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, 8 insertions, 0 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 272e49a7997..5a64c67f9b8 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2361,6 +2361,14 @@ static DeclT *getDefinitionOrSelf(DeclT *D) {
   return D;
 }
 
+bool VarDecl::isEscapingByref() const {
+  return hasAttr<BlocksAttr>() && NonParmVarDeclBits.EscapingByref;
+}
+
+bool VarDecl::isNonEscapingByref() const {
+  return hasAttr<BlocksAttr>() && !NonParmVarDeclBits.EscapingByref;
+}
+
 VarDecl *VarDecl::getTemplateInstantiationPattern() const {
   // If it's a variable template specialization, find the template or partial
   // specialization from which it was instantiated.