Address review comment

Author: phoebewang

clang/lib/Driver/ToolChains/Clang.cpp

@@ -8269,23 +8269,22 @@ void Clang::AddClangCLArgs(const ArgList &Args, types::ID InputType,
   if (const Arg *A = Args.getLastArg(options::OPT__SLASH_vlen,
                                      options::OPT__SLASH_vlen_EQ_256,
                                      options::OPT__SLASH_vlen_EQ_512)) {
-    llvm::SmallSet<std::string, 4> Arch512 = {"AVX512F", "AVX512"};
-    llvm::SmallSet<std::string, 4> Arch256 = {"AVX", "AVX2"};
-
-    StringRef Arch = Args.getLastArgValue(options::OPT__SLASH_arch);
+    llvm::Triple::ArchType AT = getToolChain().getArch();
+    StringRef Default = AT == llvm::Triple::x86 ? "IA32" : "SSE2";
+    StringRef Arch = Args.getLastArgValue(options::OPT__SLASH_arch, Default);
 
     if (A->getOption().matches(options::OPT__SLASH_vlen_EQ_512)) {
-      if (Arch512.contains(Arch.str()))
+      if (Arch == "AVX512F" || Arch == "AVX512")
         CmdArgs.push_back("-mprefer-vector-width=512");
       else
         D.Diag(diag::warn_drv_argument_not_allowed_with)
             << "/vlen=512" << std::string("/arch:").append(Arch);
     }
 
     if (A->getOption().matches(options::OPT__SLASH_vlen_EQ_256)) {
-      if (Arch512.contains(Arch.str()))
+      if (Arch == "AVX512F" || Arch == "AVX512")
         CmdArgs.push_back("-mprefer-vector-width=256");
-      else if (!Arch256.contains(Arch.str()))
+      else if (Arch != "AVX" && Arch != "AVX2")
         D.Diag(diag::warn_drv_argument_not_allowed_with)
             << "/vlen=256" << std::string("/arch:").append(Arch);
     }

clang/test/Driver/cl-x86-flags.c

@@ -139,8 +139,8 @@
 // RUN: %clang_cl -m64 -arch:AVX512 -vlen=256 --target=x86_64-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=vlen256 %s
 // vlen256: "-mprefer-vector-width=256"
 
-// RUN: %clang_cl -m64 -arch:AVX512 -vlen=512 -vlen --target=x86_64-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=noprefer %s
-// noprefer-NOT: -mprefer-vector-width
+// RUN: %clang_cl -m64 -arch:AVX512 -vlen=512 -vlen --target=x86_64-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=novlen %s
+// novlen-NOT: -mprefer-vector-width
 
 // RUN: %clang_cl -m64 -arch:AVX2 -vlen=512 --target=x86_64-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=avx2vlen512 %s
 // avx2vlen512: invalid argument '/vlen=512' not allowed with '/arch:AVX2'
@@ -149,8 +149,12 @@
 // avx2vlen256-NOT: invalid argument
 
 // RUN: %clang_cl -m32 -arch:SSE2 -vlen=256 --target=i386-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=sse2vlen256 %s
+// RUN: %clang_cl -m64 -vlen=256 --target=x86_64-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=sse2vlen256 %s
 // sse2vlen256: invalid argument '/vlen=256' not allowed with '/arch:SSE2'
 
+// RUN: %clang_cl -m32 -vlen=256 --target=i386-pc-windows -### -- 2>&1 %s | FileCheck -check-prefix=ia32vlen256 %s
+// ia32vlen256: invalid argument '/vlen=256' not allowed with '/arch:IA32'
+
 void f(void) {
 }