SPIRV-Tools/source/opt/wrap_opkill.cpp
Steven Perron c18c9ff6bc
Handle OpKill better (#2933)
We want to handle OpKill better.  The wrap opkill causes lots of extra
code to be generated, even when they are not needed to avoid the main
problem: OpKill cannot be found directly in a continue construct.

This change will be more selective on which functions the OpKill will be
wrapped and inlining will avoid inlining.

Fixes #2912
2019-10-04 13:05:32 -04:00

182 lines
5.4 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/opt/wrap_opkill.h"
#include "ir_builder.h"
namespace spvtools {
namespace opt {
Pass::Status WrapOpKill::Process() {
bool modified = false;
auto func_to_process =
context()->GetStructuredCFGAnalysis()->FindFuncsCalledFromContinue();
for (uint32_t func_id : func_to_process) {
Function* func = context()->GetFunction(func_id);
bool successful = func->WhileEachInst([this, &modified](Instruction* inst) {
if (inst->opcode() == SpvOpKill) {
modified = true;
if (!ReplaceWithFunctionCall(inst)) {
return false;
}
}
return true;
});
if (!successful) {
return Status::Failure;
}
}
if (opkill_function_ != nullptr) {
assert(modified &&
"The function should only be generated if something was modified.");
context()->AddFunction(std::move(opkill_function_));
}
return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
}
bool WrapOpKill::ReplaceWithFunctionCall(Instruction* inst) {
assert(inst->opcode() == SpvOpKill &&
"|inst| must be an OpKill instruction.");
InstructionBuilder ir_builder(
context(), inst,
IRContext::kAnalysisDefUse | IRContext::kAnalysisInstrToBlockMapping);
uint32_t func_id = GetOpKillFuncId();
if (func_id == 0) {
return false;
}
if (ir_builder.AddFunctionCall(GetVoidTypeId(), func_id, {}) == nullptr) {
return false;
}
Instruction* return_inst = nullptr;
uint32_t return_type_id = GetOwningFunctionsReturnType(inst);
if (return_type_id != GetVoidTypeId()) {
Instruction* undef = ir_builder.AddNullaryOp(return_type_id, SpvOpUndef);
if (undef == nullptr) {
return false;
}
return_inst =
ir_builder.AddUnaryOp(0, SpvOpReturnValue, undef->result_id());
} else {
return_inst = ir_builder.AddNullaryOp(0, SpvOpReturn);
}
if (return_inst == nullptr) {
return false;
}
context()->KillInst(inst);
return true;
}
uint32_t WrapOpKill::GetVoidTypeId() {
if (void_type_id_ != 0) {
return void_type_id_;
}
analysis::TypeManager* type_mgr = context()->get_type_mgr();
analysis::Void void_type;
void_type_id_ = type_mgr->GetTypeInstruction(&void_type);
return void_type_id_;
}
uint32_t WrapOpKill::GetVoidFunctionTypeId() {
analysis::TypeManager* type_mgr = context()->get_type_mgr();
analysis::Void void_type;
const analysis::Type* registered_void_type =
type_mgr->GetRegisteredType(&void_type);
analysis::Function func_type(registered_void_type, {});
return type_mgr->GetTypeInstruction(&func_type);
}
uint32_t WrapOpKill::GetOpKillFuncId() {
if (opkill_function_ != nullptr) {
return opkill_function_->result_id();
}
uint32_t opkill_func_id = TakeNextId();
if (opkill_func_id == 0) {
return 0;
}
uint32_t void_type_id = GetVoidTypeId();
if (void_type_id == 0) {
return 0;
}
// Generate the function start instruction
std::unique_ptr<Instruction> func_start(new Instruction(
context(), SpvOpFunction, void_type_id, opkill_func_id, {}));
func_start->AddOperand({SPV_OPERAND_TYPE_FUNCTION_CONTROL, {0}});
func_start->AddOperand({SPV_OPERAND_TYPE_ID, {GetVoidFunctionTypeId()}});
opkill_function_.reset(new Function(std::move(func_start)));
// Generate the function end instruction
std::unique_ptr<Instruction> func_end(
new Instruction(context(), SpvOpFunctionEnd, 0, 0, {}));
opkill_function_->SetFunctionEnd(std::move(func_end));
// Create the one basic block for the function.
uint32_t lab_id = TakeNextId();
if (lab_id == 0) {
return 0;
}
std::unique_ptr<Instruction> label_inst(
new Instruction(context(), SpvOpLabel, 0, lab_id, {}));
std::unique_ptr<BasicBlock> bb(new BasicBlock(std::move(label_inst)));
// Add the OpKill to the basic block
std::unique_ptr<Instruction> kill_inst(
new Instruction(context(), SpvOpKill, 0, 0, {}));
bb->AddInstruction(std::move(kill_inst));
// Add the bb to the function
opkill_function_->AddBasicBlock(std::move(bb));
// Add the function to the module.
if (context()->AreAnalysesValid(IRContext::kAnalysisDefUse)) {
opkill_function_->ForEachInst(
[this](Instruction* inst) { context()->AnalyzeDefUse(inst); });
}
if (context()->AreAnalysesValid(IRContext::kAnalysisInstrToBlockMapping)) {
for (BasicBlock& basic_block : *opkill_function_) {
context()->set_instr_block(basic_block.GetLabelInst(), &basic_block);
for (Instruction& inst : basic_block) {
context()->set_instr_block(&inst, &basic_block);
}
}
}
return opkill_function_->result_id();
}
uint32_t WrapOpKill::GetOwningFunctionsReturnType(Instruction* inst) {
BasicBlock* bb = context()->get_instr_block(inst);
if (bb == nullptr) {
return 0;
}
Function* func = bb->GetParent();
return func->type_id();
}
} // namespace opt
} // namespace spvtools