[cfe-commits] r166703 - /cfe/trunk/lib/CodeGen/CGBlocks.cpp

[Fariborz Jahanian]

Author: fjahanian
Date: Thu Oct 25 13:06:53 2012
New Revision: 166703

URL: http://llvm.org/viewvc/llvm-project?rev=166703&view=rev
Log:
Provide comment describing what buildBlockDescriptor does.


Modified:
    cfe/trunk/lib/CodeGen/CGBlocks.cpp

Modified: cfe/trunk/lib/CodeGen/CGBlocks.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.cpp?rev=166703&r1=166702&r2=166703&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGBlocks.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGBlocks.cpp Thu Oct 25 13:06:53 2012
@@ -56,7 +56,18 @@
   return CodeGenFunction(CGM).GenerateDestroyHelperFunction(blockInfo);
 }
 
-/// Build the block descriptor constant for a block.
+/// buildBlockDescriptor - Build the block descriptor meta-data for a block.
+/// buildBlockDescriptor is accessed from 5th field of the Block_literal
+/// meta-data and contains stationary information about the block literal.
+/// Its definition will have 4 (or optinally 6) words.
+/// struct Block_descriptor {
+///   unsigned long reserved;
+///   unsigned long size;  // size of Block_literal metadata in bytes.
+///   void *copy_func_helper_decl;  // optional copy helper.
+///   void *destroy_func_decl; // optioanl destructor helper.
+///   void *block_method_encoding_address;//@encode for block literal signature.
+///   void *block_layout_info; // encoding of captured block variables.
+/// };
 static llvm::Constant *buildBlockDescriptor(CodeGenModule &CGM,
                                             const CGBlockInfo &blockInfo) {
   ASTContext &C = CGM.getContext();