[compiler-rt] Library load interceptor does not need to be called for RTLD_NOLOAD (PR #190102)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Andrew Haberlandt (ndrewh)

<details>
<summary>Changes</summary>

`dlopen` can be called with `RTLD_NOLOAD` flag which will not load any new modules (and thus return NULL if the module is not already loaded). We can skip a lot of work in the interceptor if the user code is just trying to check if a module ia already loaded.

rdar://173907074

---
Full diff: https://github.com/llvm/llvm-project/pull/190102.diff


1 Files Affected:

- (modified) compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc (+5-2) 


``````````diff
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
index b10ce7fa44afc..d68cac02e7eb6 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -33,6 +33,7 @@
 //   COMMON_INTERCEPTOR_STRERROR
 //===----------------------------------------------------------------------===//
 
+#include <dlfcn.h>
 #include <stdarg.h>
 
 #include "interception/interception.h"
@@ -6537,8 +6538,10 @@ INTERCEPTOR(void*, dlopen, const char *filename, int flag) {
   }
 
   void *res = COMMON_INTERCEPTOR_DLOPEN(filename, flag);
-  Symbolizer::GetOrInit()->InvalidateModuleList();
-  COMMON_INTERCEPTOR_LIBRARY_LOADED(filename, res);
+  if ((flag & RTLD_NOLOAD) == 0) {
+    Symbolizer::GetOrInit()->InvalidateModuleList();
+    COMMON_INTERCEPTOR_LIBRARY_LOADED(filename, res);
+  }
   return res;
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/190102