[CodeGen] Merge equivalent block copy/helper functions.
Clang generates copy and dispose helper functions for each block literal
on the stack. Often these functions are equivalent for different blocks.
This commit makes changes to merge equivalent copy and dispose helper
functions and reduce code size.
To enable merging equivalent copy/dispose functions, the captured object
infomation is encoded into the helper function name. This allows IRGen
to check whether an equivalent helper function has already been emitted
and reuse the function instead of generating a new helper function
whenever a block is defined. In addition, the helper functions are
marked as linkonce_odr to enable merging helper functions that have the
same name across translation units and marked as unnamed_addr to enable
the linker's deduplication pass to merge functions that have different
names but the same content.
rdar://problem/42640608
Differential Revision: https://reviews.llvm.org/D50152
llvm-svn: 339438
diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 5d03477..b1dbb50 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "CGBlocks.h"
+#include "CGCXXABI.h"
#include "CGDebugInfo.h"
#include "CGObjCRuntime.h"
#include "CGOpenCLRuntime.h"
@@ -25,6 +26,7 @@
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Module.h"
+#include "llvm/Support/ScopedPrinter.h"
#include <algorithm>
#include <cstdio>
@@ -34,8 +36,8 @@
CGBlockInfo::CGBlockInfo(const BlockDecl *block, StringRef name)
: Name(name), CXXThisIndex(0), CanBeGlobal(false), NeedsCopyDispose(false),
HasCXXObject(false), UsesStret(false), HasCapturedVariableLayout(false),
- LocalAddress(Address::invalid()), StructureType(nullptr), Block(block),
- DominatingIP(nullptr) {
+ CapturesNonExternalType(false), LocalAddress(Address::invalid()),
+ StructureType(nullptr), Block(block), DominatingIP(nullptr) {
// Skip asm prefix, if any. 'name' is usually taken directly from
// the mangled name of the enclosing function.
@@ -464,6 +466,8 @@
} else if (CI.hasCopyExpr()) {
info.NeedsCopyDispose = true;
info.HasCXXObject = true;
+ if (!variable->getType()->getAsCXXRecordDecl()->isExternallyVisible())
+ info.CapturesNonExternalType = true;
// So do C structs that require non-trivial copy construction or
// destruction.
@@ -480,6 +484,8 @@
if (!record->hasTrivialDestructor()) {
info.HasCXXObject = true;
info.NeedsCopyDispose = true;
+ if (!record->isExternallyVisible())
+ info.CapturesNonExternalType = true;
}
}
}
@@ -1522,13 +1528,17 @@
struct BlockCaptureManagedEntity {
BlockCaptureEntityKind Kind;
BlockFieldFlags Flags;
- const BlockDecl::Capture &CI;
- const CGBlockInfo::Capture &Capture;
+ const BlockDecl::Capture *CI;
+ const CGBlockInfo::Capture *Capture;
BlockCaptureManagedEntity(BlockCaptureEntityKind Type, BlockFieldFlags Flags,
const BlockDecl::Capture &CI,
const CGBlockInfo::Capture &Capture)
- : Kind(Type), Flags(Flags), CI(CI), Capture(Capture) {}
+ : Kind(Type), Flags(Flags), CI(&CI), Capture(&Capture) {}
+
+ bool operator<(const BlockCaptureManagedEntity &Other) const {
+ return Capture->getOffset() < Other.Capture->getOffset();
+ }
};
} // end anonymous namespace
@@ -1607,6 +1617,9 @@
if (Info.first != BlockCaptureEntityKind::None)
ManagedCaptures.emplace_back(Info.first, Info.second, CI, Capture);
}
+
+ // Sort the captures by offset.
+ llvm::sort(ManagedCaptures.begin(), ManagedCaptures.end());
}
namespace {
@@ -1614,10 +1627,12 @@
struct CallBlockRelease final : EHScopeStack::Cleanup {
Address Addr;
BlockFieldFlags FieldFlags;
- bool LoadBlockVarAddr;
+ bool LoadBlockVarAddr, CanThrow;
- CallBlockRelease(Address Addr, BlockFieldFlags Flags, bool LoadValue)
- : Addr(Addr), FieldFlags(Flags), LoadBlockVarAddr(LoadValue) {}
+ CallBlockRelease(Address Addr, BlockFieldFlags Flags, bool LoadValue,
+ bool CT)
+ : Addr(Addr), FieldFlags(Flags), LoadBlockVarAddr(LoadValue),
+ CanThrow(CT) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
llvm::Value *BlockVarAddr;
@@ -1628,15 +1643,112 @@
BlockVarAddr = Addr.getPointer();
}
- CGF.BuildBlockRelease(BlockVarAddr, FieldFlags);
+ CGF.BuildBlockRelease(BlockVarAddr, FieldFlags, CanThrow);
}
};
} // end anonymous namespace
+/// Check if \p T is a C++ class that has a destructor that can throw.
+bool CodeGenFunction::cxxDestructorCanThrow(QualType T) {
+ if (const auto *RD = T->getAsCXXRecordDecl())
+ if (const CXXDestructorDecl *DD = RD->getDestructor())
+ return DD->getType()->getAs<FunctionProtoType>()->canThrow();
+ return false;
+}
+
+static std::string getCopyDestroyHelperFuncName(
+ const SmallVectorImpl<BlockCaptureManagedEntity> &Captures,
+ CharUnits BlockAlignment, bool IsCopyHelper, CodeGenModule &CGM) {
+ ASTContext &Ctx = CGM.getContext();
+ std::unique_ptr<ItaniumMangleContext> MC(
+ ItaniumMangleContext::create(Ctx, Ctx.getDiagnostics()));
+
+ std::string Name =
+ IsCopyHelper ? "__copy_helper_block_" : "__destroy_helper_block_";
+ if (CGM.getLangOpts().Exceptions)
+ Name += "e";
+ if (CGM.getCodeGenOpts().ObjCAutoRefCountExceptions)
+ Name += "a";
+ Name += llvm::to_string(BlockAlignment.getQuantity()) + "_";
+
+ for (const BlockCaptureManagedEntity &E : Captures) {
+ const BlockDecl::Capture &CI = *E.CI;
+ BlockFieldFlags Flags = E.Flags;
+ QualType CaptureTy = CI.getVariable()->getType();
+ Name += llvm::to_string(E.Capture->getOffset().getQuantity());
+
+ switch (E.Kind) {
+ case BlockCaptureEntityKind::CXXRecord: {
+ Name += "c";
+ SmallString<256> Str;
+ llvm::raw_svector_ostream Out(Str);
+ MC->mangleTypeName(CaptureTy, Out);
+ Name += llvm::to_string(Str.size()) + Str.c_str();
+ break;
+ }
+ case BlockCaptureEntityKind::ARCWeak:
+ Name += "w";
+ break;
+ case BlockCaptureEntityKind::ARCStrong:
+ Name += "s";
+ break;
+ case BlockCaptureEntityKind::BlockObject: {
+ const VarDecl *Var = CI.getVariable();
+ unsigned F = Flags.getBitMask();
+ if (F & BLOCK_FIELD_IS_BYREF) {
+ Name += "r";
+ if (F & BLOCK_FIELD_IS_WEAK)
+ Name += "w";
+ else {
+ if (IsCopyHelper) {
+ if (Ctx.getBlockVarCopyInit(Var).canThrow())
+ Name += "c";
+ } else {
+ if (CodeGenFunction::cxxDestructorCanThrow(CaptureTy))
+ Name += "d";
+ }
+ }
+ } else {
+ assert((F & BLOCK_FIELD_IS_OBJECT) && "unexpected flag value");
+ if (F == BLOCK_FIELD_IS_BLOCK)
+ Name += "b";
+ else
+ Name += "o";
+ }
+ break;
+ }
+ case BlockCaptureEntityKind::NonTrivialCStruct: {
+ bool IsVolatile = CaptureTy.isVolatileQualified();
+ CharUnits Alignment =
+ BlockAlignment.alignmentAtOffset(E.Capture->getOffset());
+
+ Name += "n";
+ std::string Str;
+ if (IsCopyHelper)
+ Str = CodeGenFunction::getNonTrivialCopyConstructorStr(
+ CaptureTy, Alignment, IsVolatile, Ctx);
+ else
+ Str = CodeGenFunction::getNonTrivialDestructorStr(CaptureTy, Alignment,
+ IsVolatile, Ctx);
+ // The underscore is necessary here because non-trivial copy constructor
+ // and destructor strings can start with a number.
+ Name += llvm::to_string(Str.size()) + "_" + Str;
+ break;
+ }
+ case BlockCaptureEntityKind::None:
+ llvm_unreachable("unexpected block capture kind");
+ }
+ }
+
+ return Name;
+}
+
static void pushCaptureCleanup(BlockCaptureEntityKind CaptureKind,
Address Field, QualType CaptureType,
- BlockFieldFlags Flags, bool EHOnly,
- CodeGenFunction &CGF) {
+ BlockFieldFlags Flags, bool ForCopyHelper,
+ VarDecl *Var, CodeGenFunction &CGF) {
+ bool EHOnly = ForCopyHelper;
+
switch (CaptureKind) {
case BlockCaptureEntityKind::CXXRecord:
case BlockCaptureEntityKind::ARCWeak:
@@ -1658,7 +1770,13 @@
case BlockCaptureEntityKind::BlockObject: {
if (!EHOnly || CGF.getLangOpts().Exceptions) {
CleanupKind Kind = EHOnly ? EHCleanup : NormalAndEHCleanup;
- CGF.enterByrefCleanup(Kind, Field, Flags, /*LoadBlockVarAddr*/ true);
+ // Calls to _Block_object_dispose along the EH path in the copy helper
+ // function don't throw as newly-copied __block variables always have a
+ // reference count of 2.
+ bool CanThrow =
+ !ForCopyHelper && CGF.cxxDestructorCanThrow(CaptureType);
+ CGF.enterByrefCleanup(Kind, Field, Flags, /*LoadBlockVarAddr*/ true,
+ CanThrow);
}
break;
}
@@ -1667,6 +1785,19 @@
}
}
+static void setBlockHelperAttributesVisibility(bool CapturesNonExternalType,
+ llvm::Function *Fn,
+ const CGFunctionInfo &FI,
+ CodeGenModule &CGM) {
+ if (CapturesNonExternalType) {
+ CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
+ } else {
+ Fn->setVisibility(llvm::GlobalValue::HiddenVisibility);
+ Fn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+ CGM.SetLLVMFunctionAttributes(nullptr, FI, Fn);
+ CGM.SetLLVMFunctionAttributesForDefinition(nullptr, Fn);
+ }
+}
/// Generate the copy-helper function for a block closure object:
/// static void block_copy_helper(block_t *dst, block_t *src);
/// The runtime will have previously initialized 'dst' by doing a
@@ -1677,6 +1808,16 @@
/// the contents of an individual __block variable to the heap.
llvm::Constant *
CodeGenFunction::GenerateCopyHelperFunction(const CGBlockInfo &blockInfo) {
+ SmallVector<BlockCaptureManagedEntity, 4> CopiedCaptures;
+ findBlockCapturedManagedEntities(blockInfo, getLangOpts(), CopiedCaptures,
+ computeCopyInfoForBlockCapture);
+ std::string FuncName =
+ getCopyDestroyHelperFuncName(CopiedCaptures, blockInfo.BlockAlign,
+ /*IsCopyHelper*/ true, CGM);
+
+ if (llvm::GlobalValue *Func = CGM.getModule().getNamedValue(FuncName))
+ return Func;
+
ASTContext &C = getContext();
FunctionArgList args;
@@ -1695,11 +1836,11 @@
llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
llvm::Function *Fn =
- llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
- "__copy_helper_block_", &CGM.getModule());
+ llvm::Function::Create(LTy, llvm::GlobalValue::LinkOnceODRLinkage,
+ FuncName, &CGM.getModule());
IdentifierInfo *II
- = &CGM.getContext().Idents.get("__copy_helper_block_");
+ = &CGM.getContext().Idents.get(FuncName);
FunctionDecl *FD = FunctionDecl::Create(C,
C.getTranslationUnitDecl(),
@@ -1709,8 +1850,8 @@
false,
false);
- CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
-
+ setBlockHelperAttributesVisibility(blockInfo.CapturesNonExternalType, Fn, FI,
+ CGM);
StartFunction(FD, C.VoidTy, Fn, FI, args);
ApplyDebugLocation NL{*this, blockInfo.getBlockExpr()->getBeginLoc()};
llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
@@ -1723,13 +1864,9 @@
dst = Address(Builder.CreateLoad(dst), blockInfo.BlockAlign);
dst = Builder.CreateBitCast(dst, structPtrTy, "block.dest");
- SmallVector<BlockCaptureManagedEntity, 4> CopiedCaptures;
- findBlockCapturedManagedEntities(blockInfo, getLangOpts(), CopiedCaptures,
- computeCopyInfoForBlockCapture);
-
for (const auto &CopiedCapture : CopiedCaptures) {
- const BlockDecl::Capture &CI = CopiedCapture.CI;
- const CGBlockInfo::Capture &capture = CopiedCapture.Capture;
+ const BlockDecl::Capture &CI = *CopiedCapture.CI;
+ const CGBlockInfo::Capture &capture = *CopiedCapture.Capture;
QualType captureType = CI.getVariable()->getType();
BlockFieldFlags flags = CopiedCapture.Flags;
@@ -1783,28 +1920,17 @@
dstAddr, srcValue, llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
};
- const VarDecl *variable = CI.getVariable();
- bool copyCanThrow = false;
- if (CI.isByRef() && variable->getType()->getAsCXXRecordDecl()) {
- const Expr *copyExpr =
- CGM.getContext().getBlockVarCopyInits(variable);
- if (copyExpr) {
- copyCanThrow = true; // FIXME: reuse the noexcept logic
- }
- }
-
- if (copyCanThrow) {
+ if (CI.isByRef() && C.getBlockVarCopyInit(CI.getVariable()).canThrow())
EmitRuntimeCallOrInvoke(CGM.getBlockObjectAssign(), args);
- } else {
+ else
EmitNounwindRuntimeCall(CGM.getBlockObjectAssign(), args);
- }
}
}
// Ensure that we destroy the copied object if an exception is thrown later
// in the helper function.
- pushCaptureCleanup(CopiedCapture.Kind, dstField, captureType, flags, /*EHOnly*/ true,
- *this);
+ pushCaptureCleanup(CopiedCapture.Kind, dstField, captureType, flags,
+ /*ForCopyHelper*/ true, CI.getVariable(), *this);
}
FinishFunction();
@@ -1868,6 +1994,16 @@
/// variable.
llvm::Constant *
CodeGenFunction::GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo) {
+ SmallVector<BlockCaptureManagedEntity, 4> DestroyedCaptures;
+ findBlockCapturedManagedEntities(blockInfo, getLangOpts(), DestroyedCaptures,
+ computeDestroyInfoForBlockCapture);
+ std::string FuncName =
+ getCopyDestroyHelperFuncName(DestroyedCaptures, blockInfo.BlockAlign,
+ /*IsCopyHelper*/ false, CGM);
+
+ if (llvm::GlobalValue *Func = CGM.getModule().getNamedValue(FuncName))
+ return Func;
+
ASTContext &C = getContext();
FunctionArgList args;
@@ -1883,11 +2019,11 @@
llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
llvm::Function *Fn =
- llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
- "__destroy_helper_block_", &CGM.getModule());
+ llvm::Function::Create(LTy, llvm::GlobalValue::LinkOnceODRLinkage,
+ FuncName, &CGM.getModule());
IdentifierInfo *II
- = &CGM.getContext().Idents.get("__destroy_helper_block_");
+ = &CGM.getContext().Idents.get(FuncName);
FunctionDecl *FD = FunctionDecl::Create(C, C.getTranslationUnitDecl(),
SourceLocation(),
@@ -1895,9 +2031,11 @@
nullptr, SC_Static,
false, false);
- CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
-
+ setBlockHelperAttributesVisibility(blockInfo.CapturesNonExternalType, Fn, FI,
+ CGM);
StartFunction(FD, C.VoidTy, Fn, FI, args);
+ markAsIgnoreThreadCheckingAtRuntime(Fn);
+
ApplyDebugLocation NL{*this, blockInfo.getBlockExpr()->getBeginLoc()};
llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
@@ -1908,20 +2046,17 @@
CodeGenFunction::RunCleanupsScope cleanups(*this);
- SmallVector<BlockCaptureManagedEntity, 4> DestroyedCaptures;
- findBlockCapturedManagedEntities(blockInfo, getLangOpts(), DestroyedCaptures,
- computeDestroyInfoForBlockCapture);
-
for (const auto &DestroyedCapture : DestroyedCaptures) {
- const BlockDecl::Capture &CI = DestroyedCapture.CI;
- const CGBlockInfo::Capture &capture = DestroyedCapture.Capture;
+ const BlockDecl::Capture &CI = *DestroyedCapture.CI;
+ const CGBlockInfo::Capture &capture = *DestroyedCapture.Capture;
BlockFieldFlags flags = DestroyedCapture.Flags;
Address srcField =
Builder.CreateStructGEP(src, capture.getIndex(), capture.getOffset());
pushCaptureCleanup(DestroyedCapture.Kind, srcField,
- CI.getVariable()->getType(), flags, /*EHOnly*/ false, *this);
+ CI.getVariable()->getType(), flags,
+ /*ForCopyHelper*/ false, CI.getVariable(), *this);
}
cleanups.ForceCleanup();
@@ -1961,7 +2096,7 @@
field = CGF.Builder.CreateBitCast(field, CGF.Int8PtrTy->getPointerTo(0));
llvm::Value *value = CGF.Builder.CreateLoad(field);
- CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER);
+ CGF.BuildBlockRelease(value, Flags | BLOCK_BYREF_CALLER, false);
}
void profileImpl(llvm::FoldingSetNodeID &id) const override {
@@ -2288,7 +2423,8 @@
byrefInfo.ByrefAlignment.alignmentAtOffset(byrefInfo.FieldOffset);
if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) {
- const Expr *copyExpr = CGM.getContext().getBlockVarCopyInits(&var);
+ const Expr *copyExpr =
+ CGM.getContext().getBlockVarCopyInit(&var).getCopyExpr();
if (!copyExpr && record->hasTrivialDestructor()) return nullptr;
return ::buildByrefHelpers(
@@ -2591,19 +2727,25 @@
}
}
-void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags) {
+void CodeGenFunction::BuildBlockRelease(llvm::Value *V, BlockFieldFlags flags,
+ bool CanThrow) {
llvm::Value *F = CGM.getBlockObjectDispose();
llvm::Value *args[] = {
Builder.CreateBitCast(V, Int8PtrTy),
llvm::ConstantInt::get(Int32Ty, flags.getBitMask())
};
- EmitNounwindRuntimeCall(F, args); // FIXME: throwing destructors?
+
+ if (CanThrow)
+ EmitRuntimeCallOrInvoke(F, args);
+ else
+ EmitNounwindRuntimeCall(F, args);
}
void CodeGenFunction::enterByrefCleanup(CleanupKind Kind, Address Addr,
BlockFieldFlags Flags,
- bool LoadBlockVarAddr) {
- EHStack.pushCleanup<CallBlockRelease>(Kind, Addr, Flags, LoadBlockVarAddr);
+ bool LoadBlockVarAddr, bool CanThrow) {
+ EHStack.pushCleanup<CallBlockRelease>(Kind, Addr, Flags, LoadBlockVarAddr,
+ CanThrow);
}
/// Adjust the declaration of something from the blocks API.