AliasAnalysis.h revision c46530b6a32a53edf0d6d32bcd09ea5d76940472
14df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner//===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===// 29769ab22265b313171d201b5928688524a01bd87Misha Brukman// 36fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// The LLVM Compiler Infrastructure 46fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// 57ed47a13356daed2a34cd2209a31f92552e3bdd8Chris Lattner// This file is distributed under the University of Illinois Open Source 67ed47a13356daed2a34cd2209a31f92552e3bdd8Chris Lattner// License. See LICENSE.TXT for details. 79769ab22265b313171d201b5928688524a01bd87Misha Brukman// 86fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell//===----------------------------------------------------------------------===// 94df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// 104df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// This file defines the generic AliasAnalysis interface, which is used as the 114df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// common interface used by all clients of alias analysis information, and 121c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// implemented by all alias analysis implementations. Mod/Ref information is 131c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// also captured by this interface. 144df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// 154df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// Implementations of this interface must implement the various virtual methods, 164df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// which automatically provides functionality for the entire suite of client 174df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// APIs. 184df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// 191c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// This API represents memory as a (Pointer, Size) pair. The Pointer component 201c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// specifies the base memory address of the region, the Size specifies how large 211c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// of an area is being queried. If Size is 0, two pointers only alias if they 221c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// are exactly equal. If size is greater than zero, but small, the two pointers 231c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// alias if the areas pointed to overlap. If the size is very large (ie, ~0U), 241c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// then the two pointers alias if they may be pointing to components of the same 251c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// memory object. Pointers that point to two completely different objects in 261c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// memory never alias, regardless of the value of the Size component. 271c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// 284df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner//===----------------------------------------------------------------------===// 294df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 304df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H 314df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H 324df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 331c56b730a6313886076d7b293a126ae5576f5288Chris Lattner#include "llvm/Support/CallSite.h" 347107c3badfe78ec89dcab6c02cf1b1bcaccc42a8Reid Spencer#include "llvm/System/IncludeFile.h" 3536f78c8935da34074ccd06d5674e45b9cd45da8bChris Lattner#include <vector> 36d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 37d0fde30ce850b78371fd1386338350591f9ff494Brian Gaekenamespace llvm { 38d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 391c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass LoadInst; 401c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass StoreInst; 4114f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharthclass VAArgInst; 421c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass TargetData; 436df60a9effe4d20a48cfd9d105c0ab3c5dc3e690Reid Spencerclass Pass; 446df60a9effe4d20a48cfd9d105c0ab3c5dc3e690Reid Spencerclass AnalysisUsage; 451c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 461c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass AliasAnalysis { 471c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerprotected: 48ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner const TargetData *TD; 49ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner AliasAnalysis *AA; // Previous Alias Analysis to chain to. 50ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 511c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// InitializeAliasAnalysis - Subclasses must call this method to initialize 521c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// the AliasAnalysis interface before any other methods are called. This is 531c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// typically called by the run* methods of these subclasses. This may be 541c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// called multiple times. 551c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 561c56b730a6313886076d7b293a126ae5576f5288Chris Lattner void InitializeAliasAnalysis(Pass *P); 579769ab22265b313171d201b5928688524a01bd87Misha Brukman 5864d237cfae6bcb11157d525c79b5a5335e30370bDan Gohman /// getAnalysisUsage - All alias analysis implementations should invoke this 59fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// directly (using AliasAnalysis::getAnalysisUsage(AU)). 601c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const; 611c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 621c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerpublic: 631997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel static char ID; // Class identification, replacement for typeinfo 64ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner AliasAnalysis() : TD(0), AA(0) {} 651c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual ~AliasAnalysis(); // We want to be subclassed 661c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 67fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// getTargetData - Return a pointer to the current TargetData object, or 68fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// null if no TargetData object is available. 69dd298c8c6eb036baf35bf5a559c59d2afd2c7944Misha Brukman /// 70fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman const TargetData *getTargetData() const { return TD; } 71fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman 72fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// getTypeStoreSize - Return the TargetData store size for the given type, 73fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// if known, or a conservative value otherwise. 74fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// 75fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman unsigned getTypeStoreSize(const Type *Ty); 764df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 771c56b730a6313886076d7b293a126ae5576f5288Chris Lattner //===--------------------------------------------------------------------===// 781c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Alias Queries... 791c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 804df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 81f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Alias analysis result - Either we know for sure that it does not alias, we 82f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// know for sure it must alias, or we don't know anything: The two pointers 83f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// _might_ alias. This enum is designed so you can do things like: 84f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// if (AA.alias(P1, P2)) { ... } 85f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// to check to see if two pointers might alias. 86f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 871c56b730a6313886076d7b293a126ae5576f5288Chris Lattner enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }; 884df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 89f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// alias - The main low level interface to the alias analysis implementation. 90f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Returns a Result indicating whether the two pointers are aliased to each 91f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// other. This is the interface that must be implemented by specific alias 92f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// analysis implementations. 93f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 941c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual AliasResult alias(const Value *V1, unsigned V1Size, 95ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner const Value *V2, unsigned V2Size); 964df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 97c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner /// isNoAlias - A trivial helper function to check to see if the specified 98c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner /// pointers are no-alias. 99c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner bool isNoAlias(const Value *V1, unsigned V1Size, 100c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner const Value *V2, unsigned V2Size) { 101c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner return alias(V1, V1Size, V2, V2Size) == NoAlias; 102c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner } 103c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner 104762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// pointsToConstantMemory - If the specified pointer is known to point into 105762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// constant global memory, return true. This allows disambiguation of store 106762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// instructions from constant pointers. 107762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// 108ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual bool pointsToConstantMemory(const Value *P); 10962b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner 110248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner //===--------------------------------------------------------------------===// 111248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Simple mod/ref information... 112248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 113248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner 114248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are 115248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// bits which may be or'd together. 116248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 117248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }; 1189769ab22265b313171d201b5928688524a01bd87Misha Brukman 1199769ab22265b313171d201b5928688524a01bd87Misha Brukman 120248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefBehavior - Summary of how a function affects memory in the program. 121248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Loads from constant globals are not considered memory accesses for this 122248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// interface. Also, functions may freely modify stack space local to their 123248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// invocation without having to report it through these interfaces. 124248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefBehavior { 125248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // DoesNotAccessMemory - This function does not perform any non-local loads 126248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // or stores to memory. 127248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 128248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'const' attribute. 129248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner DoesNotAccessMemory, 1309769ab22265b313171d201b5928688524a01bd87Misha Brukman 131070fbe69d36b24616de4e484ecbea221a2c7e8c2Duncan Sands // AccessesArguments - This function accesses function arguments in well 132070fbe69d36b24616de4e484ecbea221a2c7e8c2Duncan Sands // known (possibly volatile) ways, but does not access any other memory. 133248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 1344c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // Clients may use the Info parameter of getModRefBehavior to get specific 1354c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // information about how pointer arguments are used. 136248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArguments, 1379769ab22265b313171d201b5928688524a01bd87Misha Brukman 138248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // AccessesArgumentsAndGlobals - This function has accesses function 139070fbe69d36b24616de4e484ecbea221a2c7e8c2Duncan Sands // arguments and global variables well known (possibly volatile) ways, but 140248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // does not access any other memory. 141248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 1424c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // Clients may use the Info parameter of getModRefBehavior to get specific 1434c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // information about how pointer arguments are used. 144248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArgumentsAndGlobals, 1459769ab22265b313171d201b5928688524a01bd87Misha Brukman 146248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // OnlyReadsMemory - This function does not perform any non-local stores or 147248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // volatile loads, but may read from any memory location. 148248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 149248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'pure' attribute. 150248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner OnlyReadsMemory, 1519769ab22265b313171d201b5928688524a01bd87Misha Brukman 152248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // UnknownModRefBehavior - This indicates that the function could not be 153248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // classified into one of the behaviors above. 154248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner UnknownModRefBehavior 155248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner }; 1569769ab22265b313171d201b5928688524a01bd87Misha Brukman 157248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// PointerAccessInfo - This struct is used to return results for pointers, 158248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// globals, and the return value of a function. 159248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner struct PointerAccessInfo { 160248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// V - The value this record corresponds to. This may be an Argument for 161248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// the function, a GlobalVariable, or null, corresponding to the return 162248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// value for the function. 163248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner Value *V; 1649769ab22265b313171d201b5928688524a01bd87Misha Brukman 165248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefInfo - Whether the pointer is loaded or stored to/from. 166248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 167248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ModRefResult ModRefInfo; 1689769ab22265b313171d201b5928688524a01bd87Misha Brukman 169248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// AccessType - Specific fine-grained access information for the argument. 170248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// If none of these classifications is general enough, the 171248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// getModRefBehavior method should not return AccessesArguments*. If a 172248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// record is not returned for a particular argument, the argument is never 173248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// dead and never dereferenced. 174248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum AccessType { 175248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ScalarAccess - The pointer is dereferenced. 176248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 177248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ScalarAccess, 1789769ab22265b313171d201b5928688524a01bd87Misha Brukman 179248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ArrayAccess - The pointer is indexed through as an array of elements. 180248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 181248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ArrayAccess, 1829769ab22265b313171d201b5928688524a01bd87Misha Brukman 183248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ElementAccess ?? P->F only? 1849769ab22265b313171d201b5928688524a01bd87Misha Brukman 185248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// CallsThrough - Indirect calls are made through the specified function 186248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// pointer. 187410354fe0c052141dadeca939395743f8dd58e38Chris Lattner CallsThrough 188248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner }; 1899769ab22265b313171d201b5928688524a01bd87Misha Brukman }; 1909769ab22265b313171d201b5928688524a01bd87Misha Brukman 191dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// getModRefBehavior - Return the behavior when calling the given call site. 192e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson virtual ModRefBehavior getModRefBehavior(CallSite CS, 193dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands std::vector<PointerAccessInfo> *Info = 0); 194dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 195dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// getModRefBehavior - Return the behavior when calling the given function. 196dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// For use when the call site is not known. 197e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson virtual ModRefBehavior getModRefBehavior(Function *F, 198dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands std::vector<PointerAccessInfo> *Info = 0); 199dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 200dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// doesNotAccessMemory - If the specified call is known to never read or 201dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// write memory, return true. If the call only reads from known-constant 202dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// memory, it is also legal to return true. Calls that unwind the stack 203dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// are legal for this predicate. 2043e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 205dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// Many optimizations (such as CSE and LICM) can be performed on such calls 206dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// without worrying about aliasing properties, and many calls have this 207dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// property (e.g. calls to 'sin' and 'cos'). 2083e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2093e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'const' attribute. 2103e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 211652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng bool doesNotAccessMemory(CallSite CS) { 212652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng return getModRefBehavior(CS) == DoesNotAccessMemory; 213dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands } 214dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 215dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// doesNotAccessMemory - If the specified function is known to never read or 216dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// write memory, return true. For use when the call site is not known. 217dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// 218248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool doesNotAccessMemory(Function *F) { 219dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands return getModRefBehavior(F) == DoesNotAccessMemory; 220248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2213e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner 222dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// onlyReadsMemory - If the specified call is known to only read from 223dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// non-volatile memory (or not access memory at all), return true. Calls 224dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// that unwind the stack are legal for this predicate. 2253e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2263e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property allows many common optimizations to be performed in the 2273e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// absence of interfering store instructions, such as CSE of strlen calls. 2283e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2293e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'pure' attribute. 2303e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 231652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng bool onlyReadsMemory(CallSite CS) { 232652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng ModRefBehavior MRB = getModRefBehavior(CS); 233dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory; 234dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands } 235dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 236dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// onlyReadsMemory - If the specified function is known to only read from 237dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// non-volatile memory (or not access memory at all), return true. For use 238dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// when the call site is not known. 239dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// 240248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool onlyReadsMemory(Function *F) { 241dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands ModRefBehavior MRB = getModRefBehavior(F); 2428eec644862251e14add0d2707d655fcce91e8f70Chris Lattner return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory; 243248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2444df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 2451c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2461c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether or not an instruction may 2471c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// read or write memory specified by the pointer operand. An instruction 2481c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// that doesn't read or write memory may be trivially LICM'd for example. 2491c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2501c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo (for call sites) - Return whether information about whether 2511c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// a particular call site modifies or reads the memory specified by the 2521c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// pointer. 2531c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 254652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 2551c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2561c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether two call sites may refer 2571c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// to the same set of memory locations. This function returns NoModRef if 258414c36769aff6ec688c49f493122529394357d05Chris Lattner /// the two calls refer to disjoint memory locations, Ref if CS1 reads memory 259414c36769aff6ec688c49f493122529394357d05Chris Lattner /// written by CS2, Mod if CS1 writes to memory read or written by CS2, or 260414c36769aff6ec688c49f493122529394357d05Chris Lattner /// ModRef if CS1 might read or write memory accessed by CS2. 2611c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 262652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2); 2631c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 264dff6710717b159f089c76a07eda074eb6347eb92Duncan Sandspublic: 2651c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Convenience functions... 2661c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size); 2675cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(StoreInst *S, Value *P, unsigned Size); 2685cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) { 2691c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(C), P, Size); 2701c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2715cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) { 2721c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(I), P, Size); 2731c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 27414f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth ModRefResult getModRefInfo(VAArgInst* I, Value* P, unsigned Size) { 2751ef14f6e768eac76fc272320e79bdbd90747ef47Owen Anderson return AliasAnalysis::ModRef; 27614f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth } 2771c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) { 2781c56b730a6313886076d7b293a126ae5576f5288Chris Lattner switch (I->getOpcode()) { 27914f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth case Instruction::VAArg: return getModRefInfo((VAArgInst*)I, P, Size); 2801c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Load: return getModRefInfo((LoadInst*)I, P, Size); 2811c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Store: return getModRefInfo((StoreInst*)I, P, Size); 2821c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Call: return getModRefInfo((CallInst*)I, P, Size); 2831c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Invoke: return getModRefInfo((InvokeInst*)I, P, Size); 2841c56b730a6313886076d7b293a126ae5576f5288Chris Lattner default: return NoModRef; 2851c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2861c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2874df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 288ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 289ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Higher level methods for querying mod/ref information. 290ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 291ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 292f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canBasicBlockModify - Return true if it is possible for execution of the 293f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// specified basic block to modify the value pointed to by Ptr. 294f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 2951c56b730a6313886076d7b293a126ae5576f5288Chris Lattner bool canBasicBlockModify(const BasicBlock &BB, const Value *P, unsigned Size); 2964df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 297f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canInstructionRangeModify - Return true if it is possible for the 298f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// execution of the specified instructions to modify the value pointed to by 299f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Ptr. The instructions to consider are all of the instructions in the 300f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// range of [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block. 301f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 3024df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2, 3031c56b730a6313886076d7b293a126ae5576f5288Chris Lattner const Value *Ptr, unsigned Size); 304ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 305ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 306ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Methods that clients should call when they transform the program to allow 307ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// alias analyses to update their internal data structures. Note that these 308ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// methods may be called on any instruction, regardless of whether or not 309ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// they have pointer-analysis implications. 310ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 311ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 312ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleteValue - This method should be called whenever an LLVM Value is 313ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleted from the program, for example when an instruction is found to be 314ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// redundant and is eliminated. 315ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 316ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void deleteValue(Value *V); 317ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 318ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// copyValue - This method should be used whenever a preexisting value in the 319ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// program is copied or cloned, introducing a new value. Note that analysis 320ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// implementations should tolerate clients that use this method to introduce 321ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// the same value multiple times: if the analysis already knows about a 322ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// value, it should ignore the request. 323ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 324ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void copyValue(Value *From, Value *To); 325ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 326ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// replaceWithNewValue - This method is the obvious combination of the two 327ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// above, and it provided as a helper to simplify client code. 328ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 329ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner void replaceWithNewValue(Value *Old, Value *New) { 330ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner copyValue(Old, New); 331ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner deleteValue(Old); 332ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner } 3334df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner}; 3344df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 335a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// isNoAliasCall - Return true if this pointer is returned by a noalias 336a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// function. 337a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohmanbool isNoAliasCall(const Value *V); 338a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman 3393311a1f8f0d8a2c6d940802bbb95eba0b801a615Dan Gohman/// isIdentifiedObject - Return true if this pointer refers to a distinct and 340a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// identifiable object. This returns true for: 3415753a4a0033da4add45f2e9930a4e1159d92a869Dan Gohman/// Global Variables and Functions (but not Global Aliases) 342a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// Allocas and Mallocs 343a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// ByVal and NoAlias Arguments 344a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// NoAlias returns 3453311a1f8f0d8a2c6d940802bbb95eba0b801a615Dan Gohman/// 3463311a1f8f0d8a2c6d940802bbb95eba0b801a615Dan Gohmanbool isIdentifiedObject(const Value *V); 3473311a1f8f0d8a2c6d940802bbb95eba0b801a615Dan Gohman 3484f1bd9e9963239c119db70070db1d68286b3de7eReid Spencer} // End llvm namespace 3494f1bd9e9963239c119db70070db1d68286b3de7eReid Spencer 350fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// Because of the way .a files work, we must force the BasicAA implementation to 351fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// be pulled in if the AliasAnalysis header is included. Otherwise we run 352fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// the risk of AliasAnalysis being used, but the default implementation not 353fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// being linked into the tool that uses it. 3544f1bd9e9963239c119db70070db1d68286b3de7eReid SpencerFORCE_DEFINING_FILE_TO_BE_LINKED(AliasAnalysis) 3554f1bd9e9963239c119db70070db1d68286b3de7eReid SpencerFORCE_DEFINING_FILE_TO_BE_LINKED(BasicAliasAnalysis) 356d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3574df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#endif 358