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SPIRV-Tools/source/fuzz/transformation_add_dead_block.cpp

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spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
2020-01-13 22:04:01 +00:00
// 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/fuzz/transformation_add_dead_block.h"
#include "source/fuzz/fuzzer_util.h"
namespace spvtools {
namespace fuzz {
TransformationAddDeadBlock::TransformationAddDeadBlock(
const spvtools::fuzz::protobufs::TransformationAddDeadBlock& message)
: message_(message) {}
TransformationAddDeadBlock::TransformationAddDeadBlock(uint32_t fresh_id,
uint32_t existing_block,
bool condition_value) {
message_.set_fresh_id(fresh_id);
message_.set_existing_block(existing_block);
message_.set_condition_value(condition_value);
}
bool TransformationAddDeadBlock::IsApplicable(
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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opt::IRContext* ir_context, const TransformationContext& /*unused*/) const {
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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// The new block's id must be fresh.
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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if (!fuzzerutil::IsFreshId(ir_context, message_.fresh_id())) {
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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return false;
}
// First, we check that a constant with the same value as
// |message_.condition_value| is present.
spirv-fuzz: fuzzerutil::MaybeGetConstant* #3487 Part of #3428.
2020-07-07 09:46:04 +00:00
if (!fuzzerutil::MaybeGetBoolConstant(ir_context,
message_.condition_value())) {
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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// The required constant is not present, so the transformation cannot be
// applied.
return false;
}
// The existing block must indeed exist.
auto existing_block =
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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fuzzerutil::MaybeFindBlock(ir_context, message_.existing_block());
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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if (!existing_block) {
return false;
}
// It must not head a loop.
if (existing_block->IsLoopHeader()) {
return false;
}
// It must end with OpBranch.
if (existing_block->terminator()->opcode() != SpvOpBranch) {
return false;
}
// Its successor must not be a merge block nor continue target.
auto successor_block_id =
existing_block->terminator()->GetSingleWordInOperand(0);
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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if (fuzzerutil::IsMergeOrContinue(ir_context, successor_block_id)) {
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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return false;
}
// The successor must not be a loop header (i.e., |message_.existing_block|
// must not be a back-edge block.
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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if (ir_context->cfg()->block(successor_block_id)->IsLoopHeader()) {
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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return false;
}
return true;
}
void TransformationAddDeadBlock::Apply(
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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opt::IRContext* ir_context,
TransformationContext* transformation_context) const {
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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// Update the module id bound so that it is at least the id of the new block.
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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fuzzerutil::UpdateModuleIdBound(ir_context, message_.fresh_id());
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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// Get the existing block and its successor.
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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auto existing_block = ir_context->cfg()->block(message_.existing_block());
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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auto successor_block_id =
existing_block->terminator()->GetSingleWordInOperand(0);
// Get the id of the boolean value that will be used as the branch condition.
spirv-fuzz: fuzzerutil::MaybeGetConstant* #3487 Part of #3428.
2020-07-07 09:46:04 +00:00
auto bool_id =
fuzzerutil::MaybeGetBoolConstant(ir_context, message_.condition_value());
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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// Make a new block that unconditionally branches to the original successor
// block.
auto enclosing_function = existing_block->GetParent();
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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std::unique_ptr<opt::BasicBlock> new_block =
MakeUnique<opt::BasicBlock>(MakeUnique<opt::Instruction>(
ir_context, SpvOpLabel, 0, message_.fresh_id(),
opt::Instruction::OperandList()));
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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new_block->AddInstruction(MakeUnique<opt::Instruction>(
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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ir_context, SpvOpBranch, 0, 0,
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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opt::Instruction::OperandList(
{{SPV_OPERAND_TYPE_ID, {successor_block_id}}})));
// Turn the original block into a selection merge, with its original successor
// as the merge block.
existing_block->terminator()->InsertBefore(MakeUnique<opt::Instruction>(
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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ir_context, SpvOpSelectionMerge, 0, 0,
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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opt::Instruction::OperandList(
{{SPV_OPERAND_TYPE_ID, {successor_block_id}},
{SPV_OPERAND_TYPE_SELECTION_CONTROL,
{SpvSelectionControlMaskNone}}})));
// Change the original block's terminator to be a conditional branch on the
// given boolean, with the original successor and the new successor as branch
// targets, and such that at runtime control will always transfer to the
// original successor.
existing_block->terminator()->SetOpcode(SpvOpBranchConditional);
existing_block->terminator()->SetInOperands(
{{SPV_OPERAND_TYPE_ID, {bool_id}},
{SPV_OPERAND_TYPE_ID,
{message_.condition_value() ? successor_block_id
: message_.fresh_id()}},
{SPV_OPERAND_TYPE_ID,
{message_.condition_value() ? message_.fresh_id()
: successor_block_id}}});
// Add the new block to the enclosing function.
new_block->SetParent(enclosing_function);
enclosing_function->InsertBasicBlockAfter(std::move(new_block),
existing_block);
// Record the fact that the new block is dead.
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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transformation_context->GetFactManager()->AddFactBlockIsDead(
message_.fresh_id());
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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// Fix up OpPhi instructions in the successor block, so that the values they
// yield when control has transferred from the new block are the same as if
// control had transferred from |message_.existing_block|. This is guaranteed
// to be valid since |message_.existing_block| dominates the new block by
// construction. Other transformations can change these phi operands to more
// interesting values.
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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ir_context->cfg()
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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->block(successor_block_id)
->ForEachPhiInst([this](opt::Instruction* phi_inst) {
// Copy the operand that provides the phi value for the first of any
// existing predecessors.
opt::Operand copy_of_existing_operand = phi_inst->GetInOperand(0);
// Use this as the value associated with the new predecessor.
phi_inst->AddOperand(std::move(copy_of_existing_operand));
phi_inst->AddOperand({SPV_OPERAND_TYPE_ID, {message_.fresh_id()}});
});
// Do not rely on any existing analysis results since the control flow graph
// of the module has changed.
spirv-fuzz: Introduce TransformationContext (#3272) Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
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ir_context->InvalidateAnalysesExceptFor(opt::IRContext::kAnalysisNone);
spirv-fuzz: add dead blocks (#3135) This adds a new kind of fact to the fact manager that knows whether a block is dead - i.e. guaranteed to be statically unreachable - and a new transformation for adding a selection construct to a CFG that conditionally branches to a fresh, dead block, such that the branch will never be dynamically taken. Transformations that may create new blocks ('split block' and 'outline function') are updated to propagate dead block facts to newly-created blocks where appropriate. A fuzzer pass randomly adds dead blocks to the module. Future transformations will be able to exploit the fact that such blocks are known to be dead.
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}
protobufs::Transformation TransformationAddDeadBlock::ToMessage() const {
protobufs::Transformation result;
*result.mutable_add_dead_block() = message_;
return result;
}
} // namespace fuzz
} // namespace spvtools
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