376 lines
12 KiB
C++
376 lines
12 KiB
C++
//== BodyFarm.cpp - Factory for conjuring up fake bodies ----------*- C++ -*-//
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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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// BodyFarm is a factory for creating faux implementations for functions/methods
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// for analysis purposes.
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//
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//===----------------------------------------------------------------------===//
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#include "BodyFarm.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/Decl.h"
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#include "clang/AST/Expr.h"
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#include "clang/AST/ExprObjC.h"
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#include "llvm/ADT/StringSwitch.h"
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using namespace clang;
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//===----------------------------------------------------------------------===//
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// Helper creation functions for constructing faux ASTs.
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//===----------------------------------------------------------------------===//
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static bool isDispatchBlock(QualType Ty) {
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// Is it a block pointer?
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const BlockPointerType *BPT = Ty->getAs<BlockPointerType>();
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if (!BPT)
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return false;
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// Check if the block pointer type takes no arguments and
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// returns void.
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const FunctionProtoType *FT =
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BPT->getPointeeType()->getAs<FunctionProtoType>();
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if (!FT || !FT->getResultType()->isVoidType() ||
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FT->getNumArgs() != 0)
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return false;
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return true;
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}
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namespace {
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class ASTMaker {
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public:
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ASTMaker(ASTContext &C) : C(C) {}
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/// Create a new BinaryOperator representing a simple assignment.
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BinaryOperator *makeAssignment(const Expr *LHS, const Expr *RHS, QualType Ty);
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/// Create a new BinaryOperator representing a comparison.
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BinaryOperator *makeComparison(const Expr *LHS, const Expr *RHS,
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BinaryOperator::Opcode Op);
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/// Create a new compound stmt using the provided statements.
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CompoundStmt *makeCompound(ArrayRef<Stmt*>);
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/// Create a new DeclRefExpr for the referenced variable.
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DeclRefExpr *makeDeclRefExpr(const VarDecl *D);
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/// Create a new UnaryOperator representing a dereference.
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UnaryOperator *makeDereference(const Expr *Arg, QualType Ty);
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/// Create an implicit cast for an integer conversion.
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Expr *makeIntegralCast(const Expr *Arg, QualType Ty);
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/// Create an implicit cast to a builtin boolean type.
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ImplicitCastExpr *makeIntegralCastToBoolean(const Expr *Arg);
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// Create an implicit cast for lvalue-to-rvaluate conversions.
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ImplicitCastExpr *makeLvalueToRvalue(const Expr *Arg, QualType Ty);
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/// Create an Objective-C bool literal.
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ObjCBoolLiteralExpr *makeObjCBool(bool Val);
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/// Create a Return statement.
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ReturnStmt *makeReturn(const Expr *RetVal);
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private:
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ASTContext &C;
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};
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}
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BinaryOperator *ASTMaker::makeAssignment(const Expr *LHS, const Expr *RHS,
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QualType Ty) {
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return new (C) BinaryOperator(const_cast<Expr*>(LHS), const_cast<Expr*>(RHS),
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BO_Assign, Ty, VK_RValue,
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OK_Ordinary, SourceLocation(), false);
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}
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BinaryOperator *ASTMaker::makeComparison(const Expr *LHS, const Expr *RHS,
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BinaryOperator::Opcode Op) {
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assert(BinaryOperator::isLogicalOp(Op) ||
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BinaryOperator::isComparisonOp(Op));
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return new (C) BinaryOperator(const_cast<Expr*>(LHS),
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const_cast<Expr*>(RHS),
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Op,
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C.getLogicalOperationType(),
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VK_RValue,
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OK_Ordinary, SourceLocation(), false);
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}
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CompoundStmt *ASTMaker::makeCompound(ArrayRef<Stmt *> Stmts) {
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return new (C) CompoundStmt(C, Stmts, SourceLocation(), SourceLocation());
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}
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DeclRefExpr *ASTMaker::makeDeclRefExpr(const VarDecl *D) {
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DeclRefExpr *DR =
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DeclRefExpr::Create(/* Ctx = */ C,
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/* QualifierLoc = */ NestedNameSpecifierLoc(),
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/* TemplateKWLoc = */ SourceLocation(),
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/* D = */ const_cast<VarDecl*>(D),
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/* isEnclosingLocal = */ false,
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/* NameLoc = */ SourceLocation(),
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/* T = */ D->getType(),
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/* VK = */ VK_LValue);
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return DR;
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}
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UnaryOperator *ASTMaker::makeDereference(const Expr *Arg, QualType Ty) {
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return new (C) UnaryOperator(const_cast<Expr*>(Arg), UO_Deref, Ty,
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VK_LValue, OK_Ordinary, SourceLocation());
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}
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ImplicitCastExpr *ASTMaker::makeLvalueToRvalue(const Expr *Arg, QualType Ty) {
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return ImplicitCastExpr::Create(C, Ty, CK_LValueToRValue,
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const_cast<Expr*>(Arg), 0, VK_RValue);
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}
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Expr *ASTMaker::makeIntegralCast(const Expr *Arg, QualType Ty) {
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if (Arg->getType() == Ty)
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return const_cast<Expr*>(Arg);
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return ImplicitCastExpr::Create(C, Ty, CK_IntegralCast,
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const_cast<Expr*>(Arg), 0, VK_RValue);
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}
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ImplicitCastExpr *ASTMaker::makeIntegralCastToBoolean(const Expr *Arg) {
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return ImplicitCastExpr::Create(C, C.BoolTy, CK_IntegralToBoolean,
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const_cast<Expr*>(Arg), 0, VK_RValue);
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}
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ObjCBoolLiteralExpr *ASTMaker::makeObjCBool(bool Val) {
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QualType Ty = C.getBOOLDecl() ? C.getBOOLType() : C.ObjCBuiltinBoolTy;
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return new (C) ObjCBoolLiteralExpr(Val, Ty, SourceLocation());
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}
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ReturnStmt *ASTMaker::makeReturn(const Expr *RetVal) {
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return new (C) ReturnStmt(SourceLocation(), const_cast<Expr*>(RetVal), 0);
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}
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//===----------------------------------------------------------------------===//
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// Creation functions for faux ASTs.
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//===----------------------------------------------------------------------===//
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typedef Stmt *(*FunctionFarmer)(ASTContext &C, const FunctionDecl *D);
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/// Create a fake body for dispatch_once.
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static Stmt *create_dispatch_once(ASTContext &C, const FunctionDecl *D) {
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// Check if we have at least two parameters.
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if (D->param_size() != 2)
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return 0;
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// Check if the first parameter is a pointer to integer type.
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const ParmVarDecl *Predicate = D->getParamDecl(0);
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QualType PredicateQPtrTy = Predicate->getType();
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const PointerType *PredicatePtrTy = PredicateQPtrTy->getAs<PointerType>();
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if (!PredicatePtrTy)
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return 0;
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QualType PredicateTy = PredicatePtrTy->getPointeeType();
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if (!PredicateTy->isIntegerType())
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return 0;
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// Check if the second parameter is the proper block type.
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const ParmVarDecl *Block = D->getParamDecl(1);
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QualType Ty = Block->getType();
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if (!isDispatchBlock(Ty))
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return 0;
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// Everything checks out. Create a fakse body that checks the predicate,
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// sets it, and calls the block. Basically, an AST dump of:
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//
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// void dispatch_once(dispatch_once_t *predicate, dispatch_block_t block) {
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// if (!*predicate) {
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// *predicate = 1;
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// block();
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// }
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// }
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ASTMaker M(C);
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// (1) Create the call.
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DeclRefExpr *DR = M.makeDeclRefExpr(Block);
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ImplicitCastExpr *ICE = M.makeLvalueToRvalue(DR, Ty);
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CallExpr *CE = new (C) CallExpr(C, ICE, None, C.VoidTy, VK_RValue,
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SourceLocation());
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// (2) Create the assignment to the predicate.
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IntegerLiteral *IL =
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IntegerLiteral::Create(C, llvm::APInt(C.getTypeSize(C.IntTy), (uint64_t) 1),
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C.IntTy, SourceLocation());
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BinaryOperator *B =
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M.makeAssignment(
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M.makeDereference(
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M.makeLvalueToRvalue(
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M.makeDeclRefExpr(Predicate), PredicateQPtrTy),
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PredicateTy),
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M.makeIntegralCast(IL, PredicateTy),
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PredicateTy);
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// (3) Create the compound statement.
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Stmt *Stmts[2];
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Stmts[0] = B;
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Stmts[1] = CE;
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CompoundStmt *CS = M.makeCompound(ArrayRef<Stmt*>(Stmts, 2));
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// (4) Create the 'if' condition.
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ImplicitCastExpr *LValToRval =
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M.makeLvalueToRvalue(
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M.makeDereference(
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M.makeLvalueToRvalue(
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M.makeDeclRefExpr(Predicate),
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PredicateQPtrTy),
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PredicateTy),
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PredicateTy);
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UnaryOperator *UO = new (C) UnaryOperator(LValToRval, UO_LNot, C.IntTy,
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VK_RValue, OK_Ordinary,
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SourceLocation());
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// (5) Create the 'if' statement.
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IfStmt *If = new (C) IfStmt(C, SourceLocation(), 0, UO, CS);
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return If;
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}
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/// Create a fake body for dispatch_sync.
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static Stmt *create_dispatch_sync(ASTContext &C, const FunctionDecl *D) {
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// Check if we have at least two parameters.
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if (D->param_size() != 2)
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return 0;
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// Check if the second parameter is a block.
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const ParmVarDecl *PV = D->getParamDecl(1);
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QualType Ty = PV->getType();
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if (!isDispatchBlock(Ty))
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return 0;
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// Everything checks out. Create a fake body that just calls the block.
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// This is basically just an AST dump of:
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//
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// void dispatch_sync(dispatch_queue_t queue, void (^block)(void)) {
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// block();
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// }
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//
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ASTMaker M(C);
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DeclRefExpr *DR = M.makeDeclRefExpr(PV);
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ImplicitCastExpr *ICE = M.makeLvalueToRvalue(DR, Ty);
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CallExpr *CE = new (C) CallExpr(C, ICE, None, C.VoidTy, VK_RValue,
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SourceLocation());
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return CE;
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}
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static Stmt *create_OSAtomicCompareAndSwap(ASTContext &C, const FunctionDecl *D)
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{
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// There are exactly 3 arguments.
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if (D->param_size() != 3)
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return 0;
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// Signature:
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// _Bool OSAtomicCompareAndSwapPtr(void *__oldValue,
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// void *__newValue,
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// void * volatile *__theValue)
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// Generate body:
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// if (oldValue == *theValue) {
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// *theValue = newValue;
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// return YES;
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// }
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// else return NO;
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QualType ResultTy = D->getResultType();
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bool isBoolean = ResultTy->isBooleanType();
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if (!isBoolean && !ResultTy->isIntegralType(C))
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return 0;
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const ParmVarDecl *OldValue = D->getParamDecl(0);
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QualType OldValueTy = OldValue->getType();
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const ParmVarDecl *NewValue = D->getParamDecl(1);
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QualType NewValueTy = NewValue->getType();
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assert(OldValueTy == NewValueTy);
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const ParmVarDecl *TheValue = D->getParamDecl(2);
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QualType TheValueTy = TheValue->getType();
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const PointerType *PT = TheValueTy->getAs<PointerType>();
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if (!PT)
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return 0;
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QualType PointeeTy = PT->getPointeeType();
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ASTMaker M(C);
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// Construct the comparison.
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Expr *Comparison =
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M.makeComparison(
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M.makeLvalueToRvalue(M.makeDeclRefExpr(OldValue), OldValueTy),
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M.makeLvalueToRvalue(
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M.makeDereference(
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M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy),
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PointeeTy),
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PointeeTy),
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BO_EQ);
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// Construct the body of the IfStmt.
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Stmt *Stmts[2];
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Stmts[0] =
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M.makeAssignment(
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M.makeDereference(
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M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy),
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PointeeTy),
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M.makeLvalueToRvalue(M.makeDeclRefExpr(NewValue), NewValueTy),
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NewValueTy);
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Expr *BoolVal = M.makeObjCBool(true);
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Expr *RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal)
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: M.makeIntegralCast(BoolVal, ResultTy);
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Stmts[1] = M.makeReturn(RetVal);
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CompoundStmt *Body = M.makeCompound(ArrayRef<Stmt*>(Stmts, 2));
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// Construct the else clause.
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BoolVal = M.makeObjCBool(false);
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RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal)
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: M.makeIntegralCast(BoolVal, ResultTy);
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Stmt *Else = M.makeReturn(RetVal);
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/// Construct the If.
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Stmt *If =
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new (C) IfStmt(C, SourceLocation(), 0, Comparison, Body,
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SourceLocation(), Else);
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return If;
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}
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Stmt *BodyFarm::getBody(const FunctionDecl *D) {
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D = D->getCanonicalDecl();
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Optional<Stmt *> &Val = Bodies[D];
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if (Val.hasValue())
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return Val.getValue();
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Val = 0;
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if (D->getIdentifier() == 0)
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return 0;
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StringRef Name = D->getName();
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if (Name.empty())
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return 0;
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FunctionFarmer FF;
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if (Name.startswith("OSAtomicCompareAndSwap") ||
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Name.startswith("objc_atomicCompareAndSwap")) {
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FF = create_OSAtomicCompareAndSwap;
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}
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else {
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FF = llvm::StringSwitch<FunctionFarmer>(Name)
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.Case("dispatch_sync", create_dispatch_sync)
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.Case("dispatch_once", create_dispatch_once)
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.Default(NULL);
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}
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if (FF) { Val = FF(C, D); }
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return Val.getValue();
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}
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