Revert r324557, "gold-plugin: Do not set codegen opt level based on LTO opt level."

It was reported that this change measurably regressed -plugin-opt=O3
performance.

There is an ongoing discussion on llvm-dev about the correct way to
set the CG opt level, see thread "[llvm-dev] [RFC] Adding function
attributes to represent codegen optimization level".

llvm-svn: 329458

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
index d2d0e77d719..6123b8e5a46 100644
--- a/llvm/tools/gold/gold-plugin.cpp
+++ b/llvm/tools/gold/gold-plugin.cpp
@@ -779,6 +779,20 @@ static int getOutputFileName(StringRef InFilename, bool TempOutFile,
   return FD;
 }
 
+static CodeGenOpt::Level getCGOptLevel() {
+  switch (options::OptLevel) {
+  case 0:
+    return CodeGenOpt::None;
+  case 1:
+    return CodeGenOpt::Less;
+  case 2:
+    return CodeGenOpt::Default;
+  case 3:
+    return CodeGenOpt::Aggressive;
+  }
+  llvm_unreachable("Invalid optimization level");
+}
+
 /// Parse the thinlto_prefix_replace option into the \p OldPrefix and
 /// \p NewPrefix strings, if it was specified.
 static void getThinLTOOldAndNewPrefix(std::string &OldPrefix,
@@ -810,6 +824,7 @@ static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
 
   Conf.MAttrs = MAttrs;
   Conf.RelocModel = RelocationModel;
+  Conf.CGOptLevel = getCGOptLevel();
   Conf.DisableVerify = options::DisableVerify;
   Conf.OptLevel = options::OptLevel;
   if (options::Parallelism)