[asan] add a new interface function __asan_describe_address, useful for running asan-ified binary under a debugger (e.g. gdb)

llvm-svn: 171217

compiler-rt/include/sanitizer/asan_interface.h

@@ -122,6 +122,10 @@ extern "C" {
   uptr __asan_region_is_poisoned(uptr beg, uptr size)
       SANITIZER_INTERFACE_ATTRIBUTE;
 
+  // Print the description of addr (useful when debugging in gdb).
+  void __asan_describe_address(uptr addr)
+      SANITIZER_INTERFACE_ATTRIBUTE;
+
   // This is an internal function that is called to report an error.
   // However it is still a part of the interface because users may want to
   // set a breakpoint on this function in a debugger.

compiler-rt/lib/asan/asan_report.cc

@@ -669,6 +669,10 @@ void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
   }
 }
 
+void __asan_describe_address(uptr addr) {
+  DescribeAddress(addr, 1);
+}
+
 #if !SANITIZER_SUPPORTS_WEAK_HOOKS
 // Provide default implementation of __asan_on_error that does nothing
 // and may be overriden by user.

compiler-rt/lib/asan/asan_rtl.cc

@@ -254,6 +254,7 @@ static NOINLINE void force_interface_symbols() {
     case 32: __asan_poison_stack_memory(0, 0); break;
     case 33: __asan_unpoison_stack_memory(0, 0); break;
     case 34: __asan_region_is_poisoned(0, 0); break;
+    case 35: __asan_describe_address(0); break;
   }
 }