[UBSan] Introduce more flexible __ubsan_default_options function instead of UBSAN_DEFAULT_OPTIONS compile definition

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@218137 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 36 insertions, 21 deletions

diff --git a/lib/ubsan/ubsan_flags.cc b/lib/ubsan/ubsan_flags.cc
index 843f9a6c5..eda11f1b2 100644
--- a/lib/ubsan/ubsan_flags.cc
+++ b/lib/ubsan/ubsan_flags.cc
@@ -17,23 +17,16 @@
 
 namespace __ubsan {
 
-static const char *GetRuntimeFlagsFromCompileDefinition() {
-#ifdef UBSAN_DEFAULT_OPTIONS
-// Stringize the macro value
-# define UBSAN_STRINGIZE(x) #x
-# define UBSAN_STRINGIZE_OPTIONS(options) UBSAN_STRINGIZE(options)
-  return UBSAN_STRINGIZE_OPTIONS(UBSAN_DEFAULT_OPTIONS);
-#else
-  return "";
-#endif
+static const char *MaybeCallUbsanDefaultOptions() {
+  return (&__ubsan_default_options) ? __ubsan_default_options() : "";
 }
 
 void InitializeCommonFlags() {
   CommonFlags *cf = common_flags();
   SetCommonFlagsDefaults(cf);
   cf->print_summary = false;
-  // Override from compile definition.
-  ParseCommonFlagsFromString(cf, GetRuntimeFlagsFromCompileDefinition());
+  // Override from user-specified string.
+  ParseCommonFlagsFromString(cf, MaybeCallUbsanDefaultOptions());
   // Override from environment variable.
   ParseCommonFlagsFromString(cf, GetEnv("UBSAN_OPTIONS"));
 }
@@ -54,10 +47,17 @@ void InitializeFlags() {
   // Default values.
   f->halt_on_error = false;
   f->print_stacktrace = false;
-  // Override from compile definition.
-  ParseFlagsFromString(f, GetRuntimeFlagsFromCompileDefinition());
+  // Override from user-specified string.
+  ParseFlagsFromString(f, MaybeCallUbsanDefaultOptions());
   // Override from environment variable.
   ParseFlagsFromString(f, GetEnv("UBSAN_OPTIONS"));
 }
 
 }  // namespace __ubsan
+
+#if !SANITIZER_SUPPORTS_WEAK_HOOKS
+extern "C" {
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
+const char *__ubsan_default_options() { return ""; }
+}  // extern "C"
+#endif
diff --git a/lib/ubsan/ubsan_flags.h b/lib/ubsan/ubsan_flags.h
index 3b1a59e4e..c496469f5 100644
--- a/lib/ubsan/ubsan_flags.h
+++ b/lib/ubsan/ubsan_flags.h
@@ -13,6 +13,8 @@
 #ifndef UBSAN_FLAGS_H
 #define UBSAN_FLAGS_H
 
+#include "sanitizer_common/sanitizer_internal_defs.h"
+
 namespace __ubsan {
 
 struct Flags {
@@ -28,4 +30,11 @@ void InitializeFlags();
 
 }  // namespace __ubsan
 
+extern "C" {
+// Users may provide their own implementation of __ubsan_default_options to
+// override the default flag values.
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
+const char *__ubsan_default_options();
+}  // extern "C"
+
 #endif  // UBSAN_FLAGS_H
diff --git a/test/ubsan/TestCases/TypeCheck/vptr.cpp b/test/ubsan/TestCases/TypeCheck/vptr.cpp
index 45b7125f8..6d6838781 100644
--- a/test/ubsan/TestCases/TypeCheck/vptr.cpp
+++ b/test/ubsan/TestCases/TypeCheck/vptr.cpp
@@ -2,14 +2,14 @@
 // RUN: %run %t rT && %run %t mT && %run %t fT && %run %t cT
 // RUN: %run %t rU && %run %t mU && %run %t fU && %run %t cU
 // RUN: %run %t rS && %run %t rV && %run %t oV
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t mS 2>&1 | FileCheck %s --check-prefix=CHECK-MEMBER --strict-whitespace
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t fS 2>&1 | FileCheck %s --check-prefix=CHECK-MEMFUN --strict-whitespace
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t cS 2>&1 | FileCheck %s --check-prefix=CHECK-DOWNCAST --strict-whitespace
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t mV 2>&1 | FileCheck %s --check-prefix=CHECK-MEMBER --strict-whitespace
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t fV 2>&1 | FileCheck %s --check-prefix=CHECK-MEMFUN --strict-whitespace
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t cV 2>&1 | FileCheck %s --check-prefix=CHECK-DOWNCAST --strict-whitespace
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t oU 2>&1 | FileCheck %s --check-prefix=CHECK-OFFSET --strict-whitespace
-// RUN: UBSAN_OPTIONS=print_stacktrace=1 %run %t m0 2>&1 | FileCheck %s --check-prefix=CHECK-NULL-MEMBER --strict-whitespace
+// RUN: %run %t mS 2>&1 | FileCheck %s --check-prefix=CHECK-MEMBER --strict-whitespace
+// RUN: %run %t fS 2>&1 | FileCheck %s --check-prefix=CHECK-MEMFUN --strict-whitespace
+// RUN: %run %t cS 2>&1 | FileCheck %s --check-prefix=CHECK-DOWNCAST --strict-whitespace
+// RUN: %run %t mV 2>&1 | FileCheck %s --check-prefix=CHECK-MEMBER --strict-whitespace
+// RUN: %run %t fV 2>&1 | FileCheck %s --check-prefix=CHECK-MEMFUN --strict-whitespace
+// RUN: %run %t cV 2>&1 | FileCheck %s --check-prefix=CHECK-DOWNCAST --strict-whitespace
+// RUN: %run %t oU 2>&1 | FileCheck %s --check-prefix=CHECK-OFFSET --strict-whitespace
+// RUN: %run %t m0 2>&1 | FileCheck %s --check-prefix=CHECK-NULL-MEMBER --strict-whitespace
 
 // RUN: (echo "vptr_check:S"; echo "vptr_check:T"; echo "vptr_check:U") > %t.supp
 // RUN: ASAN_OPTIONS=suppressions=%t.supp:halt_on_error=1 UBSAN_OPTIONS=suppressions=%t.supp:halt_on_error=1 %run %t mS 2>&1
@@ -26,6 +26,12 @@
 // FIXME: This test produces linker errors on Darwin.
 // XFAIL: darwin
 
+extern "C" {
+const char *__ubsan_default_options() {
+  return "print_stacktrace=1";
+}
+}
+
 struct S {
   S() : a(0) {}
   ~S() {}