SPIRV-Tools/source/fuzz/transformation_replace_irrelevant_id.cpp
Stefano Milizia 3daabd3212
spirv-fuzz: Transformation to replace the use of an irrelevant id (#3697)
A transformation that replaces the use of an irrelevant id with
another id of the same type.

The related fuzzer pass, for every use of an irrelevant id,
checks whether the id can be replaced in that use by another
id of the same type and randomly decides whether to replace
it.

Fixes #3503.
2020-09-01 16:28:04 +01:00

114 lines
4.0 KiB
C++

// Copyright (c) 2020 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/fuzz/transformation_replace_irrelevant_id.h"
#include "source/fuzz/fuzzer_util.h"
#include "source/fuzz/id_use_descriptor.h"
namespace spvtools {
namespace fuzz {
TransformationReplaceIrrelevantId::TransformationReplaceIrrelevantId(
const protobufs::TransformationReplaceIrrelevantId& message)
: message_(message) {}
TransformationReplaceIrrelevantId::TransformationReplaceIrrelevantId(
const protobufs::IdUseDescriptor& id_use_descriptor,
uint32_t replacement_id) {
*message_.mutable_id_use_descriptor() = id_use_descriptor;
message_.set_replacement_id(replacement_id);
}
bool TransformationReplaceIrrelevantId::IsApplicable(
opt::IRContext* ir_context,
const TransformationContext& transformation_context) const {
auto id_of_interest = message_.id_use_descriptor().id_of_interest();
// The id must be irrelevant.
if (!transformation_context.GetFactManager()->IdIsIrrelevant(
id_of_interest)) {
return false;
}
// Find the instruction containing the id use, which must exist.
auto use_instruction =
FindInstructionContainingUse(message_.id_use_descriptor(), ir_context);
if (!use_instruction) {
return false;
}
// Check that the replacement id exists and retrieve its definition.
auto replacement_id_def =
ir_context->get_def_use_mgr()->GetDef(message_.replacement_id());
if (!replacement_id_def) {
return false;
}
// The type of the id of interest and of the replacement id must be the same.
uint32_t type_id_of_interest =
ir_context->get_def_use_mgr()->GetDef(id_of_interest)->type_id();
uint32_t type_replacement_id = replacement_id_def->type_id();
if (type_id_of_interest != type_replacement_id) {
return false;
}
// Consistency check: an irrelevant id cannot be a pointer.
assert(
!ir_context->get_type_mgr()->GetType(type_id_of_interest)->AsPointer() &&
"An irrelevant id cannot be a pointer");
// The id use must be replaceable with any other id of the same type.
if (!fuzzerutil::IdUseCanBeReplaced(
ir_context, use_instruction,
message_.id_use_descriptor().in_operand_index())) {
return false;
}
// The id must be available to use at the use point.
// TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/3722):
// IdIsAvailable at use always returns false if the instruction is in an
// unreachable block, so it might need to be fixed.
return fuzzerutil::IdIsAvailableAtUse(
ir_context, use_instruction,
message_.id_use_descriptor().in_operand_index(),
message_.replacement_id());
}
void TransformationReplaceIrrelevantId::Apply(
opt::IRContext* ir_context,
TransformationContext* /* transformation_context */) const {
// Find the instruction.
auto instruction_to_change =
FindInstructionContainingUse(message_.id_use_descriptor(), ir_context);
// Replace the instruction.
instruction_to_change->SetInOperand(
message_.id_use_descriptor().in_operand_index(),
{message_.replacement_id()});
// Invalidate the analyses, since the usage of ids has been changed.
ir_context->InvalidateAnalysesExceptFor(
opt::IRContext::Analysis::kAnalysisNone);
}
protobufs::Transformation TransformationReplaceIrrelevantId::ToMessage() const {
protobufs::Transformation result;
*result.mutable_replace_irrelevant_id() = message_;
return result;
}
} // namespace fuzz
} // namespace spvtools