mirror of
https://github.com/KhronosGroup/SPIRV-Tools
synced 2024-12-29 11:11:06 +00:00
8df947d2d6
When looking at the uses of the result of an instruction, code sinking assumes that all uses are in a basic block. However, this is not true if there is a decoration or name for the result of that insturction. This commit checks for this. Fixes https://crbug.com/923243.
320 lines
9.8 KiB
C++
320 lines
9.8 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 "code_sink.h"
|
|
|
|
#include <set>
|
|
#include <vector>
|
|
|
|
#include "source/opt/instruction.h"
|
|
#include "source/opt/ir_builder.h"
|
|
#include "source/opt/ir_context.h"
|
|
#include "source/util/bit_vector.h"
|
|
|
|
namespace spvtools {
|
|
namespace opt {
|
|
|
|
Pass::Status CodeSinkingPass::Process() {
|
|
bool modified = false;
|
|
for (Function& function : *get_module()) {
|
|
cfg()->ForEachBlockInPostOrder(function.entry().get(),
|
|
[&modified, this](BasicBlock* bb) {
|
|
if (SinkInstructionsInBB(bb)) {
|
|
modified = true;
|
|
}
|
|
});
|
|
}
|
|
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
|
|
}
|
|
|
|
bool CodeSinkingPass::SinkInstructionsInBB(BasicBlock* bb) {
|
|
bool modified = false;
|
|
for (auto inst = bb->rbegin(); inst != bb->rend(); ++inst) {
|
|
if (SinkInstruction(&*inst)) {
|
|
inst = bb->rbegin();
|
|
modified = true;
|
|
}
|
|
}
|
|
return modified;
|
|
}
|
|
|
|
bool CodeSinkingPass::SinkInstruction(Instruction* inst) {
|
|
if (inst->opcode() != SpvOpLoad && inst->opcode() != SpvOpAccessChain) {
|
|
return false;
|
|
}
|
|
|
|
if (ReferencesMutableMemory(inst)) {
|
|
return false;
|
|
}
|
|
|
|
if (BasicBlock* target_bb = FindNewBasicBlockFor(inst)) {
|
|
Instruction* pos = &*target_bb->begin();
|
|
while (pos->opcode() == SpvOpPhi) {
|
|
pos = pos->NextNode();
|
|
}
|
|
|
|
inst->InsertBefore(pos);
|
|
context()->set_instr_block(inst, target_bb);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
BasicBlock* CodeSinkingPass::FindNewBasicBlockFor(Instruction* inst) {
|
|
assert(inst->result_id() != 0 && "Instruction should have a result.");
|
|
BasicBlock* original_bb = context()->get_instr_block(inst);
|
|
BasicBlock* bb = original_bb;
|
|
|
|
std::unordered_set<uint32_t> bbs_with_uses;
|
|
get_def_use_mgr()->ForEachUse(
|
|
inst, [&bbs_with_uses, this](Instruction* use, uint32_t idx) {
|
|
if (use->opcode() != SpvOpPhi) {
|
|
BasicBlock* use_bb = context()->get_instr_block(use);
|
|
if (use_bb) {
|
|
bbs_with_uses.insert(use_bb->id());
|
|
}
|
|
} else {
|
|
bbs_with_uses.insert(use->GetSingleWordOperand(idx + 1));
|
|
}
|
|
});
|
|
|
|
while (true) {
|
|
// If |inst| is used in |bb|, then |inst| cannot be moved any further.
|
|
if (bbs_with_uses.count(bb->id())) {
|
|
break;
|
|
}
|
|
|
|
// If |bb| has one successor (succ_bb), and |bb| is the only predecessor
|
|
// of succ_bb, then |inst| can be moved to succ_bb. If succ_bb, has move
|
|
// then one predecessor, then moving |inst| into succ_bb could cause it to
|
|
// be executed more often, so the search has to stop.
|
|
if (bb->terminator()->opcode() == SpvOpBranch) {
|
|
uint32_t succ_bb_id = bb->terminator()->GetSingleWordInOperand(0);
|
|
if (cfg()->preds(succ_bb_id).size() == 1) {
|
|
bb = context()->get_instr_block(succ_bb_id);
|
|
continue;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// The remaining checks need to know the merge node. If there is no merge
|
|
// instruction or an OpLoopMerge, then it is a break or continue. We could
|
|
// figure it out, but not worth doing it now.
|
|
Instruction* merge_inst = bb->GetMergeInst();
|
|
if (merge_inst == nullptr || merge_inst->opcode() != SpvOpSelectionMerge) {
|
|
break;
|
|
}
|
|
|
|
// Check all of the successors of |bb| it see which lead to a use of |inst|
|
|
// before reaching the merge node.
|
|
bool used_in_multiple_blocks = false;
|
|
uint32_t bb_used_in = 0;
|
|
bb->ForEachSuccessorLabel([this, bb, &bb_used_in, &used_in_multiple_blocks,
|
|
&bbs_with_uses](uint32_t* succ_bb_id) {
|
|
if (IntersectsPath(*succ_bb_id, bb->MergeBlockIdIfAny(), bbs_with_uses)) {
|
|
if (bb_used_in == 0) {
|
|
bb_used_in = *succ_bb_id;
|
|
} else {
|
|
used_in_multiple_blocks = true;
|
|
}
|
|
}
|
|
});
|
|
|
|
// If more than one successor, which is not the merge block, uses |inst|
|
|
// then we have to leave |inst| in bb because there is none of the
|
|
// successors dominate all uses of |inst|.
|
|
if (used_in_multiple_blocks) {
|
|
break;
|
|
}
|
|
|
|
if (bb_used_in == 0) {
|
|
// If |inst| is not used before reaching the merge node, then we can move
|
|
// |inst| to the merge node.
|
|
bb = context()->get_instr_block(bb->MergeBlockIdIfAny());
|
|
} else {
|
|
// If the only successor that leads to a used of |inst| has more than 1
|
|
// predecessor, then moving |inst| could cause it to be executed more
|
|
// often, so we cannot move it.
|
|
if (cfg()->preds(bb_used_in).size() != 1) {
|
|
break;
|
|
}
|
|
|
|
// If |inst| is used after the merge block, then |bb_used_in| does not
|
|
// dominate all of the uses. So we cannot move |inst| any further.
|
|
if (IntersectsPath(bb->MergeBlockIdIfAny(), original_bb->id(),
|
|
bbs_with_uses)) {
|
|
break;
|
|
}
|
|
|
|
// Otherwise, |bb_used_in| dominates all uses, so move |inst| into that
|
|
// block.
|
|
bb = context()->get_instr_block(bb_used_in);
|
|
}
|
|
continue;
|
|
}
|
|
return (bb != original_bb ? bb : nullptr);
|
|
}
|
|
|
|
bool CodeSinkingPass::ReferencesMutableMemory(Instruction* inst) {
|
|
if (!inst->IsLoad()) {
|
|
return false;
|
|
}
|
|
|
|
Instruction* base_ptr = inst->GetBaseAddress();
|
|
if (base_ptr->opcode() != SpvOpVariable) {
|
|
return true;
|
|
}
|
|
|
|
if (base_ptr->IsReadOnlyVariable()) {
|
|
return false;
|
|
}
|
|
|
|
if (HasUniformMemorySync()) {
|
|
return true;
|
|
}
|
|
|
|
if (base_ptr->GetSingleWordInOperand(0) != SpvStorageClassUniform) {
|
|
return true;
|
|
}
|
|
|
|
return HasPossibleStore(base_ptr);
|
|
}
|
|
|
|
bool CodeSinkingPass::HasUniformMemorySync() {
|
|
if (checked_for_uniform_sync_) {
|
|
return has_uniform_sync_;
|
|
}
|
|
|
|
bool has_sync = false;
|
|
get_module()->ForEachInst([this, &has_sync](Instruction* inst) {
|
|
switch (inst->opcode()) {
|
|
case SpvOpMemoryBarrier: {
|
|
uint32_t mem_semantics_id = inst->GetSingleWordInOperand(1);
|
|
if (IsSyncOnUniform(mem_semantics_id)) {
|
|
has_sync = true;
|
|
}
|
|
break;
|
|
}
|
|
case SpvOpControlBarrier:
|
|
case SpvOpAtomicLoad:
|
|
case SpvOpAtomicStore:
|
|
case SpvOpAtomicExchange:
|
|
case SpvOpAtomicIIncrement:
|
|
case SpvOpAtomicIDecrement:
|
|
case SpvOpAtomicIAdd:
|
|
case SpvOpAtomicISub:
|
|
case SpvOpAtomicSMin:
|
|
case SpvOpAtomicUMin:
|
|
case SpvOpAtomicSMax:
|
|
case SpvOpAtomicUMax:
|
|
case SpvOpAtomicAnd:
|
|
case SpvOpAtomicOr:
|
|
case SpvOpAtomicXor:
|
|
case SpvOpAtomicFlagTestAndSet:
|
|
case SpvOpAtomicFlagClear: {
|
|
uint32_t mem_semantics_id = inst->GetSingleWordInOperand(2);
|
|
if (IsSyncOnUniform(mem_semantics_id)) {
|
|
has_sync = true;
|
|
}
|
|
break;
|
|
}
|
|
case SpvOpAtomicCompareExchange:
|
|
case SpvOpAtomicCompareExchangeWeak:
|
|
if (IsSyncOnUniform(inst->GetSingleWordInOperand(2)) ||
|
|
IsSyncOnUniform(inst->GetSingleWordInOperand(3))) {
|
|
has_sync = true;
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
});
|
|
has_uniform_sync_ = has_sync;
|
|
return has_sync;
|
|
}
|
|
|
|
bool CodeSinkingPass::IsSyncOnUniform(uint32_t mem_semantics_id) const {
|
|
const analysis::Constant* mem_semantics_const =
|
|
context()->get_constant_mgr()->FindDeclaredConstant(mem_semantics_id);
|
|
assert(mem_semantics_const != nullptr &&
|
|
"Expecting memory semantics id to be a constant.");
|
|
assert(mem_semantics_const->AsIntConstant() &&
|
|
"Memory semantics should be an integer.");
|
|
uint32_t mem_semantics_int = mem_semantics_const->GetU32();
|
|
|
|
// If it does not affect uniform memory, then it is does not apply to uniform
|
|
// memory.
|
|
if ((mem_semantics_int & SpvMemorySemanticsUniformMemoryMask) == 0) {
|
|
return false;
|
|
}
|
|
|
|
// Check if there is an acquire or release. If so not, this it does not add
|
|
// any memory constraints.
|
|
return (mem_semantics_int & (SpvMemorySemanticsAcquireMask |
|
|
SpvMemorySemanticsAcquireReleaseMask |
|
|
SpvMemorySemanticsReleaseMask)) != 0;
|
|
}
|
|
|
|
bool CodeSinkingPass::HasPossibleStore(Instruction* var_inst) {
|
|
assert(var_inst->opcode() == SpvOpVariable ||
|
|
var_inst->opcode() == SpvOpAccessChain ||
|
|
var_inst->opcode() == SpvOpPtrAccessChain);
|
|
|
|
return get_def_use_mgr()->WhileEachUser(var_inst, [this](Instruction* use) {
|
|
switch (use->opcode()) {
|
|
case SpvOpStore:
|
|
return true;
|
|
case SpvOpAccessChain:
|
|
case SpvOpPtrAccessChain:
|
|
return HasPossibleStore(use);
|
|
default:
|
|
return false;
|
|
}
|
|
});
|
|
}
|
|
|
|
bool CodeSinkingPass::IntersectsPath(uint32_t start, uint32_t end,
|
|
const std::unordered_set<uint32_t>& set) {
|
|
std::vector<uint32_t> worklist;
|
|
worklist.push_back(start);
|
|
std::unordered_set<uint32_t> already_done;
|
|
already_done.insert(start);
|
|
|
|
while (!worklist.empty()) {
|
|
BasicBlock* bb = context()->get_instr_block(worklist.back());
|
|
worklist.pop_back();
|
|
|
|
if (bb->id() == end) {
|
|
continue;
|
|
}
|
|
|
|
if (set.count(bb->id())) {
|
|
return true;
|
|
}
|
|
|
|
bb->ForEachSuccessorLabel([&already_done, &worklist](uint32_t* succ_bb_id) {
|
|
if (already_done.insert(*succ_bb_id).second) {
|
|
worklist.push_back(*succ_bb_id);
|
|
}
|
|
});
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// namespace opt
|
|
|
|
} // namespace opt
|
|
} // namespace spvtools
|