mirror of
https://github.com/KhronosGroup/SPIRV-Tools
synced 2024-11-24 20:40:13 +00:00
d90aae9a5a
* Fix .gitignore * Add missing reduction pass: RemoveBlockReductionOpportunityFinder * Add DumpShader functions in test_reduce for debugging * Add DumpShader functions in spirv-reduce for debugging * Fix include style * Don't use "using namespace"
84 lines
3.3 KiB
C++
84 lines
3.3 KiB
C++
// Copyright (c) 2019 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/merge_blocks_reduction_opportunity.h"
|
|
|
|
#include "source/opt/block_merge_util.h"
|
|
#include "source/opt/ir_context.h"
|
|
|
|
namespace spvtools {
|
|
namespace reduce {
|
|
|
|
using opt::BasicBlock;
|
|
using opt::Function;
|
|
using opt::IRContext;
|
|
|
|
MergeBlocksReductionOpportunity::MergeBlocksReductionOpportunity(
|
|
IRContext* context, Function* function, BasicBlock* block) {
|
|
// Precondition: the terminator has to be OpBranch.
|
|
assert(block->terminator()->opcode() == SpvOpBranch);
|
|
context_ = context;
|
|
function_ = function;
|
|
// Get the successor block associated with the OpBranch.
|
|
successor_block_ =
|
|
context->cfg()->block(block->terminator()->GetSingleWordInOperand(0));
|
|
}
|
|
|
|
bool MergeBlocksReductionOpportunity::PreconditionHolds() {
|
|
// Merge block opportunities can disable each other.
|
|
// Example: Given blocks: A->B->C.
|
|
// A is a loop header; B and C are blocks in the loop; C ends with OpReturn.
|
|
// There are two opportunities: B and C can be merged with their predecessors.
|
|
// Merge C. B now ends with OpReturn. We now just have: A->B.
|
|
// Merge B is now disabled, as this would lead to A, a loop header, ending
|
|
// with an OpReturn, which is invalid.
|
|
|
|
const auto predecessors = context_->cfg()->preds(successor_block_->id());
|
|
assert(1 == predecessors.size() &&
|
|
"For a successor to be merged into its predecessor, exactly one "
|
|
"predecessor must be present.");
|
|
const uint32_t predecessor_id = predecessors[0];
|
|
BasicBlock* predecessor_block = context_->get_instr_block(predecessor_id);
|
|
return opt::blockmergeutil::CanMergeWithSuccessor(context_,
|
|
predecessor_block);
|
|
}
|
|
|
|
void MergeBlocksReductionOpportunity::Apply() {
|
|
// While the original block that targeted the successor may not exist anymore
|
|
// (it might have been merged with another block), some block must exist that
|
|
// targets the successor. Find it.
|
|
|
|
const auto predecessors = context_->cfg()->preds(successor_block_->id());
|
|
assert(1 == predecessors.size() &&
|
|
"For a successor to be merged into its predecessor, exactly one "
|
|
"predecessor must be present.");
|
|
const uint32_t predecessor_id = predecessors[0];
|
|
|
|
// We need an iterator pointing to the predecessor, hence the loop.
|
|
for (auto bi = function_->begin(); bi != function_->end(); ++bi) {
|
|
if (bi->id() == predecessor_id) {
|
|
opt::blockmergeutil::MergeWithSuccessor(context_, function_, bi);
|
|
// Block merging changes the control flow graph, so invalidate it.
|
|
context_->InvalidateAnalysesExceptFor(IRContext::Analysis::kAnalysisNone);
|
|
return;
|
|
}
|
|
}
|
|
|
|
assert(false &&
|
|
"Unreachable: we should have found a block with the desired id.");
|
|
}
|
|
|
|
} // namespace reduce
|
|
} // namespace spvtools
|