[scudo] Add default implementations for weak functions

Summary:
This is in preparation for platforms where `SANITIZER_SUPPORTS_WEAK_HOOKS` is 0.
They require a default implementation.

Reviewers: alekseyshl

Reviewed By: alekseyshl

Subscribers: delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D42557

llvm-svn: 323795

compiler-rt/lib/scudo/scudo_allocator.cpp

@@ -736,6 +736,18 @@ uptr __sanitizer_get_allocated_size(const void *Ptr) {
   return Instance.getUsableSize(Ptr);
 }
 
+#if !SANITIZER_SUPPORTS_WEAK_HOOKS
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_malloc_hook,
+                             void *Ptr, uptr Size) {
+  (void)Ptr;
+  (void)Size;
+}
+
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_free_hook, void *Ptr) {
+  (void)Ptr;
+}
+#endif
+
 // Interface functions
 
 void __scudo_set_rss_limit(uptr LimitMb, s32 HardLimit) {

compiler-rt/lib/scudo/scudo_flags.cpp

@@ -12,13 +12,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "scudo_flags.h"
+#include "scudo_interface_internal.h"
 #include "scudo_utils.h"
 
 #include "sanitizer_common/sanitizer_flags.h"
 #include "sanitizer_common/sanitizer_flag_parser.h"
 
-SANITIZER_INTERFACE_WEAK_DEF(const char*, __scudo_default_options, void);
-
 namespace __scudo {
 
 static Flags ScudoFlags;  // Use via getFlags().
@@ -119,3 +118,9 @@ Flags *getFlags() {
 }
 
 }  // namespace __scudo
+
+#if !SANITIZER_SUPPORTS_WEAK_HOOKS
+SANITIZER_INTERFACE_WEAK_DEF(const char*, __scudo_default_options, void) {
+  return "";
+}
+#endif

compiler-rt/lib/scudo/scudo_interface_internal.h

@@ -20,6 +20,9 @@ using __sanitizer::uptr;
 using __sanitizer::s32;
 
 extern "C" {
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
+const char* __scudo_default_options();
+
 SANITIZER_INTERFACE_ATTRIBUTE
 void __scudo_set_rss_limit(uptr LimitMb, s32 HardLimit);
 }  // extern "C"