decompression-optimization.cc | Explore in Territory

// Copyright 2022 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/compiler/turboshaft/decompression-optimization.h"

#include "src/codegen/machine-type.h"
#include "src/compiler/turboshaft/copying-phase.h"
#include "src/compiler/turboshaft/operations.h"
#include "src/compiler/turboshaft/representations.h"

namespace v8::internal::compiler::turboshaft {

namespace {

// Analyze the uses of values to determine if a compressed value has any uses
// that need it to be decompressed. Since this analysis looks at uses, we
// iterate the graph backwards, updating the analysis state for the inputs of an
// operation. Due to loop phis, we need to compute a fixed-point. Therefore, we
// re-visit the loop if a loop phi backedge changes something. As a performance
// optimization, we keep track of operations (`candidates`) that need to be
// updated potentially, so that we don't have to walk the whole graph again.
struct DecompressionAnalyzer { … };

void DecompressionAnalyzer::ProcessOperation(const Operation& op) { … }

// Checks if {base_idx} (which should be the base of a LoadOp) can be kept
// compressed and decompressed using complex addressing mode. If not, marks it
// as needing decompressiong.
void DecompressionAnalyzer::MarkAddressingBase(OpIndex base_idx) { … }

}  // namespace

// Instead of using `CopyingPhase`, we directly mutate the operations after
// the analysis. Doing it in-place is possible because we only modify operation
// options.
void RunDecompressionOptimization(Graph& graph, Zone* phase_zone) { … }

}  // namespace v8::internal::compiler::turboshaft
chromium/v8/src/compiler/turboshaft/decompression-optimization.cc
