Add malloc call utility functions. Patch by Victor Hernandez.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81426 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/MallocHelper.cpp

@@ -0,0 +1,202 @@
+//===-- 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"
+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(Value* I) {
+  return extractMallocCall(I) || extractMallocCallFromBitCast(I);
+}
+
+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();
+  Constant *MallocFunc = M->getFunction("malloc");
+
+  if (CI->getOperand(0) != MallocFunc)
+    return false;
+
+  return true;
+}
+
+/// 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) {
+  if (!CI)
+    return false;
+
+  // Only identify array mallocs for mallocs with 1 bitcast use.  The unique 
+  // bitcast is needed to determine the type/size of the array allocation.
+  if (!CI->hasOneUse()) return false;
+
+  for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
+       UI != E; )
+    if (!isa<BitCastInst>(cast<Instruction>(*UI++)))
+      return false;
+
+  // malloc arg
+  Value* MallocArg = CI->getOperand(1);
+  // element size
+  const Type* T = getMallocAllocatedType(CI);
+  if (!T) return false;
+  Constant *ElementSize = ConstantExpr::getSizeOf(T);
+  
+  if (isa<ConstantExpr>(MallocArg))
+    return (MallocArg == ElementSize) ? false : true;
+
+  BinaryOperator *BI = dyn_cast<BinaryOperator>(MallocArg);
+  if (!BI)
+    return false;
+
+  if (BI->getOpcode() != Instruction::Mul)
+    return false;
+      
+  if (BI->getOperand(1) != ElementSize)
+    return false;
+        
+  return true;
+}
+
+/// 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 malloc's allocated type
+/// or
+///  2. the result of a multiplication by the malloc's allocated type
+/// Otherwise it returns NULL.
+/// The unique bitcast is needed to determine the type/size of the array
+/// allocation.
+CallInst* llvm::isArrayMalloc(Value* I) {
+  CallInst *CI = extractMallocCall(I);
+  return (isArrayMallocHelper(CI)) ? CI : NULL;
+}
+
+const CallInst* llvm::isArrayMalloc(const Value* I) {
+  const CallInst *CI = extractMallocCall(I);
+  return (isArrayMallocHelper(CI)) ? 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 type only if there is only 1 bitcast use of CI.
+  if (CI->hasOneUse())
+    for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
+         UI != E; )
+      BCI = dyn_cast<BitCastInst>(cast<Instruction>(*UI++));
+
+  return BCI ? reinterpret_cast<const PointerType*>(BCI->getDestTy()) : 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;
+}
+
+/// 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.  The array
+/// size is computated in 1 of 3 ways:
+///  1. If the element type if 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.
+/// This function returns constant 1 if:
+///  1. The malloc call's allocated type cannot be determined.
+///  2. IR wasn't created by a call to CallInst::CreateMalloc() with a non-NULL
+///     ArraySize.
+Value* llvm::getMallocArraySize(CallInst* CI) {
+  // Match CreateMalloc's use of constant 1 array-size for non-array mallocs.
+  if (!isArrayMalloc(CI))
+    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(cast<Constant>(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 ConstantExpr::getUDiv(CO, ElementSize);
+  
+  assert(BO && "getMallocArraySize not constant but not multiplication either");
+  return BO->getOperand(0);
+}