Create undef reference to profile hook symbol

Create undef reference to profile hook symbol when
PGO instrumentation is turned on. This allows
LLVM to omit emission of hook variable use method
for every single module instrumented.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@251385 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index e8a2d833d3cb1568568992325c0b7cee024e9ce1..d0f4dac3e13d425d0c0e8c0ba50b6c9302b1441d 100644 (file)
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/OptTable.h"
 #include "llvm/Option/Option.h"
+#include "llvm/ProfileData/InstrProf.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -3811,6 +3812,18 @@ SanitizerMask Linux::getSupportedSanitizers() const {
   return Res;
 }
 
+void Linux::addProfileRTLibs(const llvm::opt::ArgList &Args,
+                             llvm::opt::ArgStringList &CmdArgs) const {
+  if (!needsProfileRT(Args)) return;
+
+  // Add linker option -u__llvm_runtime_variable to cause runtime
+  // initialization module to be linked in.
+  if (!Args.hasArg(options::OPT_coverage))
+    CmdArgs.push_back(Args.MakeArgString(
+        Twine("-u", llvm::getInstrProfRuntimeHookVarName())));
+  ToolChain::addProfileRTLibs(Args, CmdArgs);
+}
+
 /// DragonFly - DragonFly tool chain which can call as(1) and ld(1) directly.
 
 DragonFly::DragonFly(const Driver &D, const llvm::Triple &Triple,

diff --git a/lib/Driver/ToolChains.h b/lib/Driver/ToolChains.h
index 01ff32877983467d076b6af8389d934915d75c7e..fcb7561b1ff9f1841623ee34a90c0fb4e4297f6d 100644 (file)
--- a/lib/Driver/ToolChains.h
+++ b/lib/Driver/ToolChains.h
@@ -744,6 +744,8 @@ public:
       llvm::opt::ArgStringList &CC1Args) const override;
   bool isPIEDefault() const override;
   SanitizerMask getSupportedSanitizers() const override;
+  void addProfileRTLibs(const llvm::opt::ArgList &Args,
+                        llvm::opt::ArgStringList &CmdArgs) const override;
 
   std::string Linker;
   std::vector<std::string> ExtraOpts;