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
diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 170e4f0..507ffec 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -493,7 +493,11 @@
return CGF.BlockInfo->getCapture(VD).fieldType();
if (auto *FD = CGF.LambdaCaptureFields.lookup(VD))
return FD->getType();
- return VD->getType();
+ // If the captured variable is a non-escaping __block variable, the field
+ // type is the reference type. If the variable is a __block variable that
+ // already has a reference type, the field type is the variable's type.
+ return VD->isNonEscapingByref() ?
+ CGF.getContext().getLValueReferenceType(VD->getType()) : VD->getType();
}
/// Compute the layout of the given block. Attempts to lay the block
@@ -549,7 +553,7 @@
for (const auto &CI : block->captures()) {
const VarDecl *variable = CI.getVariable();
- if (CI.isByRef()) {
+ if (CI.isEscapingByref()) {
// We have to copy/dispose of the __block reference.
info.NeedsCopyDispose = true;
@@ -1032,7 +1036,7 @@
// The lambda capture in a lambda's conversion-to-block-pointer is
// special; we'll simply emit it directly.
src = Address::invalid();
- } else if (CI.isByRef()) {
+ } else if (CI.isEscapingByref()) {
if (BlockInfo && CI.isNested()) {
// We need to use the capture from the enclosing block.
const CGBlockInfo::Capture &enclosingCapture =
@@ -1060,7 +1064,7 @@
// the block field. There's no need to chase the forwarding
// pointer at this point, since we're building something that will
// live a shorter life than the stack byref anyway.
- if (CI.isByRef()) {
+ if (CI.isEscapingByref()) {
// Get a void* that points to the byref struct.
llvm::Value *byrefPointer;
if (CI.isNested())
@@ -1279,8 +1283,7 @@
return EmitCall(FnInfo, Callee, ReturnValue, Args);
}
-Address CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable,
- bool isByRef) {
+Address CodeGenFunction::GetAddrOfBlockDecl(const VarDecl *variable) {
assert(BlockInfo && "evaluating block ref without block information?");
const CGBlockInfo::Capture &capture = BlockInfo->getCapture(variable);
@@ -1291,7 +1294,7 @@
Builder.CreateStructGEP(LoadBlockStruct(), capture.getIndex(),
capture.getOffset(), "block.capture.addr");
- if (isByRef) {
+ if (variable->isEscapingByref()) {
// addr should be a void** right now. Load, then cast the result
// to byref*.
@@ -1305,6 +1308,10 @@
variable->getName());
}
+ assert((!variable->isNonEscapingByref() ||
+ capture.fieldType()->isReferenceType()) &&
+ "the capture field of a non-escaping variable should have a "
+ "reference type");
if (capture.fieldType()->isReferenceType())
addr = EmitLoadOfReference(MakeAddrLValue(addr, capture.fieldType()));
@@ -1656,7 +1663,7 @@
return std::make_pair(BlockCaptureEntityKind::CXXRecord, BlockFieldFlags());
}
BlockFieldFlags Flags;
- if (CI.isByRef()) {
+ if (CI.isEscapingByref()) {
Flags = BLOCK_FIELD_IS_BYREF;
if (T.isObjCGCWeak())
Flags |= BLOCK_FIELD_IS_WEAK;
@@ -2102,7 +2109,7 @@
static std::pair<BlockCaptureEntityKind, BlockFieldFlags>
computeDestroyInfoForBlockCapture(const BlockDecl::Capture &CI, QualType T,
const LangOptions &LangOpts) {
- if (CI.isByRef()) {
+ if (CI.isEscapingByref()) {
BlockFieldFlags Flags = BLOCK_FIELD_IS_BYREF;
if (T.isObjCGCWeak())
Flags |= BLOCK_FIELD_IS_WEAK;
@@ -2564,6 +2571,9 @@
CodeGenFunction::buildByrefHelpers(llvm::StructType &byrefType,
const AutoVarEmission &emission) {
const VarDecl &var = *emission.Variable;
+ assert(var.isEscapingByref() &&
+ "only escaping __block variables need byref helpers");
+
QualType type = var.getType();
auto &byrefInfo = getBlockByrefInfo(&var);
diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 468d81c..aca0fd6 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -2839,7 +2839,7 @@
CallArgList CallArgs;
QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
- Address ThisPtr = GetAddrOfBlockDecl(variable, false);
+ Address ThisPtr = GetAddrOfBlockDecl(variable);
CallArgs.add(RValue::get(ThisPtr.getPointer()), ThisType);
// Add the rest of the parameters.
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 5c47212..d31802b6 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1212,8 +1212,8 @@
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 @@
// 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 @@
} else {
CharUnits allocaAlignment;
llvm::Type *allocaTy;
- if (isByRef) {
+ if (isEscapingByRef) {
auto &byrefInfo = getBlockByrefInfo(&D);
allocaTy = byrefInfo.Type;
allocaAlignment = byrefInfo.ByrefAlignment;
@@ -1505,7 +1505,7 @@
}
// 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 @@
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 @@
// 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 @@
// 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;
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index b74937e..028aa96 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2486,7 +2486,7 @@
}
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 @@
}
// Drill into block byref variables.
- bool isBlockByref = VD->hasAttr<BlocksAttr>();
+ bool isBlockByref = VD->isEscapingByref();
if (isBlockByref) {
addr = emitBlockByrefAddress(addr, VD);
}
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index f56284d..0a11d04 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1787,7 +1787,7 @@
llvm::Value *ptr);
Address LoadBlockStruct();
- Address GetAddrOfBlockDecl(const VarDecl *var, bool ByRef);
+ Address GetAddrOfBlockDecl(const VarDecl *var);
/// BuildBlockByrefAddress - Computes the location of the
/// data in a variable which is declared as __block.
@@ -2683,8 +2683,9 @@
llvm::Value *NRVOFlag;
- /// True if the variable is a __block variable.
- bool IsByRef;
+ /// True if the variable is a __block variable that is captured by an
+ /// escaping block.
+ bool IsEscapingByRef;
/// True if the variable is of aggregate type and has a constant
/// initializer.
@@ -2704,7 +2705,7 @@
AutoVarEmission(const VarDecl &variable)
: Variable(&variable), Addr(Address::invalid()), NRVOFlag(nullptr),
- IsByRef(false), IsConstantAggregate(false),
+ IsEscapingByRef(false), IsConstantAggregate(false),
SizeForLifetimeMarkers(nullptr), AllocaAddr(Address::invalid()) {}
bool wasEmittedAsGlobal() const { return !Addr.isValid(); }
@@ -2734,7 +2735,7 @@
/// Note that this does not chase the forwarding pointer for
/// __block decls.
Address getObjectAddress(CodeGenFunction &CGF) const {
- if (!IsByRef) return Addr;
+ if (!IsEscapingByRef) return Addr;
return CGF.emitBlockByrefAddress(Addr, Variable, /*forward*/ false);
}