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-rw-r--r--lib/Analysis/MallocHelper.cpp265
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diff --git a/lib/Analysis/MallocHelper.cpp b/lib/Analysis/MallocHelper.cpp
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-//===-- MallocHelper.cpp - Functions to identify malloc calls -------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This family of functions identifies calls to malloc, bitcasts of malloc
-// calls, and the types and array sizes associated with them.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Analysis/MallocHelper.h"
-#include "llvm/Constants.h"
-#include "llvm/Instructions.h"
-#include "llvm/Module.h"
-#include "llvm/Analysis/ConstantFolding.h"
-using namespace llvm;
-
-//===----------------------------------------------------------------------===//
-// malloc Call Utility Functions.
-//
-
-/// isMalloc - Returns true if the the value is either a malloc call or a
-/// bitcast of the result of a malloc call.
-bool llvm::isMalloc(const Value* I) {
- return extractMallocCall(I) || extractMallocCallFromBitCast(I);
-}
-
-static bool isMallocCall(const CallInst *CI) {
- if (!CI)
- return false;
-
- const Module* M = CI->getParent()->getParent()->getParent();
- Function *MallocFunc = M->getFunction("malloc");
-
- if (CI->getOperand(0) != MallocFunc)
- return false;
-
- // Check malloc prototype.
- // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
- // attribute will exist.
- const FunctionType *FTy = MallocFunc->getFunctionType();
- if (FTy->getNumParams() != 1)
- return false;
- if (IntegerType *ITy = dyn_cast<IntegerType>(FTy->param_begin()->get())) {
- if (ITy->getBitWidth() != 32 && ITy->getBitWidth() != 64)
- return false;
- return true;
- }
-
- return false;
-}
-
-/// extractMallocCall - Returns the corresponding CallInst if the instruction
-/// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
-/// ignore InvokeInst here.
-const CallInst* llvm::extractMallocCall(const Value* I) {
- const CallInst *CI = dyn_cast<CallInst>(I);
- return (isMallocCall(CI)) ? CI : NULL;
-}
-
-CallInst* llvm::extractMallocCall(Value* I) {
- CallInst *CI = dyn_cast<CallInst>(I);
- return (isMallocCall(CI)) ? CI : NULL;
-}
-
-static bool isBitCastOfMallocCall(const BitCastInst* BCI) {
- if (!BCI)
- return false;
-
- return isMallocCall(dyn_cast<CallInst>(BCI->getOperand(0)));
-}
-
-/// extractMallocCallFromBitCast - Returns the corresponding CallInst if the
-/// instruction is a bitcast of the result of a malloc call.
-CallInst* llvm::extractMallocCallFromBitCast(Value* I) {
- BitCastInst *BCI = dyn_cast<BitCastInst>(I);
- return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
- : NULL;
-}
-
-const CallInst* llvm::extractMallocCallFromBitCast(const Value* I) {
- const BitCastInst *BCI = dyn_cast<BitCastInst>(I);
- return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
- : NULL;
-}
-
-static bool isArrayMallocHelper(const CallInst *CI, LLVMContext &Context,
- const TargetData* TD) {
- if (!CI)
- return false;
-
- const Type* T = getMallocAllocatedType(CI);
-
- // We can only indentify an array malloc if we know the type of the malloc
- // call.
- if (!T) return false;
-
- Value* MallocArg = CI->getOperand(1);
- Constant *ElementSize = ConstantExpr::getSizeOf(T);
- ElementSize = ConstantExpr::getTruncOrBitCast(ElementSize,
- MallocArg->getType());
- Constant *FoldedElementSize = ConstantFoldConstantExpression(
- cast<ConstantExpr>(ElementSize),
- Context, TD);
-
-
- if (isa<ConstantExpr>(MallocArg))
- return (MallocArg != ElementSize);
-
- BinaryOperator *BI = dyn_cast<BinaryOperator>(MallocArg);
- if (!BI)
- return false;
-
- if (BI->getOpcode() == Instruction::Mul)
- // ArraySize * ElementSize
- if (BI->getOperand(1) == ElementSize ||
- (FoldedElementSize && BI->getOperand(1) == FoldedElementSize))
- return true;
-
- // TODO: Detect case where MallocArg mul has been transformed to shl.
-
- return false;
-}
-
-/// isArrayMalloc - Returns the corresponding CallInst if the instruction
-/// matches the malloc call IR generated by CallInst::CreateMalloc(). This
-/// means that it is a malloc call with one bitcast use AND the malloc call's
-/// size argument is:
-/// 1. a constant not equal to the size of the malloced type
-/// or
-/// 2. the result of a multiplication by the size of the malloced type
-/// Otherwise it returns NULL.
-/// The unique bitcast is needed to determine the type/size of the array
-/// allocation.
-CallInst* llvm::isArrayMalloc(Value* I, LLVMContext &Context,
- const TargetData* TD) {
- CallInst *CI = extractMallocCall(I);
- return (isArrayMallocHelper(CI, Context, TD)) ? CI : NULL;
-}
-
-const CallInst* llvm::isArrayMalloc(const Value* I, LLVMContext &Context,
- const TargetData* TD) {
- const CallInst *CI = extractMallocCall(I);
- return (isArrayMallocHelper(CI, Context, TD)) ? CI : NULL;
-}
-
-/// getMallocType - Returns the PointerType resulting from the malloc call.
-/// This PointerType is the result type of the call's only bitcast use.
-/// If there is no unique bitcast use, then return NULL.
-const PointerType* llvm::getMallocType(const CallInst* CI) {
- assert(isMalloc(CI) && "GetMallocType and not malloc call");
-
- const BitCastInst* BCI = NULL;
-
- // Determine if CallInst has a bitcast use.
- for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
- UI != E; )
- if ((BCI = dyn_cast<BitCastInst>(cast<Instruction>(*UI++))))
- break;
-
- // Malloc call has 1 bitcast use and no other uses, so type is the bitcast's
- // destination type.
- if (BCI && CI->hasOneUse())
- return cast<PointerType>(BCI->getDestTy());
-
- // Malloc call was not bitcast, so type is the malloc function's return type.
- if (!BCI)
- return cast<PointerType>(CI->getType());
-
- // Type could not be determined.
- return NULL;
-}
-
-/// getMallocAllocatedType - Returns the Type allocated by malloc call. This
-/// Type is the result type of the call's only bitcast use. If there is no
-/// unique bitcast use, then return NULL.
-const Type* llvm::getMallocAllocatedType(const CallInst* CI) {
- const PointerType* PT = getMallocType(CI);
- return PT ? PT->getElementType() : NULL;
-}
-
-/// isSafeToGetMallocArraySize - Returns true if the array size of a malloc can
-/// be determined. It can be determined in these 3 cases of malloc codegen:
-/// 1. non-array malloc: The malloc's size argument is a constant and equals the /// size of the type being malloced.
-/// 2. array malloc: This is a malloc call with one bitcast use AND the malloc
-/// call's size argument is a constant multiple of the size of the malloced
-/// type.
-/// 3. array malloc: This is a malloc call with one bitcast use AND the malloc
-/// call's size argument is the result of a multiplication by the size of the
-/// malloced type.
-/// Otherwise returns false.
-static bool isSafeToGetMallocArraySize(const CallInst *CI,
- LLVMContext &Context,
- const TargetData* TD) {
- if (!CI)
- return false;
-
- // Type must be known to determine array size.
- const Type* T = getMallocAllocatedType(CI);
- if (!T) return false;
-
- Value* MallocArg = CI->getOperand(1);
- Constant *ElementSize = ConstantExpr::getSizeOf(T);
- ElementSize = ConstantExpr::getTruncOrBitCast(ElementSize,
- MallocArg->getType());
-
- // First, check if it is a non-array malloc.
- if (isa<ConstantExpr>(MallocArg) && (MallocArg == ElementSize))
- return true;
-
- // Second, check if it can be determined that this is an array malloc.
- return isArrayMallocHelper(CI, Context, TD);
-}
-
-/// isConstantOne - Return true only if val is constant int 1.
-static bool isConstantOne(Value *val) {
- return isa<ConstantInt>(val) && cast<ConstantInt>(val)->isOne();
-}
-
-/// getMallocArraySize - Returns the array size of a malloc call. For array
-/// mallocs, the size is computated in 1 of 3 ways:
-/// 1. If the element type is of size 1, then array size is the argument to
-/// malloc.
-/// 2. Else if the malloc's argument is a constant, the array size is that
-/// argument divided by the element type's size.
-/// 3. Else the malloc argument must be a multiplication and the array size is
-/// the first operand of the multiplication.
-/// For non-array mallocs, the computed size is constant 1.
-/// This function returns NULL for all mallocs whose array size cannot be
-/// determined.
-Value* llvm::getMallocArraySize(CallInst* CI, LLVMContext &Context,
- const TargetData* TD) {
- if (!isSafeToGetMallocArraySize(CI, Context, TD))
- return NULL;
-
- // Match CreateMalloc's use of constant 1 array-size for non-array mallocs.
- if (!isArrayMalloc(CI, Context, TD))
- return ConstantInt::get(CI->getOperand(1)->getType(), 1);
-
- Value* MallocArg = CI->getOperand(1);
- assert(getMallocAllocatedType(CI) && "getMallocArraySize and no type");
- Constant *ElementSize = ConstantExpr::getSizeOf(getMallocAllocatedType(CI));
- ElementSize = ConstantExpr::getTruncOrBitCast(ElementSize,
- MallocArg->getType());
-
- Constant* CO = dyn_cast<Constant>(MallocArg);
- BinaryOperator* BO = dyn_cast<BinaryOperator>(MallocArg);
- assert((isConstantOne(ElementSize) || CO || BO) &&
- "getMallocArraySize and malformed malloc IR");
-
- if (isConstantOne(ElementSize))
- return MallocArg;
-
- if (CO)
- return CO->getOperand(0);
-
- // TODO: Detect case where MallocArg mul has been transformed to shl.
-
- assert(BO && "getMallocArraySize not constant but not multiplication either");
- return BO->getOperand(0);
-}
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