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#include <torch/csrc/jit/passes/dbr_quantization/remove_redundant_aliases.h>
#include <torch/csrc/jit/ir/alias_analysis.h>
#include <torch/csrc/jit/jit_log.h>
#include <torch/csrc/jit/passes/quantization/helper.h>
#include <torch/csrc/jit/runtime/graph_iterator.h>
namespace torch {
namespace jit {
namespace {
void DBRQuantRemoveRedundantAliasesImpl(const Method& method) {
auto g = method.graph();
const bool is_frozen = false;
const bool descend_function_calls = true;
AliasDb alias_db(g, is_frozen, descend_function_calls);
// find the alias nodes
std::vector<Node*> alias_nodes;
DepthFirstGraphNodeIterator it(g);
Node* node = nullptr;
while ((node = it.next()) != nullptr) {
if (node->kind() == Symbol::aten("alias")) {
alias_nodes.push_back(node);
}
}
// remove the alias nodes, if it is safe to do so
for (auto* node : alias_nodes) {
GRAPH_DEBUG(*node);
Value* input_value = node->input();
Value* output_value = node->output();
bool always_safe_to_mutate = alias_db.safeToChangeAliasingRelationship(
node->inputs(), node->outputs());
const auto g_in = g->inputs();
const auto g_out = g->outputs();
bool is_input =
std::find(g_in.begin(), g_in.end(), input_value) != g_in.end();
bool is_output =
std::find(g_out.begin(), g_out.end(), output_value) != g_out.end();
// We assume that aliasing is safe to update on inputs and outputs if they
// do not have writers.
bool input_safe_to_mutate =
(is_input && !alias_db.hasWriters(input_value) &&
!alias_db.hasWriters(output_value));
bool output_safe_to_mutate =
(is_output && !alias_db.hasWriters(input_value) &&
!alias_db.hasWriters(output_value));
if (always_safe_to_mutate || input_safe_to_mutate ||
output_safe_to_mutate) {
output_value->replaceAllUsesWith(input_value);
node->destroy();
}
}
}
} // namespace
Module DBRQuantRemoveRedundantAliases(Module& module) {
for (const auto& child : module.modules()) {
for (const auto& method : child.get_methods()) {
DBRQuantRemoveRedundantAliasesImpl(method);
}
}
return module;
}
} // namespace jit
} // namespace torch
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