clang-cl: Don't store the cl compiler Tool on the stack (PR20131)

The Command will refer back to the Tool as its source,
so it has to outlive the Command.

Having the Tool on the stack would cause us to crash
when using "clang-cl -GR -fallback", because if the
Command fails, Driver::ExecuteCompilation tries to
peek at the Command's source.

Differential Revision: http://reviews.llvm.org/D4314

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211802 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 18 insertions, 4 deletions

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 843177414d..28528ffbd0 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -4184,9 +4184,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (Args.hasArg(options::OPT__SLASH_fallback) &&
       Output.getType() == types::TY_Object &&
       (InputType == types::TY_C || InputType == types::TY_CXX)) {
-    tools::visualstudio::Compile CL(getToolChain());
-    Command *CLCommand = CL.GetCommand(C, JA, Output, Inputs, Args,
-                                       LinkingOutput);
+    Command *CLCommand = getCLFallback()->GetCommand(C, JA, Output, Inputs,
+                                                     Args, LinkingOutput);
     // RTTI support in clang-cl is a work in progress.  Fall back to MSVC early
     // if we are using 'clang-cl /fallback /GR'.
     // FIXME: Remove this when RTTI is finished.
@@ -4450,6 +4449,12 @@ void Clang::AddClangCLArgs(const ArgList &Args, ArgStringList &CmdArgs) const {
   }
 }
 
+visualstudio::Compile *Clang::getCLFallback() const {
+  if (!CLFallback)
+    CLFallback.reset(new visualstudio::Compile(getToolChain()));
+  return CLFallback.get();
+}
+
 void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,
                            const InputInfo &Output,
                            const InputInfoList &Inputs,
diff --git a/lib/Driver/Tools.h b/lib/Driver/Tools.h
index a25653ea70..c4e6d6c829 100644
--- a/lib/Driver/Tools.h
+++ b/lib/Driver/Tools.h
@@ -29,6 +29,11 @@ namespace toolchains {
 }
 
 namespace tools {
+
+namespace visualstudio {
+  class Compile;
+}
+
 using llvm::opt::ArgStringList;
 
   /// \brief Clang compiler tool.
@@ -78,6 +83,10 @@ using llvm::opt::ArgStringList;
     void AddClangCLArgs(const llvm::opt::ArgList &Args,
                         llvm::opt::ArgStringList &CmdArgs) const;
 
+    visualstudio::Compile *getCLFallback() const;
+
+    mutable std::unique_ptr<visualstudio::Compile> CLFallback;
+
   public:
     Clang(const ToolChain &TC) : Tool("clang", "clang frontend", TC) {}
 
@@ -563,7 +572,7 @@ namespace dragonfly {
   };
 } // end namespace dragonfly
 
-  /// Visual studio tools.
+/// Visual studio tools.
 namespace visualstudio {
   class LLVM_LIBRARY_VISIBILITY Link : public Tool {
   public: