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91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
//===--- CodeGenTypes.cpp - TBAA information for LLVM CodeGen -------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This is the code that manages TBAA information.
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//
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//===----------------------------------------------------------------------===//
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#include "CodeGenTBAA.h"
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#include "clang/AST/ASTContext.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Metadata.h"
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using namespace clang;
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using namespace CodeGen;
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CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext& VMContext,
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const LangOptions &Features)
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: Context(Ctx), VMContext(VMContext), Features(Features), Root(0), Char(0) {
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}
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CodeGenTBAA::~CodeGenTBAA() {
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}
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llvm::MDNode *CodeGenTBAA::getTBAAInfoForNamedType(const char *NameStr,
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llvm::MDNode *Parent) {
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llvm::Value *Ops[] = {
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llvm::MDString::get(VMContext, NameStr),
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Parent
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};
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return llvm::MDNode::get(VMContext, Ops, llvm::array_lengthof(Ops));
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}
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llvm::MDNode *
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CodeGenTBAA::getTBAAInfo(QualType QTy) {
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Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
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if (llvm::MDNode *N = MetadataCache[Ty])
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return N;
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if (!Root) {
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Root = getTBAAInfoForNamedType("Experimental TBAA", 0);
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Char = getTBAAInfoForNamedType("omnipotent char", Root);
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}
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// For now, just emit a very minimal tree.
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if (const BuiltinType *BTy = dyn_cast<BuiltinType>(Ty)) {
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switch (BTy->getKind()) {
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// Character types are special and can alias anything.
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// In C++, this technically only includes "char" and "unsigned char",
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// and not "signed char". In C, it includes all three. For now,
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// the risk of exploting this detail in C++ seems likely to outweigh
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// the benefit.
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case BuiltinType::Char_U:
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case BuiltinType::Char_S:
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case BuiltinType::UChar:
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case BuiltinType::SChar:
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return Char;
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// Unsigned types can alias their corresponding signed types.
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case BuiltinType::UShort:
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return getTBAAInfo(Context.ShortTy);
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case BuiltinType::UInt:
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return getTBAAInfo(Context.IntTy);
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case BuiltinType::ULong:
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return getTBAAInfo(Context.LongTy);
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case BuiltinType::ULongLong:
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return getTBAAInfo(Context.LongLongTy);
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case BuiltinType::UInt128:
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return getTBAAInfo(Context.Int128Ty);
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// Other builtin types.
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default:
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return MetadataCache[Ty] =
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getTBAAInfoForNamedType(BTy->getName(Features), Char);
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}
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}
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// For now, treat all pointers as equivalent to each other.
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if (Ty->isPointerType())
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return MetadataCache[Ty] = getTBAAInfoForNamedType("TBAA.pointer", Char);
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// For now, handle any other kind of type conservatively.
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return MetadataCache[Ty] = Char;
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}
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