// Copyright (c) 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "source/reduce/reducer.h"
#include <cassert>
#include <sstream>
#include "source/reduce/conditional_branch_to_simple_conditional_branch_opportunity_finder.h"
#include "source/reduce/merge_blocks_reduction_opportunity_finder.h"
#include "source/reduce/operand_to_const_reduction_opportunity_finder.h"
#include "source/reduce/operand_to_dominating_id_reduction_opportunity_finder.h"
#include "source/reduce/operand_to_undef_reduction_opportunity_finder.h"
#include "source/reduce/remove_block_reduction_opportunity_finder.h"
#include "source/reduce/remove_function_reduction_opportunity_finder.h"
#include "source/reduce/remove_selection_reduction_opportunity_finder.h"
#include "source/reduce/remove_unused_instruction_reduction_opportunity_finder.h"
#include "source/reduce/remove_unused_struct_member_reduction_opportunity_finder.h"
#include "source/reduce/simple_conditional_branch_to_branch_opportunity_finder.h"
#include "source/reduce/structured_loop_to_selection_reduction_opportunity_finder.h"
#include "source/spirv_reducer_options.h"
namespace spvtools {
namespace reduce {
Reducer::Reducer(spv_target_env target_env) : target_env_(target_env) {}
Reducer::~Reducer() = default;
void Reducer::SetMessageConsumer(MessageConsumer c) {
for (auto& pass : passes_) {
pass->SetMessageConsumer(c);
}
for (auto& pass : cleanup_passes_) {
pass->SetMessageConsumer(c);
}
consumer_ = std::move(c);
}
void Reducer::SetInterestingnessFunction(
Reducer::InterestingnessFunction interestingness_function) {
interestingness_function_ = std::move(interestingness_function);
}
Reducer::ReductionResultStatus Reducer::Run(
std::vector<uint32_t>&& binary_in, std::vector<uint32_t>* binary_out,
spv_const_reducer_options options,
spv_validator_options validator_options) {
std::vector<uint32_t> current_binary(std::move(binary_in));
spvtools::SpirvTools tools(target_env_);
assert(tools.IsValid() && "Failed to create SPIRV-Tools interface");
// Keeps track of how many reduction attempts have been tried. Reduction
// bails out if this reaches a given limit.
uint32_t reductions_applied = 0;
// Initial state should be valid.
if (!tools.Validate(¤t_binary[0], current_binary.size(),
validator_options)) {
consumer_(SPV_MSG_INFO, nullptr, {},
"Initial binary is invalid; stopping.");
return Reducer::ReductionResultStatus::kInitialStateInvalid;
}
// Initial state should be interesting.
if (!interestingness_function_(current_binary, reductions_applied)) {
consumer_(SPV_MSG_INFO, nullptr, {},
"Initial state was not interesting; stopping.");
return Reducer::ReductionResultStatus::kInitialStateNotInteresting;
}
Reducer::ReductionResultStatus result =
RunPasses(&passes_, options, validator_options, tools, ¤t_binary,
&reductions_applied);
if (result == Reducer::ReductionResultStatus::kComplete) {
// Cleanup passes.
result = RunPasses(&cleanup_passes_, options, validator_options, tools,
¤t_binary, &reductions_applied);
}
if (result == Reducer::ReductionResultStatus::kComplete) {
consumer_(SPV_MSG_INFO, nullptr, {}, "No more to reduce; stopping.");
}
// Even if the reduction has failed by this point (e.g. due to producing an
// invalid binary), we still update the output binary for better debugging.
*binary_out = std::move(current_binary);
return result;
}
void Reducer::AddDefaultReductionPasses() {
AddReductionPass(
spvtools::MakeUnique<RemoveUnusedInstructionReductionOpportunityFinder>(
false));
AddReductionPass(
spvtools::MakeUnique<OperandToUndefReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<OperandToConstReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<OperandToDominatingIdReductionOpportunityFinder>());
AddReductionPass(spvtools::MakeUnique<
StructuredLoopToSelectionReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<MergeBlocksReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<RemoveFunctionReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<RemoveBlockReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<RemoveSelectionReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<
ConditionalBranchToSimpleConditionalBranchOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<SimpleConditionalBranchToBranchOpportunityFinder>());
AddReductionPass(spvtools::MakeUnique<
RemoveUnusedStructMemberReductionOpportunityFinder>());
// Cleanup passes.
AddCleanupReductionPass(
spvtools::MakeUnique<RemoveUnusedInstructionReductionOpportunityFinder>(
true));
}
void Reducer::AddReductionPass(
std::unique_ptr<ReductionOpportunityFinder>&& finder) {
passes_.push_back(
spvtools::MakeUnique<ReductionPass>(target_env_, std::move(finder)));
}
void Reducer::AddCleanupReductionPass(
std::unique_ptr<ReductionOpportunityFinder>&& finder) {
cleanup_passes_.push_back(
spvtools::MakeUnique<ReductionPass>(target_env_, std::move(finder)));
}
bool Reducer::ReachedStepLimit(uint32_t current_step,
spv_const_reducer_options options) {
return current_step >= options->step_limit;
}
Reducer::ReductionResultStatus Reducer::RunPasses(
std::vector<std::unique_ptr<ReductionPass>>* passes,
spv_const_reducer_options options, spv_validator_options validator_options,
const SpirvTools& tools, std::vector<uint32_t>* current_binary,
uint32_t* const reductions_applied) {
// Determines whether, on completing one round of reduction passes, it is
// worthwhile trying a further round.
bool another_round_worthwhile = true;
// Apply round after round of reduction passes until we hit the reduction
// step limit, or deem that another round is not going to be worthwhile.
while (!ReachedStepLimit(*reductions_applied, options) &&
another_round_worthwhile) {
// At the start of a round of reduction passes, assume another round will
// not be worthwhile unless we find evidence to the contrary.
another_round_worthwhile = false;
// Iterate through the available passes.
for (auto& pass : *passes) {
// If this pass hasn't reached its minimum granularity then it's
// worth eventually doing another round of reductions, in order to
// try this pass at a finer granularity.
another_round_worthwhile |= !pass->ReachedMinimumGranularity();
// Keep applying this pass at its current granularity until it stops
// working or we hit the reduction step limit.
consumer_(SPV_MSG_INFO, nullptr, {},
("Trying pass " + pass->GetName() + ".").c_str());
do {
auto maybe_result =
pass->TryApplyReduction(*current_binary, options->target_function);
if (maybe_result.empty()) {
// For this round, the pass has no more opportunities (chunks) to
// apply, so move on to the next pass.
consumer_(
SPV_MSG_INFO, nullptr, {},
("Pass " + pass->GetName() + " did not make a reduction step.")
.c_str());
break;
}
bool interesting = false;
std::stringstream stringstream;
(*reductions_applied)++;
stringstream << "Pass " << pass->GetName() << " made reduction step "
<< *reductions_applied << ".";
consumer_(SPV_MSG_INFO, nullptr, {}, (stringstream.str().c_str()));
if (!tools.Validate(&maybe_result[0], maybe_result.size(),
validator_options)) {
// The reduction step went wrong and an invalid binary was produced.
// By design, this shouldn't happen; this is a safeguard to stop an
// invalid binary from being regarded as interesting.
consumer_(SPV_MSG_INFO, nullptr, {},
"Reduction step produced an invalid binary.");
if (options->fail_on_validation_error) {
// In this mode, we fail, so we update the current binary so it is
// output for debugging.
*current_binary = std::move(maybe_result);
return Reducer::ReductionResultStatus::kStateInvalid;
}
} else if (interestingness_function_(maybe_result,
*reductions_applied)) {
// Success! The binary produced by this reduction step is
// interesting, so make it the binary of interest henceforth, and
// note that it's worth doing another round of reduction passes.
consumer_(SPV_MSG_INFO, nullptr, {}, "Reduction step succeeded.");
*current_binary = std::move(maybe_result);
interesting = true;
another_round_worthwhile = true;
}
// We must call this before the next call to TryApplyReduction.
pass->NotifyInteresting(interesting);
// Bail out if the reduction step limit has been reached.
} while (!ReachedStepLimit(*reductions_applied, options));
}
}
// Report whether reduction completed, or bailed out early due to reaching
// the step limit.
if (ReachedStepLimit(*reductions_applied, options)) {
consumer_(SPV_MSG_INFO, nullptr, {},
"Reached reduction step limit; stopping.");
return Reducer::ReductionResultStatus::kReachedStepLimit;
}
// The passes completed successfully, although we may still run more passes.
return Reducer::ReductionResultStatus::kComplete;
}
} // namespace reduce
} // namespace spvtools