[clang-cl] Add support for CL and _CL_ environment variables

cl uses 'CL' and '_CL_' to prepend and append command line options to
the given argument vector.  There is an additional quirk whereby '#' is
transformed into '='.

Differential Revision: http://reviews.llvm.org/D11896

llvm-svn: 244473

1 files changed, 32 insertions, 0 deletions

diff --git a/clang/tools/driver/driver.cpp b/clang/tools/driver/driver.cpp
index 40c5a6198a8..eeced7eab00 100644
--- a/clang/tools/driver/driver.cpp
+++ b/clang/tools/driver/driver.cpp
@@ -300,6 +300,15 @@ static void insertArgsFromProgramName(StringRef ProgName,
   }
 }
 
+static void getCLEnvVarOptions(std::string &EnvValue, llvm::StringSaver &Saver,
+                               SmallVectorImpl<const char *> &Opts) {
+  llvm::cl::TokenizeWindowsCommandLine(EnvValue, Saver, Opts);
+  // The first instance of '#' should be replaced with '=' in each option.
+  for (const char *Opt : Opts)
+    if (char *NumberSignPtr = const_cast<char *>(::strchr(Opt, '#')))
+      *NumberSignPtr = '=';
+}
+
 static void SetBackdoorDriverOutputsFromEnvVars(Driver &TheDriver) {
   // Handle CC_PRINT_OPTIONS and CC_PRINT_OPTIONS_FILE.
   TheDriver.CCPrintOptions = !!::getenv("CC_PRINT_OPTIONS");
@@ -445,6 +454,29 @@ int main(int argc_, const char **argv_) {
     }
   }
 
+  // Handle CL and _CL_ which permits additional command line options to be
+  // prepended or appended.
+  if (Tokenizer == &llvm::cl::TokenizeWindowsCommandLine) {
+    // Arguments in "CL" are prepended.
+    llvm::Optional<std::string> OptCL = llvm::sys::Process::GetEnv("CL");
+    if (OptCL.hasValue()) {
+      SmallVector<const char *, 8> PrependedOpts;
+      getCLEnvVarOptions(OptCL.getValue(), Saver, PrependedOpts);
+
+      // Insert right after the program name to prepend to the argument list.
+      argv.insert(argv.begin() + 1, PrependedOpts.begin(), PrependedOpts.end());
+    }
+    // Arguments in "_CL_" are appended.
+    llvm::Optional<std::string> Opt_CL_ = llvm::sys::Process::GetEnv("_CL_");
+    if (Opt_CL_.hasValue()) {
+      SmallVector<const char *, 8> AppendedOpts;
+      getCLEnvVarOptions(Opt_CL_.getValue(), Saver, AppendedOpts);
+
+      // Insert at the end of the argument list to append.
+      argv.append(AppendedOpts.begin(), AppendedOpts.end());
+    }
+  }
+
   std::set<std::string> SavedStrings;
   // Handle CCC_OVERRIDE_OPTIONS, used for editing a command line behind the
   // scenes.