Set default CPU for Darwin targets with LTO. <rdar://problem/12457841>

This is a temporary hack until Bill's project to record command line options
in the LLVM IR is ready. Clang currently sets a default CPU but that isn't
recorded anywhere and it doesn't get used in the final LTO compilation.

llvm-svn: 165809

1 files changed, 14 insertions, 6 deletions

diff --git a/llvm/tools/lto/LTOCodeGenerator.cpp b/llvm/tools/lto/LTOCodeGenerator.cpp
index f1814ab9aab..dd74ddde13d 100644
--- a/llvm/tools/lto/LTOCodeGenerator.cpp
+++ b/llvm/tools/lto/LTOCodeGenerator.cpp
@@ -218,12 +218,13 @@ bool LTOCodeGenerator::determineTarget(std::string& errMsg) {
   if (_target != NULL)
     return false;
 
-  std::string Triple = _linker.getModule()->getTargetTriple();
-  if (Triple.empty())
-    Triple = sys::getDefaultTargetTriple();
+  std::string TripleStr = _linker.getModule()->getTargetTriple();
+  if (TripleStr.empty())
+    TripleStr = sys::getDefaultTargetTriple();
+  llvm::Triple Triple(TripleStr);
 
   // create target machine from info for merged modules
-  const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
+  const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
   if (march == NULL)
     return true;
 
@@ -244,11 +245,18 @@ bool LTOCodeGenerator::determineTarget(std::string& errMsg) {
 
   // construct LTOModule, hand over ownership of module and target
   SubtargetFeatures Features;
-  Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
+  Features.getDefaultSubtargetFeatures(Triple);
   std::string FeatureStr = Features.getString();
+  // Set a default CPU for Darwin triples.
+  if (_mCpu.empty() && Triple.isOSDarwin()) {
+    if (Triple.getArch() == llvm::Triple::x86_64)
+      _mCpu = "core2";
+    else if (Triple.getArch() == llvm::Triple::x86)
+      _mCpu = "yonah";
+  }
   TargetOptions Options;
   LTOModule::getTargetOptions(Options);
-  _target = march->createTargetMachine(Triple, _mCpu, FeatureStr, Options,
+  _target = march->createTargetMachine(TripleStr, _mCpu, FeatureStr, Options,
                                        RelocModel, CodeModel::Default,
                                        CodeGenOpt::Aggressive);
   return false;