Convert some ObjC msgSends to runtime calls.

It is faster to directly call the ObjC runtime for methods such as alloc/allocWithZone instead of sending a message to those functions.

This patch adds support for converting messages to alloc/allocWithZone to their equivalent runtime calls.

Tests included for the positive case of applying this transformation, negative tests that we ensure we only convert "alloc" to objc_alloc, not "alloc2", and also a driver test to ensure we enable this only for supported runtime versions.

Reviewed By: rjmccall

https://reviews.llvm.org/D55349

llvm-svn: 348687

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index bd04317966f..eaaa1bbff26 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2866,6 +2866,18 @@ static void RenderObjCOptions(const ToolChain &TC, const Driver &D,
     Args.ClaimAllArgs(options::OPT_fno_objc_arc_exceptions);
   }
 
+  // Allow the user to control whether messages can be converted to runtime
+  // functions.
+  if (types::isObjC(Input.getType())) {
+    auto *Arg = Args.getLastArg(
+        options::OPT_fobjc_convert_messages_to_runtime_calls,
+        options::OPT_fno_objc_convert_messages_to_runtime_calls);
+    if (Arg &&
+        Arg->getOption().matches(
+            options::OPT_fno_objc_convert_messages_to_runtime_calls))
+      CmdArgs.push_back("-fno-objc-convert-messages-to-runtime-calls");
+  }
+
   // -fobjc-infer-related-result-type is the default, except in the Objective-C
   // rewriter.
   if (InferCovariantReturns)