Backed out changeset 870b38a3dc28 (bug 1602482) for as per dev's requ…

…est. a=backout

build/build-clang/clang-android.json

@@ -49,6 +49,7 @@
     "patches": [
       "static-llvm-symbolizer.patch",
       "find_symbolizer_linux.patch",
+      "rename_gcov_flush.patch",
       "rG7e18aeba5062.patch",
       "revert-r362047-and-r362065.patch"
     ]

build/build-clang/clang-linux64-aarch64-cross.json

@@ -14,6 +14,7 @@
     "patches": [
       "static-llvm-symbolizer.patch",
       "find_symbolizer_linux.patch",
+      "rename_gcov_flush.patch",
       "rG7e18aeba5062.patch",
       "android-mangling-error.patch"
     ]

build/build-clang/clang-linux64-cross.json

@@ -12,6 +12,7 @@
     "patches": [
       "static-llvm-symbolizer.patch",
       "find_symbolizer_linux.patch",
+      "rename_gcov_flush.patch",
       "android-mangling-error.patch",
       "revert-r359260-due-to-bug41817.patch",
       "r372020-r372182-profiler-linkage.patch",

build/build-clang/clang-linux64.json

@@ -13,6 +13,7 @@
     "patches": [
       "static-llvm-symbolizer.patch",
       "find_symbolizer_linux.patch",
+      "rename_gcov_flush.patch",
       "rG7e18aeba5062.patch",
       "android-mangling-error.patch"
     ]

build/build-clang/clang-macosx64.json

@@ -15,6 +15,7 @@
     "ld": "{MOZ_FETCHES_DIR}/clang/bin/clang",
     "patches": [
       "static-llvm-symbolizer.patch",
+      "rename_gcov_flush.patch",
       "rG7e18aeba5062.patch",
       "compiler-rt-cross-compile.patch",
       "compiler-rt-no-codesign.patch"

build/build-clang/rename_gcov_flush.patch

@@ -0,0 +1,40 @@
+Index: compiler-rt/lib/profile/GCDAProfiling.c
+===================================================================
+diff --git a/compiler-rt/lib/profile/GCDAProfiling.c b/compiler-rt/lib/profile/GCDAProfiling.c
+--- a/compiler-rt/lib/profile/GCDAProfiling.c
++++ b/compiler-rt/lib/profile/GCDAProfiling.c
+@@ -619,7 +619,7 @@
+   fn_list_insert(&flush_fn_list, fn);
+ }
+
+-void __gcov_flush() {
++void __custom_llvm_gcov_flush() {
+   struct fn_node* curr = flush_fn_list.head;
+
+   while (curr) {
+diff --git a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+index 9af64ed332c..bcebe303ff4 100644
+--- a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
++++ b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+@@ -647,7 +647,7 @@
+   for (auto I : ForkAndExecs) {
+     IRBuilder<> Builder(I);
+     FunctionType *FTy = FunctionType::get(Builder.getVoidTy(), {}, false);
+-    FunctionCallee GCOVFlush = M->getOrInsertFunction("__gcov_flush", FTy);
++    FunctionCallee GCOVFlush = M->getOrInsertFunction("__custom_llvm_gcov_flush", FTy);
+     Builder.CreateCall(GCOVFlush);
+     I->getParent()->splitBasicBlock(I);
+   }
+diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
+index e113f9a679..b3a07b18c0 100644
+--- a/clang/lib/Driver/ToolChains/Darwin.cpp
++++ b/clang/lib/Driver/ToolChains/Darwin.cpp
+@@ -1122,7 +1122,7 @@
+   // runtime's functionality.
+   if (hasExportSymbolDirective(Args)) {
+     if (needsGCovInstrumentation(Args)) {
+-      addExportedSymbol(CmdArgs, "___gcov_flush");
++      addExportedSymbol(CmdArgs, "___custom_llvm_gcov_flush");
+       addExportedSymbol(CmdArgs, "_flush_fn_list");
+       addExportedSymbol(CmdArgs, "_writeout_fn_list");
+     } else {

tools/code-coverage/CodeCoverageHandler.cpp

@@ -29,6 +29,14 @@ using namespace mozilla;
 // __gcov_flush is protected by a mutex in GCC, but not in LLVM, so we are using
 // a CrossProcessMutex to protect it.
 
+// We rename __gcov_flush to __custom_llvm_gcov_flush in our build of LLVM for
+// Linux, to avoid naming clashes in builds which mix GCC and LLVM. So, when we
+// are building with LLVM exclusively, we need to use __custom_llvm_gcov_flush
+// instead.
+#if !defined(XP_WIN) && defined(__clang__)
+#  define __gcov_flush __custom_llvm_gcov_flush
+#endif
+
 extern "C" void __gcov_flush();
 
 StaticAutoPtr<CodeCoverageHandler> CodeCoverageHandler::instance;