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//===--------- PolyhedralInfo.cpp - Create Scops from LLVM IR-------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// An interface to the Polyhedral analysis engine(Polly) of LLVM.
//
// This pass provides an interface to the polyhedral analysis performed by
// Polly.
//
// This interface provides basic interface like isParallel, isVectorizable
// that can be used in LLVM transformation passes.
//
// Work in progress, this file is subject to change.
//
//===----------------------------------------------------------------------===//
#include "polly/PolyhedralInfo.h"
#include "polly/DependenceInfo.h"
#include "polly/LinkAllPasses.h"
#include "polly/Options.h"
#include "polly/ScopInfo.h"
#include "polly/Support/GICHelper.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Debug.h"
#include "isl/union_map.h"
using namespace llvm;
using namespace polly;
#define DEBUG_TYPE "polyhedral-info"
static cl::opt<bool> CheckParallel("polly-check-parallel",
cl::desc("Check for parallel loops"),
cl::Hidden, cl::init(false), cl::ZeroOrMore,
cl::cat(PollyCategory));
static cl::opt<bool> CheckVectorizable("polly-check-vectorizable",
cl::desc("Check for vectorizable loops"),
cl::Hidden, cl::init(false),
cl::ZeroOrMore, cl::cat(PollyCategory));
void PolyhedralInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredTransitive<DependenceInfoWrapperPass>();
AU.addRequired<LoopInfoWrapperPass>();
AU.addRequiredTransitive<ScopInfoWrapperPass>();
AU.setPreservesAll();
}
bool PolyhedralInfo::runOnFunction(Function &F) {
DI = &getAnalysis<DependenceInfoWrapperPass>();
SI = getAnalysis<ScopInfoWrapperPass>().getSI();
return false;
}
void PolyhedralInfo::print(raw_ostream &OS, const Module *) const {
auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
for (auto *TopLevelLoop : LI) {
for (auto *L : depth_first(TopLevelLoop)) {
OS.indent(2) << L->getHeader()->getName() << ":\t";
if (CheckParallel && isParallel(L))
OS << "Loop is parallel.\n";
else if (CheckParallel)
OS << "Loop is not parallel.\n";
}
}
}
bool PolyhedralInfo::checkParallel(Loop *L, isl_pw_aff **MinDepDistPtr) const {
bool IsParallel;
const Scop *S = getScopContainingLoop(L);
if (!S)
return false;
const Dependences &D =
DI->getDependences(const_cast<Scop *>(S), Dependences::AL_Access);
if (!D.hasValidDependences())
return false;
LLVM_DEBUG(dbgs() << "Loop :\t" << L->getHeader()->getName() << ":\n");
isl_union_map *Deps =
D.getDependences(Dependences::TYPE_RAW | Dependences::TYPE_WAW |
Dependences::TYPE_WAR | Dependences::TYPE_RED)
.release();
LLVM_DEBUG(dbgs() << "Dependences :\t" << stringFromIslObj(Deps) << "\n");
isl_union_map *Schedule = getScheduleForLoop(S, L);
LLVM_DEBUG(dbgs() << "Schedule: \t" << stringFromIslObj(Schedule) << "\n");
IsParallel = D.isParallel(Schedule, Deps, MinDepDistPtr);
isl_union_map_free(Schedule);
return IsParallel;
}
bool PolyhedralInfo::isParallel(Loop *L) const { return checkParallel(L); }
const Scop *PolyhedralInfo::getScopContainingLoop(Loop *L) const {
assert((SI) && "ScopInfoWrapperPass is required by PolyhedralInfo pass!\n");
for (auto &It : *SI) {
Region *R = It.first;
if (R->contains(L))
return It.second.get();
}
return nullptr;
}
// Given a Loop and the containing SCoP, we compute the partial schedule
// by taking union of individual schedules of each ScopStmt within the loop
// and projecting out the inner dimensions from the range of the schedule.
// for (i = 0; i < n; i++)
// for (j = 0; j < n; j++)
// A[j] = 1; //Stmt
//
// The original schedule will be
// Stmt[i0, i1] -> [i0, i1]
// The schedule for the outer loop will be
// Stmt[i0, i1] -> [i0]
// The schedule for the inner loop will be
// Stmt[i0, i1] -> [i0, i1]
__isl_give isl_union_map *PolyhedralInfo::getScheduleForLoop(const Scop *S,
Loop *L) const {
isl_union_map *Schedule = isl_union_map_empty(S->getParamSpace().release());
int CurrDim = S->getRelativeLoopDepth(L);
LLVM_DEBUG(dbgs() << "Relative loop depth:\t" << CurrDim << "\n");
assert(CurrDim >= 0 && "Loop in region should have at least depth one");
for (auto &SS : *S) {
if (L->contains(SS.getSurroundingLoop())) {
unsigned int MaxDim = SS.getNumIterators();
LLVM_DEBUG(dbgs() << "Maximum depth of Stmt:\t" << MaxDim << "\n");
isl_map *ScheduleMap = SS.getSchedule().release();
assert(
ScheduleMap &&
"Schedules that contain extension nodes require special handling.");
ScheduleMap = isl_map_project_out(ScheduleMap, isl_dim_out, CurrDim + 1,
MaxDim - CurrDim - 1);
ScheduleMap = isl_map_set_tuple_id(ScheduleMap, isl_dim_in,
SS.getDomainId().release());
Schedule =
isl_union_map_union(Schedule, isl_union_map_from_map(ScheduleMap));
}
}
Schedule = isl_union_map_coalesce(Schedule);
return Schedule;
}
char PolyhedralInfo::ID = 0;
Pass *polly::createPolyhedralInfoPass() { return new PolyhedralInfo(); }
INITIALIZE_PASS_BEGIN(PolyhedralInfo, "polyhedral-info",
"Polly - Interface to polyhedral analysis engine", false,
false);
INITIALIZE_PASS_DEPENDENCY(DependenceInfoWrapperPass);
INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
INITIALIZE_PASS_DEPENDENCY(ScopInfoWrapperPass);
INITIALIZE_PASS_END(PolyhedralInfo, "polyhedral-info",
"Polly - Interface to polyhedral analysis engine", false,
false)
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