//===- ThreadSafetyTIL.cpp -------------------------------------*- C++ --*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT in the llvm repository for details.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
#include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
using namespace clang;
using namespace threadSafety;
using namespace til;
StringRef til::getUnaryOpcodeString(TIL_UnaryOpcode Op) {
switch (Op) {
case UOP_Minus: return "-";
case UOP_BitNot: return "~";
case UOP_LogicNot: return "!";
}
return "";
}
StringRef til::getBinaryOpcodeString(TIL_BinaryOpcode Op) {
switch (Op) {
case BOP_Mul: return "*";
case BOP_Div: return "/";
case BOP_Rem: return "%";
case BOP_Add: return "+";
case BOP_Sub: return "-";
case BOP_Shl: return "<<";
case BOP_Shr: return ">>";
case BOP_BitAnd: return "&";
case BOP_BitXor: return "^";
case BOP_BitOr: return "|";
case BOP_Eq: return "==";
case BOP_Neq: return "!=";
case BOP_Lt: return "<";
case BOP_Leq: return "<=";
case BOP_LogicAnd: return "&&";
case BOP_LogicOr: return "||";
}
return "";
}
SExpr* Future::force() {
Status = FS_evaluating;
Result = compute();
Status = FS_done;
return Result;
}
unsigned BasicBlock::addPredecessor(BasicBlock *Pred) {
unsigned Idx = Predecessors.size();
Predecessors.reserveCheck(1, Arena);
Predecessors.push_back(Pred);
for (SExpr *E : Args) {
if (Phi* Ph = dyn_cast<Phi>(E)) {
Ph->values().reserveCheck(1, Arena);
Ph->values().push_back(nullptr);
}
}
return Idx;
}
void BasicBlock::reservePredecessors(unsigned NumPreds) {
Predecessors.reserve(NumPreds, Arena);
for (SExpr *E : Args) {
if (Phi* Ph = dyn_cast<Phi>(E)) {
Ph->values().reserve(NumPreds, Arena);
}
}
}
// If E is a variable, then trace back through any aliases or redundant
// Phi nodes to find the canonical definition.
const SExpr *til::getCanonicalVal(const SExpr *E) {
while (true) {
if (auto *V = dyn_cast<Variable>(E)) {
if (V->kind() == Variable::VK_Let) {
E = V->definition();
continue;
}
}
if (const Phi *Ph = dyn_cast<Phi>(E)) {
if (Ph->status() == Phi::PH_SingleVal) {
E = Ph->values()[0];
continue;
}
}
break;
}
return E;
}
// If E is a variable, then trace back through any aliases or redundant
// Phi nodes to find the canonical definition.
// The non-const version will simplify incomplete Phi nodes.
SExpr *til::simplifyToCanonicalVal(SExpr *E) {
while (true) {
if (auto *V = dyn_cast<Variable>(E)) {
if (V->kind() != Variable::VK_Let)
return V;
// Eliminate redundant variables, e.g. x = y, or x = 5,
// but keep anything more complicated.
if (til::ThreadSafetyTIL::isTrivial(V->definition())) {
E = V->definition();
continue;
}
return V;
}
if (auto *Ph = dyn_cast<Phi>(E)) {
if (Ph->status() == Phi::PH_Incomplete)
simplifyIncompleteArg(Ph);
// Eliminate redundant Phi nodes.
if (Ph->status() == Phi::PH_SingleVal) {
E = Ph->values()[0];
continue;
}
}
return E;
}
}
// Trace the arguments of an incomplete Phi node to see if they have the same
// canonical definition. If so, mark the Phi node as redundant.
// getCanonicalVal() will recursively call simplifyIncompletePhi().
void til::simplifyIncompleteArg(til::Phi *Ph) {
assert(Ph && Ph->status() == Phi::PH_Incomplete);
// eliminate infinite recursion -- assume that this node is not redundant.
Ph->setStatus(Phi::PH_MultiVal);
SExpr *E0 = simplifyToCanonicalVal(Ph->values()[0]);
for (unsigned i=1, n=Ph->values().size(); i<n; ++i) {
SExpr *Ei = simplifyToCanonicalVal(Ph->values()[i]);
if (Ei == Ph)
continue; // Recursive reference to itself. Don't count.
if (Ei != E0) {
return; // Status is already set to MultiVal.
}
}
Ph->setStatus(Phi::PH_SingleVal);
}
// Renumbers the arguments and instructions to have unique, sequential IDs.
int BasicBlock::renumberInstrs(int ID) {
for (auto *Arg : Args)
Arg->setID(this, ID++);
for (auto *Instr : Instrs)
Instr->setID(this, ID++);
TermInstr->setID(this, ID++);
return ID;
}
// Sorts the CFGs blocks using a reverse post-order depth-first traversal.
// Each block will be written into the Blocks array in order, and its BlockID
// will be set to the index in the array. Sorting should start from the entry
// block, and ID should be the total number of blocks.
int BasicBlock::topologicalSort(SimpleArray<BasicBlock*>& Blocks, int ID) {
if (Visited) return ID;
Visited = true;
for (auto *Block : successors())
ID = Block->topologicalSort(Blocks, ID);
// set ID and update block array in place.
// We may lose pointers to unreachable blocks.
assert(ID > 0);
BlockID = --ID;
Blocks[BlockID] = this;
return ID;
}
// Performs a reverse topological traversal, starting from the exit block and
// following back-edges. The dominator is serialized before any predecessors,
// which guarantees that all blocks are serialized after their dominator and
// before their post-dominator (because it's a reverse topological traversal).
// ID should be initially set to 0.
//
// This sort assumes that (1) dominators have been computed, (2) there are no
// critical edges, and (3) the entry block is reachable from the exit block
// and no blocks are accessable via traversal of back-edges from the exit that
// weren't accessable via forward edges from the entry.
int BasicBlock::topologicalFinalSort(SimpleArray<BasicBlock*>& Blocks, int ID) {
// Visited is assumed to have been set by the topologicalSort. This pass
// assumes !Visited means that we've visited this node before.
if (!Visited) return ID;
Visited = false;
if (DominatorNode.Parent)
ID = DominatorNode.Parent->topologicalFinalSort(Blocks, ID);
for (auto *Pred : Predecessors)
ID = Pred->topologicalFinalSort(Blocks, ID);
assert(static_cast<size_t>(ID) < Blocks.size());
BlockID = ID++;
Blocks[BlockID] = this;
return ID;
}
// Computes the immediate dominator of the current block. Assumes that all of
// its predecessors have already computed their dominators. This is achieved
// by visiting the nodes in topological order.
void BasicBlock::computeDominator() {
BasicBlock *Candidate = nullptr;
// Walk backwards from each predecessor to find the common dominator node.
for (auto *Pred : Predecessors) {
// Skip back-edges
if (Pred->BlockID >= BlockID) continue;
// If we don't yet have a candidate for dominator yet, take this one.
if (Candidate == nullptr) {
Candidate = Pred;
continue;
}
// Walk the alternate and current candidate back to find a common ancestor.
auto *Alternate = Pred;
while (Alternate != Candidate) {
if (Candidate->BlockID > Alternate->BlockID)
Candidate = Candidate->DominatorNode.Parent;
else
Alternate = Alternate->DominatorNode.Parent;
}
}
DominatorNode.Parent = Candidate;
DominatorNode.SizeOfSubTree = 1;
}
// Computes the immediate post-dominator of the current block. Assumes that all
// of its successors have already computed their post-dominators. This is
// achieved visiting the nodes in reverse topological order.
void BasicBlock::computePostDominator() {
BasicBlock *Candidate = nullptr;
// Walk back from each predecessor to find the common post-dominator node.
for (auto *Succ : successors()) {
// Skip back-edges
if (Succ->BlockID <= BlockID) continue;
// If we don't yet have a candidate for post-dominator yet, take this one.
if (Candidate == nullptr) {
Candidate = Succ;
continue;
}
// Walk the alternate and current candidate back to find a common ancestor.
auto *Alternate = Succ;
while (Alternate != Candidate) {
if (Candidate->BlockID < Alternate->BlockID)
Candidate = Candidate->PostDominatorNode.Parent;
else
Alternate = Alternate->PostDominatorNode.Parent;
}
}
PostDominatorNode.Parent = Candidate;
PostDominatorNode.SizeOfSubTree = 1;
}
// Renumber instructions in all blocks
void SCFG::renumberInstrs() {
int InstrID = 0;
for (auto *Block : Blocks)
InstrID = Block->renumberInstrs(InstrID);
}
static inline void computeNodeSize(BasicBlock *B,
BasicBlock::TopologyNode BasicBlock::*TN) {
BasicBlock::TopologyNode *N = &(B->*TN);
if (N->Parent) {
BasicBlock::TopologyNode *P = &(N->Parent->*TN);
// Initially set ID relative to the (as yet uncomputed) parent ID
N->NodeID = P->SizeOfSubTree;
P->SizeOfSubTree += N->SizeOfSubTree;
}
}
static inline void computeNodeID(BasicBlock *B,
BasicBlock::TopologyNode BasicBlock::*TN) {
BasicBlock::TopologyNode *N = &(B->*TN);
if (N->Parent) {
BasicBlock::TopologyNode *P = &(N->Parent->*TN);
N->NodeID += P->NodeID; // Fix NodeIDs relative to starting node.
}
}
// Normalizes a CFG. Normalization has a few major components:
// 1) Removing unreachable blocks.
// 2) Computing dominators and post-dominators
// 3) Topologically sorting the blocks into the "Blocks" array.
void SCFG::computeNormalForm() {
// Topologically sort the blocks starting from the entry block.
int NumUnreachableBlocks = Entry->topologicalSort(Blocks, Blocks.size());
if (NumUnreachableBlocks > 0) {
// If there were unreachable blocks shift everything down, and delete them.
for (size_t I = NumUnreachableBlocks, E = Blocks.size(); I < E; ++I) {
size_t NI = I - NumUnreachableBlocks;
Blocks[NI] = Blocks[I];
Blocks[NI]->BlockID = NI;
// FIXME: clean up predecessor pointers to unreachable blocks?
}
Blocks.drop(NumUnreachableBlocks);
}
// Compute dominators.
for (auto *Block : Blocks)
Block->computeDominator();
// Once dominators have been computed, the final sort may be performed.
int NumBlocks = Exit->topologicalFinalSort(Blocks, 0);
assert(static_cast<size_t>(NumBlocks) == Blocks.size());
(void) NumBlocks;
// Renumber the instructions now that we have a final sort.
renumberInstrs();
// Compute post-dominators and compute the sizes of each node in the
// dominator tree.
for (auto *Block : Blocks.reverse()) {
Block->computePostDominator();
computeNodeSize(Block, &BasicBlock::DominatorNode);
}
// Compute the sizes of each node in the post-dominator tree and assign IDs in
// the dominator tree.
for (auto *Block : Blocks) {
computeNodeID(Block, &BasicBlock::DominatorNode);
computeNodeSize(Block, &BasicBlock::PostDominatorNode);
}
// Assign IDs in the post-dominator tree.
for (auto *Block : Blocks.reverse()) {
computeNodeID(Block, &BasicBlock::PostDominatorNode);
}
}