2003-10-05 04:26:39 +00:00
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//===- PromoteMemoryToRegister.cpp - Convert allocas to registers ---------===//
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2005-04-21 23:48:37 +00:00
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//
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2003-10-20 19:43:21 +00:00
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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2005-04-21 23:48:37 +00:00
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//
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2003-10-20 19:43:21 +00:00
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//===----------------------------------------------------------------------===//
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2002-02-12 17:16:22 +00:00
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//
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2003-10-05 04:26:39 +00:00
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// This file promote memory references to be register references. It promotes
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2004-09-19 18:51:51 +00:00
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// alloca instructions which only have loads and stores as uses. An alloca is
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// transformed by using dominator frontiers to place PHI nodes, then traversing
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// the function in depth-first order to rewrite loads and stores as appropriate.
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// This is just the standard SSA construction algorithm to construct "pruned"
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// SSA form.
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2002-02-12 17:16:22 +00:00
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//
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//===----------------------------------------------------------------------===//
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2003-02-22 23:57:48 +00:00
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#include "llvm/Transforms/Utils/PromoteMemToReg.h"
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2004-10-16 18:10:06 +00:00
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#include "llvm/Constants.h"
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2004-09-15 01:02:54 +00:00
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/Instructions.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Analysis/AliasSetTracker.h"
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2007-02-05 23:37:20 +00:00
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#include "llvm/ADT/DenseMap.h"
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2007-02-05 22:13:11 +00:00
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#include "llvm/ADT/SmallPtrSet.h"
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2007-02-05 21:58:48 +00:00
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#include "llvm/ADT/SmallVector.h"
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2004-09-15 01:02:54 +00:00
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#include "llvm/ADT/StringExtras.h"
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2003-04-18 19:25:22 +00:00
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#include "llvm/Support/CFG.h"
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2006-08-27 12:54:02 +00:00
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#include "llvm/Support/Compiler.h"
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2004-09-03 18:19:51 +00:00
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#include <algorithm>
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2004-01-09 06:12:26 +00:00
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using namespace llvm;
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2003-11-11 22:41:34 +00:00
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2007-02-07 01:15:04 +00:00
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// Provide DenseMapKeyInfo for all pointers.
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namespace llvm {
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template<>
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struct DenseMapKeyInfo<std::pair<BasicBlock*, unsigned> > {
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static inline std::pair<BasicBlock*, unsigned> getEmptyKey() {
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return std::make_pair((BasicBlock*)-1, ~0U);
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}
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static inline std::pair<BasicBlock*, unsigned> getTombstoneKey() {
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return std::make_pair((BasicBlock*)-2, 0U);
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}
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static unsigned getHashValue(const std::pair<BasicBlock*, unsigned> &Val) {
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return DenseMapKeyInfo<void*>::getHashValue(Val.first) + Val.second*2;
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}
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static bool isPod() { return true; }
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};
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}
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2003-02-22 23:57:48 +00:00
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/// isAllocaPromotable - Return true if this alloca is legal for promotion.
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2004-09-19 18:51:51 +00:00
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/// This is true if there are only loads and stores to the alloca.
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2003-02-22 23:57:48 +00:00
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///
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2007-04-25 17:15:20 +00:00
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bool llvm::isAllocaPromotable(const AllocaInst *AI) {
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2003-03-03 17:25:18 +00:00
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// FIXME: If the memory unit is of pointer or integer type, we can permit
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// assignments to subsections of the memory unit.
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2003-02-22 23:57:48 +00:00
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// Only allow direct loads and stores...
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for (Value::use_const_iterator UI = AI->use_begin(), UE = AI->use_end();
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UI != UE; ++UI) // Loop over all of the uses of the alloca
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2004-01-12 01:18:32 +00:00
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if (isa<LoadInst>(*UI)) {
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// noop
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} else if (const StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
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if (SI->getOperand(0) == AI)
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return false; // Don't allow a store OF the AI, only INTO the AI.
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} else {
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2004-09-19 18:51:51 +00:00
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return false; // Not a load or store.
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2004-01-12 01:18:32 +00:00
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}
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2005-04-21 23:48:37 +00:00
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2003-02-22 23:57:48 +00:00
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return true;
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}
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2002-03-27 23:28:40 +00:00
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namespace {
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2007-03-09 23:39:14 +00:00
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// Data package used by RenamePass()
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class VISIBILITY_HIDDEN RenamePassData {
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public:
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RenamePassData(BasicBlock *B, BasicBlock *P,
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2007-03-26 23:19:29 +00:00
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const std::vector<Value *> &V) : BB(B), Pred(P), Values(V) {}
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2007-03-09 23:39:14 +00:00
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BasicBlock *BB;
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BasicBlock *Pred;
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std::vector<Value *> Values;
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};
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2006-06-28 23:17:24 +00:00
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struct VISIBILITY_HIDDEN PromoteMem2Reg {
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2004-09-15 01:02:54 +00:00
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/// Allocas - The alloca instructions being promoted.
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///
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2003-10-05 20:54:03 +00:00
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std::vector<AllocaInst*> Allocas;
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2007-02-05 21:58:48 +00:00
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SmallVector<AllocaInst*, 16> &RetryList;
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2007-06-07 21:57:03 +00:00
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DominatorTree &DT;
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2003-02-22 23:57:48 +00:00
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DominanceFrontier &DF;
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2002-10-01 22:38:41 +00:00
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2004-09-15 01:02:54 +00:00
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/// AST - An AliasSetTracker object to update. If null, don't update it.
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///
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AliasSetTracker *AST;
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/// AllocaLookup - Reverse mapping of Allocas.
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///
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2003-10-05 03:16:07 +00:00
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std::map<AllocaInst*, unsigned> AllocaLookup;
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2004-09-15 01:02:54 +00:00
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/// NewPhiNodes - The PhiNodes we're adding.
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///
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2007-02-07 01:15:04 +00:00
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DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*> NewPhiNodes;
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/// PhiToAllocaMap - For each PHI node, keep track of which entry in Allocas
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/// it corresponds to.
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DenseMap<PHINode*, unsigned> PhiToAllocaMap;
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2004-09-15 01:02:54 +00:00
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/// PointerAllocaValues - If we are updating an AliasSetTracker, then for
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/// each alloca that is of pointer type, we keep track of what to copyValue
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/// to the inserted PHI nodes here.
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///
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std::vector<Value*> PointerAllocaValues;
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/// Visited - The set of basic blocks the renamer has already visited.
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///
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2007-02-05 22:15:21 +00:00
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SmallPtrSet<BasicBlock*, 16> Visited;
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2002-03-27 23:17:37 +00:00
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2004-09-15 01:02:54 +00:00
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/// BBNumbers - Contains a stable numbering of basic blocks to avoid
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/// non-determinstic behavior.
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2007-02-05 23:37:20 +00:00
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DenseMap<BasicBlock*, unsigned> BBNumbers;
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2004-06-19 07:40:14 +00:00
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2002-04-28 19:12:38 +00:00
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public:
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2005-06-30 07:29:44 +00:00
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PromoteMem2Reg(const std::vector<AllocaInst*> &A,
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2007-06-07 21:57:03 +00:00
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SmallVector<AllocaInst*, 16> &Retry, DominatorTree &dt,
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2007-04-25 18:32:35 +00:00
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DominanceFrontier &df, AliasSetTracker *ast)
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2007-06-07 21:57:03 +00:00
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: Allocas(A), RetryList(Retry), DT(dt), DF(df), AST(ast) {}
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2002-04-28 19:12:38 +00:00
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2003-02-22 23:57:48 +00:00
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void run();
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2002-04-28 19:12:38 +00:00
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2005-11-18 07:29:44 +00:00
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/// properlyDominates - Return true if I1 properly dominates I2.
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2004-10-17 21:25:56 +00:00
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///
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2005-11-18 07:29:44 +00:00
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bool properlyDominates(Instruction *I1, Instruction *I2) const {
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2004-10-18 01:21:17 +00:00
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if (InvokeInst *II = dyn_cast<InvokeInst>(I1))
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I1 = II->getNormalDest()->begin();
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2007-06-07 21:57:03 +00:00
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return DT.properlyDominates(I1->getParent(), I2->getParent());
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2005-11-18 07:29:44 +00:00
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}
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2007-06-07 21:57:03 +00:00
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/// dominates - Return true if BB1 dominates BB2 using the DominatorTree.
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2005-11-18 07:29:44 +00:00
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///
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bool dominates(BasicBlock *BB1, BasicBlock *BB2) const {
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2007-06-07 21:57:03 +00:00
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return DT.dominates(BB1, BB2);
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2004-10-17 21:25:56 +00:00
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}
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2002-04-28 19:12:38 +00:00
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private:
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2003-10-05 22:19:20 +00:00
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void MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
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2007-02-05 23:11:37 +00:00
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SmallPtrSet<PHINode*, 16> &DeadPHINodes);
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2005-06-30 07:29:44 +00:00
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bool PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI);
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2005-04-21 23:48:37 +00:00
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void PromoteLocallyUsedAllocas(BasicBlock *BB,
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2004-02-03 22:34:12 +00:00
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const std::vector<AllocaInst*> &AIs);
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2003-10-05 20:54:03 +00:00
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2003-02-22 22:25:17 +00:00
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void RenamePass(BasicBlock *BB, BasicBlock *Pred,
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2007-08-04 01:04:40 +00:00
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std::vector<Value*> &IncVals,
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std::vector<RenamePassData> &Worklist);
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2003-10-05 22:19:20 +00:00
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bool QueuePhiNode(BasicBlock *BB, unsigned AllocaIdx, unsigned &Version,
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2007-02-05 23:11:37 +00:00
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SmallPtrSet<PHINode*, 16> &InsertedPHINodes);
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2002-04-28 19:12:38 +00:00
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};
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2007-03-09 23:39:14 +00:00
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2002-03-27 23:28:40 +00:00
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} // end of anonymous namespace
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2002-02-12 17:16:22 +00:00
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2003-02-22 23:57:48 +00:00
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void PromoteMem2Reg::run() {
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Function &F = *DF.getRoot()->getParent();
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2003-10-05 01:52:53 +00:00
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2004-02-03 22:34:12 +00:00
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// LocallyUsedAllocas - Keep track of all of the alloca instructions which are
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// only used in a single basic block. These instructions can be efficiently
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// promoted by performing a single linear scan over that one block. Since
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// individual basic blocks are sometimes large, we group together all allocas
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// that are live in a single basic block by the basic block they are live in.
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std::map<BasicBlock*, std::vector<AllocaInst*> > LocallyUsedAllocas;
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2004-09-15 01:02:54 +00:00
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if (AST) PointerAllocaValues.resize(Allocas.size());
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2004-06-19 07:40:14 +00:00
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2003-10-05 22:19:20 +00:00
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for (unsigned AllocaNum = 0; AllocaNum != Allocas.size(); ++AllocaNum) {
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AllocaInst *AI = Allocas[AllocaNum];
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2003-10-05 03:16:07 +00:00
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2007-04-25 17:15:20 +00:00
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assert(isAllocaPromotable(AI) &&
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2003-02-22 23:57:48 +00:00
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"Cannot promote non-promotable alloca!");
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2003-10-05 22:19:20 +00:00
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assert(AI->getParent()->getParent() == &F &&
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2003-02-22 23:57:48 +00:00
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"All allocas should be in the same function, which is same as DF!");
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2003-10-05 02:37:36 +00:00
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2003-10-05 20:54:03 +00:00
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if (AI->use_empty()) {
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// If there are no uses of the alloca, just delete it now.
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2004-09-15 01:02:54 +00:00
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if (AST) AST->deleteValue(AI);
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2006-04-27 01:14:43 +00:00
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AI->eraseFromParent();
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2003-10-05 20:54:03 +00:00
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// Remove the alloca from the Allocas list, since it has been processed
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2003-10-05 22:19:20 +00:00
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Allocas[AllocaNum] = Allocas.back();
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2003-10-05 20:54:03 +00:00
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Allocas.pop_back();
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2003-10-05 22:19:20 +00:00
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--AllocaNum;
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2003-10-05 20:54:03 +00:00
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continue;
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}
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2003-10-05 22:19:20 +00:00
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// Calculate the set of read and write-locations for each alloca. This is
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2004-01-12 01:18:32 +00:00
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// analogous to finding the 'uses' and 'definitions' of each variable.
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2003-10-05 03:39:10 +00:00
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std::vector<BasicBlock*> DefiningBlocks;
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2003-10-05 22:19:20 +00:00
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std::vector<BasicBlock*> UsingBlocks;
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2003-10-05 20:54:03 +00:00
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2005-11-18 07:31:42 +00:00
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StoreInst *OnlyStore = 0;
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2003-10-05 20:54:03 +00:00
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BasicBlock *OnlyBlock = 0;
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bool OnlyUsedInOneBlock = true;
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// As we scan the uses of the alloca instruction, keep track of stores, and
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// decide whether all of the loads and stores to the alloca are within the
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// same basic block.
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2004-09-15 01:02:54 +00:00
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Value *AllocaPointerVal = 0;
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2003-10-05 20:54:03 +00:00
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for (Value::use_iterator U =AI->use_begin(), E = AI->use_end(); U != E;++U){
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Instruction *User = cast<Instruction>(*U);
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if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
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// Remember the basic blocks which define new values for the alloca
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2003-10-05 03:39:10 +00:00
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DefiningBlocks.push_back(SI->getParent());
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2004-09-15 01:02:54 +00:00
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AllocaPointerVal = SI->getOperand(0);
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2005-11-18 07:31:42 +00:00
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OnlyStore = SI;
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2005-11-18 07:29:44 +00:00
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} else {
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LoadInst *LI = cast<LoadInst>(User);
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2003-10-05 22:19:20 +00:00
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// Otherwise it must be a load instruction, keep track of variable reads
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2004-01-12 01:18:32 +00:00
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UsingBlocks.push_back(LI->getParent());
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2004-09-15 01:02:54 +00:00
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AllocaPointerVal = LI;
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2003-10-05 20:54:03 +00:00
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}
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if (OnlyUsedInOneBlock) {
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if (OnlyBlock == 0)
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OnlyBlock = User->getParent();
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else if (OnlyBlock != User->getParent())
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OnlyUsedInOneBlock = false;
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}
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}
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// If the alloca is only read and written in one basic block, just perform a
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// linear sweep over the block to eliminate it.
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if (OnlyUsedInOneBlock) {
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2004-02-03 22:34:12 +00:00
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LocallyUsedAllocas[OnlyBlock].push_back(AI);
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2003-10-05 20:54:03 +00:00
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2004-02-03 22:34:12 +00:00
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// Remove the alloca from the Allocas list, since it will be processed.
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2003-10-05 22:19:20 +00:00
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Allocas[AllocaNum] = Allocas.back();
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2003-10-05 20:54:03 +00:00
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Allocas.pop_back();
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2003-10-05 22:19:20 +00:00
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--AllocaNum;
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2003-10-05 20:54:03 +00:00
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continue;
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}
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2003-10-05 03:16:07 +00:00
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2005-11-18 07:31:42 +00:00
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// If there is only a single store to this value, replace any loads of
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// it that are directly dominated by the definition with the value stored.
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if (DefiningBlocks.size() == 1) {
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// Be aware of loads before the store.
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std::set<BasicBlock*> ProcessedBlocks;
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for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
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// If the store dominates the block and if we haven't processed it yet,
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// do so now.
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if (dominates(OnlyStore->getParent(), UsingBlocks[i]))
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if (ProcessedBlocks.insert(UsingBlocks[i]).second) {
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BasicBlock *UseBlock = UsingBlocks[i];
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// If the use and store are in the same block, do a quick scan to
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// verify that there are no uses before the store.
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if (UseBlock == OnlyStore->getParent()) {
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BasicBlock::iterator I = UseBlock->begin();
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for (; &*I != OnlyStore; ++I) { // scan block for store.
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if (isa<LoadInst>(I) && I->getOperand(0) == AI)
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break;
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}
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|
|
|
if (&*I != OnlyStore) break; // Do not handle this case.
|
|
|
|
}
|
|
|
|
|
|
|
|
// Otherwise, if this is a different block or if all uses happen
|
|
|
|
// after the store, do a simple linear scan to replace loads with
|
|
|
|
// the stored value.
|
|
|
|
for (BasicBlock::iterator I = UseBlock->begin(),E = UseBlock->end();
|
|
|
|
I != E; ) {
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(I++)) {
|
|
|
|
if (LI->getOperand(0) == AI) {
|
|
|
|
LI->replaceAllUsesWith(OnlyStore->getOperand(0));
|
|
|
|
if (AST && isa<PointerType>(LI->getType()))
|
|
|
|
AST->deleteValue(LI);
|
|
|
|
LI->eraseFromParent();
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Finally, remove this block from the UsingBlock set.
|
|
|
|
UsingBlocks[i] = UsingBlocks.back();
|
|
|
|
--i; --e;
|
|
|
|
}
|
|
|
|
|
|
|
|
// Finally, after the scan, check to see if the store is all that is left.
|
|
|
|
if (UsingBlocks.empty()) {
|
|
|
|
// The alloca has been processed, move on.
|
|
|
|
Allocas[AllocaNum] = Allocas.back();
|
|
|
|
Allocas.pop_back();
|
|
|
|
--AllocaNum;
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2005-11-18 07:29:44 +00:00
|
|
|
|
2004-09-15 01:02:54 +00:00
|
|
|
if (AST)
|
|
|
|
PointerAllocaValues[AllocaNum] = AllocaPointerVal;
|
|
|
|
|
2004-06-19 07:40:14 +00:00
|
|
|
// If we haven't computed a numbering for the BB's in the function, do so
|
|
|
|
// now.
|
2007-02-05 23:37:20 +00:00
|
|
|
if (BBNumbers.empty()) {
|
|
|
|
unsigned ID = 0;
|
|
|
|
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
|
|
|
|
BBNumbers[I] = ID++;
|
|
|
|
}
|
2004-06-19 07:40:14 +00:00
|
|
|
|
2003-10-05 02:37:36 +00:00
|
|
|
// Compute the locations where PhiNodes need to be inserted. Look at the
|
|
|
|
// dominance frontier of EACH basic-block we have a write in.
|
|
|
|
//
|
2003-10-05 04:33:22 +00:00
|
|
|
unsigned CurrentVersion = 0;
|
2007-02-05 23:11:37 +00:00
|
|
|
SmallPtrSet<PHINode*, 16> InsertedPHINodes;
|
2007-02-05 23:31:26 +00:00
|
|
|
std::vector<std::pair<unsigned, BasicBlock*> > DFBlocks;
|
2003-10-05 03:39:10 +00:00
|
|
|
while (!DefiningBlocks.empty()) {
|
|
|
|
BasicBlock *BB = DefiningBlocks.back();
|
|
|
|
DefiningBlocks.pop_back();
|
|
|
|
|
2002-04-28 18:27:55 +00:00
|
|
|
// Look up the DF for this write, add it to PhiNodes
|
2003-10-05 03:39:10 +00:00
|
|
|
DominanceFrontier::const_iterator it = DF.find(BB);
|
2003-04-10 19:41:13 +00:00
|
|
|
if (it != DF.end()) {
|
|
|
|
const DominanceFrontier::DomSetType &S = it->second;
|
2004-06-19 07:40:14 +00:00
|
|
|
|
|
|
|
// In theory we don't need the indirection through the DFBlocks vector.
|
|
|
|
// In practice, the order of calling QueuePhiNode would depend on the
|
|
|
|
// (unspecified) ordering of basic blocks in the dominance frontier,
|
|
|
|
// which would give PHI nodes non-determinstic subscripts. Fix this by
|
|
|
|
// processing blocks in order of the occurance in the function.
|
2004-10-18 14:38:48 +00:00
|
|
|
for (DominanceFrontier::DomSetType::const_iterator P = S.begin(),
|
|
|
|
PE = S.end(); P != PE; ++P)
|
2007-02-05 23:37:20 +00:00
|
|
|
DFBlocks.push_back(std::make_pair(BBNumbers[*P], *P));
|
2004-06-19 07:40:14 +00:00
|
|
|
|
|
|
|
// Sort by which the block ordering in the function.
|
|
|
|
std::sort(DFBlocks.begin(), DFBlocks.end());
|
|
|
|
|
|
|
|
for (unsigned i = 0, e = DFBlocks.size(); i != e; ++i) {
|
2007-02-05 23:31:26 +00:00
|
|
|
BasicBlock *BB = DFBlocks[i].second;
|
2004-06-19 07:40:14 +00:00
|
|
|
if (QueuePhiNode(BB, AllocaNum, CurrentVersion, InsertedPHINodes))
|
|
|
|
DefiningBlocks.push_back(BB);
|
|
|
|
}
|
|
|
|
DFBlocks.clear();
|
2003-04-10 19:41:13 +00:00
|
|
|
}
|
2002-04-28 18:27:55 +00:00
|
|
|
}
|
2003-10-05 22:19:20 +00:00
|
|
|
|
|
|
|
// Now that we have inserted PHI nodes along the Iterated Dominance Frontier
|
|
|
|
// of the writes to the variable, scan through the reads of the variable,
|
|
|
|
// marking PHI nodes which are actually necessary as alive (by removing them
|
|
|
|
// from the InsertedPHINodes set). This is not perfect: there may PHI
|
|
|
|
// marked alive because of loads which are dominated by stores, but there
|
|
|
|
// will be no unmarked PHI nodes which are actually used.
|
|
|
|
//
|
|
|
|
for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
|
|
|
|
MarkDominatingPHILive(UsingBlocks[i], AllocaNum, InsertedPHINodes);
|
|
|
|
UsingBlocks.clear();
|
|
|
|
|
|
|
|
// If there are any PHI nodes which are now known to be dead, remove them!
|
2007-02-05 23:11:37 +00:00
|
|
|
for (SmallPtrSet<PHINode*, 16>::iterator I = InsertedPHINodes.begin(),
|
2003-10-05 22:19:20 +00:00
|
|
|
E = InsertedPHINodes.end(); I != E; ++I) {
|
|
|
|
PHINode *PN = *I;
|
2007-02-07 01:15:04 +00:00
|
|
|
bool Erased=NewPhiNodes.erase(std::make_pair(PN->getParent(), AllocaNum));
|
|
|
|
Erased=Erased;
|
|
|
|
assert(Erased && "PHI already removed?");
|
|
|
|
|
2004-09-15 01:02:54 +00:00
|
|
|
if (AST && isa<PointerType>(PN->getType()))
|
|
|
|
AST->deleteValue(PN);
|
2006-04-27 01:14:43 +00:00
|
|
|
PN->eraseFromParent();
|
2007-02-07 01:15:04 +00:00
|
|
|
PhiToAllocaMap.erase(PN);
|
2003-10-05 22:19:20 +00:00
|
|
|
}
|
|
|
|
|
2005-04-21 23:48:37 +00:00
|
|
|
// Keep the reverse mapping of the 'Allocas' array.
|
2003-10-05 22:19:20 +00:00
|
|
|
AllocaLookup[Allocas[AllocaNum]] = AllocaNum;
|
2002-04-28 18:27:55 +00:00
|
|
|
}
|
2005-04-21 23:48:37 +00:00
|
|
|
|
2004-02-03 22:34:12 +00:00
|
|
|
// Process all allocas which are only used in a single basic block.
|
|
|
|
for (std::map<BasicBlock*, std::vector<AllocaInst*> >::iterator I =
|
|
|
|
LocallyUsedAllocas.begin(), E = LocallyUsedAllocas.end(); I != E; ++I){
|
2005-06-30 07:29:44 +00:00
|
|
|
const std::vector<AllocaInst*> &LocAllocas = I->second;
|
|
|
|
assert(!LocAllocas.empty() && "empty alloca list??");
|
2004-02-03 22:34:12 +00:00
|
|
|
|
|
|
|
// It's common for there to only be one alloca in the list. Handle it
|
|
|
|
// efficiently.
|
2005-06-30 07:29:44 +00:00
|
|
|
if (LocAllocas.size() == 1) {
|
|
|
|
// If we can do the quick promotion pass, do so now.
|
|
|
|
if (PromoteLocallyUsedAlloca(I->first, LocAllocas[0]))
|
|
|
|
RetryList.push_back(LocAllocas[0]); // Failed, retry later.
|
|
|
|
} else {
|
|
|
|
// Locally promote anything possible. Note that if this is unable to
|
|
|
|
// promote a particular alloca, it puts the alloca onto the Allocas vector
|
|
|
|
// for global processing.
|
|
|
|
PromoteLocallyUsedAllocas(I->first, LocAllocas);
|
|
|
|
}
|
2004-02-03 22:34:12 +00:00
|
|
|
}
|
|
|
|
|
2003-10-05 20:54:03 +00:00
|
|
|
if (Allocas.empty())
|
|
|
|
return; // All of the allocas must have been trivial!
|
2002-04-28 18:27:55 +00:00
|
|
|
|
2002-04-28 18:39:46 +00:00
|
|
|
// Set the incoming values for the basic block to be null values for all of
|
|
|
|
// the alloca's. We do this in case there is a load of a value that has not
|
|
|
|
// been stored yet. In this case, it will get this null value.
|
|
|
|
//
|
2003-02-22 22:25:17 +00:00
|
|
|
std::vector<Value *> Values(Allocas.size());
|
2002-04-28 18:39:46 +00:00
|
|
|
for (unsigned i = 0, e = Allocas.size(); i != e; ++i)
|
2004-10-16 18:10:06 +00:00
|
|
|
Values[i] = UndefValue::get(Allocas[i]->getAllocatedType());
|
2002-04-28 18:39:46 +00:00
|
|
|
|
2002-04-28 18:27:55 +00:00
|
|
|
// Walks all basic blocks in the function performing the SSA rename algorithm
|
|
|
|
// and inserting the phi nodes we marked as necessary
|
|
|
|
//
|
2007-08-04 01:04:40 +00:00
|
|
|
|
|
|
|
std::vector<RenamePassData> RenamePassWorkList;
|
2007-03-26 23:19:29 +00:00
|
|
|
RenamePassWorkList.push_back(RenamePassData(F.begin(), 0, Values));
|
2007-03-09 23:39:14 +00:00
|
|
|
while(!RenamePassWorkList.empty()) {
|
2007-03-26 23:19:29 +00:00
|
|
|
RenamePassData RPD = RenamePassWorkList.back();
|
|
|
|
RenamePassWorkList.pop_back();
|
2007-03-09 23:39:14 +00:00
|
|
|
// RenamePass may add new worklist entries.
|
2007-08-04 01:04:40 +00:00
|
|
|
RenamePass(RPD.BB, RPD.Pred, RPD.Values, RenamePassWorkList);
|
2007-03-09 23:39:14 +00:00
|
|
|
}
|
|
|
|
|
2003-10-05 04:26:39 +00:00
|
|
|
// The renamer uses the Visited set to avoid infinite loops. Clear it now.
|
2003-10-05 01:52:53 +00:00
|
|
|
Visited.clear();
|
2002-04-28 18:27:55 +00:00
|
|
|
|
2006-04-27 01:14:43 +00:00
|
|
|
// Remove the allocas themselves from the function.
|
2003-10-05 01:52:53 +00:00
|
|
|
for (unsigned i = 0, e = Allocas.size(); i != e; ++i) {
|
|
|
|
Instruction *A = Allocas[i];
|
2002-04-28 18:27:55 +00:00
|
|
|
|
2003-10-05 01:52:53 +00:00
|
|
|
// If there are any uses of the alloca instructions left, they must be in
|
2003-04-10 19:41:13 +00:00
|
|
|
// sections of dead code that were not processed on the dominance frontier.
|
|
|
|
// Just delete the users now.
|
|
|
|
//
|
2003-10-05 01:52:53 +00:00
|
|
|
if (!A->use_empty())
|
2004-10-16 18:10:06 +00:00
|
|
|
A->replaceAllUsesWith(UndefValue::get(A->getType()));
|
2004-09-15 01:02:54 +00:00
|
|
|
if (AST) AST->deleteValue(A);
|
2006-04-27 01:14:43 +00:00
|
|
|
A->eraseFromParent();
|
2002-04-28 18:27:55 +00:00
|
|
|
}
|
2003-10-05 04:26:39 +00:00
|
|
|
|
2006-04-27 01:14:43 +00:00
|
|
|
|
|
|
|
// Loop over all of the PHI nodes and see if there are any that we can get
|
|
|
|
// rid of because they merge all of the same incoming values. This can
|
|
|
|
// happen due to undef values coming into the PHI nodes. This process is
|
|
|
|
// iterative, because eliminating one PHI node can cause others to be removed.
|
|
|
|
bool EliminatedAPHI = true;
|
|
|
|
while (EliminatedAPHI) {
|
|
|
|
EliminatedAPHI = false;
|
|
|
|
|
2007-02-07 01:15:04 +00:00
|
|
|
for (DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator I =
|
|
|
|
NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E;) {
|
|
|
|
PHINode *PN = I->second;
|
|
|
|
|
|
|
|
// If this PHI node merges one value and/or undefs, get the value.
|
|
|
|
if (Value *V = PN->hasConstantValue(true)) {
|
|
|
|
if (!isa<Instruction>(V) ||
|
|
|
|
properlyDominates(cast<Instruction>(V), PN)) {
|
|
|
|
if (AST && isa<PointerType>(PN->getType()))
|
|
|
|
AST->deleteValue(PN);
|
|
|
|
PN->replaceAllUsesWith(V);
|
|
|
|
PN->eraseFromParent();
|
|
|
|
NewPhiNodes.erase(I++);
|
|
|
|
EliminatedAPHI = true;
|
|
|
|
continue;
|
2006-04-27 01:14:43 +00:00
|
|
|
}
|
|
|
|
}
|
2007-02-07 01:15:04 +00:00
|
|
|
++I;
|
2006-04-27 01:14:43 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2003-10-05 04:26:39 +00:00
|
|
|
// At this point, the renamer has added entries to PHI nodes for all reachable
|
2007-02-05 22:13:11 +00:00
|
|
|
// code. Unfortunately, there may be unreachable blocks which the renamer
|
|
|
|
// hasn't traversed. If this is the case, the PHI nodes may not
|
2003-10-05 04:26:39 +00:00
|
|
|
// have incoming values for all predecessors. Loop over all PHI nodes we have
|
2004-10-17 21:25:56 +00:00
|
|
|
// created, inserting undef values if they are missing any incoming values.
|
2003-10-05 04:26:39 +00:00
|
|
|
//
|
2007-02-07 01:15:04 +00:00
|
|
|
for (DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator I =
|
2003-10-05 04:26:39 +00:00
|
|
|
NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E; ++I) {
|
2007-02-07 01:15:04 +00:00
|
|
|
// We want to do this once per basic block. As such, only process a block
|
|
|
|
// when we find the PHI that is the first entry in the block.
|
|
|
|
PHINode *SomePHI = I->second;
|
|
|
|
BasicBlock *BB = SomePHI->getParent();
|
|
|
|
if (&BB->front() != SomePHI)
|
|
|
|
continue;
|
2003-10-05 04:26:39 +00:00
|
|
|
|
2007-02-07 01:15:04 +00:00
|
|
|
// Count the number of preds for BB.
|
|
|
|
SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB));
|
2004-10-17 21:25:56 +00:00
|
|
|
|
2003-10-05 04:26:39 +00:00
|
|
|
// Only do work here if there the PHI nodes are missing incoming values. We
|
|
|
|
// know that all PHI nodes that were inserted in a block will have the same
|
2007-02-07 01:15:04 +00:00
|
|
|
// number of incoming values, so we can just check any of them.
|
|
|
|
if (SomePHI->getNumIncomingValues() == Preds.size())
|
|
|
|
continue;
|
|
|
|
|
|
|
|
// Ok, now we know that all of the PHI nodes are missing entries for some
|
|
|
|
// basic blocks. Start by sorting the incoming predecessors for efficient
|
|
|
|
// access.
|
|
|
|
std::sort(Preds.begin(), Preds.end());
|
|
|
|
|
|
|
|
// Now we loop through all BB's which have entries in SomePHI and remove
|
|
|
|
// them from the Preds list.
|
|
|
|
for (unsigned i = 0, e = SomePHI->getNumIncomingValues(); i != e; ++i) {
|
|
|
|
// Do a log(n) search of the Preds list for the entry we want.
|
|
|
|
SmallVector<BasicBlock*, 16>::iterator EntIt =
|
|
|
|
std::lower_bound(Preds.begin(), Preds.end(),
|
|
|
|
SomePHI->getIncomingBlock(i));
|
|
|
|
assert(EntIt != Preds.end() && *EntIt == SomePHI->getIncomingBlock(i)&&
|
|
|
|
"PHI node has entry for a block which is not a predecessor!");
|
|
|
|
|
|
|
|
// Remove the entry
|
|
|
|
Preds.erase(EntIt);
|
|
|
|
}
|
2003-10-05 04:26:39 +00:00
|
|
|
|
2007-02-07 01:15:04 +00:00
|
|
|
// At this point, the blocks left in the preds list must have dummy
|
|
|
|
// entries inserted into every PHI nodes for the block. Update all the phi
|
|
|
|
// nodes in this block that we are inserting (there could be phis before
|
|
|
|
// mem2reg runs).
|
|
|
|
unsigned NumBadPreds = SomePHI->getNumIncomingValues();
|
|
|
|
BasicBlock::iterator BBI = BB->begin();
|
|
|
|
while ((SomePHI = dyn_cast<PHINode>(BBI++)) &&
|
|
|
|
SomePHI->getNumIncomingValues() == NumBadPreds) {
|
|
|
|
Value *UndefVal = UndefValue::get(SomePHI->getType());
|
|
|
|
for (unsigned pred = 0, e = Preds.size(); pred != e; ++pred)
|
|
|
|
SomePHI->addIncoming(UndefVal, Preds[pred]);
|
2003-10-05 04:26:39 +00:00
|
|
|
}
|
|
|
|
}
|
2007-02-07 01:15:04 +00:00
|
|
|
|
|
|
|
NewPhiNodes.clear();
|
2002-04-28 18:27:55 +00:00
|
|
|
}
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2003-10-05 22:19:20 +00:00
|
|
|
// MarkDominatingPHILive - Mem2Reg wants to construct "pruned" SSA form, not
|
|
|
|
// "minimal" SSA form. To do this, it inserts all of the PHI nodes on the IDF
|
|
|
|
// as usual (inserting the PHI nodes in the DeadPHINodes set), then processes
|
|
|
|
// each read of the variable. For each block that reads the variable, this
|
|
|
|
// function is called, which removes used PHI nodes from the DeadPHINodes set.
|
|
|
|
// After all of the reads have been processed, any PHI nodes left in the
|
|
|
|
// DeadPHINodes set are removed.
|
|
|
|
//
|
|
|
|
void PromoteMem2Reg::MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
|
2007-02-05 23:11:37 +00:00
|
|
|
SmallPtrSet<PHINode*, 16> &DeadPHINodes) {
|
2003-10-05 22:19:20 +00:00
|
|
|
// Scan the immediate dominators of this block looking for a block which has a
|
|
|
|
// PHI node for Alloca num. If we find it, mark the PHI node as being alive!
|
2007-06-07 21:57:03 +00:00
|
|
|
DomTreeNode *IDomNode = DT.getNode(BB);
|
|
|
|
for (DomTreeNode *IDom = IDomNode; IDom; IDom = IDom->getIDom()) {
|
|
|
|
BasicBlock *DomBB = IDom->getBlock();
|
2007-02-07 01:15:04 +00:00
|
|
|
DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator
|
|
|
|
I = NewPhiNodes.find(std::make_pair(DomBB, AllocaNum));
|
|
|
|
if (I != NewPhiNodes.end()) {
|
2003-10-05 22:19:20 +00:00
|
|
|
// Ok, we found an inserted PHI node which dominates this value.
|
2007-02-07 01:15:04 +00:00
|
|
|
PHINode *DominatingPHI = I->second;
|
2003-10-05 22:19:20 +00:00
|
|
|
|
2007-02-05 22:13:11 +00:00
|
|
|
// Find out if we previously thought it was dead. If so, mark it as being
|
|
|
|
// live by removing it from the DeadPHINodes set.
|
|
|
|
if (DeadPHINodes.erase(DominatingPHI)) {
|
2003-10-05 22:19:20 +00:00
|
|
|
// Now that we have marked the PHI node alive, also mark any PHI nodes
|
|
|
|
// which it might use as being alive as well.
|
|
|
|
for (pred_iterator PI = pred_begin(DomBB), PE = pred_end(DomBB);
|
|
|
|
PI != PE; ++PI)
|
|
|
|
MarkDominatingPHILive(*PI, AllocaNum, DeadPHINodes);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2004-02-03 22:34:12 +00:00
|
|
|
/// PromoteLocallyUsedAlloca - Many allocas are only used within a single basic
|
|
|
|
/// block. If this is the case, avoid traversing the CFG and inserting a lot of
|
|
|
|
/// potentially useless PHI nodes by just performing a single linear pass over
|
|
|
|
/// the basic block using the Alloca.
|
|
|
|
///
|
2005-06-30 07:29:44 +00:00
|
|
|
/// If we cannot promote this alloca (because it is read before it is written),
|
|
|
|
/// return true. This is necessary in cases where, due to control flow, the
|
|
|
|
/// alloca is potentially undefined on some control flow paths. e.g. code like
|
|
|
|
/// this is potentially correct:
|
|
|
|
///
|
|
|
|
/// for (...) { if (c) { A = undef; undef = B; } }
|
|
|
|
///
|
|
|
|
/// ... so long as A is not used before undef is set.
|
|
|
|
///
|
|
|
|
bool PromoteMem2Reg::PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI) {
|
2003-10-05 20:54:03 +00:00
|
|
|
assert(!AI->use_empty() && "There are no uses of the alloca!");
|
2004-02-03 22:00:33 +00:00
|
|
|
|
|
|
|
// Handle degenerate cases quickly.
|
|
|
|
if (AI->hasOneUse()) {
|
|
|
|
Instruction *U = cast<Instruction>(AI->use_back());
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
|
|
|
|
// Must be a load of uninitialized value.
|
2004-10-16 18:10:06 +00:00
|
|
|
LI->replaceAllUsesWith(UndefValue::get(AI->getAllocatedType()));
|
2004-09-15 01:02:54 +00:00
|
|
|
if (AST && isa<PointerType>(LI->getType()))
|
|
|
|
AST->deleteValue(LI);
|
2004-02-03 22:00:33 +00:00
|
|
|
} else {
|
|
|
|
// Otherwise it must be a store which is never read.
|
|
|
|
assert(isa<StoreInst>(U));
|
|
|
|
}
|
|
|
|
BB->getInstList().erase(U);
|
|
|
|
} else {
|
2004-10-16 18:10:06 +00:00
|
|
|
// Uses of the uninitialized memory location shall get undef.
|
2005-06-30 07:29:44 +00:00
|
|
|
Value *CurVal = 0;
|
2005-04-21 23:48:37 +00:00
|
|
|
|
2004-02-03 22:00:33 +00:00
|
|
|
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
|
|
|
|
Instruction *Inst = I++;
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
|
|
|
|
if (LI->getOperand(0) == AI) {
|
2005-06-30 07:29:44 +00:00
|
|
|
if (!CurVal) return true; // Could not locally promote!
|
|
|
|
|
2004-02-03 22:34:12 +00:00
|
|
|
// Loads just returns the "current value"...
|
2004-02-03 22:00:33 +00:00
|
|
|
LI->replaceAllUsesWith(CurVal);
|
2004-09-15 01:02:54 +00:00
|
|
|
if (AST && isa<PointerType>(LI->getType()))
|
|
|
|
AST->deleteValue(LI);
|
2004-02-03 22:00:33 +00:00
|
|
|
BB->getInstList().erase(LI);
|
|
|
|
}
|
|
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
|
|
|
if (SI->getOperand(1) == AI) {
|
2004-02-03 22:34:12 +00:00
|
|
|
// Store updates the "current value"...
|
2004-02-03 22:00:33 +00:00
|
|
|
CurVal = SI->getOperand(0);
|
|
|
|
BB->getInstList().erase(SI);
|
|
|
|
}
|
2003-10-05 20:54:03 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// After traversing the basic block, there should be no more uses of the
|
|
|
|
// alloca, remove it now.
|
|
|
|
assert(AI->use_empty() && "Uses of alloca from more than one BB??");
|
2004-09-15 01:02:54 +00:00
|
|
|
if (AST) AST->deleteValue(AI);
|
2003-10-05 20:54:03 +00:00
|
|
|
AI->getParent()->getInstList().erase(AI);
|
2005-06-30 07:29:44 +00:00
|
|
|
return false;
|
2003-10-05 20:54:03 +00:00
|
|
|
}
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2004-02-03 22:34:12 +00:00
|
|
|
/// PromoteLocallyUsedAllocas - This method is just like
|
|
|
|
/// PromoteLocallyUsedAlloca, except that it processes multiple alloca
|
|
|
|
/// instructions in parallel. This is important in cases where we have large
|
|
|
|
/// basic blocks, as we don't want to rescan the entire basic block for each
|
|
|
|
/// alloca which is locally used in it (which might be a lot).
|
|
|
|
void PromoteMem2Reg::
|
|
|
|
PromoteLocallyUsedAllocas(BasicBlock *BB, const std::vector<AllocaInst*> &AIs) {
|
|
|
|
std::map<AllocaInst*, Value*> CurValues;
|
|
|
|
for (unsigned i = 0, e = AIs.size(); i != e; ++i)
|
|
|
|
CurValues[AIs[i]] = 0; // Insert with null value
|
|
|
|
|
|
|
|
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
|
|
|
|
Instruction *Inst = I++;
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
|
|
|
|
// Is this a load of an alloca we are tracking?
|
|
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(LI->getOperand(0))) {
|
|
|
|
std::map<AllocaInst*, Value*>::iterator AIt = CurValues.find(AI);
|
|
|
|
if (AIt != CurValues.end()) {
|
2005-06-30 07:29:44 +00:00
|
|
|
// If loading an uninitialized value, allow the inter-block case to
|
|
|
|
// handle it. Due to control flow, this might actually be ok.
|
|
|
|
if (AIt->second == 0) { // Use of locally uninitialized value??
|
|
|
|
RetryList.push_back(AI); // Retry elsewhere.
|
|
|
|
CurValues.erase(AIt); // Stop tracking this here.
|
|
|
|
if (CurValues.empty()) return;
|
|
|
|
} else {
|
|
|
|
// Loads just returns the "current value"...
|
|
|
|
LI->replaceAllUsesWith(AIt->second);
|
|
|
|
if (AST && isa<PointerType>(LI->getType()))
|
|
|
|
AST->deleteValue(LI);
|
|
|
|
BB->getInstList().erase(LI);
|
|
|
|
}
|
2004-02-03 22:34:12 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
|
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(SI->getOperand(1))) {
|
|
|
|
std::map<AllocaInst*, Value*>::iterator AIt = CurValues.find(AI);
|
|
|
|
if (AIt != CurValues.end()) {
|
|
|
|
// Store updates the "current value"...
|
|
|
|
AIt->second = SI->getOperand(0);
|
|
|
|
BB->getInstList().erase(SI);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
2002-04-28 18:27:55 +00:00
|
|
|
// QueuePhiNode - queues a phi-node to be added to a basic-block for a specific
|
|
|
|
// Alloca returns true if there wasn't already a phi-node for that variable
|
|
|
|
//
|
2003-10-05 04:33:22 +00:00
|
|
|
bool PromoteMem2Reg::QueuePhiNode(BasicBlock *BB, unsigned AllocaNo,
|
2003-10-05 22:19:20 +00:00
|
|
|
unsigned &Version,
|
2007-02-05 23:11:37 +00:00
|
|
|
SmallPtrSet<PHINode*, 16> &InsertedPHINodes) {
|
2004-09-15 01:02:54 +00:00
|
|
|
// Look up the basic-block in question.
|
2007-02-07 01:15:04 +00:00
|
|
|
PHINode *&PN = NewPhiNodes[std::make_pair(BB, AllocaNo)];
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2002-04-28 18:27:55 +00:00
|
|
|
// If the BB already has a phi node added for the i'th alloca then we're done!
|
2007-02-07 01:15:04 +00:00
|
|
|
if (PN) return false;
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2002-09-10 22:38:47 +00:00
|
|
|
// Create a PhiNode using the dereferenced type... and add the phi-node to the
|
2003-04-18 19:25:22 +00:00
|
|
|
// BasicBlock.
|
2007-02-07 01:15:04 +00:00
|
|
|
PN = new PHINode(Allocas[AllocaNo]->getAllocatedType(),
|
|
|
|
Allocas[AllocaNo]->getName() + "." +
|
|
|
|
utostr(Version++), BB->begin());
|
|
|
|
PhiToAllocaMap[PN] = AllocaNo;
|
|
|
|
|
2004-09-15 01:02:54 +00:00
|
|
|
InsertedPHINodes.insert(PN);
|
|
|
|
|
|
|
|
if (AST && isa<PointerType>(PN->getType()))
|
|
|
|
AST->copyValue(PointerAllocaValues[AllocaNo], PN);
|
|
|
|
|
2002-04-28 18:27:55 +00:00
|
|
|
return true;
|
|
|
|
}
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2003-10-05 22:19:20 +00:00
|
|
|
|
|
|
|
// RenamePass - Recursively traverse the CFG of the function, renaming loads and
|
|
|
|
// stores to the allocas which we are promoting. IncomingVals indicates what
|
|
|
|
// value each Alloca contains on exit from the predecessor block Pred.
|
|
|
|
//
|
2003-02-22 23:57:48 +00:00
|
|
|
void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
|
2007-08-04 01:04:40 +00:00
|
|
|
std::vector<Value*> &IncomingVals,
|
|
|
|
std::vector<RenamePassData> &Worklist) {
|
2007-02-07 01:15:04 +00:00
|
|
|
// If we are inserting any phi nodes into this BB, they will already be in the
|
|
|
|
// block.
|
|
|
|
if (PHINode *APN = dyn_cast<PHINode>(BB->begin())) {
|
|
|
|
// Pred may have multiple edges to BB. If so, we want to add N incoming
|
|
|
|
// values to each PHI we are inserting on the first time we see the edge.
|
|
|
|
// Check to see if APN already has incoming values from Pred. This also
|
|
|
|
// prevents us from modifying PHI nodes that are not currently being
|
|
|
|
// inserted.
|
|
|
|
bool HasPredEntries = false;
|
|
|
|
for (unsigned i = 0, e = APN->getNumIncomingValues(); i != e; ++i) {
|
|
|
|
if (APN->getIncomingBlock(i) == Pred) {
|
|
|
|
HasPredEntries = true;
|
|
|
|
break;
|
2003-04-25 00:54:58 +00:00
|
|
|
}
|
2007-02-07 01:15:04 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
// If we have PHI nodes to update, compute the number of edges from Pred to
|
|
|
|
// BB.
|
|
|
|
if (!HasPredEntries) {
|
|
|
|
TerminatorInst *PredTerm = Pred->getTerminator();
|
|
|
|
unsigned NumEdges = 0;
|
|
|
|
for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) {
|
|
|
|
if (PredTerm->getSuccessor(i) == BB)
|
|
|
|
++NumEdges;
|
|
|
|
}
|
|
|
|
assert(NumEdges && "Must be at least one edge from Pred to BB!");
|
|
|
|
|
|
|
|
// Add entries for all the phis.
|
|
|
|
BasicBlock::iterator PNI = BB->begin();
|
|
|
|
do {
|
|
|
|
unsigned AllocaNo = PhiToAllocaMap[APN];
|
|
|
|
|
|
|
|
// Add N incoming values to the PHI node.
|
|
|
|
for (unsigned i = 0; i != NumEdges; ++i)
|
|
|
|
APN->addIncoming(IncomingVals[AllocaNo], Pred);
|
|
|
|
|
|
|
|
// The currently active variable for this block is now the PHI.
|
|
|
|
IncomingVals[AllocaNo] = APN;
|
|
|
|
|
|
|
|
// Get the next phi node.
|
|
|
|
++PNI;
|
|
|
|
APN = dyn_cast<PHINode>(PNI);
|
|
|
|
if (APN == 0) break;
|
|
|
|
|
|
|
|
// Verify it doesn't already have entries for Pred. If it does, it is
|
|
|
|
// not being inserted by this mem2reg invocation.
|
|
|
|
HasPredEntries = false;
|
|
|
|
for (unsigned i = 0, e = APN->getNumIncomingValues(); i != e; ++i) {
|
|
|
|
if (APN->getIncomingBlock(i) == Pred) {
|
|
|
|
HasPredEntries = true;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
} while (!HasPredEntries);
|
|
|
|
}
|
2003-10-05 02:37:36 +00:00
|
|
|
}
|
2007-02-07 01:15:04 +00:00
|
|
|
|
|
|
|
// Don't revisit blocks.
|
|
|
|
if (!Visited.insert(BB)) return;
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2003-10-05 03:45:44 +00:00
|
|
|
for (BasicBlock::iterator II = BB->begin(); !isa<TerminatorInst>(II); ) {
|
2003-10-05 01:52:53 +00:00
|
|
|
Instruction *I = II++; // get the instruction, increment iterator
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2002-04-28 18:27:55 +00:00
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
|
2003-02-22 22:25:17 +00:00
|
|
|
if (AllocaInst *Src = dyn_cast<AllocaInst>(LI->getPointerOperand())) {
|
2003-10-05 03:16:07 +00:00
|
|
|
std::map<AllocaInst*, unsigned>::iterator AI = AllocaLookup.find(Src);
|
2002-04-28 18:54:01 +00:00
|
|
|
if (AI != AllocaLookup.end()) {
|
|
|
|
Value *V = IncomingVals[AI->second];
|
2002-03-27 23:17:37 +00:00
|
|
|
|
2002-04-28 18:27:55 +00:00
|
|
|
// walk the use list of this load and replace all uses with r
|
|
|
|
LI->replaceAllUsesWith(V);
|
2004-09-15 01:02:54 +00:00
|
|
|
if (AST && isa<PointerType>(LI->getType()))
|
|
|
|
AST->deleteValue(LI);
|
2003-10-05 01:52:53 +00:00
|
|
|
BB->getInstList().erase(LI);
|
2002-04-28 18:27:55 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
|
2003-02-22 22:25:17 +00:00
|
|
|
// Delete this instruction and mark the name as the current holder of the
|
2002-04-28 18:27:55 +00:00
|
|
|
// value
|
2003-02-22 22:25:17 +00:00
|
|
|
if (AllocaInst *Dest = dyn_cast<AllocaInst>(SI->getPointerOperand())) {
|
2003-10-05 03:16:07 +00:00
|
|
|
std::map<AllocaInst *, unsigned>::iterator ai = AllocaLookup.find(Dest);
|
2002-04-28 18:27:55 +00:00
|
|
|
if (ai != AllocaLookup.end()) {
|
|
|
|
// what value were we writing?
|
2002-04-28 18:54:01 +00:00
|
|
|
IncomingVals[ai->second] = SI->getOperand(0);
|
2003-10-05 01:52:53 +00:00
|
|
|
BB->getInstList().erase(SI);
|
2002-04-28 18:27:55 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
2003-10-05 03:45:44 +00:00
|
|
|
|
2003-10-05 22:19:20 +00:00
|
|
|
// Recurse to our successors.
|
2003-10-05 03:45:44 +00:00
|
|
|
TerminatorInst *TI = BB->getTerminator();
|
2007-03-26 23:19:29 +00:00
|
|
|
for (unsigned i = 0; i != TI->getNumSuccessors(); i++)
|
2007-08-04 01:04:40 +00:00
|
|
|
Worklist.push_back(RenamePassData(TI->getSuccessor(i), BB, IncomingVals));
|
2002-02-12 17:16:22 +00:00
|
|
|
}
|
2002-03-27 23:28:40 +00:00
|
|
|
|
2003-02-22 23:57:48 +00:00
|
|
|
/// PromoteMemToReg - Promote the specified list of alloca instructions into
|
|
|
|
/// scalar registers, inserting PHI nodes as appropriate. This function makes
|
|
|
|
/// use of DominanceFrontier information. This function does not modify the CFG
|
|
|
|
/// of the function at all. All allocas must be from the same function.
|
|
|
|
///
|
2004-09-15 01:02:54 +00:00
|
|
|
/// If AST is specified, the specified tracker is updated to reflect changes
|
|
|
|
/// made to the IR.
|
|
|
|
///
|
2004-01-09 06:12:26 +00:00
|
|
|
void llvm::PromoteMemToReg(const std::vector<AllocaInst*> &Allocas,
|
2007-06-07 21:57:03 +00:00
|
|
|
DominatorTree &DT, DominanceFrontier &DF,
|
2007-04-25 18:32:35 +00:00
|
|
|
AliasSetTracker *AST) {
|
2003-10-05 01:52:53 +00:00
|
|
|
// If there is nothing to do, bail out...
|
|
|
|
if (Allocas.empty()) return;
|
2005-06-30 07:29:44 +00:00
|
|
|
|
2007-02-05 21:58:48 +00:00
|
|
|
SmallVector<AllocaInst*, 16> RetryList;
|
2007-06-07 21:57:03 +00:00
|
|
|
PromoteMem2Reg(Allocas, RetryList, DT, DF, AST).run();
|
2005-06-30 07:29:44 +00:00
|
|
|
|
|
|
|
// PromoteMem2Reg may not have been able to promote all of the allocas in one
|
|
|
|
// pass, run it again if needed.
|
2007-02-05 21:58:48 +00:00
|
|
|
std::vector<AllocaInst*> NewAllocas;
|
2005-06-30 07:29:44 +00:00
|
|
|
while (!RetryList.empty()) {
|
|
|
|
// If we need to retry some allocas, this is due to there being no store
|
|
|
|
// before a read in a local block. To counteract this, insert a store of
|
|
|
|
// undef into the alloca right after the alloca itself.
|
|
|
|
for (unsigned i = 0, e = RetryList.size(); i != e; ++i) {
|
|
|
|
BasicBlock::iterator BBI = RetryList[i];
|
2005-07-27 06:12:32 +00:00
|
|
|
|
2005-06-30 07:29:44 +00:00
|
|
|
new StoreInst(UndefValue::get(RetryList[i]->getAllocatedType()),
|
|
|
|
RetryList[i], ++BBI);
|
|
|
|
}
|
|
|
|
|
2007-02-05 21:58:48 +00:00
|
|
|
NewAllocas.assign(RetryList.begin(), RetryList.end());
|
|
|
|
RetryList.clear();
|
2007-06-07 21:57:03 +00:00
|
|
|
PromoteMem2Reg(NewAllocas, RetryList, DT, DF, AST).run();
|
2007-02-05 21:58:48 +00:00
|
|
|
NewAllocas.clear();
|
2005-06-30 07:29:44 +00:00
|
|
|
}
|
2002-03-27 23:28:40 +00:00
|
|
|
}
|