Distinguish `__block` variables that are captured by escaping blocks

from those that aren't.

This patch changes the way __block variables that aren't captured by
escaping blocks are handled:

- Since non-escaping blocks on the stack never get copied to the heap
  (see https://reviews.llvm.org/D49303), Sema shouldn't error out when
  the type of a non-escaping __block variable doesn't have an accessible
  copy constructor.

- IRGen doesn't have to use the specialized byref structure (see
  https://clang.llvm.org/docs/Block-ABI-Apple.html#id8) for a
  non-escaping __block variable anymore. Instead IRGen can emit the
  variable as a normal variable and copy the reference to the block
  literal. Byref copy/dispose helpers aren't needed either.

rdar://problem/39352313

Differential Revision: https://reviews.llvm.org/D51564

llvm-svn: 341754

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/Sema/ScopeInfo.cpp b/clang/lib/Sema/ScopeInfo.cpp
index 62a83ccb70aa..bd8db6f4ed91 100644
--- a/clang/lib/Sema/ScopeInfo.cpp
+++ b/clang/lib/Sema/ScopeInfo.cpp
@@ -54,6 +54,8 @@ void FunctionScopeInfo::Clear() {
   PossiblyUnreachableDiags.clear();
   WeakObjectUses.clear();
   ModifiedNonNullParams.clear();
+  Blocks.clear();
+  ByrefBlockVars.clear();
 }
 
 static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {