ValueTracking.h revision cf5128ec01f45d2bf7eadc20b253cb44486e473f
1656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project//===- llvm/Analysis/ValueTracking.h - Walk computations --------*- C++ -*-===// 2656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// 3656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// The LLVM Compiler Infrastructure 4656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// 5656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// This file is distributed under the University of Illinois Open Source 6656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// License. See LICENSE.TXT for details. 7221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom// 8656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project//===----------------------------------------------------------------------===// 9656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// 10656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// This file contains routines that help analyze properties that chains of 11656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// computations have. 12656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project// 13656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project//===----------------------------------------------------------------------===// 14656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 15656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#ifndef LLVM_ANALYSIS_VALUETRACKING_H 16656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#define LLVM_ANALYSIS_VALUETRACKING_H 17656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 18656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include "llvm/Support/DataTypes.h" 19656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project#include <string> 20656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 21656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Projectnamespace llvm { 22656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project class Value; 23656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project class Instruction; 24656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project class APInt; 25656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project class TargetData; 26656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project class LLVMContext; 27656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 28656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// ComputeMaskedBits - Determine which of the bits specified in Mask are 29656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// known to be either zero or one and return them in the KnownZero/KnownOne 30656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// bit sets. This code only analyzes bits in Mask, in order to short-circuit 31656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// processing. 32656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// 33656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// This function is defined on values with integer type, values with pointer 34656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// type (but only if TD is non-null), and vectors of integers. In the case 35656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// where V is a vector, the mask, known zero, and known one values are the 36656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// same width as the vector element, and the bit is set only if it is true 37656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// for all of the elements in the vector. 38656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero, 39656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project APInt &KnownOne, const TargetData *TD = 0, 40656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project unsigned Depth = 0); 41656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 42656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use 43656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// this predicate to simplify operations downstream. Mask is known to be 44656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// zero for bits that V cannot have. 45656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// 46656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// This function is defined on values with integer type, values with pointer 47656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// type (but only if TD is non-null), and vectors of integers. In the case 48656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// where V is a vector, the mask, known zero, and known one values are the 49656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// same width as the vector element, and the bit is set only if it is true 50656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// for all of the elements in the vector. 51656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project bool MaskedValueIsZero(Value *V, const APInt &Mask, 52656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const TargetData *TD = 0, unsigned Depth = 0); 53656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 54656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 55656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// ComputeNumSignBits - Return the number of times the sign bit of the 56656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// register is replicated into the other bits. We know that at least 1 bit 57656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// is always equal to the sign bit (itself), but other cases can give us 58656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// information. For example, immediately after an "ashr X, 2", we know that 59656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// the top 3 bits are all equal to each other, so we return 3. 60656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// 61656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// 'Op' must have a scalar integer type. 62656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// 63656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project unsigned ComputeNumSignBits(Value *Op, const TargetData *TD = 0, 64656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project unsigned Depth = 0); 65656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 66656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// CannotBeNegativeZero - Return true if we can prove that the specified FP 67656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// value is never equal to -0.0. 68656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// 69656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0); 70656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 71656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// FindScalarValue - Given an aggregrate and an sequence of indices, see if 72656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// the scalar value indexed is already around as a register, for example if 73656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// it were inserted directly into the aggregrate. 74656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// 75656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// If InsertBefore is not null, this function will duplicate (modified) 76656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// insertvalues when a part of a nested struct is extracted. 77656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project Value *FindInsertedValue(Value *V, 78656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned *idx_begin, 79656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned *idx_end, 80656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project LLVMContext &Context, 81656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project Instruction *InsertBefore = 0); 82656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 83656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// This is a convenience wrapper for finding values indexed by a single index 84221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom /// only. 85221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom inline Value *FindInsertedValue(Value *V, const unsigned Idx, 86656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project LLVMContext &Context, 87656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project Instruction *InsertBefore = 0) { 88656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project const unsigned Idxs[1] = { Idx }; 89221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom return FindInsertedValue(V, &Idxs[0], &Idxs[1], Context, InsertBefore); 90221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom } 91656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 92221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom /// GetConstantStringInfo - This function computes the length of a 93656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project /// null-terminated C string pointed to by V. If successful, it returns true 94221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom /// and returns the string in Str. If unsuccessful, it returns false. If 95221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom /// StopAtNul is set to true (the default), the returned string is truncated 96221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom /// by a nul character in the global. If StopAtNul is false, the nul 97221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom /// character is included in the result string. 98221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom bool GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset = 0, 99656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project bool StopAtNul = true); 100221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom} // end namespace llvm 101656d9c7f52f88b3a3daccafa7655dec086c4756eThe Android Open Source Project 102221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom#endif 103221304ee937bc0910948a8be1320cb8cc4eb6d36Brian Carlstrom