| // Copyright (c) 2015-2016 The Khronos Group Inc. |
| // |
| // 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/val/validate.h" |
| |
| #include <algorithm> |
| #include <cassert> |
| #include <functional> |
| #include <iostream> |
| #include <iterator> |
| #include <map> |
| #include <string> |
| #include <tuple> |
| #include <unordered_map> |
| #include <unordered_set> |
| #include <utility> |
| #include <vector> |
| |
| #include "source/cfa.h" |
| #include "source/opcode.h" |
| #include "source/spirv_target_env.h" |
| #include "source/spirv_validator_options.h" |
| #include "source/val/basic_block.h" |
| #include "source/val/construct.h" |
| #include "source/val/function.h" |
| #include "source/val/validation_state.h" |
| |
| namespace spvtools { |
| namespace val { |
| namespace { |
| |
| spv_result_t ValidatePhi(ValidationState_t& _, const Instruction* inst) { |
| auto block = inst->block(); |
| size_t num_in_ops = inst->words().size() - 3; |
| if (num_in_ops % 2 != 0) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpPhi does not have an equal number of incoming values and " |
| "basic blocks."; |
| } |
| |
| const Instruction* type_inst = _.FindDef(inst->type_id()); |
| assert(type_inst); |
| |
| const SpvOp type_opcode = type_inst->opcode(); |
| if (type_opcode == SpvOpTypePointer && |
| _.addressing_model() == SpvAddressingModelLogical) { |
| if (!_.features().variable_pointers && |
| !_.features().variable_pointers_storage_buffer) { |
| return _.diag(SPV_ERROR_INVALID_DATA, inst) |
| << "Using pointers with OpPhi requires capability " |
| << "VariablePointers or VariablePointersStorageBuffer"; |
| } |
| } |
| |
| // Create a uniqued vector of predecessor ids for comparison against |
| // incoming values. OpBranchConditional %cond %label %label produces two |
| // predecessors in the CFG. |
| std::vector<uint32_t> pred_ids; |
| std::transform(block->predecessors()->begin(), block->predecessors()->end(), |
| std::back_inserter(pred_ids), |
| [](const BasicBlock* b) { return b->id(); }); |
| std::sort(pred_ids.begin(), pred_ids.end()); |
| pred_ids.erase(std::unique(pred_ids.begin(), pred_ids.end()), pred_ids.end()); |
| |
| size_t num_edges = num_in_ops / 2; |
| if (num_edges != pred_ids.size()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpPhi's number of incoming blocks (" << num_edges |
| << ") does not match block's predecessor count (" |
| << block->predecessors()->size() << ")."; |
| } |
| |
| for (size_t i = 3; i < inst->words().size(); ++i) { |
| auto inc_id = inst->word(i); |
| if (i % 2 == 1) { |
| // Incoming value type must match the phi result type. |
| auto inc_type_id = _.GetTypeId(inc_id); |
| if (inst->type_id() != inc_type_id) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpPhi's result type <id> " << _.getIdName(inst->type_id()) |
| << " does not match incoming value <id> " << _.getIdName(inc_id) |
| << " type <id> " << _.getIdName(inc_type_id) << "."; |
| } |
| } else { |
| if (_.GetIdOpcode(inc_id) != SpvOpLabel) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpPhi's incoming basic block <id> " << _.getIdName(inc_id) |
| << " is not an OpLabel."; |
| } |
| |
| // Incoming basic block must be an immediate predecessor of the phi's |
| // block. |
| if (!std::binary_search(pred_ids.begin(), pred_ids.end(), inc_id)) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpPhi's incoming basic block <id> " << _.getIdName(inc_id) |
| << " is not a predecessor of <id> " << _.getIdName(block->id()) |
| << "."; |
| } |
| } |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t ValidateBranch(ValidationState_t& _, const Instruction* inst) { |
| // target operands must be OpLabel |
| const auto id = inst->GetOperandAs<uint32_t>(0); |
| const auto target = _.FindDef(id); |
| if (!target || SpvOpLabel != target->opcode()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "'Target Label' operands for OpBranch must be the ID " |
| "of an OpLabel instruction"; |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t ValidateBranchConditional(ValidationState_t& _, |
| const Instruction* inst) { |
| // num_operands is either 3 or 5 --- if 5, the last two need to be literal |
| // integers |
| const auto num_operands = inst->operands().size(); |
| if (num_operands != 3 && num_operands != 5) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpBranchConditional requires either 3 or 5 parameters"; |
| } |
| |
| // grab the condition operand and check that it is a bool |
| const auto cond_id = inst->GetOperandAs<uint32_t>(0); |
| const auto cond_op = _.FindDef(cond_id); |
| if (!cond_op || !cond_op->type_id() || |
| !_.IsBoolScalarType(cond_op->type_id())) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) << "Condition operand for " |
| "OpBranchConditional must be " |
| "of boolean type"; |
| } |
| |
| // target operands must be OpLabel |
| // note that we don't need to check that the target labels are in the same |
| // function, |
| // PerformCfgChecks already checks for that |
| const auto true_id = inst->GetOperandAs<uint32_t>(1); |
| const auto true_target = _.FindDef(true_id); |
| if (!true_target || SpvOpLabel != true_target->opcode()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "The 'True Label' operand for OpBranchConditional must be the " |
| "ID of an OpLabel instruction"; |
| } |
| |
| const auto false_id = inst->GetOperandAs<uint32_t>(2); |
| const auto false_target = _.FindDef(false_id); |
| if (!false_target || SpvOpLabel != false_target->opcode()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "The 'False Label' operand for OpBranchConditional must be the " |
| "ID of an OpLabel instruction"; |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t ValidateSwitch(ValidationState_t& _, const Instruction* inst) { |
| const auto num_operands = inst->operands().size(); |
| // At least two operands (selector, default), any more than that are |
| // literal/target. |
| |
| // target operands must be OpLabel |
| for (size_t i = 2; i < num_operands; i += 2) { |
| // literal, id |
| const auto id = inst->GetOperandAs<uint32_t>(i + 1); |
| const auto target = _.FindDef(id); |
| if (!target || SpvOpLabel != target->opcode()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "'Target Label' operands for OpSwitch must be IDs of an " |
| "OpLabel instruction"; |
| } |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t ValidateReturnValue(ValidationState_t& _, |
| const Instruction* inst) { |
| const auto value_id = inst->GetOperandAs<uint32_t>(0); |
| const auto value = _.FindDef(value_id); |
| if (!value || !value->type_id()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpReturnValue Value <id> '" << _.getIdName(value_id) |
| << "' does not represent a value."; |
| } |
| auto value_type = _.FindDef(value->type_id()); |
| if (!value_type || SpvOpTypeVoid == value_type->opcode()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpReturnValue value's type <id> '" |
| << _.getIdName(value->type_id()) << "' is missing or void."; |
| } |
| |
| const bool uses_variable_pointer = |
| _.features().variable_pointers || |
| _.features().variable_pointers_storage_buffer; |
| |
| if (_.addressing_model() == SpvAddressingModelLogical && |
| SpvOpTypePointer == value_type->opcode() && !uses_variable_pointer && |
| !_.options()->relax_logical_pointer) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpReturnValue value's type <id> '" |
| << _.getIdName(value->type_id()) |
| << "' is a pointer, which is invalid in the Logical addressing " |
| "model."; |
| } |
| |
| const auto function = inst->function(); |
| const auto return_type = _.FindDef(function->GetResultTypeId()); |
| if (!return_type || return_type->id() != value_type->id()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "OpReturnValue Value <id> '" << _.getIdName(value_id) |
| << "'s type does not match OpFunction's return type."; |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t ValidateLoopMerge(ValidationState_t& _, const Instruction* inst) { |
| const auto merge_id = inst->GetOperandAs<uint32_t>(0); |
| const auto merge = _.FindDef(merge_id); |
| if (!merge || merge->opcode() != SpvOpLabel) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "Merge Block " << _.getIdName(merge_id) << " must be an OpLabel"; |
| } |
| if (merge_id == inst->block()->id()) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "Merge Block may not be the block containing the OpLoopMerge\n"; |
| } |
| |
| const auto continue_id = inst->GetOperandAs<uint32_t>(1); |
| const auto continue_target = _.FindDef(continue_id); |
| if (!continue_target || continue_target->opcode() != SpvOpLabel) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "Continue Target " << _.getIdName(continue_id) |
| << " must be an OpLabel"; |
| } |
| |
| if (merge_id == continue_id) { |
| return _.diag(SPV_ERROR_INVALID_ID, inst) |
| << "Merge Block and Continue Target must be different ids"; |
| } |
| |
| const auto loop_control = inst->GetOperandAs<uint32_t>(2); |
| if ((loop_control >> SpvLoopControlUnrollShift) & 0x1 && |
| (loop_control >> SpvLoopControlDontUnrollShift) & 0x1) { |
| return _.diag(SPV_ERROR_INVALID_DATA, inst) |
| << "Unroll and DontUnroll loop controls must not both be specified"; |
| } |
| if ((loop_control >> SpvLoopControlDontUnrollShift) & 0x1 && |
| (loop_control >> SpvLoopControlPeelCountShift) & 0x1) { |
| return _.diag(SPV_ERROR_INVALID_DATA, inst) << "PeelCount and DontUnroll " |
| "loop controls must not " |
| "both be specified"; |
| } |
| if ((loop_control >> SpvLoopControlDontUnrollShift) & 0x1 && |
| (loop_control >> SpvLoopControlPartialCountShift) & 0x1) { |
| return _.diag(SPV_ERROR_INVALID_DATA, inst) << "PartialCount and " |
| "DontUnroll loop controls " |
| "must not both be specified"; |
| } |
| |
| uint32_t operand = 3; |
| if ((loop_control >> SpvLoopControlDependencyLengthShift) & 0x1) { |
| ++operand; |
| } |
| if ((loop_control >> SpvLoopControlMinIterationsShift) & 0x1) { |
| ++operand; |
| } |
| if ((loop_control >> SpvLoopControlMaxIterationsShift) & 0x1) { |
| ++operand; |
| } |
| if ((loop_control >> SpvLoopControlIterationMultipleShift) & 0x1) { |
| if (inst->operands().size() < operand || |
| inst->GetOperandAs<uint32_t>(operand) == 0) { |
| return _.diag(SPV_ERROR_INVALID_DATA, inst) << "IterationMultiple loop " |
| "control operand must be " |
| "greater than zero"; |
| } |
| ++operand; |
| } |
| if ((loop_control >> SpvLoopControlPeelCountShift) & 0x1) { |
| ++operand; |
| } |
| if ((loop_control >> SpvLoopControlPartialCountShift) & 0x1) { |
| ++operand; |
| } |
| |
| // That the right number of operands is present is checked by the parser. The |
| // above code tracks operands for expanded validation checking in the future. |
| |
| return SPV_SUCCESS; |
| } |
| |
| } // namespace |
| |
| void printDominatorList(const BasicBlock& b) { |
| std::cout << b.id() << " is dominated by: "; |
| const BasicBlock* bb = &b; |
| while (bb->immediate_dominator() != bb) { |
| bb = bb->immediate_dominator(); |
| std::cout << bb->id() << " "; |
| } |
| } |
| |
| #define CFG_ASSERT(ASSERT_FUNC, TARGET) \ |
| if (spv_result_t rcode = ASSERT_FUNC(_, TARGET)) return rcode |
| |
| spv_result_t FirstBlockAssert(ValidationState_t& _, uint32_t target) { |
| if (_.current_function().IsFirstBlock(target)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(_.current_function().id())) |
| << "First block " << _.getIdName(target) << " of function " |
| << _.getIdName(_.current_function().id()) << " is targeted by block " |
| << _.getIdName(_.current_function().current_block()->id()); |
| } |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t MergeBlockAssert(ValidationState_t& _, uint32_t merge_block) { |
| if (_.current_function().IsBlockType(merge_block, kBlockTypeMerge)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(_.current_function().id())) |
| << "Block " << _.getIdName(merge_block) |
| << " is already a merge block for another header"; |
| } |
| return SPV_SUCCESS; |
| } |
| |
| /// Update the continue construct's exit blocks once the backedge blocks are |
| /// identified in the CFG. |
| void UpdateContinueConstructExitBlocks( |
| Function& function, |
| const std::vector<std::pair<uint32_t, uint32_t>>& back_edges) { |
| auto& constructs = function.constructs(); |
| // TODO(umar): Think of a faster way to do this |
| for (auto& edge : back_edges) { |
| uint32_t back_edge_block_id; |
| uint32_t loop_header_block_id; |
| std::tie(back_edge_block_id, loop_header_block_id) = edge; |
| auto is_this_header = [=](Construct& c) { |
| return c.type() == ConstructType::kLoop && |
| c.entry_block()->id() == loop_header_block_id; |
| }; |
| |
| for (auto construct : constructs) { |
| if (is_this_header(construct)) { |
| Construct* continue_construct = |
| construct.corresponding_constructs().back(); |
| assert(continue_construct->type() == ConstructType::kContinue); |
| |
| BasicBlock* back_edge_block; |
| std::tie(back_edge_block, std::ignore) = |
| function.GetBlock(back_edge_block_id); |
| continue_construct->set_exit(back_edge_block); |
| } |
| } |
| } |
| } |
| |
| std::tuple<std::string, std::string, std::string> ConstructNames( |
| ConstructType type) { |
| std::string construct_name, header_name, exit_name; |
| |
| switch (type) { |
| case ConstructType::kSelection: |
| construct_name = "selection"; |
| header_name = "selection header"; |
| exit_name = "merge block"; |
| break; |
| case ConstructType::kLoop: |
| construct_name = "loop"; |
| header_name = "loop header"; |
| exit_name = "merge block"; |
| break; |
| case ConstructType::kContinue: |
| construct_name = "continue"; |
| header_name = "continue target"; |
| exit_name = "back-edge block"; |
| break; |
| case ConstructType::kCase: |
| construct_name = "case"; |
| header_name = "case entry block"; |
| exit_name = "case exit block"; |
| break; |
| default: |
| assert(1 == 0 && "Not defined type"); |
| } |
| |
| return std::make_tuple(construct_name, header_name, exit_name); |
| } |
| |
| /// Constructs an error message for construct validation errors |
| std::string ConstructErrorString(const Construct& construct, |
| const std::string& header_string, |
| const std::string& exit_string, |
| const std::string& dominate_text) { |
| std::string construct_name, header_name, exit_name; |
| std::tie(construct_name, header_name, exit_name) = |
| ConstructNames(construct.type()); |
| |
| // TODO(umar): Add header block for continue constructs to error message |
| return "The " + construct_name + " construct with the " + header_name + " " + |
| header_string + " " + dominate_text + " the " + exit_name + " " + |
| exit_string; |
| } |
| |
| // Finds the fall through case construct of |target_block| and records it in |
| // |case_fall_through|. Returns SPV_ERROR_INVALID_CFG if the case construct |
| // headed by |target_block| branches to multiple case constructs. |
| spv_result_t FindCaseFallThrough( |
| ValidationState_t& _, BasicBlock* target_block, uint32_t* case_fall_through, |
| const BasicBlock* merge, const std::unordered_set<uint32_t>& case_targets, |
| Function* function) { |
| std::vector<BasicBlock*> stack; |
| stack.push_back(target_block); |
| std::unordered_set<const BasicBlock*> visited; |
| bool target_reachable = target_block->reachable(); |
| int target_depth = function->GetBlockDepth(target_block); |
| while (!stack.empty()) { |
| auto block = stack.back(); |
| stack.pop_back(); |
| |
| if (block == merge) continue; |
| |
| if (!visited.insert(block).second) continue; |
| |
| if (target_reachable && block->reachable() && |
| target_block->dominates(*block)) { |
| // Still in the case construct. |
| for (auto successor : *block->successors()) { |
| stack.push_back(successor); |
| } |
| } else { |
| // Exiting the case construct to non-merge block. |
| if (!case_targets.count(block->id())) { |
| int depth = function->GetBlockDepth(block); |
| if ((depth < target_depth) || |
| (depth == target_depth && block->is_type(kBlockTypeContinue))) { |
| continue; |
| } |
| |
| return _.diag(SPV_ERROR_INVALID_CFG, target_block->label()) |
| << "Case construct that targets " |
| << _.getIdName(target_block->id()) |
| << " has invalid branch to block " << _.getIdName(block->id()) |
| << " (not another case construct, corresponding merge, outer " |
| "loop merge or outer loop continue)"; |
| } |
| |
| if (*case_fall_through == 0u) { |
| if (target_block != block) { |
| *case_fall_through = block->id(); |
| } |
| } else if (*case_fall_through != block->id()) { |
| // Case construct has at most one branch to another case construct. |
| return _.diag(SPV_ERROR_INVALID_CFG, target_block->label()) |
| << "Case construct that targets " |
| << _.getIdName(target_block->id()) |
| << " has branches to multiple other case construct targets " |
| << _.getIdName(*case_fall_through) << " and " |
| << _.getIdName(block->id()); |
| } |
| } |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t StructuredSwitchChecks(ValidationState_t& _, Function* function, |
| const Instruction* switch_inst, |
| const BasicBlock* header, |
| const BasicBlock* merge) { |
| std::unordered_set<uint32_t> case_targets; |
| for (uint32_t i = 1; i < switch_inst->operands().size(); i += 2) { |
| uint32_t target = switch_inst->GetOperandAs<uint32_t>(i); |
| if (target != merge->id()) case_targets.insert(target); |
| } |
| // Tracks how many times each case construct is targeted by another case |
| // construct. |
| std::map<uint32_t, uint32_t> num_fall_through_targeted; |
| uint32_t default_case_fall_through = 0u; |
| uint32_t default_target = switch_inst->GetOperandAs<uint32_t>(1u); |
| bool default_appears_multiple_times = false; |
| for (uint32_t i = 3; i < switch_inst->operands().size(); i += 2) { |
| if (default_target == switch_inst->GetOperandAs<uint32_t>(i)) { |
| default_appears_multiple_times = true; |
| break; |
| } |
| } |
| std::unordered_map<uint32_t, uint32_t> seen_to_fall_through; |
| for (uint32_t i = 1; i < switch_inst->operands().size(); i += 2) { |
| uint32_t target = switch_inst->GetOperandAs<uint32_t>(i); |
| if (target == merge->id()) continue; |
| |
| uint32_t case_fall_through = 0u; |
| auto seen_iter = seen_to_fall_through.find(target); |
| if (seen_iter == seen_to_fall_through.end()) { |
| const auto target_block = function->GetBlock(target).first; |
| // OpSwitch must dominate all its case constructs. |
| if (header->reachable() && target_block->reachable() && |
| !header->dominates(*target_block)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, header->label()) |
| << "Selection header " << _.getIdName(header->id()) |
| << " does not dominate its case construct " |
| << _.getIdName(target); |
| } |
| |
| if (auto error = FindCaseFallThrough(_, target_block, &case_fall_through, |
| merge, case_targets, function)) { |
| return error; |
| } |
| |
| // Track how many time the fall through case has been targeted. |
| if (case_fall_through != 0u) { |
| auto where = num_fall_through_targeted.lower_bound(case_fall_through); |
| if (where == num_fall_through_targeted.end() || |
| where->first != case_fall_through) { |
| num_fall_through_targeted.insert( |
| where, std::make_pair(case_fall_through, 1)); |
| } else { |
| where->second++; |
| } |
| } |
| seen_to_fall_through.insert(std::make_pair(target, case_fall_through)); |
| } else { |
| case_fall_through = seen_iter->second; |
| } |
| |
| if (case_fall_through == default_target && |
| !default_appears_multiple_times) { |
| case_fall_through = default_case_fall_through; |
| } |
| if (case_fall_through != 0u) { |
| bool is_default = i == 1; |
| if (is_default) { |
| default_case_fall_through = case_fall_through; |
| } else { |
| // Allow code like: |
| // case x: |
| // case y: |
| // ... |
| // case z: |
| // |
| // Where x and y target the same block and fall through to z. |
| uint32_t j = i; |
| while ((j + 2 < switch_inst->operands().size()) && |
| target == switch_inst->GetOperandAs<uint32_t>(j + 2)) { |
| j += 2; |
| } |
| // If Target T1 branches to Target T2, or if Target T1 branches to the |
| // Default target and the Default target branches to Target T2, then T1 |
| // must immediately precede T2 in the list of OpSwitch Target operands. |
| if ((switch_inst->operands().size() < j + 2) || |
| (case_fall_through != switch_inst->GetOperandAs<uint32_t>(j + 2))) { |
| return _.diag(SPV_ERROR_INVALID_CFG, switch_inst) |
| << "Case construct that targets " << _.getIdName(target) |
| << " has branches to the case construct that targets " |
| << _.getIdName(case_fall_through) |
| << ", but does not immediately precede it in the " |
| "OpSwitch's target list"; |
| } |
| } |
| } |
| } |
| |
| // Each case construct must be branched to by at most one other case |
| // construct. |
| for (const auto& pair : num_fall_through_targeted) { |
| if (pair.second > 1) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(pair.first)) |
| << "Multiple case constructs have branches to the case construct " |
| "that targets " |
| << _.getIdName(pair.first); |
| } |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t StructuredControlFlowChecks( |
| ValidationState_t& _, Function* function, |
| const std::vector<std::pair<uint32_t, uint32_t>>& back_edges) { |
| /// Check all backedges target only loop headers and have exactly one |
| /// back-edge branching to it |
| |
| // Map a loop header to blocks with back-edges to the loop header. |
| std::map<uint32_t, std::unordered_set<uint32_t>> loop_latch_blocks; |
| for (auto back_edge : back_edges) { |
| uint32_t back_edge_block; |
| uint32_t header_block; |
| std::tie(back_edge_block, header_block) = back_edge; |
| if (!function->IsBlockType(header_block, kBlockTypeLoop)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(back_edge_block)) |
| << "Back-edges (" << _.getIdName(back_edge_block) << " -> " |
| << _.getIdName(header_block) |
| << ") can only be formed between a block and a loop header."; |
| } |
| loop_latch_blocks[header_block].insert(back_edge_block); |
| } |
| |
| // Check the loop headers have exactly one back-edge branching to it |
| for (BasicBlock* loop_header : function->ordered_blocks()) { |
| if (!loop_header->reachable()) continue; |
| if (!loop_header->is_type(kBlockTypeLoop)) continue; |
| auto loop_header_id = loop_header->id(); |
| auto num_latch_blocks = loop_latch_blocks[loop_header_id].size(); |
| if (num_latch_blocks != 1) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(loop_header_id)) |
| << "Loop header " << _.getIdName(loop_header_id) |
| << " is targeted by " << num_latch_blocks |
| << " back-edge blocks but the standard requires exactly one"; |
| } |
| } |
| |
| // Check construct rules |
| for (const Construct& construct : function->constructs()) { |
| auto header = construct.entry_block(); |
| auto merge = construct.exit_block(); |
| |
| if (header->reachable() && !merge) { |
| std::string construct_name, header_name, exit_name; |
| std::tie(construct_name, header_name, exit_name) = |
| ConstructNames(construct.type()); |
| return _.diag(SPV_ERROR_INTERNAL, _.FindDef(header->id())) |
| << "Construct " + construct_name + " with " + header_name + " " + |
| _.getIdName(header->id()) + " does not have a " + |
| exit_name + ". This may be a bug in the validator."; |
| } |
| |
| // If the exit block is reachable then it's dominated by the |
| // header. |
| if (merge && merge->reachable()) { |
| if (!header->dominates(*merge)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(merge->id())) |
| << ConstructErrorString(construct, _.getIdName(header->id()), |
| _.getIdName(merge->id()), |
| "does not dominate"); |
| } |
| // If it's really a merge block for a selection or loop, then it must be |
| // *strictly* dominated by the header. |
| if (construct.ExitBlockIsMergeBlock() && (header == merge)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(merge->id())) |
| << ConstructErrorString(construct, _.getIdName(header->id()), |
| _.getIdName(merge->id()), |
| "does not strictly dominate"); |
| } |
| } |
| // Check post-dominance for continue constructs. But dominance and |
| // post-dominance only make sense when the construct is reachable. |
| if (header->reachable() && construct.type() == ConstructType::kContinue) { |
| if (!merge->postdominates(*header)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(merge->id())) |
| << ConstructErrorString(construct, _.getIdName(header->id()), |
| _.getIdName(merge->id()), |
| "is not post dominated by"); |
| } |
| } |
| |
| Construct::ConstructBlockSet construct_blocks = construct.blocks(function); |
| for (auto block : construct_blocks) { |
| std::string construct_name, header_name, exit_name; |
| std::tie(construct_name, header_name, exit_name) = |
| ConstructNames(construct.type()); |
| // Check that all exits from the construct are via structured exits. |
| for (auto succ : *block->successors()) { |
| if (block->reachable() && !construct_blocks.count(succ) && |
| !construct.IsStructuredExit(_, succ)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "block <ID> " << _.getIdName(block->id()) << " exits the " |
| << construct_name << " headed by <ID> " |
| << _.getIdName(header->id()) |
| << ", but not via a structured exit"; |
| } |
| } |
| if (block == header) continue; |
| // Check that for all non-header blocks, all predecessors are within this |
| // construct. |
| for (auto pred : *block->predecessors()) { |
| if (pred->reachable() && !construct_blocks.count(pred)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(pred->id())) |
| << "block <ID> " << pred->id() << " branches to the " |
| << construct_name << " construct, but not to the " |
| << header_name << " <ID> " << header->id(); |
| } |
| } |
| } |
| |
| // Checks rules for case constructs. |
| if (construct.type() == ConstructType::kSelection && |
| header->terminator()->opcode() == SpvOpSwitch) { |
| const auto terminator = header->terminator(); |
| if (auto error = |
| StructuredSwitchChecks(_, function, terminator, header, merge)) { |
| return error; |
| } |
| } |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t PerformWebGPUCfgChecks(ValidationState_t& _, Function* function) { |
| for (auto& block : function->ordered_blocks()) { |
| if (block->reachable()) continue; |
| if (block->is_type(kBlockTypeMerge)) { |
| // 1. Find the referencing merge and confirm that it is reachable. |
| BasicBlock* merge_header = function->GetMergeHeader(block); |
| assert(merge_header != nullptr); |
| if (!merge_header->reachable()) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable merge-blocks must be referenced by " |
| "a reachable merge instruction."; |
| } |
| |
| // 2. Check that the only instructions are OpLabel and OpUnreachable. |
| auto* label_inst = block->label(); |
| auto* terminator_inst = block->terminator(); |
| assert(label_inst != nullptr); |
| assert(terminator_inst != nullptr); |
| |
| if (terminator_inst->opcode() != SpvOpUnreachable) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable merge-blocks must terminate with " |
| "OpUnreachable."; |
| } |
| |
| auto label_idx = label_inst - &_.ordered_instructions()[0]; |
| auto terminator_idx = terminator_inst - &_.ordered_instructions()[0]; |
| if (label_idx + 1 != terminator_idx) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable merge-blocks must only contain an " |
| "OpLabel and OpUnreachable instruction."; |
| } |
| |
| // 3. Use label instruction to confirm there is no uses by branches. |
| for (auto use : label_inst->uses()) { |
| const auto* use_inst = use.first; |
| if (spvOpcodeIsBranch(use_inst->opcode())) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable merge-blocks cannot be the target " |
| "of a branch."; |
| } |
| } |
| } else if (block->is_type(kBlockTypeContinue)) { |
| // 1. Find referencing loop and confirm that it is reachable. |
| std::vector<BasicBlock*> continue_headers = |
| function->GetContinueHeaders(block); |
| if (continue_headers.empty()) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable continue-target must be referenced " |
| "by a loop instruction."; |
| } |
| |
| std::vector<BasicBlock*> reachable_headers(continue_headers.size()); |
| auto iter = |
| std::copy_if(continue_headers.begin(), continue_headers.end(), |
| reachable_headers.begin(), |
| [](BasicBlock* header) { return header->reachable(); }); |
| reachable_headers.resize(std::distance(reachable_headers.begin(), iter)); |
| |
| if (reachable_headers.empty()) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable continue-target must be referenced " |
| "by a reachable loop instruction."; |
| } |
| |
| // 2. Check that the only instructions are OpLabel and OpBranch. |
| auto* label_inst = block->label(); |
| auto* terminator_inst = block->terminator(); |
| assert(label_inst != nullptr); |
| assert(terminator_inst != nullptr); |
| |
| if (terminator_inst->opcode() != SpvOpBranch) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable continue-target must terminate with " |
| "OpBranch."; |
| } |
| |
| auto label_idx = label_inst - &_.ordered_instructions()[0]; |
| auto terminator_idx = terminator_inst - &_.ordered_instructions()[0]; |
| if (label_idx + 1 != terminator_idx) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable continue-target must only contain " |
| "an OpLabel and an OpBranch instruction."; |
| } |
| |
| // 3. Use label instruction to confirm there is no uses by branches. |
| for (auto use : label_inst->uses()) { |
| const auto* use_inst = use.first; |
| if (spvOpcodeIsBranch(use_inst->opcode())) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable continue-target cannot be the " |
| "target of a branch."; |
| } |
| } |
| |
| // 4. Confirm that continue-target has a back edge to a reachable loop |
| // header block. |
| auto branch_target = terminator_inst->GetOperandAs<uint32_t>(0); |
| for (auto* continue_header : reachable_headers) { |
| if (branch_target != continue_header->id()) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, unreachable continue-target must only have a " |
| "back edge to a single reachable loop instruction."; |
| } |
| } |
| } else { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(block->id())) |
| << "For WebGPU, all blocks must be reachable, unless they are " |
| << "degenerate cases of merge-block or continue-target."; |
| } |
| } |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t PerformCfgChecks(ValidationState_t& _) { |
| for (auto& function : _.functions()) { |
| // Check all referenced blocks are defined within a function |
| if (function.undefined_block_count() != 0) { |
| std::string undef_blocks("{"); |
| bool first = true; |
| for (auto undefined_block : function.undefined_blocks()) { |
| undef_blocks += _.getIdName(undefined_block); |
| if (!first) { |
| undef_blocks += " "; |
| } |
| first = false; |
| } |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(function.id())) |
| << "Block(s) " << undef_blocks << "}" |
| << " are referenced but not defined in function " |
| << _.getIdName(function.id()); |
| } |
| |
| // Set each block's immediate dominator and immediate postdominator, |
| // and find all back-edges. |
| // |
| // We want to analyze all the blocks in the function, even in degenerate |
| // control flow cases including unreachable blocks. So use the augmented |
| // CFG to ensure we cover all the blocks. |
| std::vector<const BasicBlock*> postorder; |
| std::vector<const BasicBlock*> postdom_postorder; |
| std::vector<std::pair<uint32_t, uint32_t>> back_edges; |
| auto ignore_block = [](const BasicBlock*) {}; |
| auto ignore_edge = [](const BasicBlock*, const BasicBlock*) {}; |
| if (!function.ordered_blocks().empty()) { |
| /// calculate dominators |
| CFA<BasicBlock>::DepthFirstTraversal( |
| function.first_block(), function.AugmentedCFGSuccessorsFunction(), |
| ignore_block, [&](const BasicBlock* b) { postorder.push_back(b); }, |
| ignore_edge); |
| auto edges = CFA<BasicBlock>::CalculateDominators( |
| postorder, function.AugmentedCFGPredecessorsFunction()); |
| for (auto edge : edges) { |
| if (edge.first != edge.second) |
| edge.first->SetImmediateDominator(edge.second); |
| } |
| |
| /// calculate post dominators |
| CFA<BasicBlock>::DepthFirstTraversal( |
| function.pseudo_exit_block(), |
| function.AugmentedCFGPredecessorsFunction(), ignore_block, |
| [&](const BasicBlock* b) { postdom_postorder.push_back(b); }, |
| ignore_edge); |
| auto postdom_edges = CFA<BasicBlock>::CalculateDominators( |
| postdom_postorder, function.AugmentedCFGSuccessorsFunction()); |
| for (auto edge : postdom_edges) { |
| edge.first->SetImmediatePostDominator(edge.second); |
| } |
| /// calculate back edges. |
| CFA<BasicBlock>::DepthFirstTraversal( |
| function.pseudo_entry_block(), |
| function |
| .AugmentedCFGSuccessorsFunctionIncludingHeaderToContinueEdge(), |
| ignore_block, ignore_block, |
| [&](const BasicBlock* from, const BasicBlock* to) { |
| back_edges.emplace_back(from->id(), to->id()); |
| }); |
| } |
| UpdateContinueConstructExitBlocks(function, back_edges); |
| |
| auto& blocks = function.ordered_blocks(); |
| if (!blocks.empty()) { |
| // Check if the order of blocks in the binary appear before the blocks |
| // they dominate |
| for (auto block = begin(blocks) + 1; block != end(blocks); ++block) { |
| if (auto idom = (*block)->immediate_dominator()) { |
| if (idom != function.pseudo_entry_block() && |
| block == std::find(begin(blocks), block, idom)) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef(idom->id())) |
| << "Block " << _.getIdName((*block)->id()) |
| << " appears in the binary before its dominator " |
| << _.getIdName(idom->id()); |
| } |
| } |
| |
| // For WebGPU check that all unreachable blocks are degenerate cases for |
| // merge-block or continue-target. |
| if (spvIsWebGPUEnv(_.context()->target_env)) { |
| spv_result_t result = PerformWebGPUCfgChecks(_, &function); |
| if (result != SPV_SUCCESS) return result; |
| } |
| } |
| // If we have structed control flow, check that no block has a control |
| // flow nesting depth larger than the limit. |
| if (_.HasCapability(SpvCapabilityShader)) { |
| const int control_flow_nesting_depth_limit = |
| _.options()->universal_limits_.max_control_flow_nesting_depth; |
| for (auto block = begin(blocks); block != end(blocks); ++block) { |
| if (function.GetBlockDepth(*block) > |
| control_flow_nesting_depth_limit) { |
| return _.diag(SPV_ERROR_INVALID_CFG, _.FindDef((*block)->id())) |
| << "Maximum Control Flow nesting depth exceeded."; |
| } |
| } |
| } |
| } |
| |
| /// Structured control flow checks are only required for shader capabilities |
| if (_.HasCapability(SpvCapabilityShader)) { |
| if (auto error = StructuredControlFlowChecks(_, &function, back_edges)) |
| return error; |
| } |
| } |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t CfgPass(ValidationState_t& _, const Instruction* inst) { |
| SpvOp opcode = inst->opcode(); |
| switch (opcode) { |
| case SpvOpLabel: |
| if (auto error = _.current_function().RegisterBlock(inst->id())) |
| return error; |
| |
| // TODO(github:1661) This should be done in the |
| // ValidationState::RegisterInstruction method but because of the order of |
| // passes the OpLabel ends up not being part of the basic block it starts. |
| _.current_function().current_block()->set_label(inst); |
| break; |
| case SpvOpLoopMerge: { |
| uint32_t merge_block = inst->GetOperandAs<uint32_t>(0); |
| uint32_t continue_block = inst->GetOperandAs<uint32_t>(1); |
| CFG_ASSERT(MergeBlockAssert, merge_block); |
| |
| if (auto error = _.current_function().RegisterLoopMerge(merge_block, |
| continue_block)) |
| return error; |
| } break; |
| case SpvOpSelectionMerge: { |
| uint32_t merge_block = inst->GetOperandAs<uint32_t>(0); |
| CFG_ASSERT(MergeBlockAssert, merge_block); |
| |
| if (auto error = _.current_function().RegisterSelectionMerge(merge_block)) |
| return error; |
| } break; |
| case SpvOpBranch: { |
| uint32_t target = inst->GetOperandAs<uint32_t>(0); |
| CFG_ASSERT(FirstBlockAssert, target); |
| |
| _.current_function().RegisterBlockEnd({target}, opcode); |
| } break; |
| case SpvOpBranchConditional: { |
| uint32_t tlabel = inst->GetOperandAs<uint32_t>(1); |
| uint32_t flabel = inst->GetOperandAs<uint32_t>(2); |
| CFG_ASSERT(FirstBlockAssert, tlabel); |
| CFG_ASSERT(FirstBlockAssert, flabel); |
| |
| _.current_function().RegisterBlockEnd({tlabel, flabel}, opcode); |
| } break; |
| |
| case SpvOpSwitch: { |
| std::vector<uint32_t> cases; |
| for (size_t i = 1; i < inst->operands().size(); i += 2) { |
| uint32_t target = inst->GetOperandAs<uint32_t>(i); |
| CFG_ASSERT(FirstBlockAssert, target); |
| cases.push_back(target); |
| } |
| _.current_function().RegisterBlockEnd({cases}, opcode); |
| } break; |
| case SpvOpReturn: { |
| const uint32_t return_type = _.current_function().GetResultTypeId(); |
| const Instruction* return_type_inst = _.FindDef(return_type); |
| assert(return_type_inst); |
| if (return_type_inst->opcode() != SpvOpTypeVoid) |
| return _.diag(SPV_ERROR_INVALID_CFG, inst) |
| << "OpReturn can only be called from a function with void " |
| << "return type."; |
| } |
| // Fallthrough. |
| case SpvOpKill: |
| case SpvOpReturnValue: |
| case SpvOpUnreachable: |
| _.current_function().RegisterBlockEnd(std::vector<uint32_t>(), opcode); |
| if (opcode == SpvOpKill) { |
| _.current_function().RegisterExecutionModelLimitation( |
| SpvExecutionModelFragment, |
| "OpKill requires Fragment execution model"); |
| } |
| break; |
| default: |
| break; |
| } |
| return SPV_SUCCESS; |
| } |
| |
| spv_result_t ControlFlowPass(ValidationState_t& _, const Instruction* inst) { |
| switch (inst->opcode()) { |
| case SpvOpPhi: |
| if (auto error = ValidatePhi(_, inst)) return error; |
| break; |
| case SpvOpBranch: |
| if (auto error = ValidateBranch(_, inst)) return error; |
| break; |
| case SpvOpBranchConditional: |
| if (auto error = ValidateBranchConditional(_, inst)) return error; |
| break; |
| case SpvOpReturnValue: |
| if (auto error = ValidateReturnValue(_, inst)) return error; |
| break; |
| case SpvOpSwitch: |
| if (auto error = ValidateSwitch(_, inst)) return error; |
| break; |
| case SpvOpLoopMerge: |
| if (auto error = ValidateLoopMerge(_, inst)) return error; |
| break; |
| default: |
| break; |
| } |
| |
| return SPV_SUCCESS; |
| } |
| |
| } // namespace val |
| } // namespace spvtools |
