Hide some symbols to avoid a crash on shutdown when using code coverage

Summary:
gcov / gcda-based profiling crashes when shared libraries are unloaded

Patch by Benoit Belley and test by Marco Castelluccio for Firefox

See https://bugs.llvm.org/show_bug.cgi?id=27224 & https://bugzilla.mozilla.org/show_bug.cgi?id=1401230

Reviewers: davidxl, rnk, void

Subscribers: jessicah, marco-c, belleyb, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D38124

llvm-svn: 321703

compiler-rt/lib/profile/GCDAProfiling.c

@@ -228,6 +228,7 @@ static void unmap_file() {
  * profiling enabled will emit to a different file. Only one file may be
  * started at a time.
  */
+COMPILER_RT_VISIBILITY
 void llvm_gcda_start_file(const char *orig_filename, const char version[4],
                           uint32_t checksum) {
   const char *mode = "r+b";
@@ -295,6 +296,7 @@ void llvm_gcda_start_file(const char *orig_filename, const char version[4],
 /* Given an array of pointers to counters (counters), increment the n-th one,
  * where we're also given a pointer to n (predecessor).
  */
+COMPILER_RT_VISIBILITY
 void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
                                           uint64_t **counters) {
   uint64_t *counter;
@@ -317,6 +319,7 @@ void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
 #endif
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
                              uint32_t func_checksum, uint8_t use_extra_checksum,
                              uint32_t cfg_checksum) {
@@ -343,6 +346,7 @@ void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
     write_string(function_name);
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
   uint32_t i;
   uint64_t *old_ctrs = NULL;
@@ -394,6 +398,7 @@ void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
 #endif
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_gcda_summary_info() {
   const uint32_t obj_summary_len = 9; /* Length for gcov compatibility. */
   uint32_t i;
@@ -447,6 +452,7 @@ void llvm_gcda_summary_info() {
 #endif
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_gcda_end_file() {
   /* Write out EOF record. */
   if (output_file) {
@@ -472,6 +478,7 @@ void llvm_gcda_end_file() {
 #endif
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_register_writeout_function(writeout_fn fn) {
   struct writeout_fn_node *new_node = malloc(sizeof(struct writeout_fn_node));
   new_node->fn = fn;
@@ -485,6 +492,7 @@ void llvm_register_writeout_function(writeout_fn fn) {
   }
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_writeout_files(void) {
   struct writeout_fn_node *curr = writeout_fn_head;
 
@@ -494,6 +502,7 @@ void llvm_writeout_files(void) {
   }
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_delete_writeout_function_list(void) {
   while (writeout_fn_head) {
     struct writeout_fn_node *node = writeout_fn_head;
@@ -504,6 +513,7 @@ void llvm_delete_writeout_function_list(void) {
   writeout_fn_head = writeout_fn_tail = NULL;
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_register_flush_function(flush_fn fn) {
   struct flush_fn_node *new_node = malloc(sizeof(struct flush_fn_node));
   new_node->fn = fn;
@@ -517,6 +527,7 @@ void llvm_register_flush_function(flush_fn fn) {
   }
 }
 
+COMPILER_RT_VISIBILITY
 void __gcov_flush() {
   struct flush_fn_node *curr = flush_fn_head;
 
@@ -526,6 +537,7 @@ void __gcov_flush() {
   }
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_delete_flush_function_list(void) {
   while (flush_fn_head) {
     struct flush_fn_node *node = flush_fn_head;
@@ -536,6 +548,7 @@ void llvm_delete_flush_function_list(void) {
   flush_fn_head = flush_fn_tail = NULL;
 }
 
+COMPILER_RT_VISIBILITY
 void llvm_gcov_init(writeout_fn wfn, flush_fn ffn) {
   static int atexit_ran = 0;
 

compiler-rt/test/profile/Inputs/instrprof-dlopen-dlclose-main.c

@@ -0,0 +1,26 @@
+#include <dlfcn.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[]) {
+  dlerror();
+  void *f1_handle = dlopen("func.shared", RTLD_LAZY | RTLD_GLOBAL);
+  if (f1_handle == NULL) {
+    fprintf(stderr, "unable to open 'func.shared': %s\n", dlerror());
+    return EXIT_FAILURE;
+  }
+
+  void *f2_handle = dlopen("func2.shared", RTLD_LAZY | RTLD_GLOBAL);
+  if (f2_handle == NULL) {
+    fprintf(stderr, "unable to open 'func2.shared': %s\n", dlerror());
+    return EXIT_FAILURE;
+  }
+
+  if (dlclose(f2_handle) != 0) {
+    fprintf(stderr, "unable to close 'func2.shared': %s\n", dlerror());
+    return EXIT_FAILURE;
+  }
+
+  return EXIT_SUCCESS;
+}
+

compiler-rt/test/profile/instrprof-dlopen-dlclose-gcov.test

@@ -0,0 +1,6 @@
+RUN: mkdir -p %t.d
+RUN: %clang --coverage -o %t.d/func.shared -fPIC -shared %S/Inputs/instrprof-dlopen-func.c
+RUN: %clang --coverage -o %t.d/func2.shared -fPIC -shared %S/Inputs/instrprof-dlopen-func2.c
+RUN: %clang --coverage -o %t -fPIC -rpath %t.d %S/Inputs/instrprof-dlopen-dlclose-main.c
+
+RUN: %run %t