[Driver] Don't override '-march' when using '-arch x86_64h'

[thegameg]

Summary

On Darwin, using '-arch x86_64h' would always override the option passed through '-march'.

This patch allows users to use '-march' with x86_64h, while keeping the default to 'core-avx2'

[Gerolf]

+ Akira, Quentin for their driver / x86_64h experience for a quick double check. Fwiw, LGTM.

[arphaman]

LGTM

[qcolombet]

Should we emit an error if we request x86_64h with an arch older than haswell?

[thegameg]

In D55775#1338512, @qcolombet wrote:

Should we emit an error if we request x86_64h with an arch older than haswell?

Makes sense. I'll put up a patch soon.

Edit: Patch here: https://reviews.llvm.org/D56394

lib/Driver/ToolChains/Arch/X86.cpp

 using namespace clang::driver;
 using namespace clang::driver::tools;
 using namespace clang;
 using namespace llvm::opt;
 
 const char *x86::getX86TargetCPU(const ArgList &Args,
                                  const llvm::Triple &Triple) {
   if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_march_EQ)) {
-    if (StringRef(A->getValue()) != "native") {
-      if (Triple.isOSDarwin() && Triple.getArchName() == "x86_64h")
-        return "core-avx2";
-
+    if (StringRef(A->getValue()) != "native")
       return A->getValue();
-    }
 
     // FIXME: Reject attempts to use -march=native unless the target matches
     // the host.
     //
     // FIXME: We should also incorporate the detected target features for use
     // with -native.
     std::string CPU = llvm::sys::getHostCPUName();
     if (!CPU.empty() && CPU != "generic")

lib/Driver/ToolChains/Darwin.cpp

else if (Name == "pentium")
       DAL->AddJoinedArg(nullptr, MArch, "pentium");
     else if (Name == "pentium2")
       DAL->AddJoinedArg(nullptr, MArch, "pentium2");
     else if (Name == "pentpro")
       DAL->AddJoinedArg(nullptr, MArch, "pentiumpro");
     else if (Name == "pentIIm3")
       DAL->AddJoinedArg(nullptr, MArch, "pentium2");
 
-    else if (Name == "x86_64")
+    else if (Name == "x86_64" || Name == "x86_64h")
       DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_m64));
-    else if (Name == "x86_64h") {
-      DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_m64));
-      DAL->AddJoinedArg(nullptr, MArch, "x86_64h");
-    }
 
     else if (Name == "arm")
       DAL->AddJoinedArg(nullptr, MArch, "armv4t");
     else if (Name == "armv4t")
       DAL->AddJoinedArg(nullptr, MArch, "armv4t");
     else if (Name == "armv5")
       DAL->AddJoinedArg(nullptr, MArch, "armv5tej");
     else if (Name == "xscale")

test/Driver/clang-translation.c

 
 // RUN: %clang -target x86_64h-apple-darwin -### -S %s -o %t.s 2>&1 | \
 // RUN: FileCheck -check-prefix=AVX2 %s
 // RUN: %clang -target x86_64h-apple-macosx10.12 -### -S %s -o %t.s 2>&1 | \
 // RUN: FileCheck -check-prefix=AVX2 %s
 // AVX2: "-target-cpu"
 // AVX2: "core-avx2"
 
+// RUN: %clang -target x86_64h-apple-darwin -march=skx -### %s -o /dev/null 2>&1 | \
+// RUN: FileCheck -check-prefix=X8664HSKX %s
+// X8664HSKX: "-target-cpu"
+// X8664HSKX: "skx"
+
 // RUN: %clang -target i386-apple-macosx10.12 -### -S %s -o %t.s 2>&1 | \
 // RUN: FileCheck -check-prefix=PENRYN %s
 // RUN: %clang -target x86_64-apple-macosx10.12 -### -S %s -o %t.s 2>&1 | \
 // RUN: FileCheck -check-prefix=PENRYN %s
 // PENRYN: "-target-cpu"
 // PENRYN: "penryn"