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81 lines
2.2 KiB
C++
81 lines
2.2 KiB
C++
//===--- LLVMSwiftRCIdentity.cpp - LLVM RCIdentity Analysis for Swift -----===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include "swift/LLVMPasses/Passes.h"
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#include "LLVMARCOpts.h"
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#include "llvm/IR/Module.h"
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using namespace llvm;
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using swift::SwiftRCIdentity;
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llvm::Value *
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SwiftRCIdentity::stripPointerCasts(llvm::Value *Val) {
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return Val->stripPointerCasts();
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}
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llvm::Value *
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SwiftRCIdentity::stripReferenceForwarding(llvm::Value *Val) {
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auto Inst = dyn_cast<Instruction>(Val);
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if (!Inst)
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return Val;
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auto Kind = classifyInstruction(*Inst);
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switch(Kind) {
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case RT_RetainN:
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case RT_UnknownObjectRetainN:
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case RT_BridgeRetainN:
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case RT_ReleaseN:
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case RT_UnknownObjectReleaseN:
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case RT_BridgeReleaseN:
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case RT_FixLifetime:
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case RT_Retain:
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case RT_UnknownObjectRetain:
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case RT_Release:
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case RT_UnknownObjectRelease:
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case RT_Unknown:
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case RT_AllocObject:
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case RT_NoMemoryAccessed:
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case RT_BridgeRelease:
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case RT_BridgeRetain:
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case RT_RetainUnowned:
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case RT_CheckUnowned:
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case RT_ObjCRelease:
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case RT_EndBorrow:
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break;
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// ObjC forwards references.
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case RT_ObjCRetain:
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Val = cast<CallInst>(Inst)->getArgOperand(0);
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break;
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}
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return Val;
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}
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llvm::Value *
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SwiftRCIdentity::getSwiftRCIdentityRoot(llvm::Value *Val) {
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// Only allow this method to go up a fixed number of levels to make sure
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// we don't explode compile time.
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llvm::Value *OldVal = Val;
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unsigned levels = 0;
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do {
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llvm::Value *NewVal = Val;
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// Try to strip off pointer casts and reference forwarding.
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Val = stripPointerCasts(Val);
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Val = stripReferenceForwarding(Val);
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// Nothing was stripped off.
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if (NewVal == Val)
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break;
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// Hit max number of levels.
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if (++levels > MaxRecursionDepth)
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return OldVal;
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} while (true);
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return Val;
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}
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