SPIRV-Tools/source/opt/opextinst_forward_ref_fixup_pass.cpp
Nathan Gauër bc28ac7c19
opt: add OpExtInst forward ref fixup pass (#5708)
This pass fixups the opcode used for OpExtInst instructions
to use OpExtInstWithForwardRefsKHR when it contains a forward
reference.
This pass is agnostic to the extension used, hence the validity
of the code depends of the validity of the usage:

If a forward reference is used on a non-semantic extended instruction,
the generated code will remain invalid, but the opcode will change.
What this pass guarantees is valid code won't become invalid.

---------

Signed-off-by: Nathan Gauër <brioche@google.com>
Co-authored-by: Steven Perron <stevenperron@google.com>
2024-06-13 02:09:58 -07:00

113 lines
3.8 KiB
C++

// Copyright (c) 2024 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/opextinst_forward_ref_fixup_pass.h"
#include <string>
#include <unordered_set>
#include "source/extensions.h"
#include "source/opt/ir_context.h"
#include "source/opt/module.h"
#include "type_manager.h"
namespace spvtools {
namespace opt {
namespace {
// Returns true if the instruction |inst| has a forward reference to another
// debug instruction.
// |debug_ids| contains the list of IDs belonging to debug instructions.
// |seen_ids| contains the list of IDs already seen.
bool HasForwardReference(const Instruction& inst,
const std::unordered_set<uint32_t>& debug_ids,
const std::unordered_set<uint32_t>& seen_ids) {
const uint32_t num_in_operands = inst.NumInOperands();
for (uint32_t i = 0; i < num_in_operands; ++i) {
const Operand& op = inst.GetInOperand(i);
if (!spvIsIdType(op.type)) continue;
if (debug_ids.count(op.AsId()) == 0) continue;
if (seen_ids.count(op.AsId()) == 0) return true;
}
return false;
}
// Replace |inst| opcode with OpExtInstWithForwardRefsKHR or OpExtInst
// if required to comply with forward references.
bool ReplaceOpcodeIfRequired(Instruction& inst, bool hasForwardReferences) {
if (hasForwardReferences &&
inst.opcode() != spv::Op::OpExtInstWithForwardRefsKHR)
inst.SetOpcode(spv::Op::OpExtInstWithForwardRefsKHR);
else if (!hasForwardReferences && inst.opcode() != spv::Op::OpExtInst)
inst.SetOpcode(spv::Op::OpExtInst);
else
return false;
return true;
}
// Returns all the result IDs of the instructions in |range|.
std::unordered_set<uint32_t> gatherResultIds(
const IteratorRange<Module::inst_iterator>& range) {
std::unordered_set<uint32_t> output;
for (const auto& it : range) output.insert(it.result_id());
return output;
}
} // namespace
Pass::Status OpExtInstWithForwardReferenceFixupPass::Process() {
std::unordered_set<uint32_t> seen_ids =
gatherResultIds(get_module()->ext_inst_imports());
std::unordered_set<uint32_t> debug_ids =
gatherResultIds(get_module()->ext_inst_debuginfo());
for (uint32_t id : seen_ids) debug_ids.insert(id);
bool moduleChanged = false;
bool hasAtLeastOneForwardReference = false;
IRContext* ctx = context();
for (Instruction& inst : get_module()->ext_inst_debuginfo()) {
if (inst.opcode() != spv::Op::OpExtInst &&
inst.opcode() != spv::Op::OpExtInstWithForwardRefsKHR)
continue;
seen_ids.insert(inst.result_id());
bool hasForwardReferences = HasForwardReference(inst, debug_ids, seen_ids);
hasAtLeastOneForwardReference |= hasForwardReferences;
if (ReplaceOpcodeIfRequired(inst, hasForwardReferences)) {
moduleChanged = true;
ctx->AnalyzeUses(&inst);
}
}
if (hasAtLeastOneForwardReference !=
ctx->get_feature_mgr()->HasExtension(
kSPV_KHR_relaxed_extended_instruction)) {
if (hasAtLeastOneForwardReference)
ctx->AddExtension("SPV_KHR_relaxed_extended_instruction");
else
ctx->RemoveExtension(Extension::kSPV_KHR_relaxed_extended_instruction);
moduleChanged = true;
}
return moduleChanged ? Status::SuccessWithChange
: Status::SuccessWithoutChange;
}
} // namespace opt
} // namespace spvtools