Add support for attribute 'noescape'.

The attribute informs the compiler that the annotated pointer parameter
of a function cannot escape and enables IRGen to attach attribute
'nocapture' to parameters that are annotated with the attribute. That is
the only optimization that currently takes advantage of 'noescape', but
there are other optimizations that will be added later that improves
IRGen for ObjC blocks.

rdar://problem/19886775

Differential Revision: https://reviews.llvm.org/D32520

llvm-svn: 313720

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index c6988b5a9f3..a432c3ca20d 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -455,11 +455,15 @@ const CGFunctionInfo &
 CodeGenTypes::arrangeObjCMessageSendSignature(const ObjCMethodDecl *MD,
                                               QualType receiverType) {
   SmallVector<CanQualType, 16> argTys;
+  SmallVector<FunctionProtoType::ExtParameterInfo, 4> extParamInfos(2);
   argTys.push_back(Context.getCanonicalParamType(receiverType));
   argTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
   // FIXME: Kill copy?
   for (const auto *I : MD->parameters()) {
     argTys.push_back(Context.getCanonicalParamType(I->getType()));
+    auto extParamInfo = FunctionProtoType::ExtParameterInfo().withIsNoEscape(
+        I->hasAttr<NoEscapeAttr>());
+    extParamInfos.push_back(extParamInfo);
   }
 
   FunctionType::ExtInfo einfo;
@@ -475,7 +479,7 @@ CodeGenTypes::arrangeObjCMessageSendSignature(const ObjCMethodDecl *MD,
 
   return arrangeLLVMFunctionInfo(
       GetReturnType(MD->getReturnType()), /*instanceMethod=*/false,
-      /*chainCall=*/false, argTys, einfo, {}, required);
+      /*chainCall=*/false, argTys, einfo, extParamInfos, required);
 }
 
 const CGFunctionInfo &
@@ -2093,6 +2097,9 @@ void CodeGenModule::ConstructAttributeList(
       break;
     }
 
+    if (FI.getExtParameterInfo(ArgNo).isNoEscape())
+      Attrs.addAttribute(llvm::Attribute::NoCapture);
+
     if (Attrs.hasAttributes()) {
       unsigned FirstIRArg, NumIRArgs;
       std::tie(FirstIRArg, NumIRArgs) = IRFunctionArgs.getIRArgs(ArgNo);