From: Xinliang David Li <davidxl@google.com>
Date: Tue, 27 Oct 2015 05:15:35 +0000 (+0000)
Subject: Create undef reference to profile hook symbol
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c365da6eea9b4d573a1379686776a8780e799307;p=clang

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 e8a2d833d3..d0f4dac3e1 100644
--- 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 01ff328779..fcb7561b1f 100644
--- 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;