Add an -mattr option to the gold plugin to support subtarget features in LTO

This adds support for an -mattr option to the gold plugin and to llvm-lto. This
allows the caller to specify details of the subtarget architecture, like +aes,
or +ssse3 on x86.  Note that this requires a change to the include/llvm-c/lto.h
interface: it adds a function lto_codegen_set_attr and it increments the
version of the interface.

llvm-svn: 207279

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index da74c57c589..105fb6900db 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -301,8 +301,9 @@ bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
     break;
   }
 
-  // construct LTOModule, hand over ownership of module and target
-  SubtargetFeatures Features;
+  // Construct LTOModule, hand over ownership of module and target. Use MAttr as
+  // the default set of features.
+  SubtargetFeatures Features(MAttr);
   Features.getDefaultSubtargetFeatures(Triple);
   std::string FeatureStr = Features.getString();
   // Set a default CPU for Darwin triples.