[PATCH] D32210: [Sema][ObjC] Add support for attribute "noescape"

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak created this revision.

This patch adds support for attribute "noescape", which is used to tell the compiler that a block passed to a function will not be called after the function returns.

To ensure that the block does not escape, clang imposes the following restrictions on its usage:

- Cannot be passed to a function expecting an escaping block
- Cannot be returned from a function
- Cannot be captured by a block
- Cannot be assigned to a variable

There are other improvements we can make to Sema and CodeGen if the compiler can tell whether a block escapes or not, which should follow this patch.

rdar://problem/19886775


https://reviews.llvm.org/D32210

Files:
  include/clang/Basic/Attr.td
  include/clang/Basic/AttrDocs.td
  include/clang/Basic/DiagnosticSemaKinds.td
  lib/Sema/SemaChecking.cpp
  lib/Sema/SemaDeclAttr.cpp
  lib/Sema/SemaExpr.cpp
  lib/Sema/SemaStmt.cpp
  test/SemaObjCXX/noescape.mm

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