return false;
 
   rtl = DECL_RTL (decl);
@@ -2197,14 +2208,15 @@ asan_dynamic_init_call (bool after_p)
 static tree
 asan_global_struct (void)
 {
-  static const char *field_names[8]
+  static const char *field_names[]
     = { "__beg", "__size", "__size_with_redzone",
-	"__name", "__module_name", "__has_dynamic_init", "__location", "__odr_indicator"};
-  tree fields[8], ret;
-  int i;
+	"__name", "__module_name", "__has_dynamic_init", "__location",
+	"__odr_indicator"};
+  tree fields[ARRAY_SIZE (field_names)], ret;
+  unsigned i;
 
   ret = make_node (RECORD_TYPE);
-  for (i = 0; i < 8; i++)
+  for (i = 0; i < ARRAY_SIZE (field_names); i++)
     {
       fields[i]
 	= build_decl (UNKNOWN_LOCATION, FIELD_DECL,
@@ -2226,6 +2238,52 @@ asan_global_struct (void)
   return ret;
 }
 
+/* Create and return odr indicator symbol for DECL.
+   TYPE is __asan_global struct type as returned by asan_global_struct.  */
+
+static tree
+create_odr_indicator (tree decl, tree type)
+{
+  char sym_name[100], tmp_name[100];
+  static int lasan_odr_ind_cnt = 0;
+  tree uptr = TREE_TYPE (DECL_CHAIN (TYPE_FIELDS (type)));
+
+  snprintf (tmp_name, sizeof (tmp_name), "__odr_asan_%s_",
+	    IDENTIFIER_POINTER (DECL_NAME (decl)));
+  ASM_GENERATE_INTERNAL_LABEL (sym_name, tmp_name, ++lasan_odr_ind_cnt);
+  char *asterisk = sym_name;
+  while ((asterisk = strchr (asterisk, '*')))
+    *asterisk = '_';
+  tree var = build_decl (UNKNOWN_LOCATION, VAR_DECL, get_identifier (sym_name),
+			 char_type_node);
+  TREE_ADDRESSABLE (var) = TREE_ADDRESSABLE (decl);
+  TREE_READONLY (var) = 0;
+  TREE_THIS_VOLATILE (var) = 1;
+  DECL_GIMPLE_REG_P (var) = DECL_GIMPLE_REG_P (decl);
+  DECL_ARTIFICIAL (var) = 1;
+  DECL_IGNORED_P (var) = DECL_IGNORED_P (decl);
+  TREE_STATIC (var) = 1;
+  TREE_PUBLIC (var) = 1;
+  DECL_VISIBILITY (var) = DECL_VISIBILITY (decl);
+  TREE_USED (var) = 1;
+  tree ctor = build_constructor_va (TREE_TYPE (var), 1, NULL_TREE,
+				    build_int_cst (unsigned_type_node, 0));
+  TREE_CONSTANT (ctor) = 1;
+  TREE_STATIC (ctor) = 1;
+  DECL_INITIAL (var) = ctor;
+  varpool_node::finalize_decl (var);
+  return fold_convert (uptr, build_fold_addr_expr (var));
+}
+
+/* Return true if DECL, a global var, might be overridden and needs
+   an additional odr indicator symbol.  */
+
+static bool
+asan_needs_odr_indicator_p (tree decl)
+{
+  return !DECL_ARTIFICIAL (decl) && !DECL_WEAK (decl) && TREE_PUBLIC (decl);
+}
+
 /* Append description of a single global DECL into vector V.
    TYPE is __asan_global struct type as returned by asan_global_struct.  */
 
@@ -2266,6 +2324,9 @@ asan_add_global (tree decl, tree type, vec<constructor_elt, va_gc> *v)
       assemble_alias (refdecl, DECL_ASSEMBLER_NAME (decl));
     }
 
+  tree odr_indicator_ptr = asan_needs_odr_indicator_p (decl)
+			     ? create_odr_indicator (decl, type)
+			     : build_int_cst (uptr, 0);
   CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE,
 			  fold_convert (const_ptr_type_node,
 					build_fold_addr_expr (refdecl)));
@@ -2313,8 +2374,7 @@ asan_add_global (tree decl, tree type, vec<constructor_elt, va_gc> *v)
   else
     locptr = build_int_cst (uptr, 0);
   CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE, locptr);
-  /* TODO: support ODR indicators.  */
-  CONSTRUCTOR_APPEND_ELT(vinner, NULL_TREE, build_int_cst (uptr, 0));
+  CONSTRUCTOR_APPEND_ELT(vinner, NULL_TREE, odr_indicator_ptr);
   init = build_constructor (type, vinner);
   CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, init);
 }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index afa77a8..7d11a7c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2016-11-07  Maxim Ostapenko  <m.ostapenko@samsung.com>
 
+	* c-c++-common/asan/no-redundant-odr-indicators-1.c: New test.
+
+2016-11-07  Maxim Ostapenko  <m.ostapenko@samsung.com>
+
 	* c-c++-common/asan/default_options.h: New file.
 	* c-c++-common/asan/strcasestr-1.c: New test.
 	* c-c++-common/asan/strcasestr-2.c: Likewise.
diff --git a/gcc/testsuite/c-c++-common/asan/no-redundant-odr-indicators-1.c b/gcc/testsuite/c-c++-common/asan/no-redundant-odr-indicators-1.c
new file mode 100644
index 0000000..ff1f272
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/no-redundant-odr-indicators-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-skip-if "" { *-*-* } { "*" } { "-O0" } } */
+
+/* Local variables should not have odr indicators.  */
+static int a = 2;
+/* Thread local variables should not have odr indicators.  */
+__thread int b = 3;
+/* Externally visible  variables should have odr indicators.  */
+int c = 1;
+
+int main () {
+    return 0;
+}
+
+/* { dg-final { scan-assembler-not ".*odr_asan_a.*" } } */
+/* { dg-final { scan-assembler-not ".*odr_asan_b.*" } } */
+/* { dg-final { scan-assembler ".*odr_asan_c.*" } } */
-- 
1.9.1