Improve llvm-gcc compatibility, -Os implies -O2 (sortof).

llvm-svn: 58374

1 files changed, 7 insertions, 1 deletions

diff --git a/clang/Driver/clang.cpp b/clang/Driver/clang.cpp
index 696e8842c9d..84eb341b61e 100644
--- a/clang/Driver/clang.cpp
+++ b/clang/Driver/clang.cpp
@@ -1140,8 +1140,14 @@ OptLevel("O", llvm::cl::Prefix,
          llvm::cl::init(0));
 
 static void InitializeCompileOptions(CompileOptions &Opts) {
-  Opts.OptimizationLevel = OptLevel;
   Opts.OptimizeSize = OptSize;
+  if (OptSize) {
+    // -Os implies -O2
+    // FIXME: Diagnose conflicting options.
+    Opts.OptimizationLevel = 2;
+  } else {
+    Opts.OptimizationLevel = OptLevel;
+  }
 
   // FIXME: There are llvm-gcc options to control these selectively.
   Opts.InlineFunctions = (Opts.OptimizationLevel > 1);