mirror of
https://github.com/bkaradzic/bgfx.git
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212 lines
8.3 KiB
C++
212 lines
8.3 KiB
C++
// Copyright (c) 2019 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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#include "source/fuzz/fuzzer_util.h"
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namespace spvtools {
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namespace fuzz {
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namespace fuzzerutil {
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bool IsFreshId(opt::IRContext* context, uint32_t id) {
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return !context->get_def_use_mgr()->GetDef(id);
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}
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void UpdateModuleIdBound(opt::IRContext* context, uint32_t id) {
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// TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/2541) consider the
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// case where the maximum id bound is reached.
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context->module()->SetIdBound(
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std::max(context->module()->id_bound(), id + 1));
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}
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opt::BasicBlock* MaybeFindBlock(opt::IRContext* context,
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uint32_t maybe_block_id) {
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auto inst = context->get_def_use_mgr()->GetDef(maybe_block_id);
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if (inst == nullptr) {
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// No instruction defining this id was found.
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return nullptr;
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}
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if (inst->opcode() != SpvOpLabel) {
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// The instruction defining the id is not a label, so it cannot be a block
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// id.
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return nullptr;
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}
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return context->cfg()->block(maybe_block_id);
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}
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bool PhiIdsOkForNewEdge(
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opt::IRContext* context, opt::BasicBlock* bb_from, opt::BasicBlock* bb_to,
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const google::protobuf::RepeatedField<google::protobuf::uint32>& phi_ids) {
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if (bb_from->IsSuccessor(bb_to)) {
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// There is already an edge from |from_block| to |to_block|, so there is
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// no need to extend OpPhi instructions. Do not allow phi ids to be
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// present. This might turn out to be too strict; perhaps it would be OK
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// just to ignore the ids in this case.
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return phi_ids.empty();
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}
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// The edge would add a previously non-existent edge from |from_block| to
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// |to_block|, so we go through the given phi ids and check that they exactly
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// match the OpPhi instructions in |to_block|.
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uint32_t phi_index = 0;
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// An explicit loop, rather than applying a lambda to each OpPhi in |bb_to|,
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// makes sense here because we need to increment |phi_index| for each OpPhi
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// instruction.
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for (auto& inst : *bb_to) {
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if (inst.opcode() != SpvOpPhi) {
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// The OpPhi instructions all occur at the start of the block; if we find
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// a non-OpPhi then we have seen them all.
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break;
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}
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if (phi_index == static_cast<uint32_t>(phi_ids.size())) {
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// Not enough phi ids have been provided to account for the OpPhi
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// instructions.
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return false;
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}
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// Look for an instruction defining the next phi id.
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opt::Instruction* phi_extension =
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context->get_def_use_mgr()->GetDef(phi_ids[phi_index]);
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if (!phi_extension) {
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// The id given to extend this OpPhi does not exist.
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return false;
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}
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if (phi_extension->type_id() != inst.type_id()) {
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// The instruction given to extend this OpPhi either does not have a type
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// or its type does not match that of the OpPhi.
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return false;
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}
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if (context->get_instr_block(phi_extension)) {
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// The instruction defining the phi id has an associated block (i.e., it
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// is not a global value). Check whether its definition dominates the
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// exit of |from_block|.
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auto dominator_analysis =
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context->GetDominatorAnalysis(bb_from->GetParent());
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if (!dominator_analysis->Dominates(phi_extension,
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bb_from->terminator())) {
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// The given id is no good as its definition does not dominate the exit
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// of |from_block|
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return false;
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}
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}
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phi_index++;
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}
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// Return false if not all of the ids for extending OpPhi instructions are
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// needed. This might turn out to be stricter than necessary; perhaps it would
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// be OK just to not use the ids in this case.
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return phi_index == static_cast<uint32_t>(phi_ids.size());
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}
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void AddUnreachableEdgeAndUpdateOpPhis(
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opt::IRContext* context, opt::BasicBlock* bb_from, opt::BasicBlock* bb_to,
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bool condition_value,
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const google::protobuf::RepeatedField<google::protobuf::uint32>& phi_ids) {
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assert(PhiIdsOkForNewEdge(context, bb_from, bb_to, phi_ids) &&
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"Precondition on phi_ids is not satisfied");
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assert(bb_from->terminator()->opcode() == SpvOpBranch &&
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"Precondition on terminator of bb_from is not satisfied");
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// Get the id of the boolean constant to be used as the condition.
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opt::analysis::Bool bool_type;
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opt::analysis::BoolConstant bool_constant(
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context->get_type_mgr()->GetRegisteredType(&bool_type)->AsBool(),
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condition_value);
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uint32_t bool_id = context->get_constant_mgr()->FindDeclaredConstant(
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&bool_constant, context->get_type_mgr()->GetId(&bool_type));
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const bool from_to_edge_already_exists = bb_from->IsSuccessor(bb_to);
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auto successor = bb_from->terminator()->GetSingleWordInOperand(0);
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// Add the dead branch, by turning OpBranch into OpBranchConditional, and
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// ordering the targets depending on whether the given boolean corresponds to
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// true or false.
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bb_from->terminator()->SetOpcode(SpvOpBranchConditional);
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bb_from->terminator()->SetInOperands(
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{{SPV_OPERAND_TYPE_ID, {bool_id}},
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{SPV_OPERAND_TYPE_ID, {condition_value ? successor : bb_to->id()}},
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{SPV_OPERAND_TYPE_ID, {condition_value ? bb_to->id() : successor}}});
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// Update OpPhi instructions in the target block if this branch adds a
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// previously non-existent edge from source to target.
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if (!from_to_edge_already_exists) {
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uint32_t phi_index = 0;
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for (auto& inst : *bb_to) {
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if (inst.opcode() != SpvOpPhi) {
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break;
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}
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assert(phi_index < static_cast<uint32_t>(phi_ids.size()) &&
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"There should be exactly one phi id per OpPhi instruction.");
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inst.AddOperand({SPV_OPERAND_TYPE_ID, {phi_ids[phi_index]}});
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inst.AddOperand({SPV_OPERAND_TYPE_ID, {bb_from->id()}});
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phi_index++;
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}
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assert(phi_index == static_cast<uint32_t>(phi_ids.size()) &&
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"There should be exactly one phi id per OpPhi instruction.");
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}
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}
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bool BlockIsInLoopContinueConstruct(opt::IRContext* context, uint32_t block_id,
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uint32_t maybe_loop_header_id) {
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// We deem a block to be part of a loop's continue construct if the loop's
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// continue target dominates the block.
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auto containing_construct_block = context->cfg()->block(maybe_loop_header_id);
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if (containing_construct_block->IsLoopHeader()) {
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auto continue_target = containing_construct_block->ContinueBlockId();
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if (context->GetDominatorAnalysis(containing_construct_block->GetParent())
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->Dominates(continue_target, block_id)) {
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return true;
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}
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}
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return false;
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}
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opt::BasicBlock::iterator GetIteratorForBaseInstructionAndOffset(
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opt::BasicBlock* block, const opt::Instruction* base_inst,
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uint32_t offset) {
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// The cases where |base_inst| is the block's label, vs. inside the block,
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// are dealt with separately.
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if (base_inst == block->GetLabelInst()) {
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// |base_inst| is the block's label.
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if (offset == 0) {
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// We cannot return an iterator to the block's label.
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return block->end();
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}
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// Conceptually, the first instruction in the block is [label + 1].
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// We thus start from 1 when applying the offset.
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auto inst_it = block->begin();
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for (uint32_t i = 1; i < offset && inst_it != block->end(); i++) {
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++inst_it;
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}
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// This is either the desired instruction, or the end of the block.
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return inst_it;
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}
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// |base_inst| is inside the block.
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for (auto inst_it = block->begin(); inst_it != block->end(); ++inst_it) {
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if (base_inst == &*inst_it) {
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// We have found the base instruction; we now apply the offset.
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for (uint32_t i = 0; i < offset && inst_it != block->end(); i++) {
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++inst_it;
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}
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// This is either the desired instruction, or the end of the block.
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return inst_it;
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}
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}
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assert(false && "The base instruction was not found.");
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return nullptr;
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}
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} // namespace fuzzerutil
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} // namespace fuzz
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} // namespace spvtools
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