[Driver] Export symbols needed to use profile runtime

Apple's API verification tool (tapi) checks that the symbols exported from a program match a whitelist. When the program uses the profile runtime, some additional symbols which are typically not part of the regular whitelist must be exported. If we're using symbol export directives along with the profile runtime on Darwin, the driver needs to export the additional symbols to avoid verification failures. rdar://problem/30067753 llvm-svn: 315518
llvm · Oct 11, 2017 · f538018 · f538018
1 parent 8c8e83a
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diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -986,6 +986,25 @@ StringRef Darwin::getOSLibraryNameSuffix() const {
   llvm_unreachable("Unsupported platform");
 }
 
+/// Check if the link command contains a symbol export directive.
+static bool hasExportSymbolDirective(const ArgList &Args) {
+  for (Arg *A : Args) {
+    if (!A->getOption().matches(options::OPT_Wl_COMMA) &&
+        !A->getOption().matches(options::OPT_Xlinker))
+      continue;
+    if (A->containsValue("-exported_symbols_list") ||
+        A->containsValue("-exported_symbol"))
+      return true;
+  }
+  return false;
+}
+
+/// Add an export directive for \p Symbol to the link command.
+static void addExportedSymbol(ArgStringList &CmdArgs, const char *Symbol) {
+  CmdArgs.push_back("-exported_symbol");
+  CmdArgs.push_back(Symbol);
+}
+
 void Darwin::addProfileRTLibs(const ArgList &Args,
                               ArgStringList &CmdArgs) const {
   if (!needsProfileRT(Args)) return;
@@ -994,6 +1013,16 @@ void Darwin::addProfileRTLibs(const ArgList &Args,
       Args, CmdArgs,
       (Twine("libclang_rt.profile_") + getOSLibraryNameSuffix() + ".a").str(),
       RuntimeLinkOptions(RLO_AlwaysLink | RLO_FirstLink));
+
+  // If we have a symbol export directive and we're linking in the profile
+  // runtime, automatically export symbols necessary to implement some of the
+  // runtime's functionality.
+  if (hasExportSymbolDirective(Args)) {
+    addExportedSymbol(CmdArgs, "_VPMergeHook");
+    addExportedSymbol(CmdArgs, "___llvm_profile_filename");
+    addExportedSymbol(CmdArgs, "___llvm_profile_raw_version");
+    addExportedSymbol(CmdArgs, "_lprofCurFilename");
+  }
 }
 
 void DarwinClang::AddLinkSanitizerLibArgs(const ArgList &Args,

diff --git a/clang/test/Driver/darwin-ld.c b/clang/test/Driver/darwin-ld.c
@@ -351,3 +351,17 @@
 // RUN: %clang -target arm64-apple-ios5.0 -miphoneos-version-min=5.0 -fprofile-instr-generate -### %t.o 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_PROFILE_FIRST %s < %t.log
 // LINK_PROFILE_FIRST: {{ld(.exe)?"}} "{{[^"]+}}libclang_rt.profile_{{[a-z]+}}.a"
+
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-instr-generate -Wl,-exported_symbols_list,/dev/null -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=PROFILE_EXPORT %s < %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-instr-generate -Wl,-exported_symbol,foo -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=PROFILE_EXPORT %s < %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-instr-generate -Xlinker -exported_symbol -Xlinker foo -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=PROFILE_EXPORT %s < %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-instr-generate -Xlinker -exported_symbols_list -Xlinker /dev/null -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=PROFILE_EXPORT %s < %t.log
+// PROFILE_EXPORT: "-exported_symbol" "_VPMergeHook" "-exported_symbol" "___llvm_profile_filename" "-exported_symbol" "___llvm_profile_raw_version" "-exported_symbol" "_lprofCurFilename"
+//
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-instr-generate -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=NO_PROFILE_EXPORT %s < %t.log
+// NO_PROFILE_EXPORT-NOT: "-exported_symbol"