From a8bd6008ee99a5b9a53d510a6523fe0a3109a0c6 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@gmail.com>
Date: Tue, 31 Mar 2015 05:45:00 +0000
Subject: [PATCH] [X86] Use getHostCPUFeatures when 'native' is specified for
 cpu.

This is necessary because not aall Sandybridge, Ivybrige, Haswell, and Broadwell CPUs support AVX. Currently we modify the CPU name back to Nehalem for this case, but that turns off additional features for these CPUs.

llvm-svn: 233672
---
 clang/lib/Driver/Tools.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 0ec9e5067a57..daaea63c7162 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -1566,6 +1566,17 @@ static void AddGoldPlugin(const ToolChain &ToolChain, const ArgList &Args,
 static void getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
                                  const ArgList &Args,
                                  std::vector<const char *> &Features) {
+  // If -march=native, autodetect the feature list.
+  if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
+    if (StringRef(A->getValue()) == "native") {
+      llvm::StringMap<bool> HostFeatures;
+      if (llvm::sys::getHostCPUFeatures(HostFeatures))
+        for (auto &F : HostFeatures)
+          Features.push_back(Args.MakeArgString((F.second ? "+" : "-") +
+                                                F.first()));
+    }
+  }
+
   if (Triple.getArchName() == "x86_64h") {
     // x86_64h implies quite a few of the more modern subtarget features
     // for Haswell class CPUs, but not all of them. Opt-out of a few.