--- /dev/null
+//===------------------- SSI.h - Creates SSI Representation -----*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass converts a list of variables to the Static Single Information
+// form. This is a program representation described by Scott Ananian in his
+// Master Thesis: "The Static Single Information Form (1999)".
+// We are building an on-demand representation, that is, we do not convert
+// every single variable in the target function to SSI form. Rather, we receive
+// a list of target variables that must be converted. We also do not
+// completely convert a target variable to the SSI format. Instead, we only
+// change the variable in the points where new information can be attached
+// to its live range, that is, at branch points.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_SSI_H
+#define LLVM_TRANSFORMS_UTILS_SSI_H
+
+#include "llvm/Pass.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+
+namespace llvm {
+
+ class DominatorTree;
+ class PHINode;
+ class Instruction;
+ class CmpInst;
+
+ class SSI : public FunctionPass {
+ public:
+ static char ID; // Pass identification, replacement for typeid.
+ SSI() :
+ FunctionPass(&ID) {
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const;
+
+ /// runOnMachineFunction - pass entry point
+ bool runOnFunction(Function&);
+
+ void createSSI(SmallVectorImpl<Instruction *> &value);
+
+ private:
+ // Variables always live
+ DominatorTree *DT_;
+
+ // Stores variables created by SSI
+ SmallPtrSet<Instruction *, 16> created;
+
+ // These variables are only live for each creation
+ unsigned num_values;
+
+ // Has a bit for each variable, true if it needs to be created
+ // and false otherwise
+ BitVector needConstruction;
+
+ // Phis created by SSI
+ DenseMap<PHINode *, unsigned> phis;
+
+ // Sigmas created by SSI
+ DenseMap<PHINode *, unsigned> sigmas;
+
+ // Phi nodes that have a phi as operand and has to be fixed
+ SmallPtrSet<PHINode *, 1> phisToFix;
+
+ // List of definition points for every variable
+ SmallVector<SmallVector<BasicBlock *, 1>, 0> defsites;
+
+ // Basic Block of the original definition of each variable
+ SmallVector<BasicBlock *, 0> value_original;
+
+ // Stack of last seen definition of a variable
+ SmallVector<SmallVector<Instruction *, 1>, 0> value_stack;
+
+ void insertSigmaFunctions(SmallVectorImpl<Instruction *> &value);
+ void insertPhiFunctions(SmallVectorImpl<Instruction *> &value);
+ void renameInit(SmallVectorImpl<Instruction *> &value);
+ void rename(BasicBlock *BB);
+
+ void substituteUse(Instruction *I);
+ bool dominateAny(BasicBlock *BB, Instruction *value);
+ void fixPhis();
+
+ unsigned getPositionPhi(PHINode *PN);
+ unsigned getPositionSigma(PHINode *PN);
+
+ unsigned isUsedInTerminator(CmpInst *CI);
+
+ void init(SmallVectorImpl<Instruction *> &value);
+ void clean();
+ };
+} // end namespace
+#endif
--- /dev/null
+//===------------------- SSI.cpp - Creates SSI Representation -------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass converts a list of variables to the Static Single Information
+// form. This is a program representation described by Scott Ananian in his
+// Master Thesis: "The Static Single Information Form (1999)".
+// We are building an on-demand representation, that is, we do not convert
+// every single variable in the target function to SSI form. Rather, we receive
+// a list of target variables that must be converted. We also do not
+// completely convert a target variable to the SSI format. Instead, we only
+// change the variable in the points where new information can be attached
+// to its live range, that is, at branch points.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "ssi"
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/SSI.h"
+#include "llvm/Analysis/Dominators.h"
+
+using namespace llvm;
+
+static const std::string SSI_PHI = "SSI_phi";
+static const std::string SSI_SIG = "SSI_sigma";
+
+static const unsigned UNSIGNED_INFINITE = ~0U;
+
+void SSI::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominanceFrontier>();
+ AU.addRequired<DominatorTree>();
+ AU.setPreservesAll();
+}
+
+bool SSI::runOnFunction(Function &F) {
+ DT_ = &getAnalysis<DominatorTree>();
+ return false;
+}
+
+/// This methods creates the SSI representation for the list of values
+/// received. It will only create SSI representation if a value is used
+/// in a to decide a branch. Repeated values are created only once.
+///
+void SSI::createSSI(SmallVectorImpl<Instruction *> &value) {
+ init(value);
+
+ for (unsigned i = 0; i < num_values; ++i) {
+ if (created.insert(value[i])) {
+ needConstruction[i] = true;
+ }
+ }
+ insertSigmaFunctions(value);
+
+ // Test if there is a need to transform to SSI
+ if (needConstruction.any()) {
+ insertPhiFunctions(value);
+ renameInit(value);
+ rename(DT_->getRoot());
+ fixPhis();
+ }
+
+ clean();
+}
+
+/// Insert sigma functions (a sigma function is a phi function with one
+/// operator)
+///
+void SSI::insertSigmaFunctions(SmallVectorImpl<Instruction *> &value) {
+ for (unsigned i = 0; i < num_values; ++i) {
+ if (!needConstruction[i])
+ continue;
+
+ bool need = false;
+ for (Value::use_iterator begin = value[i]->use_begin(), end =
+ value[i]->use_end(); begin != end; ++begin) {
+ // Test if the Use of the Value is in a comparator
+ CmpInst *CI = dyn_cast<CmpInst>(begin);
+ if (CI && isUsedInTerminator(CI)) {
+ // Basic Block of the Instruction
+ BasicBlock *BB = CI->getParent();
+ // Last Instruction of the Basic Block
+ const TerminatorInst *TI = BB->getTerminator();
+
+ for (unsigned j = 0, e = TI->getNumSuccessors(); j < e; ++j) {
+ // Next Basic Block
+ BasicBlock *BB_next = TI->getSuccessor(j);
+ if (BB_next != BB &&
+ BB_next->getUniquePredecessor() != NULL &&
+ dominateAny(BB_next, value[i])) {
+ PHINode *PN = PHINode::Create(
+ value[i]->getType(), SSI_SIG, BB_next->begin());
+ PN->addIncoming(value[i], BB);
+ sigmas.insert(std::make_pair(PN, i));
+ created.insert(PN);
+ need = true;
+ defsites[i].push_back(BB_next);
+ }
+ }
+ }
+ }
+ needConstruction[i] = need;
+ }
+}
+
+/// Insert phi functions when necessary
+///
+void SSI::insertPhiFunctions(SmallVectorImpl<Instruction *> &value) {
+ DominanceFrontier *DF = &getAnalysis<DominanceFrontier>();
+ for (unsigned i = 0; i < num_values; ++i) {
+ // Test if there were any sigmas for this variable
+ if (needConstruction[i]) {
+
+ SmallPtrSet<BasicBlock *, 1> BB_visited;
+
+ // Insert phi functions if there is any sigma function
+ while (!defsites[i].empty()) {
+
+ BasicBlock *BB = defsites[i].back();
+
+ defsites[i].pop_back();
+ DominanceFrontier::iterator DF_BB = DF->find(BB);
+
+ // Iterates through all the dominance frontier of BB
+ for (std::set<BasicBlock *>::iterator DF_BB_begin =
+ DF_BB->second.begin(), DF_BB_end = DF_BB->second.end();
+ DF_BB_begin != DF_BB_end; ++DF_BB_begin) {
+ BasicBlock *BB_dominated = *DF_BB_begin;
+
+ // Test if has not yet visited this node and if the
+ // original definition dominates this node
+ if (BB_visited.insert(BB_dominated) &&
+ DT_->properlyDominates(value_original[i], BB_dominated) &&
+ dominateAny(BB_dominated, value[i])) {
+ PHINode *PN = PHINode::Create(
+ value[i]->getType(), SSI_PHI, BB_dominated->begin());
+ phis.insert(std::make_pair(PN, i));
+ created.insert(PN);
+
+ defsites[i].push_back(BB_dominated);
+ }
+ }
+ }
+ BB_visited.clear();
+ }
+ }
+}
+
+/// Some initialization for the rename part
+///
+void SSI::renameInit(SmallVectorImpl<Instruction *> &value) {
+ value_stack.resize(num_values);
+ for (unsigned i = 0; i < num_values; ++i) {
+ value_stack[i].push_back(value[i]);
+ }
+}
+
+/// Renames all variables in the specified BasicBlock.
+/// Only variables that need to be rename will be.
+///
+void SSI::rename(BasicBlock *BB) {
+ BitVector *defined = new BitVector(num_values, false);
+
+ // Iterate through instructions and make appropriate renaming.
+ // For SSI_PHI (b = PHI()), store b at value_stack as a new
+ // definition of the variable it represents.
+ // For SSI_SIG (b = PHI(a)), substitute a with the current
+ // value of a, present in the value_stack.
+ // Then store bin the value_stack as the new definition of a.
+ // For all other instructions (b = OP(a, c, d, ...)), we need to substitute
+ // all operands with its current value, present in value_stack.
+ for (BasicBlock::iterator begin = BB->begin(), end = BB->end();
+ begin != end; ++begin) {
+ Instruction *I = begin;
+ if (PHINode *PN = dyn_cast<PHINode>(I)) { // Treat PHI functions
+ int position;
+
+ // Treat SSI_PHI
+ if ((position = getPositionPhi(PN)) != -1) {
+ value_stack[position].push_back(PN);
+ (*defined)[position] = true;
+ }
+
+ // Treat SSI_SIG
+ else if ((position = getPositionSigma(PN)) != -1) {
+ substituteUse(I);
+ value_stack[position].push_back(PN);
+ (*defined)[position] = true;
+ }
+
+ // Treat all other PHI functions
+ else {
+ substituteUse(I);
+ }
+ }
+
+ // Treat all other functions
+ else {
+ substituteUse(I);
+ }
+ }
+
+ // This loop iterates in all BasicBlocks that are successors of the current
+ // BasicBlock. For each SSI_PHI instruction found, insert an operand.
+ // This operand is the current operand in value_stack for the variable
+ // in "position". And the BasicBlock this operand represents is the current
+ // BasicBlock.
+ for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI) {
+ BasicBlock *BB_succ = *SI;
+
+ for (BasicBlock::iterator begin = BB_succ->begin(),
+ notPhi = BB_succ->getFirstNonPHI(); begin != *notPhi; ++begin) {
+ Instruction *I = begin;
+ PHINode *PN;
+ int position;
+ if ((PN = dyn_cast<PHINode>(I)) && ((position
+ = getPositionPhi(PN)) != -1)) {
+ PN->addIncoming(value_stack[position].back(), BB);
+ }
+ }
+ }
+
+ // This loop calls rename on all children from this block. This time children
+ // refers to a successor block in the dominance tree.
+ DomTreeNode *DTN = DT_->getNode(BB);
+ for (DomTreeNode::iterator begin = DTN->begin(), end = DTN->end();
+ begin != end; ++begin) {
+ DomTreeNodeBase<BasicBlock> *DTN_children = *begin;
+ BasicBlock *BB_children = DTN_children->getBlock();
+ rename(BB_children);
+ }
+
+ // Now we remove all inserted definitions of a variable from the top of
+ // the stack leaving the previous one as the top.
+ if (defined->any()) {
+ for (unsigned i = 0; i < num_values; ++i) {
+ if ((*defined)[i]) {
+ value_stack[i].pop_back();
+ }
+ }
+ }
+}
+
+/// Substitute any use in this instruction for the last definition of
+/// the variable
+///
+void SSI::substituteUse(Instruction *I) {
+ for (unsigned i = 0, e = I->getNumOperands(); i < e; ++i) {
+ Value *operand = I->getOperand(i);
+ for (unsigned j = 0; j < num_values; ++j) {
+ if (operand == value_stack[j].front() &&
+ I != value_stack[j].back()) {
+ PHINode *PN_I = dyn_cast<PHINode>(I);
+ PHINode *PN_vs = dyn_cast<PHINode>(value_stack[j].back());
+
+ // If a phi created in a BasicBlock is used as an operand of another
+ // created in the same BasicBlock, this step marks this second phi,
+ // to fix this issue later. It cannot be fixed now, because the
+ // operands of the first phi are not final yet.
+ if (PN_I && PN_vs &&
+ value_stack[j].back()->getParent() == I->getParent()) {
+
+ phisToFix.insert(PN_I);
+ }
+
+ I->setOperand(i, value_stack[j].back());
+ break;
+ }
+ }
+ }
+}
+
+/// Test if the BasicBlock BB dominates any use or definition of value.
+///
+bool SSI::dominateAny(BasicBlock *BB, Instruction *value) {
+ for (Value::use_iterator begin = value->use_begin(),
+ end = value->use_end(); begin != end; ++begin) {
+ Instruction *I = cast<Instruction>(*begin);
+ BasicBlock *BB_father = I->getParent();
+ if (DT_->dominates(BB, BB_father)) {
+ return true;
+ }
+ }
+ return false;
+}
+
+/// When there is a phi node that is created in a BasicBlock and it is used
+/// as an operand of another phi function used in the same BasicBlock,
+/// LLVM looks this as an error. So on the second phi, the first phi is called
+/// P and the BasicBlock it incomes is B. This P will be replaced by the value
+/// it has for BasicBlock B.
+///
+void SSI::fixPhis() {
+ for (SmallPtrSet<PHINode *, 1>::iterator begin = phisToFix.begin(),
+ end = phisToFix.end(); begin != end; ++begin) {
+ PHINode *PN = *begin;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
+ PHINode *PN_father;
+ if ((PN_father = dyn_cast<PHINode>(PN->getIncomingValue(i))) &&
+ PN->getParent() == PN_father->getParent()) {
+ BasicBlock *BB = PN->getIncomingBlock(i);
+ int pos = PN_father->getBasicBlockIndex(BB);
+ PN->setIncomingValue(i, PN_father->getIncomingValue(pos));
+ }
+ }
+ }
+}
+
+/// Return which variable (position on the vector of variables) this phi
+/// represents on the phis list.
+///
+unsigned SSI::getPositionPhi(PHINode *PN) {
+ DenseMap<PHINode *, unsigned>::iterator val = phis.find(PN);
+ if (val == phis.end())
+ return UNSIGNED_INFINITE;
+ else
+ return val->second;
+}
+
+/// Return which variable (position on the vector of variables) this phi
+/// represents on the sigmas list.
+///
+unsigned SSI::getPositionSigma(PHINode *PN) {
+ DenseMap<PHINode *, unsigned>::iterator val = sigmas.find(PN);
+ if (val == sigmas.end())
+ return UNSIGNED_INFINITE;
+ else
+ return val->second;
+}
+
+/// Return true if the the Comparison Instruction is an operator
+/// of the Terminator instruction of its Basic Block.
+///
+unsigned SSI::isUsedInTerminator(CmpInst *CI) {
+ TerminatorInst *TI = CI->getParent()->getTerminator();
+ if (TI->getNumOperands() == 0) {
+ return false;
+ } else if (CI == TI->getOperand(0)) {
+ return true;
+ } else {
+ return false;
+ }
+}
+
+/// Initializes
+///
+void SSI::init(SmallVectorImpl<Instruction *> &value) {
+ num_values = value.size();
+ needConstruction.resize(num_values, false);
+
+ value_original.resize(num_values);
+ defsites.resize(num_values);
+
+ for (unsigned i = 0; i < num_values; ++i) {
+ value_original[i] = value[i]->getParent();
+ defsites[i].push_back(value_original[i]);
+ }
+}
+
+/// Clean all used resources in this creation of SSI
+///
+void SSI::clean() {
+ for (unsigned i = 0; i < num_values; ++i) {
+ defsites[i].clear();
+ if (i < value_stack.size())
+ value_stack[i].clear();
+ }
+
+ phis.clear();
+ sigmas.clear();
+ phisToFix.clear();
+
+ defsites.clear();
+ value_stack.clear();
+ value_original.clear();
+ needConstruction.clear();
+}
+
+/// createSSIPass - The public interface to this file...
+///
+FunctionPass *llvm::createSSIPass() { return new SSI(); }
+
+char SSI::ID = 0;
+static RegisterPass<SSI> X("ssi", "Static Single Information Construction");
+
projects / oota-llvm.git / commitdiff