[ThinLTO] Honor -O{0,1,2,4} passed through the libLTO interface for ThinLTO

This was hardcoded to be O3 till now, without any way to change it
without changing the code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290682 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 0 deletions

diff --git a/tools/lto/lto.cpp b/tools/lto/lto.cpp
index aa61f2ad2ff..a1dd4ebbccb 100644
--- a/tools/lto/lto.cpp
+++ b/tools/lto/lto.cpp
@@ -465,6 +465,25 @@ thinlto_code_gen_t thinlto_create_codegen(void) {
   ThinLTOCodeGenerator *CodeGen = new ThinLTOCodeGenerator();
   CodeGen->setTargetOptions(InitTargetOptionsFromCodeGenFlags());
 
+  if (OptLevel.getNumOccurrences()) {
+    if (OptLevel < '0' || OptLevel > '3')
+      report_fatal_error("Optimization level must be between 0 and 3");
+    CodeGen->setOptLevel(OptLevel - '0');
+    switch (OptLevel) {
+    case '0':
+      CodeGen->setCodeGenOptLevel(CodeGenOpt::None);
+      break;
+    case '1':
+      CodeGen->setCodeGenOptLevel(CodeGenOpt::Less);
+      break;
+    case '2':
+      CodeGen->setCodeGenOptLevel(CodeGenOpt::Default);
+      break;
+    case '3':
+      CodeGen->setCodeGenOptLevel(CodeGenOpt::Aggressive);
+      break;
+    }
+  }
   return wrap(CodeGen);
 }