Add the `pass_object_size` attribute to clang.

`pass_object_size` is our way of enabling `__builtin_object_size` to
produce high quality results without requiring inlining to happen
everywhere.

A link to the design doc for this attribute is available at the
Differential review link below.

Differential Revision: http://reviews.llvm.org/D13263

llvm-svn: 254554

1 files changed, 12 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 4c1d6af..31a93e0 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -920,7 +920,18 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
     CGM.getCXXABI().buildThisParam(*this, Args);
   }
 
-  Args.append(FD->param_begin(), FD->param_end());
+  for (auto *Param : FD->params()) {
+    Args.push_back(Param);
+    if (!Param->hasAttr<PassObjectSizeAttr>())
+      continue;
+
+    IdentifierInfo *NoID = nullptr;
+    auto *Implicit = ImplicitParamDecl::Create(
+        getContext(), Param->getDeclContext(), Param->getLocation(), NoID,
+        getContext().getSizeType());
+    SizeArguments[Param] = Implicit;
+    Args.push_back(Implicit);
+  }
 
   if (MD && (isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD)))
     CGM.getCXXABI().addImplicitStructorParams(*this, ResTy, Args);