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#include <torch/csrc/jit/codegen/cuda/lower_magic_zero.h>
#include <torch/csrc/jit/codegen/cuda/dispatch.h>
#include <torch/csrc/jit/codegen/cuda/instrumentation.h>
#include <torch/csrc/jit/codegen/cuda/ir_utils.h>
#include <torch/csrc/jit/codegen/cuda/kernel_ir_dispatch.h>
#include <torch/csrc/jit/codegen/cuda/lower2device.h>
#include <torch/csrc/jit/codegen/cuda/lower_index_compute.h>
namespace torch {
namespace jit {
namespace fuser {
namespace cuda {
namespace {
class MagicZeroInserter : public kir::ExprMutator {
public:
static std::vector<Expr*> insert(const std::vector<Expr*>& exprs) {
MagicZeroInserter inserter(exprs);
return inserter.exprs_;
}
private:
struct InsertionInfo {
kir::Scope* scope = nullptr;
kir::ForLoop* fl = nullptr;
};
MagicZeroInserter(const std::vector<Expr*>& exprs) {
TORCH_INTERNAL_ASSERT(exprs.size());
kir::ExprMutator::registerInsertBefore(
exprs.front(), IrBuilder::create<kir::InitMagicZero>(), nullptr);
kir::ExprMutator::traverseAndInsert(exprs);
}
void handle(kir::ForLoop* fl) final {
if (fl->isUnrolled()) {
if (scope_.empty()) {
kir::ExprMutator::registerInsertAfter(
fl, IrBuilder::create<kir::UpdateMagicZero>());
} else {
TORCH_INTERNAL_ASSERT(
scope_.back()->exprs().size(), "Not expecting an empty loop.");
kir::ExprMutator::registerInsertAfter(
fl, IrBuilder::create<kir::UpdateMagicZero>(), scope_.back());
}
} else {
kir::ExprMutator::handle(fl);
}
}
std::vector<InsertionInfo> insertion_list_;
};
} // namespace
std::vector<Expr*> insertMagicZero(const std::vector<Expr*>& exprs) {
FUSER_PERF_SCOPE("GpuLower::Lower::insertMagicZero");
// Check if magic zero was even used, if not we don't have to define it or
// update it.
const auto gpu_lower = GpuLower::current();
auto kernel = gpu_lower->kernel();
const bool has_magic_zero =
std::any_of(kernel->vals().begin(), kernel->vals().end(), [](Val* val) {
return isMagicZero(val);
});
if (!has_magic_zero) {
return exprs;
}
return MagicZeroInserter::insert(exprs);
}
bool isMagicZero(const Val* val) {
if (!val->isA<NamedScalar>()) {
return false;
}
auto ns = val->as<NamedScalar>();
return ns->dtype() == DataType::Int &&
ns->name() == std::string(kMagicZeroName);
}
bool isProtectedWithMagicZero(const Val* val) {
if (val->definition() == nullptr || !val->definition()->isA<BinaryOp>()) {
return false;
}
auto bop = val->definition()->as<BinaryOp>();
return bop->getBinaryOpType() == BinaryOpType::Add && isMagicZero(bop->rhs());
}
bool needsMagicZero(
kir::ForLoop* loop,
IterDomain* reference_domain,
Val* ind) {
if (ind->isConstScalar()) {
return false;
}
bool ref_dom_simple =
reference_domain == nullptr || reference_domain->definition() != nullptr;
bool ind_simple =
ind == nullptr || (ind->definition() != nullptr && !ind->isZeroInt());
return loop->isUnrolled() && (!ref_dom_simple || !ind_simple);
}
void protectNonPredicateIndexWithMagicZero(
const std::vector<kir::ForLoop*>& loops,
const std::vector<IterDomain*>& loop_domains,
std::unordered_map<IterDomain*, Val*>& concrete_loop_idx_map) {
// Find magic zero insertion point
IterDomain* magic_zero_loop = nullptr;
// Search for proper magic zero insertion point,
// prefer innermost.
for (auto idx : c10::irange(loops.size())) {
auto loop = loops[idx];
auto concrete_loop_id = GpuLower::current()->caMap()->getConcreteMappedID(
loop_domains[idx], IdMappingMode::EXACT);
auto loop_ind = concrete_loop_idx_map.at(concrete_loop_id);
// Save the concrete id if this loop id is decided to
// be the insertion point by the magic zero util.
if (needsMagicZero(loop, concrete_loop_id, loop_ind)) {
magic_zero_loop = concrete_loop_id;
}
}
// Insert magic zero if insertion point found
if (magic_zero_loop != nullptr &&
concrete_loop_idx_map.count(magic_zero_loop)) {
auto& ind = concrete_loop_idx_map.at(magic_zero_loop);
ind = SimplifyingIrBuilder::addExpr(
ind, GpuLower::current()->kernel()->magicZeroVal());
}
}
namespace {
//! Protect loop_index_to_protect appearing in overall_index_val
IndexMagicZeroInfo protectIndexByReplacingLoopIndex(
IterDomain* loop_id,
Val* overall_index_val,
Val* loop_index_to_protect) {
auto protected_loop_index = SimplifyingIrBuilder::addExpr(
loop_index_to_protect, GpuLower::current()->kernel()->magicZeroVal());
std::unordered_map<Val*, Val*> replacement_map;
replacement_map[loop_index_to_protect] = protected_loop_index;
auto protected_index =
ir_utils::replaceValInIndexVal(overall_index_val, replacement_map);
IndexMagicZeroInfo info;
info.index = protected_index;
info.original_loop_index = loop_index_to_protect;
info.protected_loop_index = protected_loop_index;
info.loop_id = loop_id;
return info;
}
} // namespace
IndexMagicZeroInfo protectPredicateIndexWithMagicZero(
Val* index,
const IndexFromIdGraph& id_graph,
const std::vector<kir::ForLoop*>& loops) {
// Gather the loop indices
std::unordered_set<Val*> loop_indices;
for (auto loop_id : id_graph.resolved_loop_domains) {
auto concrete_loop_id = GpuLower::current()->caMap()->getConcreteMappedID(
loop_id, IdMappingMode::EXACT);
auto index_it = id_graph.initial_concrete_index_map.find(concrete_loop_id);
TORCH_INTERNAL_ASSERT(
index_it != id_graph.initial_concrete_index_map.end(),
"Index not found for loop: ",
concrete_loop_id->toString());
auto loop_index = index_it->second;
loop_indices.insert(loop_index);
}
// Figure out which loop indices are used in index
const auto vals = DependencyCheck::getAllValsBetween(loop_indices, {index});
// Traverser from the inner-most loop and apply the magic-zero
// prorection if needed
for (int i = static_cast<int>(loops.size()) - 1; i >= 0; --i) {
auto loop = loops.at(i);
auto loop_id = id_graph.resolved_loop_domains.at(i);
TORCH_INTERNAL_ASSERT(GpuLower::current()->caMap()->areMapped(
loop_id, loop->iter_domain(), IdMappingMode::PERMISSIVE));
IterDomain* concrete_loop_id =
GpuLower::current()->caMap()->getConcreteMappedID(
loop_id, IdMappingMode::EXACT);
auto index_it = id_graph.initial_concrete_index_map.find(concrete_loop_id);
TORCH_INTERNAL_ASSERT(
index_it != id_graph.initial_concrete_index_map.end());
auto loop_index = index_it->second;
const auto is_loop_index_used =
std::find(vals.begin(), vals.end(), loop_index) != vals.end();
if (!is_loop_index_used) {
continue;
}
if (needsMagicZero(loop, concrete_loop_id, loop_index)) {
return protectIndexByReplacingLoopIndex(loop_id, index, loop_index);
}
}
// No loop is identified to require protection with magic zero. Just
// return the index argument as is
IndexMagicZeroInfo not_proteced;
not_proteced.index = index;
return not_proteced;
}
} // namespace cuda
} // namespace fuser
} // namespace jit
} // namespace torch
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