[gcov/Darwin] Ensure external symbols are exported when using an export list

[vsk]

Summary

Make sure that symbols needed to implement runtime support for gcov are
exported when using an export list on Darwin.

Without the clang driver exporting these symbols, the linker hides them,
resulting in tapi verification failures.

rdar://45944768

[ributzka]

clang/lib/Driver/ToolChains/Darwin.cpp

1037

Are the symbols mutually exclusive?

[vsk]

clang/lib/Driver/ToolChains/Darwin.cpp

1037

Yes, since the runtime is a .a, the gcov-specific symbols aren't pulled in when clang-cov is enabled and vice versa.

[ributzka]

LGTM

clang/include/clang/Driver/ToolChain.h

public:
   std::string getArchSpecificLibPath() const;
 
   // Returns <OSname> part of above.
   StringRef getOSLibName() const;
 
   /// needsProfileRT - returns true if instrumentation profile is on.
   static bool needsProfileRT(const llvm::opt::ArgList &Args);
 
+  /// Returns true if gcov instrumentation (-fprofile-arcs or --coverage) is on.
+  static bool needsGCovInstrumentation(const llvm::opt::ArgList &Args);
+
   /// IsUnwindTablesDefault - Does this tool chain use -funwind-tables
   /// by default.
   virtual bool IsUnwindTablesDefault(const llvm::opt::ArgList &Args) const;
 
   /// Test whether this toolchain defaults to PIC.
   virtual bool isPICDefault() const = 0;
 
   /// Test whether this toolchain defaults to PIE.

clang/lib/Driver/ToolChain.cpp

 std::string ToolChain::getArchSpecificLibPath() const {
   SmallString<128> Path(getDriver().ResourceDir);
   llvm::sys::path::append(Path, "lib", getOSLibName(),
                           llvm::Triple::getArchTypeName(getArch()));
   return Path.str();
 }
 
 bool ToolChain::needsProfileRT(const ArgList &Args) {
-  if (Args.hasFlag(options::OPT_fprofile_arcs, options::OPT_fno_profile_arcs,
-                   false) ||
+  if (needsGCovInstrumentation(Args) ||
       Args.hasArg(options::OPT_fprofile_generate) ||
       Args.hasArg(options::OPT_fprofile_generate_EQ) ||
       Args.hasArg(options::OPT_fprofile_instr_generate) ||
       Args.hasArg(options::OPT_fprofile_instr_generate_EQ) ||
-      Args.hasArg(options::OPT_fcreate_profile) ||
-      Args.hasArg(options::OPT_coverage))
+      Args.hasArg(options::OPT_fcreate_profile))
     return true;
 
   return false;
 }
 
+bool ToolChain::needsGCovInstrumentation(const llvm::opt::ArgList &Args) {
+  return Args.hasFlag(options::OPT_fprofile_arcs, options::OPT_fno_profile_arcs,
+                      false) ||
+         Args.hasArg(options::OPT_coverage);
+}
+
 Tool *ToolChain::SelectTool(const JobAction &JA) const {
   if (getDriver().ShouldUseClangCompiler(JA)) return getClang();
   Action::ActionClass AC = JA.getKind();
   if (AC == Action::AssembleJobClass && useIntegratedAs())
     return getClangAs();
   return getTool(AC);
 }
 

clang/lib/Driver/ToolChains/Darwin.cpp

void Darwin::addProfileRTLibs(const ArgList &Args,
 
   AddLinkRuntimeLib(Args, CmdArgs, "profile",
                     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)) {
+    if (needsGCovInstrumentation(Args)) {
+      addExportedSymbol(CmdArgs, "___gcov_flush");
+      addExportedSymbol(CmdArgs, "_flush_fn_list");
+      addExportedSymbol(CmdArgs, "_writeout_fn_list");
+    } else {
       addExportedSymbol(CmdArgs, "___llvm_profile_filename");
       addExportedSymbol(CmdArgs, "___llvm_profile_raw_version");
       addExportedSymbol(CmdArgs, "_lprofCurFilename");
-    addExportedSymbol(CmdArgs, "_lprofDirMode");
       addExportedSymbol(CmdArgs, "_lprofMergeValueProfData");
     }
+    addExportedSymbol(CmdArgs, "_lprofDirMode");
+  }
 }
 
 void DarwinClang::AddLinkSanitizerLibArgs(const ArgList &Args,
                                           ArgStringList &CmdArgs,
                                           StringRef Sanitizer,
                                           bool Shared) const {
   auto RLO = RuntimeLinkOptions(RLO_AlwaysLink | (Shared ? RLO_AddRPath : 0U));
   AddLinkRuntimeLib(Args, CmdArgs, Sanitizer, RLO, Shared);

clang/test/Driver/darwin-ld.c

 // 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" "___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: %clang -target x86_64-apple-darwin12 -fprofile-instr-generate --coverage -### %t.o 2> %t.log
 // RUN: FileCheck -check-prefix=NO_PROFILE_EXPORT %s < %t.log
 // NO_PROFILE_EXPORT-NOT: "-exported_symbol"
 //
+// RUN: %clang -target x86_64-apple-darwin12 --coverage -exported_symbols_list /dev/null -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=GCOV_EXPORT %s < %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-arcs -Wl,-exported_symbols_list,/dev/null -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=GCOV_EXPORT %s < %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-arcs -Wl,-exported_symbol,foo -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=GCOV_EXPORT %s < %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-arcs -Xlinker -exported_symbol -Xlinker foo -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=GCOV_EXPORT %s < %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -fprofile-arcs -Xlinker -exported_symbols_list -Xlinker /dev/null -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=GCOV_EXPORT %s < %t.log
+// GCOV_EXPORT: "-exported_symbol" "___gcov_flush"
+//
 // Check that we can pass the outliner down to the linker.
 // RUN: env IPHONEOS_DEPLOYMENT_TARGET=7.0 \
 // RUN:   %clang -target arm64-apple-darwin -moutline -### %t.o 2> %t.log
 // MOUTLINE: ld
 // MOUTLINE-SAME: "-mllvm" "-enable-machine-outliner" "-mllvm" "-enable-linkonceodr-outlining"

compiler-rt/test/profile/instrprof-darwin-exports.c

 // REQUIRES: osx-ld64-live_support
 
 // Compiling with PGO/code coverage on Darwin should raise no warnings or errors
 // when using an exports list.
 
 // RUN: echo "_main" > %t.exports
 // RUN: %clang_pgogen -Werror -Wl,-exported_symbols_list,%t.exports -o %t %s 2>&1 | tee %t.log
 // RUN: %clang_profgen -Werror -fcoverage-mapping -Wl,-exported_symbols_list,%t.exports -o %t %s 2>&1 | tee -a %t.log
 // RUN: cat %t.log | count 0
 
+// RUN: %clang -Werror -Wl,-exported_symbols_list,%t.exports --coverage -o %t.gcov %s | tee -a %t.gcov.log
+// RUN: cat %t.gcov.log | count 0
+
 // The default set of weak external symbols should match the set of symbols
 // exported by clang. See Darwin::addProfileRTLibs.
 
 // RUN: %clang_pgogen -Werror -o %t.default %s
 // RUN: nm -jUg %t.default | grep -v __mh_execute_header > %t.default.exports
 // RUN: nm -jUg %t > %t.clang.exports
 // RUN: diff %t.default.exports %t.clang.exports
 
+// RUN: %clang -Werror --coverage -o %t.gcov.default %s
+// RUN: nm -jUg %t.gcov | grep -v __mh_execute_header > %t.gcov.exports
+// RUN: nm -jUg %t.gcov.default | grep -v __mh_execute_header > %t.gcov.default.exports
+// RUN: diff %t.gcov.default.exports %t.gcov.exports
+
 int main() {}