r251385 - Create undef reference to profile hook symbol

[Xinliang David Li via cfe-commits]

Author: davidxl
Date: Tue Oct 27 00:15:35 2015
New Revision: 251385

URL: http://llvm.org/viewvc/llvm-project?rev=251385&view=rev
Log:
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.

Modified:
    cfe/trunk/lib/Driver/ToolChains.cpp
    cfe/trunk/lib/Driver/ToolChains.h

Modified: cfe/trunk/lib/Driver/ToolChains.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains.cpp?rev=251385&r1=251384&r2=251385&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains.cpp (original)
+++ cfe/trunk/lib/Driver/ToolChains.cpp Tue Oct 27 00:15:35 2015
@@ -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::getSupportedSanitiz
   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,

Modified: cfe/trunk/lib/Driver/ToolChains.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains.h?rev=251385&r1=251384&r2=251385&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains.h (original)
+++ cfe/trunk/lib/Driver/ToolChains.h Tue Oct 27 00:15:35 2015
@@ -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;