[llvm] r329458 - Revert r324557, "gold-plugin: Do not set codegen opt level based on LTO opt level."

[Peter Collingbourne via llvm-commits]

Author: pcc
Date: Fri Apr  6 14:14:33 2018
New Revision: 329458

URL: http://llvm.org/viewvc/llvm-project?rev=329458&view=rev
Log:
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".

Modified:
    llvm/trunk/tools/gold/gold-plugin.cpp

Modified: llvm/trunk/tools/gold/gold-plugin.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/gold/gold-plugin.cpp?rev=329458&r1=329457&r2=329458&view=diff
==============================================================================
--- llvm/trunk/tools/gold/gold-plugin.cpp (original)
+++ llvm/trunk/tools/gold/gold-plugin.cpp Fri Apr  6 14:14:33 2018
@@ -779,6 +779,20 @@ static int getOutputFileName(StringRef I
   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(In
 
   Conf.MAttrs = MAttrs;
   Conf.RelocModel = RelocationModel;
+  Conf.CGOptLevel = getCGOptLevel();
   Conf.DisableVerify = options::DisableVerify;
   Conf.OptLevel = options::OptLevel;
   if (options::Parallelism)