// Do partial redundancy elimination, looking for copies of one expression expr
// within the basic block root. A control flow graph for root must be provided
// in cfg, with a map from nodes to their statements in node_statements, a map
// from edges to their CFG edge types in edge_type, and a map from edges to
// their insertion points in edge_insertion_point. The algorithm used is that
// of Paleri, Srikant, and Shankar ("Partial redundancy elimination: a simple,
// pragmatic, and provably correct algorithm", Science of Computer Programming
// 48 (2003) 1--20).
void PRE::partialRedundancyEliminationOne( SgExpression* expr, SgBasicBlock* root, const myControlFlowGraph& cfg)
{
// SgBasicBlock* myFunctionBody = getFunctionDefinition(expr)->get_body();
// DQ (3/16/2006): Added assertions
ROSE_ASSERT(expr != NULL);
ROSE_ASSERT(root != NULL);
vector<SgVariableSymbol*> symbols_in_expression = SageInterface::getSymbolsUsedInExpression(expr);
if (anyOfListPotentiallyModifiedIn(symbols_in_expression, expr))
{
// This expression updates its own arguments, and so is not idempotent
// Return immediately
return;
}
// Simple or not user-definable expressions
if (isSgVarRefExp(expr)) return;
if (isSgValueExp(expr)) return;
if (isSgFunctionRefExp(expr)) return;
if (isSgExprListExp(expr)) return;
if (isSgInitializer(expr)) return;
#if 0
if ( (isSgAddOp(expr) || isSgSubtractOp(expr)) &&
(isSgVarRefExp(isSgBinaryOp(expr)->get_lhs_operand()) ||
isSgValueExp(isSgBinaryOp(expr)->get_lhs_operand())) &&
(isSgVarRefExp(isSgBinaryOp(expr)->get_rhs_operand()) ||
isSgValueExp(isSgBinaryOp(expr)->get_rhs_operand())))
return;
#endif
// Expressions which do not keep a consistent value each time they are used
if (!expressionTreeEqual(expr, expr))
return;
// cerr << "Trying to do PRE using expression " << expr->unparseToString() << " whose type is " << expr->sage_class_name() << endl;
VertexIter i = cfg.graph.vertices().begin(),
end = cfg.graph.vertices().end();
// cerr << "CFG has " << distance(i, end) << " nodes" << endl;
bool needToMakeCachevar = false;
set<SgNode*> replacements;
vector<pair<SgNode*, bool /* before */> > insertions;
vector<bool> transp(cfg.graph.vertices().size()),
comp(cfg.graph.vertices().size()),
antloc(cfg.graph.vertices().size());
vector<SgNode*> first_computation(cfg.graph.vertices().size()),
last_computation(cfg.graph.vertices().size());
// Set values of local node properties
for (i = cfg.graph.vertices().begin(); i != end; ++i)
{
const vector<SgNode*>& stmts = cfg.node_statements[*i];
// Precompute test values for each statement
vector<bool> argumentsModifiedInStatement(stmts.size());
vector<int> expressionComputedInStatement(stmts.size());
for (unsigned int j = 0; j < stmts.size(); ++j)
{
if (anyOfListPotentiallyModifiedIn(symbols_in_expression, stmts[j]))
argumentsModifiedInStatement[j] = true;
expressionComputedInStatement[j] = countComputationsOfExpressionIn(expr, stmts[j]);
}
// Compute transp
transp[*i] = true;
for (unsigned int j = 0; j < stmts.size(); ++j)
if (argumentsModifiedInStatement[j])
transp[*i] = false;
// Compute comp and do local redundancy elimination
comp[*i] = false;
SgNode* firstComputationInChain = 0;
bool needToInsertComputation = false;
bool computationInsertedOrUsed = false;
// cout << "In node " << *i << endl;
for (unsigned int j = 0; j < stmts.size(); ++j)
{
// cout << "In stmt " << j << ", expressionComputedInStatement = " << expressionComputedInStatement[j]
// << ", argumentsModifiedInStatement = " << argumentsModifiedInStatement[j] << endl;
if (expressionComputedInStatement[j] && !argumentsModifiedInStatement[j] && comp[*i] /* from last iter */)
{
// Do local redundancy elimination
if (firstComputationInChain && needToInsertComputation)
{
insertions.push_back(make_pair(firstComputationInChain, true));
replacements.insert(firstComputationInChain);
needToInsertComputation = false;
}
replacements.insert(stmts[j]);
computationInsertedOrUsed = true;
needToMakeCachevar = true;
}
if (expressionComputedInStatement[j])
{
comp[*i] = true;
if (!firstComputationInChain)
{
firstComputationInChain = stmts[j];
needToInsertComputation = true;
if (expressionComputedInStatement[j] >= 2)
{
insertions.push_back(make_pair(stmts[j], true));
needToMakeCachevar = true;
needToInsertComputation = false;
computationInsertedOrUsed = true;
replacements.insert(stmts[j]);
}
}
last_computation[*i] = stmts[j];
}
if (argumentsModifiedInStatement[j])
{
comp[*i] = false; // Must come after expressionComputedInStatement check
firstComputationInChain = 0;
needToInsertComputation = false;
}
}
assert (!computationInsertedOrUsed || needToMakeCachevar);
// Compute antloc
antloc[*i] = false;
for (unsigned int j = 0; j < stmts.size(); ++j)
{
if (expressionComputedInStatement[j] && !argumentsModifiedInStatement[j])
{
antloc[*i] = true;
first_computation[*i] = stmts[j];
break;
}
if (argumentsModifiedInStatement[j])
{
antloc[*i] = false;
break;
}
}
}
// #define PRINT_PROPERTY(p) // for (i = cfg.graph.vertices().begin(); i != end; ++i) if (p[*i]) cerr << #p ": " << *i << endl;
#define PRINT_PROPERTY(p) // for (i = cfg.graph.vertices().begin(); i != end; ++i) if (p[*i]) cerr << #p ": " << *i << endl;
PRINT_PROPERTY(transp);
PRINT_PROPERTY(comp);
PRINT_PROPERTY(antloc);
int (simpleGraph::*source_ptr)(int) const = &simpleGraph::source;
int (simpleGraph::*target_ptr)(int) const = &simpleGraph::target;
vector<bool> avin(cfg.graph.vertices().size(), true);
vector<bool> avout(cfg.graph.vertices().size(), true);
FIXPOINT_BEGIN(cfg)
FIXPOINT_OUTPUT_BEGIN(avin, cfg);
FIXPOINT_OUTPUT_BEGIN(avout, cfg);
avin[v] = accumulate_neighbors(cfg, v, avout,cfg.graph.in_edges(v),&simpleGraph::source, logical_and<bool>(), true, false);
avout[v] = comp[v] || (avin[v] && transp[v]);
FIXPOINT_OUTPUT_END(avout, <=, cfg);
FIXPOINT_OUTPUT_END(avin, <=, cfg);
FIXPOINT_END(cfg, out_edges, OutEdgeIter)
PRINT_PROPERTY(avin);
PRINT_PROPERTY(avout);
vector<bool> antin(cfg.graph.vertices().size(), true);
vector<bool> antout(cfg.graph.vertices().size(), true);
FIXPOINT_BEGIN(cfg)
FIXPOINT_OUTPUT_BEGIN(antin, cfg);
FIXPOINT_OUTPUT_BEGIN(antout, cfg);
antout[v] = accumulate_neighbors(cfg, v, antin, cfg.graph.out_edges(v), target_ptr, logical_and<bool>(), true, false);
antin[v] = antloc[v] || (antout[v] && transp[v]);
FIXPOINT_OUTPUT_END(antout, <=, cfg);
FIXPOINT_OUTPUT_END(antin, <=, cfg);
FIXPOINT_END(cfg, in_edges, InEdgeIter)
PRINT_PROPERTY(antin);
PRINT_PROPERTY(antout);
vector<bool> safein(cfg.graph.vertices().size()), safeout(cfg.graph.vertices().size());
for (i = cfg.graph.vertices().begin(); i != end; ++i)
{
safein[*i] = avin[*i] || antin[*i];
safeout[*i] = avout[*i] || antout[*i];
}
PRINT_PROPERTY(safein);
PRINT_PROPERTY(safeout);
vector<bool> spavin(cfg.graph.vertices().size(), false);
vector<bool> spavout(cfg.graph.vertices().size(), false);
FIXPOINT_BEGIN(cfg)
FIXPOINT_OUTPUT_BEGIN(spavin, cfg);
FIXPOINT_OUTPUT_BEGIN(spavout, cfg);
spavin[v] = safein[v] && accumulate_neighbors(cfg, v, spavout, cfg.graph.in_edges(v), source_ptr, logical_or<bool>(), false, false);
spavout[v] = safeout[v] && (comp[v] || (spavin[v] && transp[v]));
FIXPOINT_OUTPUT_END(spavout, >=, cfg);
FIXPOINT_OUTPUT_END(spavin, >=, cfg);
FIXPOINT_END(cfg, out_edges, OutEdgeIter)
PRINT_PROPERTY(spavin);
PRINT_PROPERTY(spavout);
vector<bool> spantin(cfg.graph.vertices().size(), false);
vector<bool> spantout(cfg.graph.vertices().size(), false);
FIXPOINT_BEGIN(cfg)
FIXPOINT_OUTPUT_BEGIN(spantin, cfg);
FIXPOINT_OUTPUT_BEGIN(spantout, cfg);
spantout[v] = safeout[v] && accumulate_neighbors(cfg, v, spantin, cfg.graph.out_edges(v), target_ptr, logical_or<bool>(), false, false);
spantin[v] = safein[v] && (antloc[v] || (spantout[v] && transp[v]));
FIXPOINT_OUTPUT_END(spantout, >=, cfg);
FIXPOINT_OUTPUT_END(spantin, >=, cfg);
FIXPOINT_END(cfg, in_edges, InEdgeIter)
PRINT_PROPERTY(spantin);
PRINT_PROPERTY(spantout);
#undef PRINT_PROPERTY
vector<bool> node_insert(cfg.graph.vertices().size());
vector<bool> replacef(cfg.graph.vertices().size());
vector<bool> replacel(cfg.graph.vertices().size());
// printf ("Intermediate test 1: needToMakeCachevar = %s \n",needToMakeCachevar ? "true" : "false");
for (i = cfg.graph.vertices().begin(); i != end; ++i)
{
node_insert[*i] = comp[*i] && spantout[*i] && (!transp[*i] || !spavin[*i]);
replacef[*i] = antloc[*i] && (spavin[*i] || (transp[*i] && spantout[*i]));
replacel[*i] = comp[*i] && (spantout[*i] || (transp[*i] && spavin[*i]));
if (node_insert[*i])
{
needToMakeCachevar = true;
insertions.push_back(make_pair(last_computation[*i], true));
// cerr << "Insert computation of " << expr->unparseToString() << " just before last computation in " << *i << endl;
}
if (replacef[*i])
{
needToMakeCachevar = true;
replacements.insert(first_computation[*i]);
// cerr << "Replace first computation of " << *i << endl;
}
if (replacel[*i])
{
needToMakeCachevar = true;
replacements.insert(last_computation[*i]);
// cerr << "Replace last computation of " << *i << endl;
}
}
vector<bool> edge_insert(cfg.graph.edges().size());
// printf ("Intermediate test 2: needToMakeCachevar = %s \n",needToMakeCachevar ? "true" : "false");
EdgeIter j = cfg.graph.edges().begin(), jend = cfg.graph.edges().end();
for (; j != jend; ++j)
{
edge_insert[*j] = !spavout[cfg.graph.source(*j)] && spavin[cfg.graph.target(*j)] && spantin[cfg.graph.target(*j)];
// printf ("edge_insert[*j] = %s \n",edge_insert[*j] ? "true" : "false");
if (edge_insert[*j])
{
needToMakeCachevar = true;
// cerr << "Insert computation of " << expr->unparseToString() << " on edge from "
// << cfg.graph.source(*j) << " to " << cfg.graph.target(*j) << endl;
}
}
// printf ("Before final test: needToMakeCachevar = %s \n",needToMakeCachevar ? "true" : "false");
// Add cache variable if necessary
SgVarRefExp* cachevar = 0;
if (needToMakeCachevar)
{
SgName cachevarname = "cachevar__";
cachevarname << ++SageInterface::gensym_counter;
// printf ("Building variable name = %s \n",cachevarname.str());
SgType* type = expr->get_type();
if (isSgArrayType(type))
type = new SgPointerType(isSgArrayType(type)->get_base_type());
assert (SageInterface::isDefaultConstructible(type));
// FIXME: assert (isAssignable(type));
SgVariableDeclaration* decl = new SgVariableDeclaration(SgNULL_FILE, cachevarname, type, NULL);
decl->set_definingDeclaration(decl);
SgInitializedName* initname = decl->get_variables().back();
// DQ (10/5/2007): Added an assertion.
ROSE_ASSERT(initname != NULL);
decl->addToAttachedPreprocessingInfo(
new PreprocessingInfo(PreprocessingInfo::CplusplusStyleComment,
(string("// Partial redundancy elimination: ") + cachevarname.str() +
" is a cache of " + expr->unparseToString()).c_str(),
"Compiler-Generated in PRE", 0, 0, 0, PreprocessingInfo::before));
SgVariableSymbol* cachevarsym = new SgVariableSymbol(initname);
decl->set_parent(root);
// DQ (10/5/2007): Added scope (suggested by Jeremiah).
initname->set_scope(root);
root->get_statements().insert(root->get_statements().begin(),decl);
root->insert_symbol(cachevarname, cachevarsym);
cachevar = new SgVarRefExp(SgNULL_FILE, cachevarsym);
cachevar->set_endOfConstruct(SgNULL_FILE);
}
// Do expression computation replacements
for (set<SgNode*>::iterator i = replacements.begin(); i != replacements.end(); ++i)
{
ReplaceExpressionWithVarrefVisitor(expr, cachevar).traverse(*i, postorder);
}
// Do edge insertions
// int count = 0;
bool failAtEndOfFunction = false;
for (j = cfg.graph.edges().begin(); j != jend; ++j)
{
// printf ("Build the insertion list! count = %d \n",count++);
if (edge_insert[*j])
{
#if 0
// DQ (3/13/2006): Compiler warns that "src" is unused, so I have commented it out!
Vertex src = cfg.graph.source(*j), tgt = cfg.graph.target(*j);
cerr << "Doing insertion between " << src << " and " << tgt << endl;
#endif
pair<SgNode*, bool> insert_point = cfg.edge_insertion_point[*j];
if (insert_point.first)
{
insertions.push_back(insert_point);
}
else
{
// DQ (3/16/2006): This is a visited when we fixup the NULL pointer to the initializer in a SgForStatment.
cerr << "Warning: no insertion point found" << endl; //FIXME was assert
printf ("Need to figure out what to do here! cfg.edge_insertion_point[*j] = %p \n",&(cfg.edge_insertion_point[*j]));
failAtEndOfFunction = true;
ROSE_ASSERT(false);
}
}
}
// Do within-node insertions
// printf ("At start of loop: insertions.size() = %zu \n",insertions.size());
for (vector<pair<SgNode*, bool> >::iterator i = insertions.begin(); i != insertions.end(); ++i)
{
SgTreeCopy tc1, tc2;
SgVarRefExp* cachevarCopy = isSgVarRefExp(cachevar->copy(tc1));
ROSE_ASSERT (cachevarCopy);
cachevarCopy->set_lvalue(true);
SgExpression* operation = new SgAssignOp(SgNULL_FILE, cachevarCopy, isSgExpression(expr->copy(tc2)));
#if 0
printf ("Inside of loop: insertions.size() = %zu \n",insertions.size());
printf ("\n\ni->first = %p = %s = %s \n",i->first,i->first->class_name().c_str(),i->first->unparseToString().c_str());
printf ("operation = %p = %s = %s \n",operation,operation->class_name().c_str(),operation->unparseToString().c_str());
#endif
if (isSgExpression(i->first) && !i->second)
{
SgNode* ifp = i->first->get_parent();
SgCommaOpExp* comma = new SgCommaOpExp(SgNULL_FILE, isSgExpression(i->first), operation);
operation->set_parent(comma);
comma->set_parent(ifp);
i->first->set_parent(comma);
if (isSgForStatement(ifp))
{
isSgForStatement(ifp)->set_increment(comma);
}
else if (isSgBinaryOp(ifp) && isSgBinaryOp(ifp)->get_lhs_operand() == i->first)
{
isSgBinaryOp(ifp)->set_lhs_operand(comma);
}
else if (isSgBinaryOp(ifp) && isSgBinaryOp(ifp)->get_rhs_operand() == i->first)
{
isSgBinaryOp(ifp)->set_rhs_operand(comma);
}
else if (isSgUnaryOp(ifp) && isSgUnaryOp(ifp)->get_operand() == i->first)
{
isSgUnaryOp(ifp)->set_operand(comma);
}
else
{
cerr << ifp->sage_class_name() << endl;
assert (!"Bad parent type for inserting comma expression");
}
}
else
{
SgStatement* the_computation = new SgExprStatement(SgNULL_FILE, operation);
operation->set_parent(the_computation);
// printf ("In pre.C: the_computation = %p = %s \n",the_computation,the_computation->class_name().c_str());
if (isSgBasicBlock(i->first) && i->second)
{
isSgBasicBlock(i->first)->get_statements().insert(isSgBasicBlock(i->first)->get_statements().begin(),the_computation);
the_computation->set_parent(i->first);
}
else
{
#if 0
// DQ (3/14/2006): Bug here when SgExprStatement from SgForStatement test is used here!
printf ("Bug here when SgExprStatement from SgForStatement test is used: i->first = %s \n",i->first->class_name().c_str());
i->first->get_file_info()->display("Location i->first");
printf ("Bug here when SgExprStatement from SgForStatement test is used: TransformationSupport::getStatement(i->first) = %s \n",
TransformationSupport::getStatement(i->first)->class_name().c_str());
printf ("Bug here when SgExprStatement from SgForStatement test is used: the_computation = %s \n",the_computation->class_name().c_str());
the_computation->get_file_info()->display("Location the_computation: debug");
ROSE_ASSERT(i->first != NULL);
ROSE_ASSERT(i->first->get_parent() != NULL);
printf ("i->first->get_parent() = %s \n",i->first->get_parent()->class_name().c_str());
i->first->get_file_info()->display("Location i->first: debug");
#endif
SgForStatement* forStatement = isSgForStatement(i->first->get_parent());
if (forStatement != NULL)
{
// Make sure that both pointers are not equal because they are both NULL!
ROSE_ASSERT(forStatement->get_test() != NULL);
SgExprStatement* possibleTest = isSgExprStatement(i->first);
if ( forStatement->get_test() == possibleTest )
{
// This is a special case of a SgExpressionStatement as a target in a SgForStatement
// printf ("Found special case of target being the test of a SgForStatement \n");
forStatement->set_test(the_computation);
the_computation->set_parent(forStatement);
}
}
else
{
SgForInitStatement* forInitStatement = isSgForInitStatement(i->first->get_parent());
if (forInitStatement != NULL)
{
// printf ("Found the SgForInitStatement \n");
SgVariableDeclaration* possibleVariable = isSgVariableDeclaration(i->first);
SgExprStatement* possibleExpression = isSgExprStatement(i->first);
SgStatementPtrList & statementList = forInitStatement->get_init_stmt();
SgStatementPtrList::iterator i = statementList.begin();
bool addToForInitList = false;
while ( (addToForInitList == false) && (i != statementList.end()) )
{
// if ( *i == possibleVariable )
if ( *i == possibleVariable || *i == possibleExpression )
{
// This is a special case of a SgExpressionStatement as a target in a SgForStatement
// printf ("Found special case of SgForInitStatement transformation \n");
addToForInitList = true;
}
i++;
}
// Only modify the STL list outside of the loop over the list to avoid interator invalidation
if (addToForInitList == true)
{
// Add the the_computation statment to the list in the SgForInitStatement.
// Later if we abandon the SgForInitStatement then we would have to add it to
// the list of SgInitializedName objects in the SgVariableDeclaration OR modify
// the expression list to handle the extra expression (but I think this case in
// handled above).
// printf ("Adding the_computation to the list in the SgForInitStatement \n");
statementList.push_back(the_computation);
the_computation->set_parent(forInitStatement);
}
}
else
{
myStatementInsert(TransformationSupport::getStatement(i->first),the_computation,i->second,true);
the_computation->set_parent(TransformationSupport::getStatement(i->first));
}
}
}
}
}
// DQ (3/16/2006): debugging code to force failure at inspection point
if (failAtEndOfFunction == true)
{
printf ("Error: internal error detected \n");
ROSE_ASSERT(false);
}
}
