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, 10 insertions, 9 deletions

diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 5c47212f1b5..d31802b6a40 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1212,8 +1212,8 @@ CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
 
   AutoVarEmission emission(D);
 
-  bool isByRef = D.hasAttr<BlocksAttr>();
-  emission.IsByRef = isByRef;
+  bool isEscapingByRef = D.isEscapingByref();
+  emission.IsEscapingByRef = isEscapingByRef;
 
   CharUnits alignment = getContext().getDeclAlign(&D);
 
@@ -1252,8 +1252,8 @@ CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
       // in OpenCL.
       if ((!getLangOpts().OpenCL ||
            Ty.getAddressSpace() == LangAS::opencl_constant) &&
-          (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
-           CGM.isTypeConstant(Ty, true))) {
+          (CGM.getCodeGenOpts().MergeAllConstants && !NRVO &&
+           !isEscapingByRef && CGM.isTypeConstant(Ty, true))) {
         EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
 
         // Signal this condition to later callbacks.
@@ -1305,7 +1305,7 @@ CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
     } else {
       CharUnits allocaAlignment;
       llvm::Type *allocaTy;
-      if (isByRef) {
+      if (isEscapingByRef) {
         auto &byrefInfo = getBlockByrefInfo(&D);
         allocaTy = byrefInfo.Type;
         allocaAlignment = byrefInfo.ByrefAlignment;
@@ -1505,7 +1505,7 @@ void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
   }
 
   // Initialize the structure of a __block variable.
-  if (emission.IsByRef)
+  if (emission.IsEscapingByRef)
     emitByrefStructureInit(emission);
 
   // Initialize the variable here if it doesn't have a initializer and it is a
@@ -1515,7 +1515,7 @@ void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
       type.isNonTrivialToPrimitiveDefaultInitialize() ==
           QualType::PDIK_Struct) {
     LValue Dst = MakeAddrLValue(emission.getAllocatedAddress(), type);
-    if (emission.IsByRef)
+    if (emission.IsEscapingByRef)
       drillIntoBlockVariable(*this, Dst, &D);
     defaultInitNonTrivialCStructVar(Dst);
     return;
@@ -1527,7 +1527,7 @@ void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
   // Check whether this is a byref variable that's potentially
   // captured and moved by its own initializer.  If so, we'll need to
   // emit the initializer first, then copy into the variable.
-  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
+  bool capturedByInit = emission.IsEscapingByRef && isCapturedBy(D, Init);
 
   Address Loc =
     capturedByInit ? emission.Addr : emission.getObjectAddress(*this);
@@ -1721,7 +1721,8 @@ void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
   // If this is a block variable, call _Block_object_destroy
   // (on the unforwarded address). Don't enter this cleanup if we're in pure-GC
   // mode.
-  if (emission.IsByRef && CGM.getLangOpts().getGC() != LangOptions::GCOnly) {
+  if (emission.IsEscapingByRef &&
+      CGM.getLangOpts().getGC() != LangOptions::GCOnly) {
     BlockFieldFlags Flags = BLOCK_FIELD_IS_BYREF;
     if (emission.Variable->getType().isObjCGCWeak())
       Flags |= BLOCK_FIELD_IS_WEAK;