From f5380185623be243ba0f1b18d4bd594ac5cc7163 Mon Sep 17 00:00:00 2001
From: Vedant Kumar <vsk@apple.com>
Date: Wed, 11 Oct 2017 21:54:09 +0000
Subject: [PATCH] [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
---
 clang/lib/Driver/ToolChains/Darwin.cpp | 29 ++++++++++++++++++++++++++
 clang/test/Driver/darwin-ld.c          | 14 +++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 78d7bf4b3dc71..39c4525f84d45 100644
--- 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
index 4358d38af6dcf..3ddba02a43e88 100644
--- 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"