mirror of
https://github.com/KhronosGroup/SPIRV-Tools
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160 lines
7.6 KiB
C++
160 lines
7.6 KiB
C++
// Copyright (c) 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef SOURCE_FUZZ_TRANSFORMATION_FLATTEN_CONDITIONAL_BRANCH_H_
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#define SOURCE_FUZZ_TRANSFORMATION_FLATTEN_CONDITIONAL_BRANCH_H_
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#include "source/fuzz/transformation.h"
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namespace spvtools {
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namespace fuzz {
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class TransformationFlattenConditionalBranch : public Transformation {
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public:
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explicit TransformationFlattenConditionalBranch(
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const protobufs::TransformationFlattenConditionalBranch& message);
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TransformationFlattenConditionalBranch(
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uint32_t header_block_id, bool true_branch_first,
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uint32_t fresh_id_for_bvec2_selector,
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uint32_t fresh_id_for_bvec3_selector,
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uint32_t fresh_id_for_bvec4_selector,
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const std::vector<protobufs::SideEffectWrapperInfo>&
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side_effect_wrappers_info);
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// - |message_.header_block_id| must be the label id of a reachable selection
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// header, which ends with an OpBranchConditional instruction.
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// - The condition of the OpBranchConditional instruction must not be an
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// irrelevant id.
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// - The header block and the merge block must describe a single-entry,
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// single-exit region.
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// - The region must not contain barrier or OpSampledImage instructions.
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// - The region must not contain selection or loop constructs.
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// - The region must not define ids that are the base objects for existing
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// synonym facts.
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// - For each instruction that requires additional fresh ids, then:
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// - if the instruction is mapped to the required ids for enclosing it by
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// |message_.side_effect_wrapper_info|, these must be valid (the
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// fresh ids must be non-zero, fresh and distinct);
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// - if there is no such mapping, the transformation context must have
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// overflow ids available.
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bool IsApplicable(
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opt::IRContext* ir_context,
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const TransformationContext& transformation_context) const override;
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// Flattens the selection construct with header |message_.header_block_id|,
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// changing any OpPhi in the block where the flow converges to OpSelect and
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// enclosing any instruction with side effects in conditionals so that
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// they are only executed when they should.
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void Apply(opt::IRContext* ir_context,
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TransformationContext* transformation_context) const override;
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std::unordered_set<uint32_t> GetFreshIds() const override;
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protobufs::Transformation ToMessage() const override;
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// Returns true if the conditional headed by |header| can be flattened,
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// according to the conditions of the IsApplicable method, assuming that
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// enough fresh ids would be provided. In this case, it fills the
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// |instructions_that_need_ids| set with all the instructions that would
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// require fresh ids.
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// Returns false otherwise.
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// Assumes that |header| is the header of a conditional, so its last two
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// instructions are OpSelectionMerge and OpBranchConditional.
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static bool GetProblematicInstructionsIfConditionalCanBeFlattened(
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opt::IRContext* ir_context, opt::BasicBlock* header,
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const TransformationContext& transformation_context,
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std::set<opt::Instruction*>* instructions_that_need_ids);
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// Returns true iff the given instruction needs a placeholder to be enclosed
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// inside a conditional. So, it returns:
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// - true if the instruction has a non-void result id,
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// - false if the instruction does not have a result id or has a void result
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// id.
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// Assumes that the instruction has side effects, requiring it to be enclosed
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// inside a conditional, and that it can be enclosed inside a conditional
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// keeping the module valid. Assumes that, if the instruction has a void
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// result type, its result id is not used in the module.
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static bool InstructionNeedsPlaceholder(opt::IRContext* ir_context,
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const opt::Instruction& instruction);
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// Returns true if and only if the SPIR-V version is such that the arguments
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// to OpSelect are restricted to only scalars, pointers (if the appropriate
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// capability is enabled) and component-wise vectors.
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static bool OpSelectArgumentsAreRestricted(opt::IRContext* ir_context);
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// Find the first block where flow converges (it is not necessarily the merge
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// block) by walking the true branch until reaching a block that post-
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// dominates the header.
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// This is necessary because a potential common set of blocks at the end of
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// the construct should not be duplicated.
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static uint32_t FindConvergenceBlock(opt::IRContext* ir_context,
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const opt::BasicBlock& header_block);
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private:
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// Returns an unordered_map mapping instructions to the info required to
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// enclose them inside a conditional. It maps the instructions to the
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// corresponding entry in |message_.side_effect_wrapper_info|.
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std::unordered_map<opt::Instruction*, protobufs::SideEffectWrapperInfo>
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GetInstructionsToWrapperInfo(opt::IRContext* ir_context) const;
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// Splits the given block, adding a new selection construct so that the given
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// instruction is only executed if the boolean value of |condition_id| matches
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// the value of |exec_if_cond_true|.
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// Assumes that all parameters are consistent.
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// 2 fresh ids are required if the instruction does not have a result id (the
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// first two ids in |wrapper_info| must be valid fresh ids), 5 otherwise.
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// Returns the merge block created.
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//
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// |dead_blocks| and |irrelevant_ids| are used to record the ids of blocks
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// and instructions for which dead block and irrelevant id facts should
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// ultimately be created.
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static opt::BasicBlock* EncloseInstructionInConditional(
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opt::IRContext* ir_context,
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const TransformationContext& transformation_context,
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opt::BasicBlock* block, opt::Instruction* instruction,
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const protobufs::SideEffectWrapperInfo& wrapper_info,
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uint32_t condition_id, bool exec_if_cond_true,
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std::vector<uint32_t>* dead_blocks,
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std::vector<uint32_t>* irrelevant_ids);
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// Turns every OpPhi instruction of |convergence_block| -- the convergence
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// block for |header_block| (both in |ir_context|) into an OpSelect
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// instruction.
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void RewriteOpPhiInstructionsAtConvergenceBlock(
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const opt::BasicBlock& header_block, uint32_t convergence_block_id,
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opt::IRContext* ir_context) const;
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// Adds an OpCompositeExtract instruction to the start of |block| in
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// |ir_context|, with result id given by |fresh_id|. The instruction will
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// make a |dimension|-dimensional boolean vector with
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// |branch_condition_operand| at every component.
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static void AddBooleanVectorConstructorToBlock(
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uint32_t fresh_id, uint32_t dimension,
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const opt::Operand& branch_condition_operand, opt::IRContext* ir_context,
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opt::BasicBlock* block);
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// Returns true if the given instruction either has no side effects or it can
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// be handled by being enclosed in a conditional.
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static bool InstructionCanBeHandled(opt::IRContext* ir_context,
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const opt::Instruction& instruction);
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protobufs::TransformationFlattenConditionalBranch message_;
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};
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} // namespace fuzz
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} // namespace spvtools
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#endif // SOURCE_FUZZ_TRANSFORMATION_FLATTEN_CONDITIONAL_BRANCH_H_
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