3 files changed, 120 insertions, 4 deletions

diff --git a/clang/lib/Driver/MSVCToolChain.cpp b/clang/lib/Driver/MSVCToolChain.cpp
index c816b29dca2..b890375742e 100644
--- a/clang/lib/Driver/MSVCToolChain.cpp
+++ b/clang/lib/Driver/MSVCToolChain.cpp
@@ -528,3 +528,101 @@ SanitizerMask MSVCToolChain::getSupportedSanitizers() const {
   Res |= SanitizerKind::Address;
   return Res;
 }
+
+llvm::opt::DerivedArgList *
+MSVCToolChain::TranslateArgs(const llvm::opt::DerivedArgList &Args,
+                             const char *BoundArch) const {
+  DerivedArgList *DAL = new DerivedArgList(Args.getBaseArgs());
+  const OptTable &Opts = getDriver().getOpts();
+
+  // The -O[12xd] flag actually expands to several flags.  We must desugar the
+  // flags so that options embedded can be negated.  For example, the '-O2' flag
+  // enables '-Oy'.  Expanding '-O2' into its constituent flags allows us to
+  // correctly handle '-O2 -Oy-' where the trailing '-Oy-' disables a single
+  // aspect of '-O2'.
+  //
+  // Note that this expansion logic only applies to the *last* of '[12xd]'.
+
+  // First step is to search for the character we'd like to expand.
+  const char *ExpandChar = nullptr;
+  for (Arg *A : Args) {
+    if (!A->getOption().matches(options::OPT__SLASH_O))
+      continue;
+    StringRef OptStr = A->getValue();
+    for (size_t I = 0, E = OptStr.size(); I != E; ++I) {
+      const char &OptChar = *(OptStr.data() + I);
+      if (OptChar == '1' || OptChar == '2' || OptChar == 'x' || OptChar == 'd')
+        ExpandChar = OptStr.data() + I;
+    }
+  }
+
+  // The -O flag actually takes an amalgam of other options.  For example,
+  // '/Ogyb2' is equivalent to '/Og' '/Oy' '/Ob2'.
+  for (Arg *A : Args) {
+    if (!A->getOption().matches(options::OPT__SLASH_O)) {
+      DAL->append(A);
+      continue;
+    }
+
+    StringRef OptStr = A->getValue();
+    for (size_t I = 0, E = OptStr.size(); I != E; ++I) {
+      const char &OptChar = *(OptStr.data() + I);
+      switch (OptChar) {
+      default:
+        break;
+      case '1':
+      case '2':
+      case 'x':
+      case 'd':
+        if (&OptChar == ExpandChar) {
+          if (OptChar == 'd') {
+            DAL->AddFlagArg(A, Opts.getOption(options::OPT_O0));
+          } else {
+            if (OptChar == '1') {
+              DAL->AddJoinedArg(A, Opts.getOption(options::OPT_O), "s");
+            } else if (OptChar == '2' || OptChar == 'x') {
+              DAL->AddFlagArg(A, Opts.getOption(options::OPT_fbuiltin));
+              DAL->AddJoinedArg(A, Opts.getOption(options::OPT_O), "2");
+            }
+            DAL->AddFlagArg(A,
+                            Opts.getOption(options::OPT_fomit_frame_pointer));
+            if (OptChar == '1' || OptChar == '2')
+              DAL->AddFlagArg(A,
+                              Opts.getOption(options::OPT_ffunction_sections));
+          }
+        }
+        break;
+      case 'b':
+        if (isdigit(OptStr[I + 1]))
+          ++I;
+        break;
+      case 'g':
+        break;
+      case 'i':
+        if (OptStr[I + 1] == '-') {
+          ++I;
+          DAL->AddFlagArg(A, Opts.getOption(options::OPT_fno_builtin));
+        } else {
+          DAL->AddFlagArg(A, Opts.getOption(options::OPT_fbuiltin));
+        }
+        break;
+      case 's':
+        DAL->AddJoinedArg(A, Opts.getOption(options::OPT_O), "s");
+        break;
+      case 't':
+        DAL->AddJoinedArg(A, Opts.getOption(options::OPT_O), "2");
+        break;
+      case 'y':
+        if (OptStr[I + 1] == '-') {
+          ++I;
+          DAL->AddFlagArg(A,
+                          Opts.getOption(options::OPT_fno_omit_frame_pointer));
+        } else {
+          DAL->AddFlagArg(A, Opts.getOption(options::OPT_fomit_frame_pointer));
+        }
+        break;
+      }
+    }
+  }
+  return DAL;
+}
diff --git a/clang/lib/Driver/ToolChains.h b/clang/lib/Driver/ToolChains.h
index 8e6267428c5..27944c8b4a6 100644
--- a/clang/lib/Driver/ToolChains.h
+++ b/clang/lib/Driver/ToolChains.h
@@ -811,6 +811,10 @@ public:
   MSVCToolChain(const Driver &D, const llvm::Triple &Triple,
                 const llvm::opt::ArgList &Args);
 
+  llvm::opt::DerivedArgList *
+  TranslateArgs(const llvm::opt::DerivedArgList &Args,
+                const char *BoundArch) const override;
+
   bool IsIntegratedAssemblerDefault() const override;
   bool IsUnwindTablesDefault() const override;
   bool isPICDefault() const override;
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 96cf7fce465..0377bc561b4 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -8828,17 +8828,31 @@ std::unique_ptr<Command> visualstudio::Compiler::GetCommand(
   Args.AddAllArgs(CmdArgs, options::OPT_I);
 
   // Optimization level.
+  if (Arg *A = Args.getLastArg(options::OPT_fbuiltin, options::OPT_fno_builtin))
+    CmdArgs.push_back(A->getOption().getID() == options::OPT_fbuiltin ? "/Oi"
+                                                                      : "/Oi-");
   if (Arg *A = Args.getLastArg(options::OPT_O, options::OPT_O0)) {
     if (A->getOption().getID() == options::OPT_O0) {
       CmdArgs.push_back("/Od");
     } else {
+      CmdArgs.push_back("/Og");
+
       StringRef OptLevel = A->getValue();
-      if (OptLevel == "1" || OptLevel == "2" || OptLevel == "s")
-        A->render(Args, CmdArgs);
-      else if (OptLevel == "3")
-        CmdArgs.push_back("/Ox");
+      if (OptLevel == "s" || OptLevel == "z")
+        CmdArgs.push_back("/Os");
+      else
+        CmdArgs.push_back("/Ot");
+
+      CmdArgs.push_back("/Ob2");
     }
   }
+  if (Arg *A = Args.getLastArg(options::OPT_fomit_frame_pointer,
+                               options::OPT_fno_omit_frame_pointer))
+    CmdArgs.push_back(A->getOption().getID() == options::OPT_fomit_frame_pointer
+                          ? "/Oy"
+                          : "/Oy-");
+  if (!Args.hasArg(options::OPT_fwritable_strings))
+    CmdArgs.push_back("/GF");
 
   // Flags for which clang-cl has an alias.
   // FIXME: How can we ensure this stays in sync with relevant clang-cl options?