[llvm] r233673 - Make llc use getHostCPUFeatures when 'native' is specified for cpu.

[Craig Topper]

Author: ctopper
Date: Tue Mar 31 00:52:57 2015
New Revision: 233673

URL: http://llvm.org/viewvc/llvm-project?rev=233673&view=rev
Log:
Make llc use getHostCPUFeatures when 'native' is specified for cpu.

This is necessary for x86 where not all 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.

Modified:
    llvm/trunk/include/llvm/MC/SubtargetFeature.h
    llvm/trunk/lib/MC/SubtargetFeature.cpp
    llvm/trunk/tools/llc/llc.cpp

Modified: llvm/trunk/include/llvm/MC/SubtargetFeature.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/SubtargetFeature.h?rev=233673&r1=233672&r2=233673&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/SubtargetFeature.h (original)
+++ llvm/trunk/include/llvm/MC/SubtargetFeature.h Tue Mar 31 00:52:57 2015
@@ -78,7 +78,7 @@ public:
   std::string getString() const;
 
   /// Adding Features.
-  void AddFeature(StringRef String);
+  void AddFeature(StringRef String, bool Enable = true);
 
   /// ToggleFeature - Toggle a feature and returns the newly updated feature
   /// bits.

Modified: llvm/trunk/lib/MC/SubtargetFeature.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/SubtargetFeature.cpp?rev=233673&r1=233672&r2=233673&view=diff
==============================================================================
--- llvm/trunk/lib/MC/SubtargetFeature.cpp (original)
+++ llvm/trunk/lib/MC/SubtargetFeature.cpp Tue Mar 31 00:52:57 2015
@@ -81,11 +81,12 @@ static std::string Join(const std::vecto
 }
 
 /// Adding features.
-void SubtargetFeatures::AddFeature(StringRef String) {
+void SubtargetFeatures::AddFeature(StringRef String, bool Enable) {
   // Don't add empty features.
   if (!String.empty())
     // Convert to lowercase, prepend flag if we don't already have a flag.
-    Features.push_back(hasFlag(String) ? String.lower() : "+" + String.lower());
+    Features.push_back(hasFlag(String) ? String.lower()
+                                       : (Enable ? "+" : "-") + String.lower());
 }
 
 /// Find KV in array using binary search.

Modified: llvm/trunk/tools/llc/llc.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llc/llc.cpp?rev=233673&r1=233672&r2=233673&view=diff
==============================================================================
--- llvm/trunk/tools/llc/llc.cpp (original)
+++ llvm/trunk/tools/llc/llc.cpp Tue Mar 31 00:52:57 2015
@@ -212,12 +212,6 @@ static int compileModule(char **argv, LL
   bool SkipModule = MCPU == "help" ||
                     (!MAttrs.empty() && MAttrs.front() == "help");
 
-  // If user asked for the 'native' CPU, autodetect here. If autodection fails,
-  // this will set the CPU to an empty string which tells the target to
-  // pick a basic default.
-  if (MCPU == "native")
-    MCPU = sys::getHostCPUName();
-
   // If user just wants to list available options, skip module loading
   if (!SkipModule) {
     M = parseIRFile(InputFilename, Err, Context);
@@ -256,13 +250,31 @@ static int compileModule(char **argv, LL
 
   // Package up features to be passed to target/subtarget
   std::string FeaturesStr;
-  if (MAttrs.size()) {
+  if (!MAttrs.empty() || MCPU == "native") {
     SubtargetFeatures Features;
+
+    // If user asked for the 'native' CPU, we need to autodetect features.
+    // This is necessary for x86 where the CPU might not support all the
+    // features the autodetected CPU name lists in the target. For example,
+    // not all Sandybridge processors support AVX.
+    if (MCPU == "native") {
+      StringMap<bool> HostFeatures;
+      if (sys::getHostCPUFeatures(HostFeatures))
+        for (auto &F : HostFeatures)
+          Features.AddFeature(F.first(), F.second);
+    }
+
     for (unsigned i = 0; i != MAttrs.size(); ++i)
       Features.AddFeature(MAttrs[i]);
     FeaturesStr = Features.getString();
   }
 
+  // If user asked for the 'native' CPU, autodetect here. If autodection fails,
+  // this will set the CPU to an empty string which tells the target to
+  // pick a basic default.
+  if (MCPU == "native")
+    MCPU = sys::getHostCPUName();
+
   CodeGenOpt::Level OLvl = CodeGenOpt::Default;
   switch (OptLevel) {
   default: