3 files changed, 30 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 15c8553249b..c3709bf2e44 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1744,6 +1744,11 @@ void CodeGenModule::ConstructDefaultFnAttrList(StringRef Name, bool HasOptnone,
       FuncAttrs.addAttribute("reciprocal-estimates",
                              llvm::join(Recips, ","));
 
+    if (!CodeGenOpts.PreferVectorWidth.empty() &&
+        CodeGenOpts.PreferVectorWidth != "none")
+      FuncAttrs.addAttribute("prefer-vector-width",
+                             CodeGenOpts.PreferVectorWidth);
+
     if (CodeGenOpts.StackRealignment)
       FuncAttrs.addAttribute("stackrealign");
     if (CodeGenOpts.Backchain)
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 2d6ac642f0f..706ac5bee29 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -274,6 +274,27 @@ static void ParseMRecip(const Driver &D, const ArgList &Args,
   OutStrings.push_back(Args.MakeArgString(Out));
 }
 
+/// The -mprefer-vector-width option accepts either a positive integer
+/// or the string "none".
+static void ParseMPreferVectorWidth(const Driver &D, const ArgList &Args,
+                                    ArgStringList &CmdArgs) {
+  Arg *A = Args.getLastArg(options::OPT_mprefer_vector_width_EQ);
+  if (!A)
+    return;
+
+  StringRef Value = A->getValue();
+  if (Value == "none") {
+    CmdArgs.push_back("-mprefer-vector-width=none");
+  } else {
+    unsigned Width;
+    if (Value.getAsInteger(10, Width)) {
+      D.Diag(diag::err_drv_invalid_value) << A->getOption().getName() << Value;
+      return;
+    }
+    CmdArgs.push_back(Args.MakeArgString("-mprefer-vector-width=" + Value));
+  }
+}
+
 static void getWebAssemblyTargetFeatures(const ArgList &Args,
                                          std::vector<StringRef> &Features) {
   handleTargetFeaturesGroup(Args, Features, options::OPT_m_wasm_Features_Group);
@@ -4333,6 +4354,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                    options::OPT_fno_slp_vectorize, EnableSLPVec))
     CmdArgs.push_back("-vectorize-slp");
 
+  ParseMPreferVectorWidth(D, Args, CmdArgs);
+
   if (Arg *A = Args.getLastArg(options::OPT_fshow_overloads_EQ))
     A->render(Args, CmdArgs);
 
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 2ebdc2a62aa..3aa615b490f 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -713,6 +713,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.VectorizeLoop = Args.hasArg(OPT_vectorize_loops);
   Opts.VectorizeSLP = Args.hasArg(OPT_vectorize_slp);
 
+  Opts.PreferVectorWidth = Args.getLastArgValue(OPT_mprefer_vector_width_EQ);
+
   Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
   Opts.VerifyModule = !Args.hasArg(OPT_disable_llvm_verifier);