AliasAnalysis.h revision dff6710717b159f089c76a07eda074eb6347eb92
14df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner//===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===// 29769ab22265b313171d201b5928688524a01bd87Misha Brukman// 36fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// The LLVM Compiler Infrastructure 46fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// 56fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// This file was developed by the LLVM research group and is distributed under 66fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// the University of Illinois Open Source 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 581c56b730a6313886076d7b293a126ae5576f5288Chris Lattner // getAnalysisUsage - All alias analysis implementations should invoke this 591c56b730a6313886076d7b293a126ae5576f5288Chris Lattner // directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that 601c56b730a6313886076d7b293a126ae5576f5288Chris Lattner // TargetData is required by the pass. 611c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const; 621c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 631c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerpublic: 641997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel static char ID; // Class identification, replacement for typeinfo 65ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner AliasAnalysis() : TD(0), AA(0) {} 661c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual ~AliasAnalysis(); // We want to be subclassed 671c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 681c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getTargetData - Every alias analysis implementation depends on the size of 691c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// data items in the current Target. This provides a uniform way to handle 701c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// it. 71dd298c8c6eb036baf35bf5a559c59d2afd2c7944Misha Brukman /// 721c56b730a6313886076d7b293a126ae5576f5288Chris Lattner const TargetData &getTargetData() const { return *TD; } 734df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 741c56b730a6313886076d7b293a126ae5576f5288Chris Lattner //===--------------------------------------------------------------------===// 751c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Alias Queries... 761c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 774df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 78f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Alias analysis result - Either we know for sure that it does not alias, we 79f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// know for sure it must alias, or we don't know anything: The two pointers 80f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// _might_ alias. This enum is designed so you can do things like: 81f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// if (AA.alias(P1, P2)) { ... } 82f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// to check to see if two pointers might alias. 83f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 841c56b730a6313886076d7b293a126ae5576f5288Chris Lattner enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }; 854df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 86f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// alias - The main low level interface to the alias analysis implementation. 87f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Returns a Result indicating whether the two pointers are aliased to each 88f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// other. This is the interface that must be implemented by specific alias 89f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// analysis implementations. 90f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 911c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual AliasResult alias(const Value *V1, unsigned V1Size, 92ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner const Value *V2, unsigned V2Size); 934df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 9462b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// getMustAliases - If there are any pointers known that must alias this 9562b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// pointer, return them now. This allows alias-set based alias analyses to 9662b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// perform a form a value numbering (which is exposed by load-vn). If an 9762b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// alias analysis supports this, it should ADD any must aliased pointers to 9862b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// the specified vector. 9962b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// 100ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void getMustAliases(Value *P, std::vector<Value*> &RetVals); 10162b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner 102762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// pointsToConstantMemory - If the specified pointer is known to point into 103762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// constant global memory, return true. This allows disambiguation of store 104762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// instructions from constant pointers. 105762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// 106ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual bool pointsToConstantMemory(const Value *P); 10762b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner 108248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner //===--------------------------------------------------------------------===// 109248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Simple mod/ref information... 110248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 111248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner 112248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are 113248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// bits which may be or'd together. 114248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 115248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }; 1169769ab22265b313171d201b5928688524a01bd87Misha Brukman 1179769ab22265b313171d201b5928688524a01bd87Misha Brukman 118248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefBehavior - Summary of how a function affects memory in the program. 119248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Loads from constant globals are not considered memory accesses for this 120248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// interface. Also, functions may freely modify stack space local to their 121248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// invocation without having to report it through these interfaces. 122248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefBehavior { 123248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // DoesNotAccessMemory - This function does not perform any non-local loads 124248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // or stores to memory. 125248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 126248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'const' attribute. 127248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner DoesNotAccessMemory, 1289769ab22265b313171d201b5928688524a01bd87Misha Brukman 129248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // AccessesArguments - This function accesses function arguments in 130248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // non-volatile and well known ways, but does not access any other memory. 131248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 132248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // Clients may call getArgumentAccesses to get specific information about 133248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // how pointer arguments are used. 134248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArguments, 1359769ab22265b313171d201b5928688524a01bd87Misha Brukman 136248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // AccessesArgumentsAndGlobals - This function has accesses function 137248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // arguments and global variables in non-volatile and well-known ways, but 138248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // does not access any other memory. 139248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 140248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // Clients may call getArgumentAccesses to get specific information about 141248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // how pointer arguments and globals are used. 142248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArgumentsAndGlobals, 1439769ab22265b313171d201b5928688524a01bd87Misha Brukman 144248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // OnlyReadsMemory - This function does not perform any non-local stores or 145248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // volatile loads, but may read from any memory location. 146248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 147248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'pure' attribute. 148248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner OnlyReadsMemory, 1499769ab22265b313171d201b5928688524a01bd87Misha Brukman 150248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // UnknownModRefBehavior - This indicates that the function could not be 151248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // classified into one of the behaviors above. 152248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner UnknownModRefBehavior 153248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner }; 1549769ab22265b313171d201b5928688524a01bd87Misha Brukman 155248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// PointerAccessInfo - This struct is used to return results for pointers, 156248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// globals, and the return value of a function. 157248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner struct PointerAccessInfo { 158248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// V - The value this record corresponds to. This may be an Argument for 159248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// the function, a GlobalVariable, or null, corresponding to the return 160248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// value for the function. 161248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner Value *V; 1629769ab22265b313171d201b5928688524a01bd87Misha Brukman 163248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefInfo - Whether the pointer is loaded or stored to/from. 164248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 165248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ModRefResult ModRefInfo; 1669769ab22265b313171d201b5928688524a01bd87Misha Brukman 167248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// AccessType - Specific fine-grained access information for the argument. 168248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// If none of these classifications is general enough, the 169248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// getModRefBehavior method should not return AccessesArguments*. If a 170248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// record is not returned for a particular argument, the argument is never 171248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// dead and never dereferenced. 172248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum AccessType { 173248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ScalarAccess - The pointer is dereferenced. 174248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 175248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ScalarAccess, 1769769ab22265b313171d201b5928688524a01bd87Misha Brukman 177248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ArrayAccess - The pointer is indexed through as an array of elements. 178248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 179248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ArrayAccess, 1809769ab22265b313171d201b5928688524a01bd87Misha Brukman 181248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ElementAccess ?? P->F only? 1829769ab22265b313171d201b5928688524a01bd87Misha Brukman 183248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// CallsThrough - Indirect calls are made through the specified function 184248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// pointer. 185410354fe0c052141dadeca939395743f8dd58e38Chris Lattner CallsThrough 186248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner }; 1879769ab22265b313171d201b5928688524a01bd87Misha Brukman }; 1889769ab22265b313171d201b5928688524a01bd87Misha Brukman 189dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// getModRefBehavior - Return the behavior when calling the given call site. 190dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands ModRefBehavior getModRefBehavior(CallSite CS, 191dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands std::vector<PointerAccessInfo> *Info = 0); 192dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 193dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// getModRefBehavior - Return the behavior when calling the given function. 194dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// For use when the call site is not known. 195dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands ModRefBehavior getModRefBehavior(Function *F, 196dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands std::vector<PointerAccessInfo> *Info = 0); 197dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 198dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// doesNotAccessMemory - If the specified call is known to never read or 199dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// write memory, return true. If the call only reads from known-constant 200dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// memory, it is also legal to return true. Calls that unwind the stack 201dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// are legal for this predicate. 2023e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 203dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// Many optimizations (such as CSE and LICM) can be performed on such calls 204dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// without worrying about aliasing properties, and many calls have this 205dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// property (e.g. calls to 'sin' and 'cos'). 2063e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2073e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'const' attribute. 2083e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 209dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands bool doesNotAccessMemory(CallSite CS) { 210dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands return getModRefBehavior(CS) == DoesNotAccessMemory; 211dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands } 212dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 213dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// doesNotAccessMemory - If the specified function is known to never read or 214dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// write memory, return true. For use when the call site is not known. 215dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// 216248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool doesNotAccessMemory(Function *F) { 217dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands return getModRefBehavior(F) == DoesNotAccessMemory; 218248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2193e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner 220dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// onlyReadsMemory - If the specified call is known to only read from 221dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// non-volatile memory (or not access memory at all), return true. Calls 222dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// that unwind the stack are legal for this predicate. 2233e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2243e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property allows many common optimizations to be performed in the 2253e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// absence of interfering store instructions, such as CSE of strlen calls. 2263e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2273e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'pure' attribute. 2283e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 229dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands bool onlyReadsMemory(CallSite CS) { 230dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands ModRefBehavior MRB = getModRefBehavior(CS); 231dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory; 232dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands } 233dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 234dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// onlyReadsMemory - If the specified function is known to only read from 235dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// non-volatile memory (or not access memory at all), return true. For use 236dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// when the call site is not known. 237dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// 238248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool onlyReadsMemory(Function *F) { 239dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands ModRefBehavior MRB = getModRefBehavior(F); 2408eec644862251e14add0d2707d655fcce91e8f70Chris Lattner return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory; 241248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2424df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 2431c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2441c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether or not an instruction may 2451c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// read or write memory specified by the pointer operand. An instruction 2461c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// that doesn't read or write memory may be trivially LICM'd for example. 2471c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2481c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo (for call sites) - Return whether information about whether 2491c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// a particular call site modifies or reads the memory specified by the 2501c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// pointer. 2511c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 2525cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 2531c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2541c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether two call sites may refer 2551c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// to the same set of memory locations. This function returns NoModRef if 256414c36769aff6ec688c49f493122529394357d05Chris Lattner /// the two calls refer to disjoint memory locations, Ref if CS1 reads memory 257414c36769aff6ec688c49f493122529394357d05Chris Lattner /// written by CS2, Mod if CS1 writes to memory read or written by CS2, or 258414c36769aff6ec688c49f493122529394357d05Chris Lattner /// ModRef if CS1 might read or write memory accessed by CS2. 2591c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 2605cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2); 2611c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 262e40bb915bae2aecdd1578ea356d5e4c8ac31061cChris Lattner /// hasNoModRefInfoForCalls - Return true if the analysis has no mod/ref 263414c36769aff6ec688c49f493122529394357d05Chris Lattner /// information for pairs of function calls (other than "pure" and "const" 264414c36769aff6ec688c49f493122529394357d05Chris Lattner /// functions). This can be used by clients to avoid many pointless queries. 265414c36769aff6ec688c49f493122529394357d05Chris Lattner /// Remember that if you override this and chain to another analysis, you must 266414c36769aff6ec688c49f493122529394357d05Chris Lattner /// make sure that it doesn't have mod/ref info either. 267e40bb915bae2aecdd1578ea356d5e4c8ac31061cChris Lattner /// 268ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual bool hasNoModRefInfoForCalls() const; 269e40bb915bae2aecdd1578ea356d5e4c8ac31061cChris Lattner 270dff6710717b159f089c76a07eda074eb6347eb92Duncan Sandsprotected: 271dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// getModRefBehavior - Return the behavior of the specified function if 272dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// called from the specified call site. The call site may be null in which 273dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands /// case the most generic behavior of this function should be returned. 274dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS, 275dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands std::vector<PointerAccessInfo> *Info = 0); 276dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands 277dff6710717b159f089c76a07eda074eb6347eb92Duncan Sandspublic: 2781c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Convenience functions... 2791c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size); 2805cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(StoreInst *S, Value *P, unsigned Size); 2815cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) { 2821c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(C), P, Size); 2831c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2845cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) { 2851c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(I), P, Size); 2861c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 28714f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth ModRefResult getModRefInfo(VAArgInst* I, Value* P, unsigned Size) { 2881ef14f6e768eac76fc272320e79bdbd90747ef47Owen Anderson return AliasAnalysis::ModRef; 28914f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth } 2901c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) { 2911c56b730a6313886076d7b293a126ae5576f5288Chris Lattner switch (I->getOpcode()) { 29214f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth case Instruction::VAArg: return getModRefInfo((VAArgInst*)I, P, Size); 2931c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Load: return getModRefInfo((LoadInst*)I, P, Size); 2941c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Store: return getModRefInfo((StoreInst*)I, P, Size); 2951c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Call: return getModRefInfo((CallInst*)I, P, Size); 2961c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Invoke: return getModRefInfo((InvokeInst*)I, P, Size); 2971c56b730a6313886076d7b293a126ae5576f5288Chris Lattner default: return NoModRef; 2981c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2991c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 3004df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 301ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 302ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Higher level methods for querying mod/ref information. 303ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 304ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 305f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canBasicBlockModify - Return true if it is possible for execution of the 306f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// specified basic block to modify the value pointed to by Ptr. 307f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 3081c56b730a6313886076d7b293a126ae5576f5288Chris Lattner bool canBasicBlockModify(const BasicBlock &BB, const Value *P, unsigned Size); 3094df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 310f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canInstructionRangeModify - Return true if it is possible for the 311f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// execution of the specified instructions to modify the value pointed to by 312f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Ptr. The instructions to consider are all of the instructions in the 313f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// range of [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block. 314f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 3154df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2, 3161c56b730a6313886076d7b293a126ae5576f5288Chris Lattner const Value *Ptr, unsigned Size); 317ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 318ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 319ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Methods that clients should call when they transform the program to allow 320ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// alias analyses to update their internal data structures. Note that these 321ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// methods may be called on any instruction, regardless of whether or not 322ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// they have pointer-analysis implications. 323ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 324ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 325ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleteValue - This method should be called whenever an LLVM Value is 326ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleted from the program, for example when an instruction is found to be 327ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// redundant and is eliminated. 328ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 329ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void deleteValue(Value *V); 330ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 331ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// copyValue - This method should be used whenever a preexisting value in the 332ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// program is copied or cloned, introducing a new value. Note that analysis 333ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// implementations should tolerate clients that use this method to introduce 334ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// the same value multiple times: if the analysis already knows about a 335ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// value, it should ignore the request. 336ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 337ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void copyValue(Value *From, Value *To); 338ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 339ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// replaceWithNewValue - This method is the obvious combination of the two 340ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// above, and it provided as a helper to simplify client code. 341ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 342ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner void replaceWithNewValue(Value *Old, Value *New) { 343ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner copyValue(Old, New); 344ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner deleteValue(Old); 345ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner } 3464df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner}; 3474df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 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