| // Copyright (c) 2017 The Khronos Group Inc. |
| // Copyright (c) 2017 Valve Corporation |
| // Copyright (c) 2017 LunarG Inc. |
| // Copyright (c) 2018 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/opt/aggressive_dead_code_elim_pass.h" |
| |
| #include <memory> |
| #include <stack> |
| |
| #include "source/cfa.h" |
| #include "source/latest_version_glsl_std_450_header.h" |
| #include "source/opt/iterator.h" |
| #include "source/opt/reflect.h" |
| #include "source/spirv_constant.h" |
| |
| namespace spvtools { |
| namespace opt { |
| |
| namespace { |
| |
| const uint32_t kTypePointerStorageClassInIdx = 0; |
| const uint32_t kEntryPointFunctionIdInIdx = 1; |
| const uint32_t kSelectionMergeMergeBlockIdInIdx = 0; |
| const uint32_t kLoopMergeMergeBlockIdInIdx = 0; |
| const uint32_t kLoopMergeContinueBlockIdInIdx = 1; |
| const uint32_t kCopyMemoryTargetAddrInIdx = 0; |
| const uint32_t kCopyMemorySourceAddrInIdx = 1; |
| |
| // Sorting functor to present annotation instructions in an easy-to-process |
| // order. The functor orders by opcode first and falls back on unique id |
| // ordering if both instructions have the same opcode. |
| // |
| // Desired priority: |
| // SpvOpGroupDecorate |
| // SpvOpGroupMemberDecorate |
| // SpvOpDecorate |
| // SpvOpMemberDecorate |
| // SpvOpDecorateId |
| // SpvOpDecorateStringGOOGLE |
| // SpvOpDecorationGroup |
| struct DecorationLess { |
| bool operator()(const Instruction* lhs, const Instruction* rhs) const { |
| assert(lhs && rhs); |
| SpvOp lhsOp = lhs->opcode(); |
| SpvOp rhsOp = rhs->opcode(); |
| if (lhsOp != rhsOp) { |
| #define PRIORITY_CASE(opcode) \ |
| if (lhsOp == opcode && rhsOp != opcode) return true; \ |
| if (rhsOp == opcode && lhsOp != opcode) return false; |
| // OpGroupDecorate and OpGroupMember decorate are highest priority to |
| // eliminate dead targets early and simplify subsequent checks. |
| PRIORITY_CASE(SpvOpGroupDecorate) |
| PRIORITY_CASE(SpvOpGroupMemberDecorate) |
| PRIORITY_CASE(SpvOpDecorate) |
| PRIORITY_CASE(SpvOpMemberDecorate) |
| PRIORITY_CASE(SpvOpDecorateId) |
| PRIORITY_CASE(SpvOpDecorateStringGOOGLE) |
| // OpDecorationGroup is lowest priority to ensure use/def chains remain |
| // usable for instructions that target this group. |
| PRIORITY_CASE(SpvOpDecorationGroup) |
| #undef PRIORITY_CASE |
| } |
| |
| // Fall back to maintain total ordering (compare unique ids). |
| return *lhs < *rhs; |
| } |
| }; |
| |
| } // namespace |
| |
| bool AggressiveDCEPass::IsVarOfStorage(uint32_t varId, uint32_t storageClass) { |
| if (varId == 0) return false; |
| const Instruction* varInst = get_def_use_mgr()->GetDef(varId); |
| const SpvOp op = varInst->opcode(); |
| if (op != SpvOpVariable) return false; |
| const uint32_t varTypeId = varInst->type_id(); |
| const Instruction* varTypeInst = get_def_use_mgr()->GetDef(varTypeId); |
| if (varTypeInst->opcode() != SpvOpTypePointer) return false; |
| return varTypeInst->GetSingleWordInOperand(kTypePointerStorageClassInIdx) == |
| storageClass; |
| } |
| |
| bool AggressiveDCEPass::IsLocalVar(uint32_t varId) { |
| if (IsVarOfStorage(varId, SpvStorageClassFunction)) { |
| return true; |
| } |
| if (!private_like_local_) { |
| return false; |
| } |
| |
| return IsVarOfStorage(varId, SpvStorageClassPrivate) || |
| IsVarOfStorage(varId, SpvStorageClassWorkgroup); |
| } |
| |
| void AggressiveDCEPass::AddStores(uint32_t ptrId) { |
| get_def_use_mgr()->ForEachUser(ptrId, [this, ptrId](Instruction* user) { |
| switch (user->opcode()) { |
| case SpvOpAccessChain: |
| case SpvOpInBoundsAccessChain: |
| case SpvOpCopyObject: |
| this->AddStores(user->result_id()); |
| break; |
| case SpvOpLoad: |
| break; |
| case SpvOpCopyMemory: |
| case SpvOpCopyMemorySized: |
| if (user->GetSingleWordInOperand(kCopyMemoryTargetAddrInIdx) == ptrId) { |
| AddToWorklist(user); |
| } |
| break; |
| // If default, assume it stores e.g. frexp, modf, function call |
| case SpvOpStore: |
| default: |
| AddToWorklist(user); |
| break; |
| } |
| }); |
| } |
| |
| bool AggressiveDCEPass::AllExtensionsSupported() const { |
| // If any extension not in whitelist, return false |
| for (auto& ei : get_module()->extensions()) { |
| const char* extName = |
| reinterpret_cast<const char*>(&ei.GetInOperand(0).words[0]); |
| if (extensions_whitelist_.find(extName) == extensions_whitelist_.end()) |
| return false; |
| } |
| return true; |
| } |
| |
| bool AggressiveDCEPass::IsDead(Instruction* inst) { |
| if (IsLive(inst)) return false; |
| if ((inst->IsBranch() || inst->opcode() == SpvOpUnreachable) && |
| !IsStructuredHeader(context()->get_instr_block(inst), nullptr, nullptr, |
| nullptr)) |
| return false; |
| return true; |
| } |
| |
| bool AggressiveDCEPass::IsTargetDead(Instruction* inst) { |
| const uint32_t tId = inst->GetSingleWordInOperand(0); |
| Instruction* tInst = get_def_use_mgr()->GetDef(tId); |
| if (IsAnnotationInst(tInst->opcode())) { |
| // This must be a decoration group. We go through annotations in a specific |
| // order. So if this is not used by any group or group member decorates, it |
| // is dead. |
| assert(tInst->opcode() == SpvOpDecorationGroup); |
| bool dead = true; |
| get_def_use_mgr()->ForEachUser(tInst, [&dead](Instruction* user) { |
| if (user->opcode() == SpvOpGroupDecorate || |
| user->opcode() == SpvOpGroupMemberDecorate) |
| dead = false; |
| }); |
| return dead; |
| } |
| return IsDead(tInst); |
| } |
| |
| void AggressiveDCEPass::ProcessLoad(uint32_t varId) { |
| // Only process locals |
| if (!IsLocalVar(varId)) return; |
| // Return if already processed |
| if (live_local_vars_.find(varId) != live_local_vars_.end()) return; |
| // Mark all stores to varId as live |
| AddStores(varId); |
| // Cache varId as processed |
| live_local_vars_.insert(varId); |
| } |
| |
| bool AggressiveDCEPass::IsStructuredHeader(BasicBlock* bp, |
| Instruction** mergeInst, |
| Instruction** branchInst, |
| uint32_t* mergeBlockId) { |
| if (!bp) return false; |
| Instruction* mi = bp->GetMergeInst(); |
| if (mi == nullptr) return false; |
| Instruction* bri = &*bp->tail(); |
| if (branchInst != nullptr) *branchInst = bri; |
| if (mergeInst != nullptr) *mergeInst = mi; |
| if (mergeBlockId != nullptr) *mergeBlockId = mi->GetSingleWordInOperand(0); |
| return true; |
| } |
| |
| void AggressiveDCEPass::ComputeBlock2HeaderMaps( |
| std::list<BasicBlock*>& structuredOrder) { |
| block2headerBranch_.clear(); |
| header2nextHeaderBranch_.clear(); |
| branch2merge_.clear(); |
| structured_order_index_.clear(); |
| std::stack<Instruction*> currentHeaderBranch; |
| currentHeaderBranch.push(nullptr); |
| uint32_t currentMergeBlockId = 0; |
| uint32_t index = 0; |
| for (auto bi = structuredOrder.begin(); bi != structuredOrder.end(); |
| ++bi, ++index) { |
| structured_order_index_[*bi] = index; |
| // If this block is the merge block of the current control construct, |
| // we are leaving the current construct so we must update state |
| if ((*bi)->id() == currentMergeBlockId) { |
| currentHeaderBranch.pop(); |
| Instruction* chb = currentHeaderBranch.top(); |
| if (chb != nullptr) |
| currentMergeBlockId = branch2merge_[chb]->GetSingleWordInOperand(0); |
| } |
| Instruction* mergeInst; |
| Instruction* branchInst; |
| uint32_t mergeBlockId; |
| bool is_header = |
| IsStructuredHeader(*bi, &mergeInst, &branchInst, &mergeBlockId); |
| // Map header block to next enclosing header. |
| if (is_header) header2nextHeaderBranch_[*bi] = currentHeaderBranch.top(); |
| // If this is a loop header, update state first so the block will map to |
| // itself. |
| if (is_header && mergeInst->opcode() == SpvOpLoopMerge) { |
| currentHeaderBranch.push(branchInst); |
| branch2merge_[branchInst] = mergeInst; |
| currentMergeBlockId = mergeBlockId; |
| } |
| // Map the block to the current construct. |
| block2headerBranch_[*bi] = currentHeaderBranch.top(); |
| // If this is an if header, update state so following blocks map to the if. |
| if (is_header && mergeInst->opcode() == SpvOpSelectionMerge) { |
| currentHeaderBranch.push(branchInst); |
| branch2merge_[branchInst] = mergeInst; |
| currentMergeBlockId = mergeBlockId; |
| } |
| } |
| } |
| |
| void AggressiveDCEPass::AddBranch(uint32_t labelId, BasicBlock* bp) { |
| std::unique_ptr<Instruction> newBranch( |
| new Instruction(context(), SpvOpBranch, 0, 0, |
| {{spv_operand_type_t::SPV_OPERAND_TYPE_ID, {labelId}}})); |
| context()->AnalyzeDefUse(&*newBranch); |
| context()->set_instr_block(&*newBranch, bp); |
| bp->AddInstruction(std::move(newBranch)); |
| } |
| |
| void AggressiveDCEPass::AddBreaksAndContinuesToWorklist( |
| Instruction* mergeInst) { |
| assert(mergeInst->opcode() == SpvOpSelectionMerge || |
| mergeInst->opcode() == SpvOpLoopMerge); |
| |
| BasicBlock* header = context()->get_instr_block(mergeInst); |
| uint32_t headerIndex = structured_order_index_[header]; |
| const uint32_t mergeId = mergeInst->GetSingleWordInOperand(0); |
| BasicBlock* merge = context()->get_instr_block(mergeId); |
| uint32_t mergeIndex = structured_order_index_[merge]; |
| get_def_use_mgr()->ForEachUser( |
| mergeId, [headerIndex, mergeIndex, this](Instruction* user) { |
| if (!user->IsBranch()) return; |
| BasicBlock* block = context()->get_instr_block(user); |
| uint32_t index = structured_order_index_[block]; |
| if (headerIndex < index && index < mergeIndex) { |
| // This is a break from the loop. |
| AddToWorklist(user); |
| // Add branch's merge if there is one. |
| Instruction* userMerge = branch2merge_[user]; |
| if (userMerge != nullptr) AddToWorklist(userMerge); |
| } |
| }); |
| |
| if (mergeInst->opcode() != SpvOpLoopMerge) { |
| return; |
| } |
| |
| // For loops we need to find the continues as well. |
| const uint32_t contId = |
| mergeInst->GetSingleWordInOperand(kLoopMergeContinueBlockIdInIdx); |
| get_def_use_mgr()->ForEachUser(contId, [&contId, this](Instruction* user) { |
| SpvOp op = user->opcode(); |
| if (op == SpvOpBranchConditional || op == SpvOpSwitch) { |
| // A conditional branch or switch can only be a continue if it does not |
| // have a merge instruction or its merge block is not the continue block. |
| Instruction* hdrMerge = branch2merge_[user]; |
| if (hdrMerge != nullptr && hdrMerge->opcode() == SpvOpSelectionMerge) { |
| uint32_t hdrMergeId = |
| hdrMerge->GetSingleWordInOperand(kSelectionMergeMergeBlockIdInIdx); |
| if (hdrMergeId == contId) return; |
| // Need to mark merge instruction too |
| AddToWorklist(hdrMerge); |
| } |
| } else if (op == SpvOpBranch) { |
| // An unconditional branch can only be a continue if it is not |
| // branching to its own merge block. |
| BasicBlock* blk = context()->get_instr_block(user); |
| Instruction* hdrBranch = block2headerBranch_[blk]; |
| if (hdrBranch == nullptr) return; |
| Instruction* hdrMerge = branch2merge_[hdrBranch]; |
| if (hdrMerge->opcode() == SpvOpLoopMerge) return; |
| uint32_t hdrMergeId = |
| hdrMerge->GetSingleWordInOperand(kSelectionMergeMergeBlockIdInIdx); |
| if (contId == hdrMergeId) return; |
| } else { |
| return; |
| } |
| AddToWorklist(user); |
| }); |
| } |
| |
| bool AggressiveDCEPass::AggressiveDCE(Function* func) { |
| // Mark function parameters as live. |
| AddToWorklist(&func->DefInst()); |
| func->ForEachParam( |
| [this](const Instruction* param) { |
| AddToWorklist(const_cast<Instruction*>(param)); |
| }, |
| false); |
| |
| // Compute map from block to controlling conditional branch |
| std::list<BasicBlock*> structuredOrder; |
| cfg()->ComputeStructuredOrder(func, &*func->begin(), &structuredOrder); |
| ComputeBlock2HeaderMaps(structuredOrder); |
| bool modified = false; |
| // Add instructions with external side effects to worklist. Also add branches |
| // EXCEPT those immediately contained in an "if" selection construct or a loop |
| // or continue construct. |
| // TODO(greg-lunarg): Handle Frexp, Modf more optimally |
| call_in_func_ = false; |
| func_is_entry_point_ = false; |
| private_stores_.clear(); |
| // Stacks to keep track of when we are inside an if- or loop-construct. |
| // When immediately inside an if- or loop-construct, we do not initially |
| // mark branches live. All other branches must be marked live. |
| std::stack<bool> assume_branches_live; |
| std::stack<uint32_t> currentMergeBlockId; |
| // Push sentinel values on stack for when outside of any control flow. |
| assume_branches_live.push(true); |
| currentMergeBlockId.push(0); |
| for (auto bi = structuredOrder.begin(); bi != structuredOrder.end(); ++bi) { |
| // If exiting if or loop, update stacks |
| if ((*bi)->id() == currentMergeBlockId.top()) { |
| assume_branches_live.pop(); |
| currentMergeBlockId.pop(); |
| } |
| for (auto ii = (*bi)->begin(); ii != (*bi)->end(); ++ii) { |
| SpvOp op = ii->opcode(); |
| switch (op) { |
| case SpvOpStore: { |
| uint32_t varId; |
| (void)GetPtr(&*ii, &varId); |
| // Mark stores as live if their variable is not function scope |
| // and is not private scope. Remember private stores for possible |
| // later inclusion. We cannot call IsLocalVar at this point because |
| // private_like_local_ has not been set yet. |
| if (IsVarOfStorage(varId, SpvStorageClassPrivate) || |
| IsVarOfStorage(varId, SpvStorageClassWorkgroup)) |
| private_stores_.push_back(&*ii); |
| else if (!IsVarOfStorage(varId, SpvStorageClassFunction)) |
| AddToWorklist(&*ii); |
| } break; |
| case SpvOpCopyMemory: |
| case SpvOpCopyMemorySized: { |
| uint32_t varId; |
| (void)GetPtr(ii->GetSingleWordInOperand(kCopyMemoryTargetAddrInIdx), |
| &varId); |
| if (IsVarOfStorage(varId, SpvStorageClassPrivate) || |
| IsVarOfStorage(varId, SpvStorageClassWorkgroup)) |
| private_stores_.push_back(&*ii); |
| else if (!IsVarOfStorage(varId, SpvStorageClassFunction)) |
| AddToWorklist(&*ii); |
| } break; |
| case SpvOpLoopMerge: { |
| assume_branches_live.push(false); |
| currentMergeBlockId.push( |
| ii->GetSingleWordInOperand(kLoopMergeMergeBlockIdInIdx)); |
| } break; |
| case SpvOpSelectionMerge: { |
| assume_branches_live.push(false); |
| currentMergeBlockId.push( |
| ii->GetSingleWordInOperand(kSelectionMergeMergeBlockIdInIdx)); |
| } break; |
| case SpvOpSwitch: |
| case SpvOpBranch: |
| case SpvOpBranchConditional: |
| case SpvOpUnreachable: { |
| if (assume_branches_live.top()) { |
| AddToWorklist(&*ii); |
| } |
| } break; |
| default: { |
| // Function calls, atomics, function params, function returns, etc. |
| // TODO(greg-lunarg): function calls live only if write to non-local |
| if (!ii->IsOpcodeSafeToDelete()) { |
| AddToWorklist(&*ii); |
| } |
| // Remember function calls |
| if (op == SpvOpFunctionCall) call_in_func_ = true; |
| } break; |
| } |
| } |
| } |
| // See if current function is an entry point |
| for (auto& ei : get_module()->entry_points()) { |
| if (ei.GetSingleWordInOperand(kEntryPointFunctionIdInIdx) == |
| func->result_id()) { |
| func_is_entry_point_ = true; |
| break; |
| } |
| } |
| // If the current function is an entry point and has no function calls, |
| // we can optimize private variables as locals |
| private_like_local_ = func_is_entry_point_ && !call_in_func_; |
| // If privates are not like local, add their stores to worklist |
| if (!private_like_local_) |
| for (auto& ps : private_stores_) AddToWorklist(ps); |
| // Perform closure on live instruction set. |
| while (!worklist_.empty()) { |
| Instruction* liveInst = worklist_.front(); |
| // Add all operand instructions if not already live |
| liveInst->ForEachInId([&liveInst, this](const uint32_t* iid) { |
| Instruction* inInst = get_def_use_mgr()->GetDef(*iid); |
| // Do not add label if an operand of a branch. This is not needed |
| // as part of live code discovery and can create false live code, |
| // for example, the branch to a header of a loop. |
| if (inInst->opcode() == SpvOpLabel && liveInst->IsBranch()) return; |
| AddToWorklist(inInst); |
| }); |
| if (liveInst->type_id() != 0) { |
| AddToWorklist(get_def_use_mgr()->GetDef(liveInst->type_id())); |
| } |
| // If in a structured if or loop construct, add the controlling |
| // conditional branch and its merge. |
| BasicBlock* blk = context()->get_instr_block(liveInst); |
| Instruction* branchInst = block2headerBranch_[blk]; |
| if (branchInst != nullptr) { |
| AddToWorklist(branchInst); |
| Instruction* mergeInst = branch2merge_[branchInst]; |
| AddToWorklist(mergeInst); |
| } |
| // If the block is a header, add the next outermost controlling |
| // conditional branch and its merge. |
| Instruction* nextBranchInst = header2nextHeaderBranch_[blk]; |
| if (nextBranchInst != nullptr) { |
| AddToWorklist(nextBranchInst); |
| Instruction* mergeInst = branch2merge_[nextBranchInst]; |
| AddToWorklist(mergeInst); |
| } |
| // If local load, add all variable's stores if variable not already live |
| if (liveInst->opcode() == SpvOpLoad || liveInst->IsAtomicWithLoad()) { |
| uint32_t varId; |
| (void)GetPtr(liveInst, &varId); |
| if (varId != 0) { |
| ProcessLoad(varId); |
| } |
| // Process memory copies like loads |
| } else if (liveInst->opcode() == SpvOpCopyMemory || |
| liveInst->opcode() == SpvOpCopyMemorySized) { |
| uint32_t varId; |
| (void)GetPtr(liveInst->GetSingleWordInOperand(kCopyMemorySourceAddrInIdx), |
| &varId); |
| if (varId != 0) { |
| ProcessLoad(varId); |
| } |
| // If merge, add other branches that are part of its control structure |
| } else if (liveInst->opcode() == SpvOpLoopMerge || |
| liveInst->opcode() == SpvOpSelectionMerge) { |
| AddBreaksAndContinuesToWorklist(liveInst); |
| // If function call, treat as if it loads from all pointer arguments |
| } else if (liveInst->opcode() == SpvOpFunctionCall) { |
| liveInst->ForEachInId([this](const uint32_t* iid) { |
| // Skip non-ptr args |
| if (!IsPtr(*iid)) return; |
| uint32_t varId; |
| (void)GetPtr(*iid, &varId); |
| ProcessLoad(varId); |
| }); |
| // If function parameter, treat as if it's result id is loaded from |
| } else if (liveInst->opcode() == SpvOpFunctionParameter) { |
| ProcessLoad(liveInst->result_id()); |
| // We treat an OpImageTexelPointer as a load of the pointer, and |
| // that value is manipulated to get the result. |
| } else if (liveInst->opcode() == SpvOpImageTexelPointer) { |
| uint32_t varId; |
| (void)GetPtr(liveInst, &varId); |
| if (varId != 0) { |
| ProcessLoad(varId); |
| } |
| } |
| |
| // Add OpDecorateId instructions that apply to this instruction to the work |
| // list. We use the decoration manager to look through the group |
| // decorations to get to the OpDecorate* instructions themselves. |
| auto decorations = |
| get_decoration_mgr()->GetDecorationsFor(liveInst->result_id(), false); |
| for (Instruction* dec : decorations) { |
| // We only care about OpDecorateId instructions because the are the only |
| // decorations that will reference an id that will have to be kept live |
| // because of that use. |
| if (dec->opcode() != SpvOpDecorateId) { |
| continue; |
| } |
| if (dec->GetSingleWordInOperand(1) == |
| SpvDecorationHlslCounterBufferGOOGLE) { |
| // These decorations should not force the use id to be live. It will be |
| // removed if either the target or the in operand are dead. |
| continue; |
| } |
| AddToWorklist(dec); |
| } |
| |
| worklist_.pop(); |
| } |
| |
| // Kill dead instructions and remember dead blocks |
| for (auto bi = structuredOrder.begin(); bi != structuredOrder.end();) { |
| uint32_t mergeBlockId = 0; |
| (*bi)->ForEachInst([this, &modified, &mergeBlockId](Instruction* inst) { |
| if (!IsDead(inst)) return; |
| if (inst->opcode() == SpvOpLabel) return; |
| // If dead instruction is selection merge, remember merge block |
| // for new branch at end of block |
| if (inst->opcode() == SpvOpSelectionMerge || |
| inst->opcode() == SpvOpLoopMerge) |
| mergeBlockId = inst->GetSingleWordInOperand(0); |
| to_kill_.push_back(inst); |
| modified = true; |
| }); |
| // If a structured if or loop was deleted, add a branch to its merge |
| // block, and traverse to the merge block and continue processing there. |
| // We know the block still exists because the label is not deleted. |
| if (mergeBlockId != 0) { |
| AddBranch(mergeBlockId, *bi); |
| for (++bi; (*bi)->id() != mergeBlockId; ++bi) { |
| } |
| |
| auto merge_terminator = (*bi)->terminator(); |
| if (merge_terminator->opcode() == SpvOpUnreachable) { |
| // The merge was unreachable. This is undefined behaviour so just |
| // return (or return an undef). Then mark the new return as live. |
| auto func_ret_type_inst = get_def_use_mgr()->GetDef(func->type_id()); |
| if (func_ret_type_inst->opcode() == SpvOpTypeVoid) { |
| merge_terminator->SetOpcode(SpvOpReturn); |
| } else { |
| // Find an undef for the return value and make sure it gets kept by |
| // the pass. |
| auto undef_id = Type2Undef(func->type_id()); |
| auto undef = get_def_use_mgr()->GetDef(undef_id); |
| live_insts_.Set(undef->unique_id()); |
| merge_terminator->SetOpcode(SpvOpReturnValue); |
| merge_terminator->SetInOperands({{SPV_OPERAND_TYPE_ID, {undef_id}}}); |
| get_def_use_mgr()->AnalyzeInstUse(merge_terminator); |
| } |
| live_insts_.Set(merge_terminator->unique_id()); |
| } |
| } else { |
| ++bi; |
| } |
| } |
| |
| return modified; |
| } |
| |
| void AggressiveDCEPass::InitializeModuleScopeLiveInstructions() { |
| // Keep all execution modes. |
| for (auto& exec : get_module()->execution_modes()) { |
| AddToWorklist(&exec); |
| } |
| // Keep all entry points. |
| for (auto& entry : get_module()->entry_points()) { |
| if (get_module()->version() >= SPV_SPIRV_VERSION_WORD(1, 4)) { |
| // In SPIR-V 1.4 and later, entry points must list all global variables |
| // used. DCE can still remove non-input/output variables and update the |
| // interface list. Mark the entry point as live and inputs and outputs as |
| // live, but defer decisions all other interfaces. |
| live_insts_.Set(entry.unique_id()); |
| // The actual function is live always. |
| AddToWorklist( |
| get_def_use_mgr()->GetDef(entry.GetSingleWordInOperand(1u))); |
| for (uint32_t i = 3; i < entry.NumInOperands(); ++i) { |
| auto* var = get_def_use_mgr()->GetDef(entry.GetSingleWordInOperand(i)); |
| auto storage_class = var->GetSingleWordInOperand(0u); |
| if (storage_class == SpvStorageClassInput || |
| storage_class == SpvStorageClassOutput) { |
| AddToWorklist(var); |
| } |
| } |
| } else { |
| AddToWorklist(&entry); |
| } |
| } |
| for (auto& anno : get_module()->annotations()) { |
| if (anno.opcode() == SpvOpDecorate) { |
| // Keep workgroup size. |
| if (anno.GetSingleWordInOperand(1u) == SpvDecorationBuiltIn && |
| anno.GetSingleWordInOperand(2u) == SpvBuiltInWorkgroupSize) { |
| AddToWorklist(&anno); |
| } |
| |
| if (context()->preserve_bindings()) { |
| // Keep all bindings. |
| if ((anno.GetSingleWordInOperand(1u) == SpvDecorationDescriptorSet) || |
| (anno.GetSingleWordInOperand(1u) == SpvDecorationBinding)) { |
| AddToWorklist(&anno); |
| } |
| } |
| |
| if (context()->preserve_spec_constants()) { |
| // Keep all specialization constant instructions |
| if (anno.GetSingleWordInOperand(1u) == SpvDecorationSpecId) { |
| AddToWorklist(&anno); |
| } |
| } |
| } |
| } |
| } |
| |
| Pass::Status AggressiveDCEPass::ProcessImpl() { |
| // Current functionality assumes shader capability |
| // TODO(greg-lunarg): Handle additional capabilities |
| if (!context()->get_feature_mgr()->HasCapability(SpvCapabilityShader)) |
| return Status::SuccessWithoutChange; |
| |
| // Current functionality assumes relaxed logical addressing (see |
| // instruction.h) |
| // TODO(greg-lunarg): Handle non-logical addressing |
| if (context()->get_feature_mgr()->HasCapability(SpvCapabilityAddresses)) |
| return Status::SuccessWithoutChange; |
| |
| // The variable pointer extension is no longer needed to use the capability, |
| // so we have to look for the capability. |
| if (context()->get_feature_mgr()->HasCapability( |
| SpvCapabilityVariablePointersStorageBuffer)) |
| return Status::SuccessWithoutChange; |
| |
| // If any extensions in the module are not explicitly supported, |
| // return unmodified. |
| if (!AllExtensionsSupported()) return Status::SuccessWithoutChange; |
| |
| // Eliminate Dead functions. |
| bool modified = EliminateDeadFunctions(); |
| |
| InitializeModuleScopeLiveInstructions(); |
| |
| // Process all entry point functions. |
| ProcessFunction pfn = [this](Function* fp) { return AggressiveDCE(fp); }; |
| modified |= context()->ProcessEntryPointCallTree(pfn); |
| |
| // If the decoration manager is kept live then the context will try to keep it |
| // up to date. ADCE deals with group decorations by changing the operands in |
| // |OpGroupDecorate| instruction directly without informing the decoration |
| // manager. This can put it in an invalid state which will cause an error |
| // when the context tries to update it. To avoid this problem invalidate |
| // the decoration manager upfront. |
| // |
| // We kill it at now because it is used when processing the entry point |
| // functions. |
| context()->InvalidateAnalyses(IRContext::Analysis::kAnalysisDecorations); |
| |
| // Process module-level instructions. Now that all live instructions have |
| // been marked, it is safe to remove dead global values. |
| modified |= ProcessGlobalValues(); |
| |
| // Kill all dead instructions. |
| for (auto inst : to_kill_) { |
| context()->KillInst(inst); |
| } |
| |
| // Cleanup all CFG including all unreachable blocks. |
| ProcessFunction cleanup = [this](Function* f) { return CFGCleanup(f); }; |
| modified |= context()->ProcessEntryPointCallTree(cleanup); |
| |
| return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange; |
| } |
| |
| bool AggressiveDCEPass::EliminateDeadFunctions() { |
| // Identify live functions first. Those that are not live |
| // are dead. ADCE is disabled for non-shaders so we do not check for exported |
| // functions here. |
| std::unordered_set<const Function*> live_function_set; |
| ProcessFunction mark_live = [&live_function_set](Function* fp) { |
| live_function_set.insert(fp); |
| return false; |
| }; |
| context()->ProcessEntryPointCallTree(mark_live); |
| |
| bool modified = false; |
| for (auto funcIter = get_module()->begin(); |
| funcIter != get_module()->end();) { |
| if (live_function_set.count(&*funcIter) == 0) { |
| modified = true; |
| EliminateFunction(&*funcIter); |
| funcIter = funcIter.Erase(); |
| } else { |
| ++funcIter; |
| } |
| } |
| |
| return modified; |
| } |
| |
| void AggressiveDCEPass::EliminateFunction(Function* func) { |
| // Remove all of the instruction in the function body |
| func->ForEachInst([this](Instruction* inst) { context()->KillInst(inst); }, |
| true); |
| } |
| |
| bool AggressiveDCEPass::ProcessGlobalValues() { |
| // Remove debug and annotation statements referencing dead instructions. |
| // This must be done before killing the instructions, otherwise there are |
| // dead objects in the def/use database. |
| bool modified = false; |
| Instruction* instruction = &*get_module()->debug2_begin(); |
| while (instruction) { |
| if (instruction->opcode() != SpvOpName) { |
| instruction = instruction->NextNode(); |
| continue; |
| } |
| |
| if (IsTargetDead(instruction)) { |
| instruction = context()->KillInst(instruction); |
| modified = true; |
| } else { |
| instruction = instruction->NextNode(); |
| } |
| } |
| |
| // This code removes all unnecessary decorations safely (see #1174). It also |
| // does so in a more efficient manner than deleting them only as the targets |
| // are deleted. |
| std::vector<Instruction*> annotations; |
| for (auto& inst : get_module()->annotations()) annotations.push_back(&inst); |
| std::sort(annotations.begin(), annotations.end(), DecorationLess()); |
| for (auto annotation : annotations) { |
| switch (annotation->opcode()) { |
| case SpvOpDecorate: |
| case SpvOpMemberDecorate: |
| case SpvOpDecorateStringGOOGLE: |
| case SpvOpMemberDecorateStringGOOGLE: |
| if (IsTargetDead(annotation)) { |
| context()->KillInst(annotation); |
| modified = true; |
| } |
| break; |
| case SpvOpDecorateId: |
| if (IsTargetDead(annotation)) { |
| context()->KillInst(annotation); |
| modified = true; |
| } else { |
| if (annotation->GetSingleWordInOperand(1) == |
| SpvDecorationHlslCounterBufferGOOGLE) { |
| // HlslCounterBuffer will reference an id other than the target. |
| // If that id is dead, then the decoration can be removed as well. |
| uint32_t counter_buffer_id = annotation->GetSingleWordInOperand(2); |
| Instruction* counter_buffer_inst = |
| get_def_use_mgr()->GetDef(counter_buffer_id); |
| if (IsDead(counter_buffer_inst)) { |
| context()->KillInst(annotation); |
| modified = true; |
| } |
| } |
| } |
| break; |
| case SpvOpGroupDecorate: { |
| // Go through the targets of this group decorate. Remove each dead |
| // target. If all targets are dead, remove this decoration. |
| bool dead = true; |
| bool removed_operand = false; |
| for (uint32_t i = 1; i < annotation->NumOperands();) { |
| Instruction* opInst = |
| get_def_use_mgr()->GetDef(annotation->GetSingleWordOperand(i)); |
| if (IsDead(opInst)) { |
| // Don't increment |i|. |
| annotation->RemoveOperand(i); |
| modified = true; |
| removed_operand = true; |
| } else { |
| i++; |
| dead = false; |
| } |
| } |
| if (dead) { |
| context()->KillInst(annotation); |
| modified = true; |
| } else if (removed_operand) { |
| context()->UpdateDefUse(annotation); |
| } |
| break; |
| } |
| case SpvOpGroupMemberDecorate: { |
| // Go through the targets of this group member decorate. Remove each |
| // dead target (and member index). If all targets are dead, remove this |
| // decoration. |
| bool dead = true; |
| bool removed_operand = false; |
| for (uint32_t i = 1; i < annotation->NumOperands();) { |
| Instruction* opInst = |
| get_def_use_mgr()->GetDef(annotation->GetSingleWordOperand(i)); |
| if (IsDead(opInst)) { |
| // Don't increment |i|. |
| annotation->RemoveOperand(i + 1); |
| annotation->RemoveOperand(i); |
| modified = true; |
| removed_operand = true; |
| } else { |
| i += 2; |
| dead = false; |
| } |
| } |
| if (dead) { |
| context()->KillInst(annotation); |
| modified = true; |
| } else if (removed_operand) { |
| context()->UpdateDefUse(annotation); |
| } |
| break; |
| } |
| case SpvOpDecorationGroup: |
| // By the time we hit decoration groups we've checked everything that |
| // can target them. So if they have no uses they must be dead. |
| if (get_def_use_mgr()->NumUsers(annotation) == 0) { |
| context()->KillInst(annotation); |
| modified = true; |
| } |
| break; |
| default: |
| assert(false); |
| break; |
| } |
| } |
| |
| // Since ADCE is disabled for non-shaders, we don't check for export linkage |
| // attributes here. |
| for (auto& val : get_module()->types_values()) { |
| if (IsDead(&val)) { |
| to_kill_.push_back(&val); |
| } |
| } |
| |
| if (get_module()->version() >= SPV_SPIRV_VERSION_WORD(1, 4)) { |
| // Remove the dead interface variables from the entry point interface list. |
| for (auto& entry : get_module()->entry_points()) { |
| std::vector<Operand> new_operands; |
| for (uint32_t i = 0; i < entry.NumInOperands(); ++i) { |
| if (i < 3) { |
| // Execution model, function id and name are always valid. |
| new_operands.push_back(entry.GetInOperand(i)); |
| } else { |
| auto* var = |
| get_def_use_mgr()->GetDef(entry.GetSingleWordInOperand(i)); |
| if (!IsDead(var)) { |
| new_operands.push_back(entry.GetInOperand(i)); |
| } |
| } |
| } |
| if (new_operands.size() != entry.NumInOperands()) { |
| entry.SetInOperands(std::move(new_operands)); |
| get_def_use_mgr()->UpdateDefUse(&entry); |
| } |
| } |
| } |
| |
| return modified; |
| } |
| |
| AggressiveDCEPass::AggressiveDCEPass() = default; |
| |
| Pass::Status AggressiveDCEPass::Process() { |
| // Initialize extensions whitelist |
| InitExtensions(); |
| return ProcessImpl(); |
| } |
| |
| void AggressiveDCEPass::InitExtensions() { |
| extensions_whitelist_.clear(); |
| extensions_whitelist_.insert({ |
| "SPV_AMD_shader_explicit_vertex_parameter", |
| "SPV_AMD_shader_trinary_minmax", |
| "SPV_AMD_gcn_shader", |
| "SPV_KHR_shader_ballot", |
| "SPV_AMD_shader_ballot", |
| "SPV_AMD_gpu_shader_half_float", |
| "SPV_KHR_shader_draw_parameters", |
| "SPV_KHR_subgroup_vote", |
| "SPV_KHR_16bit_storage", |
| "SPV_KHR_device_group", |
| "SPV_KHR_multiview", |
| "SPV_NVX_multiview_per_view_attributes", |
| "SPV_NV_viewport_array2", |
| "SPV_NV_stereo_view_rendering", |
| "SPV_NV_sample_mask_override_coverage", |
| "SPV_NV_geometry_shader_passthrough", |
| "SPV_AMD_texture_gather_bias_lod", |
| "SPV_KHR_storage_buffer_storage_class", |
| // SPV_KHR_variable_pointers |
| // Currently do not support extended pointer expressions |
| "SPV_AMD_gpu_shader_int16", |
| "SPV_KHR_post_depth_coverage", |
| "SPV_KHR_shader_atomic_counter_ops", |
| "SPV_EXT_shader_stencil_export", |
| "SPV_EXT_shader_viewport_index_layer", |
| "SPV_AMD_shader_image_load_store_lod", |
| "SPV_AMD_shader_fragment_mask", |
| "SPV_EXT_fragment_fully_covered", |
| "SPV_AMD_gpu_shader_half_float_fetch", |
| "SPV_GOOGLE_decorate_string", |
| "SPV_GOOGLE_hlsl_functionality1", |
| "SPV_GOOGLE_user_type", |
| "SPV_NV_shader_subgroup_partitioned", |
| "SPV_EXT_descriptor_indexing", |
| "SPV_NV_fragment_shader_barycentric", |
| "SPV_NV_compute_shader_derivatives", |
| "SPV_NV_shader_image_footprint", |
| "SPV_NV_shading_rate", |
| "SPV_NV_mesh_shader", |
| "SPV_NV_ray_tracing", |
| "SPV_EXT_fragment_invocation_density", |
| }); |
| } |
| |
| } // namespace opt |
| } // namespace spvtools |
