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.

This reapplies r343518 after fixing a use-after-free bug in function
Sema::ActOnBlockStmtExpr where the BlockScopeInfo was dereferenced after
it was popped and deleted.

rdar://problem/39352313

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

llvm-svn: 343542

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index b74937e9ca1..028aa963cda 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2486,7 +2486,7 @@ LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
       }
 
       assert(isa<BlockDecl>(CurCodeDecl));
-      Address addr = GetAddrOfBlockDecl(VD, VD->hasAttr<BlocksAttr>());
+      Address addr = GetAddrOfBlockDecl(VD);
       return MakeAddrLValue(addr, T, AlignmentSource::Decl);
     }
   }
@@ -2538,7 +2538,7 @@ LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
     }
 
     // Drill into block byref variables.
-    bool isBlockByref = VD->hasAttr<BlocksAttr>();
+    bool isBlockByref = VD->isEscapingByref();
     if (isBlockByref) {
       addr = emitBlockByrefAddress(addr, VD);
     }