2004-06-28 06:33:13 +00:00
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//===- GlobalsModRef.cpp - Simple Mod/Ref Analysis for Globals ------------===//
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2005-04-21 21:13:18 +00:00
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//
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2004-06-28 06:33:13 +00:00
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// The LLVM Compiler Infrastructure
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//
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2007-12-29 20:36:04 +00:00
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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2005-04-21 21:13:18 +00:00
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//
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2004-06-28 06:33:13 +00:00
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//===----------------------------------------------------------------------===//
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//
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// This simple pass provides alias and mod/ref information for global values
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2004-07-27 06:40:37 +00:00
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// that do not have their address taken, and keeps track of whether functions
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// read or write memory (are "pure"). For this simple (but very common) case,
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// we can provide pretty accurate and useful information.
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2004-06-28 06:33:13 +00:00
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//
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//===----------------------------------------------------------------------===//
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2006-12-19 22:30:33 +00:00
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#define DEBUG_TYPE "globalsmodref-aa"
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2004-06-28 06:33:13 +00:00
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#include "llvm/Analysis/Passes.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Instructions.h"
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#include "llvm/Constants.h"
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2006-10-01 22:36:45 +00:00
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#include "llvm/DerivedTypes.h"
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2004-06-28 06:33:13 +00:00
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/CallGraph.h"
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2007-02-05 23:42:17 +00:00
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#include "llvm/Support/Compiler.h"
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2004-09-01 22:55:40 +00:00
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#include "llvm/Support/CommandLine.h"
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2007-02-05 23:42:17 +00:00
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#include "llvm/Support/InstIterator.h"
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2004-09-01 22:55:40 +00:00
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/SCCIterator.h"
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2004-06-28 06:33:13 +00:00
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#include <set>
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using namespace llvm;
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2006-12-19 22:30:33 +00:00
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STATISTIC(NumNonAddrTakenGlobalVars,
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"Number of global vars without address taken");
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STATISTIC(NumNonAddrTakenFunctions,"Number of functions without address taken");
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STATISTIC(NumNoMemFunctions, "Number of functions that do not access memory");
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STATISTIC(NumReadMemFunctions, "Number of functions that only read memory");
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STATISTIC(NumIndirectGlobalVars, "Number of indirect global objects");
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2004-06-28 06:33:13 +00:00
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namespace {
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2004-07-27 06:40:37 +00:00
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/// FunctionRecord - One instance of this structure is stored for every
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/// function in the program. Later, the entries for these functions are
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/// removed if the function is found to call an external function (in which
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/// case we know nothing about it.
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2007-02-05 23:42:17 +00:00
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struct VISIBILITY_HIDDEN FunctionRecord {
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2004-07-27 06:40:37 +00:00
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/// GlobalInfo - Maintain mod/ref info for all of the globals without
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/// addresses taken that are read or written (transitively) by this
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/// function.
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std::map<GlobalValue*, unsigned> GlobalInfo;
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unsigned getInfoForGlobal(GlobalValue *GV) const {
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std::map<GlobalValue*, unsigned>::const_iterator I = GlobalInfo.find(GV);
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if (I != GlobalInfo.end())
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return I->second;
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return 0;
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}
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2005-04-21 21:13:18 +00:00
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2004-07-27 06:40:37 +00:00
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/// FunctionEffect - Capture whether or not this function reads or writes to
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/// ANY memory. If not, we can do a lot of aggressive analysis on it.
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unsigned FunctionEffect;
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2004-07-27 07:46:26 +00:00
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FunctionRecord() : FunctionEffect(0) {}
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2004-07-27 06:40:37 +00:00
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};
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2004-06-28 06:33:13 +00:00
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2004-07-27 06:40:37 +00:00
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/// GlobalsModRef - The actual analysis pass.
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2008-09-03 12:55:42 +00:00
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class VISIBILITY_HIDDEN GlobalsModRef
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2007-02-05 23:42:17 +00:00
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: public ModulePass, public AliasAnalysis {
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2004-07-27 06:40:37 +00:00
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/// NonAddressTakenGlobals - The globals that do not have their addresses
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/// taken.
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std::set<GlobalValue*> NonAddressTakenGlobals;
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2004-06-28 06:33:13 +00:00
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2008-09-03 12:55:42 +00:00
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/// ReadGlobals - The globals without addresses taken that are read by
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/// some function.
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std::set<GlobalValue*> ReadGlobals;
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2006-10-01 22:36:45 +00:00
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/// IndirectGlobals - The memory pointed to by this global is known to be
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/// 'owned' by the global.
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std::set<GlobalValue*> IndirectGlobals;
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2008-09-03 12:55:42 +00:00
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2006-10-01 22:36:45 +00:00
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/// AllocsForIndirectGlobals - If an instruction allocates memory for an
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/// indirect global, this map indicates which one.
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std::map<Value*, GlobalValue*> AllocsForIndirectGlobals;
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2008-09-03 12:55:42 +00:00
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2004-06-28 06:33:13 +00:00
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/// FunctionInfo - For each function, keep track of what globals are
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/// modified or read.
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2004-07-27 06:40:37 +00:00
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std::map<Function*, FunctionRecord> FunctionInfo;
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2004-06-28 06:33:13 +00:00
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public:
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2007-05-03 01:11:54 +00:00
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static char ID;
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2008-09-04 17:05:41 +00:00
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GlobalsModRef() : ModulePass(&ID) {}
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2008-03-18 00:39:19 +00:00
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2004-09-20 04:48:05 +00:00
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bool runOnModule(Module &M) {
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2004-06-28 06:33:13 +00:00
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InitializeAliasAnalysis(this); // set up super class
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AnalyzeGlobals(M); // find non-addr taken globals
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AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG
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return false;
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}
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AliasAnalysis::getAnalysisUsage(AU);
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AU.addRequired<CallGraph>();
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AU.setPreservesAll(); // Does not transform code
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}
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//------------------------------------------------
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// Implement the AliasAnalysis API
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2005-04-21 21:13:18 +00:00
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//
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2004-06-28 06:33:13 +00:00
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AliasResult alias(const Value *V1, unsigned V1Size,
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const Value *V2, unsigned V2Size);
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ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
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2004-12-07 08:11:24 +00:00
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ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
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return AliasAnalysis::getModRefInfo(CS1,CS2);
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}
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2004-06-28 06:33:13 +00:00
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bool hasNoModRefInfoForCalls() const { return false; }
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2004-12-15 07:22:13 +00:00
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/// getModRefBehavior - Return the behavior of the specified function if
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/// called from the specified call site. The call site may be null in which
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/// case the most generic behavior of this function should be returned.
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2004-12-17 17:12:24 +00:00
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virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS,
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std::vector<PointerAccessInfo> *Info) {
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2008-02-20 11:08:44 +00:00
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if (FunctionRecord *FR = getFunctionInfo(F)) {
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2004-07-27 06:40:37 +00:00
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if (FR->FunctionEffect == 0)
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2004-12-15 07:22:13 +00:00
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return DoesNotAccessMemory;
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2005-04-22 04:01:18 +00:00
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else if ((FR->FunctionEffect & Mod) == 0)
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return OnlyReadsMemory;
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2008-02-20 11:08:44 +00:00
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}
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2005-04-21 21:13:18 +00:00
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return AliasAnalysis::getModRefBehavior(F, CS, Info);
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2004-07-27 06:40:37 +00:00
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}
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2004-06-28 06:33:13 +00:00
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virtual void deleteValue(Value *V);
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virtual void copyValue(Value *From, Value *To);
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private:
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2004-07-27 06:40:37 +00:00
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/// getFunctionInfo - Return the function info for the function, or null if
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2008-09-03 12:55:42 +00:00
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/// we don't have anything useful to say about it.
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2004-07-27 06:40:37 +00:00
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FunctionRecord *getFunctionInfo(Function *F) {
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std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F);
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if (I != FunctionInfo.end())
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return &I->second;
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return 0;
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}
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2004-06-28 06:33:13 +00:00
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void AnalyzeGlobals(Module &M);
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void AnalyzeCallGraph(CallGraph &CG, Module &M);
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2006-10-01 22:36:45 +00:00
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bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers,
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std::vector<Function*> &Writers,
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GlobalValue *OkayStoreDest = 0);
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bool AnalyzeIndirectGlobalMemory(GlobalValue *GV);
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2004-06-28 06:33:13 +00:00
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};
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}
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2008-05-13 00:00:25 +00:00
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char GlobalsModRef::ID = 0;
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static RegisterPass<GlobalsModRef>
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X("globalsmodref-aa", "Simple mod/ref analysis for globals", false, true);
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static RegisterAnalysisGroup<AliasAnalysis> Y(X);
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2004-06-28 06:33:13 +00:00
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Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); }
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2006-10-01 22:36:45 +00:00
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/// getUnderlyingObject - This traverses the use chain to figure out what object
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/// the specified value points to. If the value points to, or is derived from,
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/// a global object, return it.
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static Value *getUnderlyingObject(Value *V) {
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if (!isa<PointerType>(V->getType())) return V;
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2008-09-03 12:55:42 +00:00
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2006-10-01 22:36:45 +00:00
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// If we are at some type of object... return it.
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if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) return GV;
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2008-09-03 12:55:42 +00:00
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2006-10-01 22:36:45 +00:00
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// Traverse through different addressing mechanisms.
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if (Instruction *I = dyn_cast<Instruction>(V)) {
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2006-11-27 01:05:10 +00:00
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if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I))
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2006-10-01 22:36:45 +00:00
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return getUnderlyingObject(I->getOperand(0));
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} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
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2008-09-03 12:55:42 +00:00
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if (CE->getOpcode() == Instruction::BitCast ||
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2006-10-01 22:36:45 +00:00
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CE->getOpcode() == Instruction::GetElementPtr)
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return getUnderlyingObject(CE->getOperand(0));
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}
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2008-09-03 12:55:42 +00:00
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// Otherwise, we don't know what this is, return it as the base pointer.
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2006-10-01 22:36:45 +00:00
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return V;
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}
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2004-06-28 06:33:13 +00:00
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2006-10-01 22:36:45 +00:00
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/// AnalyzeGlobals - Scan through the users of all of the internal
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2008-09-03 12:55:42 +00:00
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/// GlobalValue's in the program. If none of them have their "address taken"
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2004-06-28 06:33:13 +00:00
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/// (really, their address passed to something nontrivial), record this fact,
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/// and record the functions that they are used directly in.
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void GlobalsModRef::AnalyzeGlobals(Module &M) {
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std::vector<Function*> Readers, Writers;
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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if (I->hasInternalLinkage()) {
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2006-10-01 22:36:45 +00:00
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if (!AnalyzeUsesOfPointer(I, Readers, Writers)) {
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2004-07-27 06:40:37 +00:00
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// Remember that we are tracking this global.
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NonAddressTakenGlobals.insert(I);
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2004-06-28 06:33:13 +00:00
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++NumNonAddrTakenFunctions;
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}
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Readers.clear(); Writers.clear();
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}
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2005-03-23 23:51:12 +00:00
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for (Module::global_iterator I = M.global_begin(), E = M.global_end();
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I != E; ++I)
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2004-06-28 06:33:13 +00:00
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if (I->hasInternalLinkage()) {
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2006-10-01 22:36:45 +00:00
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if (!AnalyzeUsesOfPointer(I, Readers, Writers)) {
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2004-06-28 06:33:13 +00:00
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// Remember that we are tracking this global, and the mod/ref fns
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2004-07-27 06:40:37 +00:00
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NonAddressTakenGlobals.insert(I);
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2008-09-03 12:55:42 +00:00
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if (!Readers.empty())
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// Some function read this global - remember that.
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ReadGlobals.insert(I);
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2004-07-27 06:40:37 +00:00
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for (unsigned i = 0, e = Readers.size(); i != e; ++i)
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FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref;
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if (!I->isConstant()) // No need to keep track of writers to constants
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for (unsigned i = 0, e = Writers.size(); i != e; ++i)
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FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod;
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2004-06-28 06:33:13 +00:00
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++NumNonAddrTakenGlobalVars;
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2008-09-03 12:55:42 +00:00
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2006-10-01 22:36:45 +00:00
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// If this global holds a pointer type, see if it is an indirect global.
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if (isa<PointerType>(I->getType()->getElementType()) &&
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AnalyzeIndirectGlobalMemory(I))
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++NumIndirectGlobalVars;
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2004-06-28 06:33:13 +00:00
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}
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Readers.clear(); Writers.clear();
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}
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}
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2006-10-01 22:36:45 +00:00
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/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer.
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/// If this is used by anything complex (i.e., the address escapes), return
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/// true. Also, while we are at it, keep track of those functions that read and
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/// write to the value.
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///
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/// If OkayStoreDest is non-null, stores into this global are allowed.
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bool GlobalsModRef::AnalyzeUsesOfPointer(Value *V,
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std::vector<Function*> &Readers,
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std::vector<Function*> &Writers,
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GlobalValue *OkayStoreDest) {
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2004-07-27 06:40:37 +00:00
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if (!isa<PointerType>(V->getType())) return true;
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2004-06-28 06:33:13 +00:00
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for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
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if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
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Readers.push_back(LI->getParent()->getParent());
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} else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
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2006-10-01 22:36:45 +00:00
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if (V == SI->getOperand(1)) {
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Writers.push_back(SI->getParent()->getParent());
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} else if (SI->getOperand(1) != OkayStoreDest) {
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return true; // Storing the pointer
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}
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2004-06-28 06:33:13 +00:00
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} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) {
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2006-10-01 22:36:45 +00:00
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if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true;
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2004-06-28 06:33:13 +00:00
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} else if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
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// Make sure that this is just the function being called, not that it is
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// passing into the function.
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for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
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if (CI->getOperand(i) == V) return true;
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} else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) {
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// Make sure that this is just the function being called, not that it is
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// passing into the function.
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for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i)
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if (II->getOperand(i) == V) return true;
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} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
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2008-09-03 12:55:42 +00:00
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if (CE->getOpcode() == Instruction::GetElementPtr ||
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2006-11-27 01:05:10 +00:00
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CE->getOpcode() == Instruction::BitCast) {
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2006-10-01 22:36:45 +00:00
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if (AnalyzeUsesOfPointer(CE, Readers, Writers))
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2004-06-28 06:33:13 +00:00
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return true;
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} else {
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return true;
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2005-04-21 21:13:18 +00:00
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}
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2006-12-23 06:05:41 +00:00
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} else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) {
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|
|
if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
|
2006-10-01 22:36:45 +00:00
|
|
|
return true; // Allow comparison against null.
|
|
|
|
} else if (FreeInst *F = dyn_cast<FreeInst>(*UI)) {
|
|
|
|
Writers.push_back(F->getParent()->getParent());
|
2004-06-28 06:33:13 +00:00
|
|
|
} else {
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable
|
|
|
|
/// which holds a pointer type. See if the global always points to non-aliased
|
|
|
|
/// heap memory: that is, all initializers of the globals are allocations, and
|
|
|
|
/// those allocations have no use other than initialization of the global.
|
|
|
|
/// Further, all loads out of GV must directly use the memory, not store the
|
|
|
|
/// pointer somewhere. If this is true, we consider the memory pointed to by
|
|
|
|
/// GV to be owned by GV and can disambiguate other pointers from it.
|
|
|
|
bool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) {
|
|
|
|
// Keep track of values related to the allocation of the memory, f.e. the
|
|
|
|
// value produced by the malloc call and any casts.
|
|
|
|
std::vector<Value*> AllocRelatedValues;
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// Walk the user list of the global. If we find anything other than a direct
|
|
|
|
// load or store, bail out.
|
|
|
|
for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(*I)) {
|
|
|
|
// The pointer loaded from the global can only be used in simple ways:
|
|
|
|
// we allow addressing of it and loading storing to it. We do *not* allow
|
|
|
|
// storing the loaded pointer somewhere else or passing to a function.
|
|
|
|
std::vector<Function*> ReadersWriters;
|
|
|
|
if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters))
|
|
|
|
return false; // Loaded pointer escapes.
|
|
|
|
// TODO: Could try some IP mod/ref of the loaded pointer.
|
|
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) {
|
|
|
|
// Storing the global itself.
|
|
|
|
if (SI->getOperand(0) == GV) return false;
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// If storing the null pointer, ignore it.
|
|
|
|
if (isa<ConstantPointerNull>(SI->getOperand(0)))
|
|
|
|
continue;
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// Check the value being stored.
|
|
|
|
Value *Ptr = getUnderlyingObject(SI->getOperand(0));
|
|
|
|
|
|
|
|
if (isa<MallocInst>(Ptr)) {
|
|
|
|
// Okay, easy case.
|
|
|
|
} else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) {
|
|
|
|
Function *F = CI->getCalledFunction();
|
2007-01-30 20:08:39 +00:00
|
|
|
if (!F || !F->isDeclaration()) return false; // Too hard to analyze.
|
2006-10-01 22:36:45 +00:00
|
|
|
if (F->getName() != "calloc") return false; // Not calloc.
|
|
|
|
} else {
|
|
|
|
return false; // Too hard to analyze.
|
|
|
|
}
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// Analyze all uses of the allocation. If any of them are used in a
|
|
|
|
// non-simple way (e.g. stored to another global) bail out.
|
|
|
|
std::vector<Function*> ReadersWriters;
|
|
|
|
if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV))
|
|
|
|
return false; // Loaded pointer escapes.
|
|
|
|
|
|
|
|
// Remember that this allocation is related to the indirect global.
|
|
|
|
AllocRelatedValues.push_back(Ptr);
|
|
|
|
} else {
|
|
|
|
// Something complex, bail out.
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
}
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// Okay, this is an indirect global. Remember all of the allocations for
|
|
|
|
// this global in AllocsForIndirectGlobals.
|
|
|
|
while (!AllocRelatedValues.empty()) {
|
|
|
|
AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV;
|
|
|
|
AllocRelatedValues.pop_back();
|
|
|
|
}
|
|
|
|
IndirectGlobals.insert(GV);
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
2004-06-28 06:33:13 +00:00
|
|
|
/// AnalyzeCallGraph - At this point, we know the functions where globals are
|
|
|
|
/// immediately stored to and read from. Propagate this information up the call
|
2004-07-27 06:40:37 +00:00
|
|
|
/// graph to all callers and compute the mod/ref info for all memory for each
|
2005-04-21 21:13:18 +00:00
|
|
|
/// function.
|
2004-06-28 06:33:13 +00:00
|
|
|
void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) {
|
|
|
|
// We do a bottom-up SCC traversal of the call graph. In other words, we
|
|
|
|
// visit all callees before callers (leaf-first).
|
2008-09-03 12:55:42 +00:00
|
|
|
for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E;
|
|
|
|
++I) {
|
|
|
|
std::vector<CallGraphNode *> &SCC = *I;
|
2008-09-04 19:16:20 +00:00
|
|
|
assert(!SCC.empty() && "SCC with no functions?");
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2008-09-04 19:16:20 +00:00
|
|
|
if (!SCC[0]->getFunction()) {
|
|
|
|
// Calls externally - can't say anything useful. Remove any existing
|
|
|
|
// function records (may have been created when scanning globals).
|
|
|
|
for (unsigned i = 0, e = SCC.size(); i != e; ++i)
|
|
|
|
FunctionInfo.erase(SCC[i]->getFunction());
|
2008-09-03 19:37:16 +00:00
|
|
|
continue;
|
2008-09-04 19:16:20 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()];
|
2004-06-28 06:33:13 +00:00
|
|
|
|
2008-09-03 12:55:42 +00:00
|
|
|
bool KnowNothing = false;
|
|
|
|
unsigned FunctionEffect = 0;
|
|
|
|
|
|
|
|
// Collect the mod/ref properties due to called functions. We only compute
|
|
|
|
// one mod-ref set.
|
|
|
|
for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) {
|
|
|
|
Function *F = SCC[i]->getFunction();
|
|
|
|
if (!F) {
|
|
|
|
KnowNothing = true;
|
2004-07-27 06:40:37 +00:00
|
|
|
break;
|
2004-06-28 06:33:13 +00:00
|
|
|
}
|
2004-07-27 06:40:37 +00:00
|
|
|
|
2008-09-03 12:55:42 +00:00
|
|
|
if (F->isDeclaration()) {
|
|
|
|
// Try to get mod/ref behaviour from function attributes.
|
2008-09-03 15:31:24 +00:00
|
|
|
if (F->doesNotAccessMemory()) {
|
|
|
|
// Can't do better than that!
|
|
|
|
} else if (F->onlyReadsMemory()) {
|
2008-09-03 12:55:42 +00:00
|
|
|
FunctionEffect |= Ref;
|
|
|
|
// This function might call back into the module and read a global, so
|
|
|
|
// mark all globals read somewhere as being read by this function.
|
|
|
|
for (std::set<GlobalValue*>::iterator GI = ReadGlobals.begin(),
|
|
|
|
E = ReadGlobals.end(); GI != E; ++GI)
|
2008-09-04 19:16:20 +00:00
|
|
|
FR.GlobalInfo[*GI] |= Ref;
|
2008-09-03 15:31:24 +00:00
|
|
|
} else {
|
2008-09-03 12:55:42 +00:00
|
|
|
// Can't say anything useful.
|
|
|
|
KnowNothing = true;
|
|
|
|
}
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end();
|
2008-09-04 19:16:20 +00:00
|
|
|
CI != E && !KnowNothing; ++CI)
|
2008-09-03 12:55:42 +00:00
|
|
|
if (Function *Callee = CI->second->getFunction()) {
|
|
|
|
if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) {
|
|
|
|
// Propagate function effect up.
|
|
|
|
FunctionEffect |= CalleeFR->FunctionEffect;
|
|
|
|
|
|
|
|
// Incorporate callee's effects on globals into our info.
|
|
|
|
for (std::map<GlobalValue*, unsigned>::iterator GI =
|
|
|
|
CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end();
|
|
|
|
GI != E; ++GI)
|
2008-09-04 19:16:20 +00:00
|
|
|
FR.GlobalInfo[GI->first] |= GI->second;
|
2008-09-03 12:55:42 +00:00
|
|
|
} else {
|
|
|
|
// Can't say anything about it. However, if it is inside our SCC,
|
|
|
|
// then nothing needs to be done.
|
|
|
|
CallGraphNode *CalleeNode = CG[Callee];
|
|
|
|
if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end())
|
|
|
|
KnowNothing = true;
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
KnowNothing = true;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// If we can't say anything useful about this SCC, remove all SCC functions
|
|
|
|
// from the FunctionInfo map.
|
|
|
|
if (KnowNothing) {
|
|
|
|
for (unsigned i = 0, e = SCC.size(); i != e; ++i)
|
|
|
|
FunctionInfo.erase(SCC[i]->getFunction());
|
2008-09-03 16:10:55 +00:00
|
|
|
continue;
|
2008-09-03 12:55:42 +00:00
|
|
|
}
|
2005-04-21 21:13:18 +00:00
|
|
|
|
2008-09-03 12:55:42 +00:00
|
|
|
// Scan the function bodies for explicit loads or stores.
|
2004-07-27 06:40:37 +00:00
|
|
|
for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i)
|
|
|
|
for (inst_iterator II = inst_begin(SCC[i]->getFunction()),
|
2005-04-21 21:13:18 +00:00
|
|
|
E = inst_end(SCC[i]->getFunction());
|
2004-07-27 06:40:37 +00:00
|
|
|
II != E && FunctionEffect != ModRef; ++II)
|
|
|
|
if (isa<LoadInst>(*II))
|
|
|
|
FunctionEffect |= Ref;
|
|
|
|
else if (isa<StoreInst>(*II))
|
|
|
|
FunctionEffect |= Mod;
|
2005-04-22 05:36:59 +00:00
|
|
|
else if (isa<MallocInst>(*II) || isa<FreeInst>(*II))
|
|
|
|
FunctionEffect |= ModRef;
|
2004-07-27 06:40:37 +00:00
|
|
|
|
2008-09-03 12:55:42 +00:00
|
|
|
if ((FunctionEffect & Mod) == 0)
|
|
|
|
++NumReadMemFunctions;
|
|
|
|
if (FunctionEffect == 0)
|
|
|
|
++NumNoMemFunctions;
|
2008-09-04 19:16:20 +00:00
|
|
|
FR.FunctionEffect = FunctionEffect;
|
2004-07-27 06:40:37 +00:00
|
|
|
|
2008-09-03 12:55:42 +00:00
|
|
|
// Finally, now that we know the full effect on this SCC, clone the
|
|
|
|
// information to each function in the SCC.
|
|
|
|
for (unsigned i = 1, e = SCC.size(); i != e; ++i)
|
2008-09-04 19:16:20 +00:00
|
|
|
FunctionInfo[SCC[i]->getFunction()] = FR;
|
2008-09-03 12:55:42 +00:00
|
|
|
}
|
2004-06-28 06:33:13 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/// alias - If one of the pointers is to a global that we are tracking, and the
|
|
|
|
/// other is some random pointer, we know there cannot be an alias, because the
|
|
|
|
/// address of the global isn't taken.
|
|
|
|
AliasAnalysis::AliasResult
|
|
|
|
GlobalsModRef::alias(const Value *V1, unsigned V1Size,
|
|
|
|
const Value *V2, unsigned V2Size) {
|
2006-10-01 22:36:45 +00:00
|
|
|
// Get the base object these pointers point to.
|
|
|
|
Value *UV1 = getUnderlyingObject(const_cast<Value*>(V1));
|
|
|
|
Value *UV2 = getUnderlyingObject(const_cast<Value*>(V2));
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// If either of the underlying values is a global, they may be non-addr-taken
|
|
|
|
// globals, which we can answer queries about.
|
|
|
|
GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1);
|
|
|
|
GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2);
|
|
|
|
if (GV1 || GV2) {
|
|
|
|
// If the global's address is taken, pretend we don't know it's a pointer to
|
|
|
|
// the global.
|
|
|
|
if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0;
|
|
|
|
if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0;
|
|
|
|
|
|
|
|
// If the the two pointers are derived from two different non-addr-taken
|
|
|
|
// globals, or if one is and the other isn't, we know these can't alias.
|
|
|
|
if ((GV1 || GV2) && GV1 != GV2)
|
|
|
|
return NoAlias;
|
|
|
|
|
|
|
|
// Otherwise if they are both derived from the same addr-taken global, we
|
|
|
|
// can't know the two accesses don't overlap.
|
|
|
|
}
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// These pointers may be based on the memory owned by an indirect global. If
|
|
|
|
// so, we may be able to handle this. First check to see if the base pointer
|
|
|
|
// is a direct load from an indirect global.
|
|
|
|
GV1 = GV2 = 0;
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(UV1))
|
|
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0)))
|
|
|
|
if (IndirectGlobals.count(GV))
|
|
|
|
GV1 = GV;
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(UV2))
|
|
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0)))
|
|
|
|
if (IndirectGlobals.count(GV))
|
|
|
|
GV2 = GV;
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// These pointers may also be from an allocation for the indirect global. If
|
|
|
|
// so, also handle them.
|
|
|
|
if (AllocsForIndirectGlobals.count(UV1))
|
|
|
|
GV1 = AllocsForIndirectGlobals[UV1];
|
|
|
|
if (AllocsForIndirectGlobals.count(UV2))
|
|
|
|
GV2 = AllocsForIndirectGlobals[UV2];
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// Now that we know whether the two pointers are related to indirect globals,
|
|
|
|
// use this to disambiguate the pointers. If either pointer is based on an
|
|
|
|
// indirect global and if they are not both based on the same indirect global,
|
|
|
|
// they cannot alias.
|
2004-06-28 06:33:13 +00:00
|
|
|
if ((GV1 || GV2) && GV1 != GV2)
|
|
|
|
return NoAlias;
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2004-06-28 06:33:13 +00:00
|
|
|
return AliasAnalysis::alias(V1, V1Size, V2, V2Size);
|
|
|
|
}
|
|
|
|
|
|
|
|
AliasAnalysis::ModRefResult
|
|
|
|
GlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
|
|
|
|
unsigned Known = ModRef;
|
|
|
|
|
|
|
|
// If we are asking for mod/ref info of a direct call with a pointer to a
|
2004-07-27 06:40:37 +00:00
|
|
|
// global we are tracking, return information if we have it.
|
2006-10-01 22:36:45 +00:00
|
|
|
if (GlobalValue *GV = dyn_cast<GlobalValue>(getUnderlyingObject(P)))
|
2004-06-28 06:33:13 +00:00
|
|
|
if (GV->hasInternalLinkage())
|
2004-07-27 06:40:37 +00:00
|
|
|
if (Function *F = CS.getCalledFunction())
|
|
|
|
if (NonAddressTakenGlobals.count(GV))
|
|
|
|
if (FunctionRecord *FR = getFunctionInfo(F))
|
|
|
|
Known = FR->getInfoForGlobal(GV);
|
2004-06-28 06:33:13 +00:00
|
|
|
|
|
|
|
if (Known == NoModRef)
|
|
|
|
return NoModRef; // No need to query other mod/ref analyses
|
|
|
|
return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size));
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
// Methods to update the analysis as a result of the client transformation.
|
|
|
|
//
|
|
|
|
void GlobalsModRef::deleteValue(Value *V) {
|
2006-10-01 22:36:45 +00:00
|
|
|
if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
|
|
|
|
if (NonAddressTakenGlobals.erase(GV)) {
|
|
|
|
// This global might be an indirect global. If so, remove it and remove
|
|
|
|
// any AllocRelatedValues for it.
|
|
|
|
if (IndirectGlobals.erase(GV)) {
|
|
|
|
// Remove any entries in AllocsForIndirectGlobals for this global.
|
|
|
|
for (std::map<Value*, GlobalValue*>::iterator
|
|
|
|
I = AllocsForIndirectGlobals.begin(),
|
|
|
|
E = AllocsForIndirectGlobals.end(); I != E; ) {
|
|
|
|
if (I->second == GV) {
|
|
|
|
AllocsForIndirectGlobals.erase(I++);
|
|
|
|
} else {
|
|
|
|
++I;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2006-10-01 22:36:45 +00:00
|
|
|
// Otherwise, if this is an allocation related to an indirect global, remove
|
|
|
|
// it.
|
|
|
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AllocsForIndirectGlobals.erase(V);
|
2008-09-03 12:55:42 +00:00
|
|
|
|
2007-11-30 18:52:58 +00:00
|
|
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AliasAnalysis::deleteValue(V);
|
2004-06-28 06:33:13 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
void GlobalsModRef::copyValue(Value *From, Value *To) {
|
2007-11-30 18:52:58 +00:00
|
|
|
AliasAnalysis::copyValue(From, To);
|
2004-06-28 06:33:13 +00:00
|
|
|
}
|