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
diff --git a/lib/Analysis/MallocHelper.cpp b/lib/Analysis/MallocHelper.cpp
new file mode 100644
index 0000000..5001110
--- /dev/null
+++ b/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);
+}