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Thread Safety Analysis: Update SSA pass to handle loops.

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llvm-svn: 206676
This commit is contained in:
DeLesley Hutchins
2014-04-19 00:35:54 +00:00
parent e808171628
commit ae497deddf
5 changed files with 273 additions and 130 deletions
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258
clang/lib/Analysis/ThreadSafetyCommon.cpp
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@@ -46,10 +46,6 @@ til::SExpr *SExprBuilder::lookupStmt(const Stmt *S) {
return nullptr;
}
void SExprBuilder::insertStmt(const Stmt *S, til::Variable *V) {
SMap.insert(std::make_pair(S, V));
}
til::SCFG *SExprBuilder::buildCFG(CFGWalker &Walker) {
Walker.walk(*this);
@@ -354,6 +350,7 @@ SExprBuilder::translateDeclStmt(const DeclStmt *S, CallingContext *Ctx) {
}
// If (E) is non-trivial, then add it to the current basic block, and
// update the statement map so that S refers to E. Returns a new variable
// that refers to E.
@@ -366,8 +363,7 @@ til::SExpr *SExprBuilder::addStatement(til::SExpr* E, const Stmt *S,
return E;
til::Variable *V = new (Arena) til::Variable(E, VD);
V->setID(CurrentBlockID, CurrentVarID++);
CurrentBB->addInstr(V);
CurrentInstructions.push_back(V);
if (S)
insertStmt(S, V);
return V;
@@ -376,9 +372,11 @@ til::SExpr *SExprBuilder::addStatement(til::SExpr* E, const Stmt *S,
// Returns the current value of VD, if known, and nullptr otherwise.
til::SExpr *SExprBuilder::lookupVarDecl(const ValueDecl *VD) {
auto It = IdxMap.find(VD);
if (It != IdxMap.end())
return CurrentNameMap[It->second].second;
auto It = LVarIdxMap.find(VD);
if (It != LVarIdxMap.end()) {
assert(CurrentLVarMap[It->second].first == VD);
return CurrentLVarMap[It->second].second;
}
return nullptr;
}
@@ -396,9 +394,9 @@ inline void maybeUpdateVD(til::SExpr *E, const ValueDecl *VD) {
// Adds a new variable declaration.
til::SExpr *SExprBuilder::addVarDecl(const ValueDecl *VD, til::SExpr *E) {
maybeUpdateVD(E, VD);
IdxMap.insert(std::make_pair(VD, CurrentNameMap.size()));
CurrentNameMap.makeWritable();
CurrentNameMap.push_back(std::make_pair(VD, E));
LVarIdxMap.insert(std::make_pair(VD, CurrentLVarMap.size()));
CurrentLVarMap.makeWritable();
CurrentLVarMap.push_back(std::make_pair(VD, E));
return E;
}
@@ -406,76 +404,151 @@ til::SExpr *SExprBuilder::addVarDecl(const ValueDecl *VD, til::SExpr *E) {
// Updates a current variable declaration. (E.g. by assignment)
til::SExpr *SExprBuilder::updateVarDecl(const ValueDecl *VD, til::SExpr *E) {
maybeUpdateVD(E, VD);
auto It = IdxMap.find(VD);
if (It == IdxMap.end()) {
auto It = LVarIdxMap.find(VD);
if (It == LVarIdxMap.end()) {
til::SExpr *Ptr = new (Arena) til::LiteralPtr(VD);
til::SExpr *St = new (Arena) til::Store(Ptr, E);
return St;
}
CurrentNameMap.makeWritable();
CurrentNameMap.elem(It->second).second = E;
CurrentLVarMap.makeWritable();
CurrentLVarMap.elem(It->second).second = E;
return E;
}
// Merge values from Map into the current entry map.
void SExprBuilder::mergeEntryMap(NameVarMap Map) {
assert(CurrentBlockInfo && "Not processing a block!");
// Return true if the given expression represents a possibly unnecessary
// variable: i.e. a variable that references a Phi node that may be removed.
inline bool isIncompleteVar(til::SExpr *E) {
if (!E)
return true; // Null values are used on unknown backedges.
if (til::Variable *V = dyn_cast<til::Variable>(E)) {
if (til::Phi *Ph = dyn_cast<til::Phi>(V->definition()))
return Ph->incomplete();
}
return false;
}
if (!CurrentNameMap.valid()) {
// Steal Map, using copy-on-write.
CurrentNameMap = std::move(Map);
// Make a Phi node in the current block for the i^th variable in CurrentVarMap.
// If E != null, sets Phi[CurrentBlockInfo->ArgIndex] = E.
// If E == null, this is a backedge and will be set later.
void SExprBuilder::makePhiNodeVar(unsigned i, unsigned NPreds, til::SExpr *E) {
unsigned ArgIndex = CurrentBlockInfo->ProcessedPredecessors;
assert(ArgIndex > 0 && ArgIndex < NPreds);
til::Variable *V = dyn_cast<til::Variable>(CurrentLVarMap[i].second);
if (V && V->getBlockID() == CurrentBB->blockID()) {
// We already have a Phi node in the current block,
// so just add the new variable to the Phi node.
til::Phi *Ph = dyn_cast<til::Phi>(V->definition());
assert(Ph && "Expecting Phi node.");
if (E)
Ph->values()[ArgIndex] = E;
if (!Ph->incomplete() && isIncompleteVar(E))
Ph->setIncomplete(true);
return;
}
if (CurrentNameMap.sameAs(Map))
// Make a new phi node: phi(..., E)
// All phi args up to the current index are set to the current value.
til::Phi *Ph = new (Arena) til::Phi(Arena, NPreds);
Ph->values().setValues(NPreds, nullptr);
for (unsigned PIdx = 0; PIdx < ArgIndex; ++PIdx)
Ph->values()[PIdx] = CurrentLVarMap[i].second;
if (E)
Ph->values()[ArgIndex] = E;
if (isIncompleteVar(E))
Ph->setIncomplete(true);
// Add Phi node to current block, and update CurrentLVarMap[i]
auto *Var = new (Arena) til::Variable(Ph, CurrentLVarMap[i].first);
CurrentArguments.push_back(Var);
CurrentLVarMap.makeWritable();
CurrentLVarMap.elem(i).second = Var;
}
// Merge values from Map into the current variable map.
// This will construct Phi nodes in the current basic block as necessary.
void SExprBuilder::mergeEntryMap(LVarDefinitionMap Map) {
assert(CurrentBlockInfo && "Not processing a block!");
if (!CurrentLVarMap.valid()) {
// Steal Map, using copy-on-write.
CurrentLVarMap = std::move(Map);
return;
}
if (CurrentLVarMap.sameAs(Map))
return; // Easy merge: maps from different predecessors are unchanged.
unsigned ESz = CurrentNameMap.size();
unsigned NPreds = CurrentBB->numPredecessors();
unsigned ESz = CurrentLVarMap.size();
unsigned MSz = Map.size();
unsigned Sz = std::max(ESz, MSz);
bool W = CurrentNameMap.writable();
unsigned Sz = std::min(ESz, MSz);
for (unsigned i=0; i<Sz; ++i) {
if (CurrentNameMap[i].first != Map[i].first) {
if (!W)
CurrentNameMap.makeWritable();
CurrentNameMap.downsize(i);
if (CurrentLVarMap[i].first != Map[i].first) {
// We've reached the end of variables in common.
CurrentLVarMap.makeWritable();
CurrentLVarMap.downsize(i);
break;
}
if (CurrentNameMap[i].second != Map[i].second) {
til::Variable *V =
dyn_cast<til::Variable>(CurrentNameMap[i].second);
if (V && V->getBlockID() == CurrentBB->blockID()) {
// We already have a Phi node, so add the new variable.
til::Phi *Ph = dyn_cast<til::Phi>(V->definition());
assert(Ph && "Expecting Phi node.");
Ph->values()[CurrentArgIndex] = Map[i].second;
}
else {
if (!W)
CurrentNameMap.makeWritable();
unsigned NPreds = CurrentBB->numPredecessors();
assert(CurrentArgIndex > 0 && CurrentArgIndex < NPreds);
// Make a new phi node. All phi args up to the current index must
// be the same, and equal to the current NameMap value.
auto *Ph = new (Arena) til::Phi(Arena, NPreds);
Ph->values().setValues(NPreds, nullptr);
for (unsigned PIdx = 0; PIdx < CurrentArgIndex; ++PIdx)
Ph->values()[PIdx] = CurrentNameMap[i].second;
Ph->values()[CurrentArgIndex] = Map[i].second;
// Add phi node to current basic block.
auto *Var = new (Arena) til::Variable(Ph, CurrentNameMap[i].first);
Var->setID(CurrentBlockID, CurrentVarID++);
CurrentBB->addArgument(Var);
CurrentNameMap.elem(i).second = Var;
}
}
if (CurrentLVarMap[i].second != Map[i].second)
makePhiNodeVar(i, NPreds, Map[i].second);
}
if (ESz > MSz) {
if (!W)
CurrentNameMap.makeWritable();
CurrentNameMap.downsize(Map.size());
CurrentLVarMap.makeWritable();
CurrentLVarMap.downsize(Map.size());
}
}
// Merge a back edge into the current variable map.
// This will create phi nodes for all variables in the variable map.
void SExprBuilder::mergeEntryMapBackEdge() {
// We don't have definitions for variables on the backedge, because we
// haven't gotten that far in the CFG. Thus, when encountering a back edge,
// we conservatively create Phi nodes for all variables. Unnecessary Phi
// nodes will be marked as incomplete, and stripped out at the end.
//
// An Phi node is unnecessary if it only refers to itself and one other
// variable, e.g. x = Phi(y, y, x) can be reduced to x = y.
assert(CurrentBlockInfo && "Not processing a block!");
if (CurrentBlockInfo->HasBackEdges)
return;
CurrentBlockInfo->HasBackEdges = true;
CurrentLVarMap.makeWritable();
unsigned Sz = CurrentLVarMap.size();
unsigned NPreds = CurrentBB->numPredecessors();
for (unsigned i=0; i < Sz; ++i) {
makePhiNodeVar(i, NPreds, nullptr);
}
}
// Update the phi nodes that were initially created for a back edge
// once the variable definitions have been computed.
// I.e., merge the current variable map into the phi nodes for Blk.
void SExprBuilder::mergePhiNodesBackEdge(const CFGBlock *Blk) {
til::BasicBlock *BB = lookupBlock(Blk);
unsigned ArgIndex = BBInfo[Blk->getBlockID()].ProcessedPredecessors;
assert(ArgIndex > 0 && ArgIndex < BB->numPredecessors());
for (til::Variable *V : BB->arguments()) {
til::Phi *Ph = dyn_cast_or_null<til::Phi>(V->definition());
assert(Ph && "Expecting Phi Node.");
assert(Ph->values()[ArgIndex] == nullptr && "Wrong index for back edge.");
assert(V->clangDecl() && "No local variable for Phi node.");
til::SExpr *E = lookupVarDecl(V->clangDecl());
assert(E && "Couldn't find local variable for Phi node.");
Ph->values()[ArgIndex] = E;
}
}
@@ -488,53 +561,60 @@ void SExprBuilder::enterCFG(CFG *Cfg, const NamedDecl *D,
Scfg = new (Arena) til::SCFG(Arena, NBlocks);
// allocate all basic blocks immediately, to handle forward references.
BlockMap.reserve(NBlocks);
BBInfo.resize(NBlocks);
BlockMap.resize(NBlocks, nullptr);
// create map from clang blockID to til::BasicBlocks
for (auto *B : *Cfg) {
auto *BB = new (Arena) til::BasicBlock(Arena, 0, B->size());
BlockMap.push_back(BB);
BlockMap[B->getBlockID()] = BB;
}
CallCtx = new SExprBuilder::CallingContext(D);
}
void SExprBuilder::enterCFGBlock(const CFGBlock *B) {
// Intialize TIL basic block and add it to the CFG.
CurrentBB = BlockMap[B->getBlockID()];
CurrentBB->setBlockID(CurrentBlockID);
CurrentBB->setNumPredecessors(B->pred_size());
Scfg->add(CurrentBB);
CurrentBlockInfo = &BBInfo[B->getBlockID()];
CurrentVarID = 0;
CurrentArgIndex = 0;
CurrentArguments.clear();
CurrentInstructions.clear();
assert(!CurrentNameMap.valid() && "CurrentNameMap already initialized.");
// CurrentLVarMap is moved to ExitMap on block exit.
assert(!CurrentLVarMap.valid() && "CurrentLVarMap already initialized.");
}
void SExprBuilder::handlePredecessor(const CFGBlock *Pred) {
// Compute CurrentNameMap on entry from ExitMaps of predecessors
// Compute CurrentLVarMap on entry from ExitMaps of predecessors
BlockInfo *PredInfo = &BBInfo[Pred->getBlockID()];
assert(PredInfo->SuccessorsToProcess > 0);
assert(PredInfo->UnprocessedSuccessors > 0);
if (--PredInfo->SuccessorsToProcess == 0)
if (--PredInfo->UnprocessedSuccessors == 0)
mergeEntryMap(std::move(PredInfo->ExitMap));
else
mergeEntryMap(PredInfo->ExitMap.clone());
++CurrentArgIndex;
++CurrentBlockInfo->ProcessedPredecessors;
}
void SExprBuilder::handlePredecessorBackEdge(const CFGBlock *Pred) {
CurrentBlockInfo->HasBackEdges = true;
mergeEntryMapBackEdge();
}
void SExprBuilder::enterCFGBlockBody(const CFGBlock *B) { }
void SExprBuilder::enterCFGBlockBody(const CFGBlock *B) {
// The merge*() methods have created arguments.
// Push those arguments onto the basic block.
CurrentBB->arguments().reserve(
static_cast<unsigned>(CurrentArguments.size()), Arena);
for (auto *V : CurrentArguments)
CurrentBB->addArgument(V);
}
void SExprBuilder::handleStatement(const Stmt *S) {
@@ -555,19 +635,25 @@ void SExprBuilder::handleDestructorCall(const VarDecl *VD,
void SExprBuilder::exitCFGBlockBody(const CFGBlock *B) {
CurrentBB->instructions().reserve(
static_cast<unsigned>(CurrentInstructions.size()), Arena);
for (auto *V : CurrentInstructions)
CurrentBB->addInstruction(V);
// Create an appropriate terminator
unsigned N = B->succ_size();
auto It = B->succ_begin();
if (N == 1) {
til::BasicBlock *BB = *It ? BlockMap[(*It)->getBlockID()] : nullptr;
til::BasicBlock *BB = *It ? lookupBlock(*It) : nullptr;
// TODO: set index
til::SExpr *Tm = new (Arena) til::Goto(BB, 0);
CurrentBB->setTerminator(Tm);
}
else if (N == 2) {
til::SExpr *C = translate(B->getTerminatorCondition(true), CallCtx);
til::BasicBlock *BB1 = *It ? BlockMap[(*It)->getBlockID()] : nullptr;
til::BasicBlock *BB1 = *It ? lookupBlock(*It) : nullptr;
++It;
til::BasicBlock *BB2 = *It ? BlockMap[(*It)->getBlockID()] : nullptr;
til::BasicBlock *BB2 = *It ? lookupBlock(*It) : nullptr;
// TODO: set conditional, set index
til::SExpr *Tm = new (Arena) til::Branch(C, BB1, BB2);
CurrentBB->setTerminator(Tm);
@@ -576,28 +662,26 @@ void SExprBuilder::exitCFGBlockBody(const CFGBlock *B) {
void SExprBuilder::handleSuccessor(const CFGBlock *Succ) {
++CurrentBlockInfo->SuccessorsToProcess;
++CurrentBlockInfo->UnprocessedSuccessors;
}
void SExprBuilder::handleSuccessorBackEdge(const CFGBlock *Succ) {
mergePhiNodesBackEdge(Succ);
++BBInfo[Succ->getBlockID()].ProcessedPredecessors;
}
void SExprBuilder::exitCFGBlock(const CFGBlock *B) {
CurrentBlockInfo->ExitMap = std::move(CurrentNameMap);
CurrentBlockID++;
CurrentBlockInfo->ExitMap = std::move(CurrentLVarMap);
CurrentBB = nullptr;
CurrentBlockInfo = nullptr;
}
void SExprBuilder::exitCFG(const CFGBlock *Last) {
CurrentBlockID = 0;
CurrentVarID = 0;
CurrentArgIndex = 0;
delete CallCtx;
CurrentArguments.clear();
CurrentInstructions.clear();
}