[PATCH] D45454: Add llvm_gcov_flush to be called outside a shared library

[Chih-Hung Hsieh via Phabricator via cfe-commits]

chh updated this revision to Diff 153532.
chh retitled this revision from "Make __gcov_flush visible outside a shared library" to "Add llvm_gcov_flush to be called outside a shared library".
chh edited the summary of this revision.
chh added a comment.

Now keep __gcov_flush hidden as libgcov; add llvm_gcov_flush to call from outside of .so files.


https://reviews.llvm.org/D45454

Files:
  lib/profile/GCDAProfiling.c
  test/profile/Inputs/instrprof-dlopen-dlclose-main.c


Index: test/profile/Inputs/instrprof-dlopen-dlclose-main.c
===================================================================
--- test/profile/Inputs/instrprof-dlopen-dlclose-main.c
+++ test/profile/Inputs/instrprof-dlopen-dlclose-main.c
@@ -16,6 +16,31 @@
     return EXIT_FAILURE;
   }
 
+  void (*gcov_flush)() = (void (*)())dlsym(f1_handle, "__gcov_flush");
+  if (gcov_flush != NULL) {
+    fprintf(stderr, "__gcov_flush should not be visible in func.shared'\n");
+    return EXIT_FAILURE;
+  }
+
+  void (*f1_flush)() = (void (*)())dlsym(f1_handle, "llvm_gcov_flush");
+  if (f1_flush == NULL) {
+    fprintf(stderr, "unable to find llvm_gcov_flush in func.shared'\n");
+    return EXIT_FAILURE;
+  }
+  f1_flush();
+
+  void (*f2_flush)() = (void (*)())dlsym(f2_handle, "llvm_gcov_flush");
+  if (f2_flush == NULL) {
+    fprintf(stderr, "unable to find llvm_gcov_flush in func2.shared'\n");
+    return EXIT_FAILURE;
+  }
+  f2_flush();
+
+  if (f1_flush == f2_flush) {
+    fprintf(stderr, "Same llvm_gcov_flush found in func.shared and func2.shared\n");
+    return EXIT_FAILURE;
+  }
+
   if (dlclose(f2_handle) != 0) {
     fprintf(stderr, "unable to close 'func2.shared': %s\n", dlerror());
     return EXIT_FAILURE;
Index: lib/profile/GCDAProfiling.c
===================================================================
--- lib/profile/GCDAProfiling.c
+++ lib/profile/GCDAProfiling.c
@@ -527,6 +527,10 @@
   }
 }
 
+// __gcov_flush is hidden. When called in a .so file,
+// it dumps profile data of the calling .so file.
+// If a main program needs to dump profile data of each linked
+// .so files, it should use dlsym to find and call llvm_gcov_flush.
 COMPILER_RT_VISIBILITY
 void __gcov_flush() {
   struct flush_fn_node *curr = flush_fn_head;
@@ -537,6 +541,14 @@
   }
 }
 
+// llvm_gcov_flush is not hidden for a program to use dlsym to
+// find and call. In that case, it dumps profile data of a .so file.
+// If it is called directly inside a .so file, the unified copy of
+// llvm_gcov_flush might dump data of other .so file or the main module.
+void llvm_gcov_flush() {
+  __gcov_flush();
+}
+
 COMPILER_RT_VISIBILITY
 void llvm_delete_flush_function_list(void) {
   while (flush_fn_head) {


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