AliasAnalysis.h revision e53e3772f3c8b4cba69b7d77c8b2148a080fe9ae
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 21e53e3772f3c8b4cba69b7d77c8b2148a080fe9aeDan Gohman// of an area is being queried, or UnknownSize if the size is not known. 22e53e3772f3c8b4cba69b7d77c8b2148a080fe9aeDan Gohman// Pointers that point to two completely different objects in memory never 23e53e3772f3c8b4cba69b7d77c8b2148a080fe9aeDan Gohman// alias, regardless of the value of the Size component. 241c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// 254df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner//===----------------------------------------------------------------------===// 264df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 274df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H 284df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H 294df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 301c56b730a6313886076d7b293a126ae5576f5288Chris Lattner#include "llvm/Support/CallSite.h" 317107c3badfe78ec89dcab6c02cf1b1bcaccc42a8Reid Spencer#include "llvm/System/IncludeFile.h" 3236f78c8935da34074ccd06d5674e45b9cd45da8bChris Lattner#include <vector> 33d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 34d0fde30ce850b78371fd1386338350591f9ff494Brian Gaekenamespace llvm { 35d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 361c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass LoadInst; 371c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass StoreInst; 3814f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharthclass VAArgInst; 391c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass TargetData; 406df60a9effe4d20a48cfd9d105c0ab3c5dc3e690Reid Spencerclass Pass; 416df60a9effe4d20a48cfd9d105c0ab3c5dc3e690Reid Spencerclass AnalysisUsage; 421c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 431c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass AliasAnalysis { 441c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerprotected: 45ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner const TargetData *TD; 46ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner AliasAnalysis *AA; // Previous Alias Analysis to chain to. 47ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 481c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// InitializeAliasAnalysis - Subclasses must call this method to initialize 491c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// the AliasAnalysis interface before any other methods are called. This is 501c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// typically called by the run* methods of these subclasses. This may be 511c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// called multiple times. 521c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 531c56b730a6313886076d7b293a126ae5576f5288Chris Lattner void InitializeAliasAnalysis(Pass *P); 549769ab22265b313171d201b5928688524a01bd87Misha Brukman 5564d237cfae6bcb11157d525c79b5a5335e30370bDan Gohman /// getAnalysisUsage - All alias analysis implementations should invoke this 56fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// directly (using AliasAnalysis::getAnalysisUsage(AU)). 571c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const; 581c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 591c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerpublic: 601997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel static char ID; // Class identification, replacement for typeinfo 61ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner AliasAnalysis() : TD(0), AA(0) {} 621c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual ~AliasAnalysis(); // We want to be subclassed 631c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 64ef1cfac9e50def9097cd3e3ab3c5cad7f4c758ccDan Gohman /// UnknownSize - This is a special value which can be used with the 65ef1cfac9e50def9097cd3e3ab3c5cad7f4c758ccDan Gohman /// size arguments in alias queries to indicate that the caller does not 66ef1cfac9e50def9097cd3e3ab3c5cad7f4c758ccDan Gohman /// know the sizes of the potential memory references. 67ef1cfac9e50def9097cd3e3ab3c5cad7f4c758ccDan Gohman static unsigned const UnknownSize = ~0u; 68ef1cfac9e50def9097cd3e3ab3c5cad7f4c758ccDan Gohman 69fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// getTargetData - Return a pointer to the current TargetData object, or 70fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// null if no TargetData object is available. 71dd298c8c6eb036baf35bf5a559c59d2afd2c7944Misha Brukman /// 72fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman const TargetData *getTargetData() const { return TD; } 73fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman 74fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// getTypeStoreSize - Return the TargetData store size for the given type, 75fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// if known, or a conservative value otherwise. 76fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman /// 77fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman unsigned getTypeStoreSize(const Type *Ty); 784df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 791c56b730a6313886076d7b293a126ae5576f5288Chris Lattner //===--------------------------------------------------------------------===// 801c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Alias Queries... 811c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 824df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 83f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Alias analysis result - Either we know for sure that it does not alias, we 84f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// know for sure it must alias, or we don't know anything: The two pointers 85f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// _might_ alias. This enum is designed so you can do things like: 86f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// if (AA.alias(P1, P2)) { ... } 87f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// to check to see if two pointers might alias. 88f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 89e53e3772f3c8b4cba69b7d77c8b2148a080fe9aeDan Gohman /// See docs/AliasAnalysis.html for more information on the specific meanings 90e53e3772f3c8b4cba69b7d77c8b2148a080fe9aeDan Gohman /// of these values. 91e53e3772f3c8b4cba69b7d77c8b2148a080fe9aeDan Gohman /// 921c56b730a6313886076d7b293a126ae5576f5288Chris Lattner enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }; 934df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 94f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// alias - The main low level interface to the alias analysis implementation. 95f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Returns a Result indicating whether the two pointers are aliased to each 96f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// other. This is the interface that must be implemented by specific alias 97f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// analysis implementations. 98f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 991c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual AliasResult alias(const Value *V1, unsigned V1Size, 100ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner const Value *V2, unsigned V2Size); 1014df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 102847a84efd23a2c7d90429b82f6e0f19d1f913d9aDan Gohman /// alias - A convenience wrapper for the case where the sizes are unknown. 103847a84efd23a2c7d90429b82f6e0f19d1f913d9aDan Gohman AliasResult alias(const Value *V1, const Value *V2) { 104ef1cfac9e50def9097cd3e3ab3c5cad7f4c758ccDan Gohman return alias(V1, UnknownSize, V2, UnknownSize); 105847a84efd23a2c7d90429b82f6e0f19d1f913d9aDan Gohman } 106847a84efd23a2c7d90429b82f6e0f19d1f913d9aDan Gohman 107c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner /// isNoAlias - A trivial helper function to check to see if the specified 108c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner /// pointers are no-alias. 109c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner bool isNoAlias(const Value *V1, unsigned V1Size, 110c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner const Value *V2, unsigned V2Size) { 111c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner return alias(V1, V1Size, V2, V2Size) == NoAlias; 112c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner } 113c46530b6a32a53edf0d6d32bcd09ea5d76940472Chris Lattner 114762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// pointsToConstantMemory - If the specified pointer is known to point into 115762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// constant global memory, return true. This allows disambiguation of store 116762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// instructions from constant pointers. 117762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// 118ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual bool pointsToConstantMemory(const Value *P); 11962b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner 120248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner //===--------------------------------------------------------------------===// 121248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Simple mod/ref information... 122248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 123248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner 124248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are 125248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// bits which may be or'd together. 126248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 127248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }; 1289769ab22265b313171d201b5928688524a01bd87Misha Brukman 1299769ab22265b313171d201b5928688524a01bd87Misha Brukman 130248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefBehavior - Summary of how a function affects memory in the program. 131248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Loads from constant globals are not considered memory accesses for this 132248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// interface. Also, functions may freely modify stack space local to their 133248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// invocation without having to report it through these interfaces. 134248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefBehavior { 135248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // DoesNotAccessMemory - This function does not perform any non-local loads 136248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // or stores to memory. 137248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 138248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'const' attribute. 139248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner DoesNotAccessMemory, 1409769ab22265b313171d201b5928688524a01bd87Misha Brukman 141070fbe69d36b24616de4e484ecbea221a2c7e8c2Duncan Sands // AccessesArguments - This function accesses function arguments in well 142070fbe69d36b24616de4e484ecbea221a2c7e8c2Duncan Sands // known (possibly volatile) ways, but does not access any other memory. 143248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 1444c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // Clients may use the Info parameter of getModRefBehavior to get specific 1454c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // information about how pointer arguments are used. 146248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArguments, 1479769ab22265b313171d201b5928688524a01bd87Misha Brukman 148248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // AccessesArgumentsAndGlobals - This function has accesses function 149070fbe69d36b24616de4e484ecbea221a2c7e8c2Duncan Sands // arguments and global variables well known (possibly volatile) ways, but 150248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // does not access any other memory. 151248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 1524c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // Clients may use the Info parameter of getModRefBehavior to get specific 1534c0d95178010c8788129b392ab6a1c62484f1620Dan Gohman // information about how pointer arguments are used. 154248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArgumentsAndGlobals, 1559769ab22265b313171d201b5928688524a01bd87Misha Brukman 156248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // OnlyReadsMemory - This function does not perform any non-local stores or 157248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // volatile loads, but may read from any memory location. 158248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 159248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'pure' attribute. 160248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner OnlyReadsMemory, 1619769ab22265b313171d201b5928688524a01bd87Misha Brukman 162248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // UnknownModRefBehavior - This indicates that the function could not be 163248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // classified into one of the behaviors above. 164248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner UnknownModRefBehavior 165248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner }; 1669769ab22265b313171d201b5928688524a01bd87Misha Brukman 167248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// PointerAccessInfo - This struct is used to return results for pointers, 168248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// globals, and the return value of a function. 169248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner struct PointerAccessInfo { 170248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// V - The value this record corresponds to. This may be an Argument for 171248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// the function, a GlobalVariable, or null, corresponding to the return 172248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// value for the function. 173248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner Value *V; 1749769ab22265b313171d201b5928688524a01bd87Misha Brukman 175248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefInfo - Whether the pointer is loaded or stored to/from. 176248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 177248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ModRefResult ModRefInfo; 1789769ab22265b313171d201b5928688524a01bd87Misha Brukman }; 1799769ab22265b313171d201b5928688524a01bd87Misha Brukman 180dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// getModRefBehavior - Return the behavior when calling the given call site. 181e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson virtual ModRefBehavior getModRefBehavior(CallSite CS, 182dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands std::vector<PointerAccessInfo> *Info = 0); 183dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 184dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// getModRefBehavior - Return the behavior when calling the given function. 185dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// For use when the call site is not known. 186e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson virtual ModRefBehavior getModRefBehavior(Function *F, 187dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands std::vector<PointerAccessInfo> *Info = 0); 188dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 1897c422ac216fe39fc9c402a704cf296cca9dc5b22Duncan Sands /// getModRefBehavior - Return the modref behavior of the intrinsic with the 1907c422ac216fe39fc9c402a704cf296cca9dc5b22Duncan Sands /// given id. 1917c422ac216fe39fc9c402a704cf296cca9dc5b22Duncan Sands static ModRefBehavior getModRefBehavior(unsigned iid); 1927c422ac216fe39fc9c402a704cf296cca9dc5b22Duncan Sands 193dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// doesNotAccessMemory - If the specified call is known to never read or 194dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// write memory, return true. If the call only reads from known-constant 195dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// memory, it is also legal to return true. Calls that unwind the stack 196dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// are legal for this predicate. 1973e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 198dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// Many optimizations (such as CSE and LICM) can be performed on such calls 199dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// without worrying about aliasing properties, and many calls have this 200dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// property (e.g. calls to 'sin' and 'cos'). 2013e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2023e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'const' attribute. 2033e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 204652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng bool doesNotAccessMemory(CallSite CS) { 205652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng return getModRefBehavior(CS) == DoesNotAccessMemory; 206dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands } 207dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 208dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// doesNotAccessMemory - If the specified function is known to never read or 209dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// write memory, return true. For use when the call site is not known. 210dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// 211248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool doesNotAccessMemory(Function *F) { 212dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands return getModRefBehavior(F) == DoesNotAccessMemory; 213248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2143e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner 215dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// onlyReadsMemory - If the specified call is known to only read from 216dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// non-volatile memory (or not access memory at all), return true. Calls 217dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// that unwind the stack are legal for this predicate. 2183e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2193e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property allows many common optimizations to be performed in the 2203e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// absence of interfering store instructions, such as CSE of strlen calls. 2213e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2223e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'pure' attribute. 2233e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 224652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng bool onlyReadsMemory(CallSite CS) { 225652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng ModRefBehavior MRB = getModRefBehavior(CS); 226dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory; 227dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands } 228dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 229dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// onlyReadsMemory - If the specified function is known to only read from 230dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// non-volatile memory (or not access memory at all), return true. For use 231dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// when the call site is not known. 232dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// 233248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool onlyReadsMemory(Function *F) { 234dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands ModRefBehavior MRB = getModRefBehavior(F); 2358eec644862251e14add0d2707d655fcce91e8f70Chris Lattner return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory; 236248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2374df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 2381c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2391c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether or not an instruction may 2401c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// read or write memory specified by the pointer operand. An instruction 2411c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// that doesn't read or write memory may be trivially LICM'd for example. 2421c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2431c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo (for call sites) - Return whether information about whether 2441c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// a particular call site modifies or reads the memory specified by the 2451c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// pointer. 2461c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 247652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 2481c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2491c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether two call sites may refer 2501c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// to the same set of memory locations. This function returns NoModRef if 251414c36769aff6ec688c49f493122529394357d05Chris Lattner /// the two calls refer to disjoint memory locations, Ref if CS1 reads memory 252414c36769aff6ec688c49f493122529394357d05Chris Lattner /// written by CS2, Mod if CS1 writes to memory read or written by CS2, or 253414c36769aff6ec688c49f493122529394357d05Chris Lattner /// ModRef if CS1 might read or write memory accessed by CS2. 2541c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 255652f7ea955bb433d6b7a4d33685dca9485fd7b8bEvan Cheng virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2); 2561c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 257dff6710717b159f089c76a07eda074eb6347eb92Duncan Sandspublic: 2581c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Convenience functions... 2591c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size); 2605cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(StoreInst *S, Value *P, unsigned Size); 2615cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) { 2621c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(C), P, Size); 2631c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2645cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) { 2651c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(I), P, Size); 2661c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 26714f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth ModRefResult getModRefInfo(VAArgInst* I, Value* P, unsigned Size) { 2681ef14f6e768eac76fc272320e79bdbd90747ef47Owen Anderson return AliasAnalysis::ModRef; 26914f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth } 2701c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) { 2711c56b730a6313886076d7b293a126ae5576f5288Chris Lattner switch (I->getOpcode()) { 27214f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth case Instruction::VAArg: return getModRefInfo((VAArgInst*)I, P, Size); 2731c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Load: return getModRefInfo((LoadInst*)I, P, Size); 2741c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Store: return getModRefInfo((StoreInst*)I, P, Size); 2751c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Call: return getModRefInfo((CallInst*)I, P, Size); 2761c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Invoke: return getModRefInfo((InvokeInst*)I, P, Size); 2771c56b730a6313886076d7b293a126ae5576f5288Chris Lattner default: return NoModRef; 2781c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2791c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2804df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 281ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 282ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Higher level methods for querying mod/ref information. 283ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 284ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 285f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canBasicBlockModify - Return true if it is possible for execution of the 286f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// specified basic block to modify the value pointed to by Ptr. 287f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 2881c56b730a6313886076d7b293a126ae5576f5288Chris Lattner bool canBasicBlockModify(const BasicBlock &BB, const Value *P, unsigned Size); 2894df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 290f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canInstructionRangeModify - Return true if it is possible for the 291f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// execution of the specified instructions to modify the value pointed to by 292f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Ptr. The instructions to consider are all of the instructions in the 293f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// range of [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block. 294f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 2954df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2, 2961c56b730a6313886076d7b293a126ae5576f5288Chris Lattner const Value *Ptr, unsigned Size); 297ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 298ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 299ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Methods that clients should call when they transform the program to allow 300ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// alias analyses to update their internal data structures. Note that these 301ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// methods may be called on any instruction, regardless of whether or not 302ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// they have pointer-analysis implications. 303ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 304ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 305ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleteValue - This method should be called whenever an LLVM Value is 306ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleted from the program, for example when an instruction is found to be 307ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// redundant and is eliminated. 308ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 309ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void deleteValue(Value *V); 310ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 311ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// copyValue - This method should be used whenever a preexisting value in the 312ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// program is copied or cloned, introducing a new value. Note that analysis 313ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// implementations should tolerate clients that use this method to introduce 314ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// the same value multiple times: if the analysis already knows about a 315ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// value, it should ignore the request. 316ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 317ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void copyValue(Value *From, Value *To); 318ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 319ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// replaceWithNewValue - This method is the obvious combination of the two 320ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// above, and it provided as a helper to simplify client code. 321ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 322ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner void replaceWithNewValue(Value *Old, Value *New) { 323ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner copyValue(Old, New); 324ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner deleteValue(Old); 325ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner } 3264df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner}; 3274df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 328a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// isNoAliasCall - Return true if this pointer is returned by a noalias 329a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// function. 330a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohmanbool isNoAliasCall(const Value *V); 331a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman 3323311a1f8f0d8a2c6d940802bbb95eba0b801a615Dan Gohman/// isIdentifiedObject - Return true if this pointer refers to a distinct and 333a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// identifiable object. This returns true for: 3345753a4a0033da4add45f2e9930a4e1159d92a869Dan Gohman/// Global Variables and Functions (but not Global Aliases) 335a5f81bba4ab18d6129774d4d67495f14b6f64375Dan Gohman/// Allocas and Mallocs 3369e86f4364b912ae743490ba01d6989acfd12c046Dan Gohman/// ByVal and NoAlias Arguments 3379e86f4364b912ae743490ba01d6989acfd12c046Dan Gohman/// NoAlias returns 3383311a1f8f0d8a2c6d940802bbb95eba0b801a615Dan Gohman/// 3399e86f4364b912ae743490ba01d6989acfd12c046Dan Gohmanbool isIdentifiedObject(const Value *V); 3403311a1f8f0d8a2c6d940802bbb95eba0b801a615Dan Gohman 3414f1bd9e9963239c119db70070db1d68286b3de7eReid Spencer} // End llvm namespace 3424f1bd9e9963239c119db70070db1d68286b3de7eReid Spencer 343fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// Because of the way .a files work, we must force the BasicAA implementation to 344fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// be pulled in if the AliasAnalysis header is included. Otherwise we run 345fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// the risk of AliasAnalysis being used, but the default implementation not 346fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// being linked into the tool that uses it. 3474f1bd9e9963239c119db70070db1d68286b3de7eReid SpencerFORCE_DEFINING_FILE_TO_BE_LINKED(AliasAnalysis) 3484f1bd9e9963239c119db70070db1d68286b3de7eReid SpencerFORCE_DEFINING_FILE_TO_BE_LINKED(BasicAliasAnalysis) 349d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3504df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#endif 351