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/*========================== begin_copyright_notice ============================
Copyright (C) 2020-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#ifndef _LOCAL_DATAFLOW_H
#define _LOCAL_DATAFLOW_H
#include "BuildIR.h"
#include "FlowGraph.h"
#include <unordered_map>
using namespace vISA;
// ToDo: move Local dataflow here and make it a class
namespace vISA {
// A simple local (within one BB) analysis that checks if a def escapes (i.e.,
// reaches the end of BB without other defines killing it). This information may
// be helpful for a number of optimizations by determining if a define has only
// local effect. Destination may be GRF or Address (i.e., direct DstRegRegion).
// Acc and other special ARFs are not considered as their defintions should
// always be local. Flag dst (i.e., conditional modifier) is currently not
// handled; while adding it is possible it may lead to confusion for
// instructions with both dst and condMod. To reduce compilation overhead and
// implementation complexity only a single killing defintion is considered for
// now; this is conservative but should cover most pratical cases as our input
// is almost SSA.
class DefEscapeBBAnalysis {
const FlowGraph &fg;
// all escaped inst for this BB
// If BB is not in the map, it means we need to run analysis for this BB
// ToDo: assumption is that there should not be many escaped inst. Can change
// to vector to set later if desired.
std::unordered_map<G4_BB *, std::vector<G4_INST *>> escapedInsts;
#ifdef _DEBUG
// for debugging only, record instructions that were killed in the BB
std::unordered_map<G4_BB *, std::vector<G4_INST *>> killedDefs;
#endif
public:
DefEscapeBBAnalysis(const FlowGraph &cfg) : fg(cfg) {}
DefEscapeBBAnalysis(const DefEscapeBBAnalysis &analysis) = delete;
DefEscapeBBAnalysis& operator=(const DefEscapeBBAnalysis&) = delete;
virtual ~DefEscapeBBAnalysis() = default;
void run() {
for (auto &&bb : const_cast<FlowGraph &>(fg)) {
analyzeBB(bb);
}
}
void analyzeBB(G4_BB *bb);
bool isBBValid(G4_BB *bb) const { return escapedInsts.count(bb); }
void invalidate() { escapedInsts.clear(); }
void invalidateBB(G4_BB *bb) { escapedInsts.erase(bb); }
bool isEscaped(G4_BB *bb, G4_INST *inst) {
if (!isBBValid(bb)) {
analyzeBB(bb);
}
auto &&vec = escapedInsts.find(bb)->second;
return std::find(vec.begin(), vec.end(), inst) != vec.end();
}
void print(std::ostream &OS) const;
void dump() const { print(std::cerr); }
};
} // namespace vISA
#endif // _LOCAL_DATAFLOW_H
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