SPIRV-Tools/source/opt/local_single_block_elim_pass.cpp

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// Copyright (c) 2017 The Khronos Group Inc.
// Copyright (c) 2017 Valve Corporation
// Copyright (c) 2017 LunarG 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/opt/local_single_block_elim_pass.h"
#include <vector>
#include "source/opt/iterator.h"
namespace spvtools {
namespace opt {
namespace {
const uint32_t kStoreValIdInIdx = 1;
} // anonymous namespace
bool LocalSingleBlockLoadStoreElimPass::HasOnlySupportedRefs(uint32_t ptrId) {
if (supported_ref_ptrs_.find(ptrId) != supported_ref_ptrs_.end()) return true;
if (get_def_use_mgr()->WhileEachUser(ptrId, [this](Instruction* user) {
auto dbg_op = user->GetOpenCL100DebugOpcode();
if (dbg_op == OpenCLDebugInfo100DebugDeclare ||
dbg_op == OpenCLDebugInfo100DebugValue) {
return true;
}
SpvOp op = user->opcode();
if (IsNonPtrAccessChain(op) || op == SpvOpCopyObject) {
if (!HasOnlySupportedRefs(user->result_id())) {
return false;
}
} else if (op != SpvOpStore && op != SpvOpLoad && op != SpvOpName &&
!IsNonTypeDecorate(op)) {
return false;
}
return true;
})) {
Adding new def -> use mapping container Replaced representation of uses * Changed uses from unordered_map<uint32_t, UseList> to set<pairInstruction*, Instruction*>> * Replaced GetUses with ForEachUser and ForEachUse functions * updated passes to use new functions * partially updated tests * lots of cleanup still todo Adding an unique id to Instruction generated by IRContext Each instruction is given an unique id that can be used for ordering purposes. The ids are generated via the IRContext. Major changes: * Instructions now contain a uint32_t for unique id and a cached context pointer * Most constructors have been modified to take a context as input * unfortunately I cannot remove the default and copy constructors, but developers should avoid these * Added accessors to parents of basic block and function * Removed the copy constructors for BasicBlock and Function and replaced them with Clone functions * Reworked BuildModule to return an IRContext owning the built module * Since all instructions require a context, the context now becomes the basic unit for IR * Added a constructor to context to create an owned module internally * Replaced uses of Instruction's copy constructor with Clone whereever I found them * Reworked the linker functionality to perform clones into a different context instead of moves * Updated many tests to be consistent with the above changes * Still need to add new tests to cover added functionality * Added comparison operators to Instruction Adding tests for Instruction, IRContext and IR loading Fixed some header comments for BuildModule Fixes to get tests passing again * Reordered two linker steps to avoid use/def problems * Fixed def/use manager uses in merge return pass * Added early return for GetAnnotations * Changed uses of Instruction::ToNop in passes to IRContext::KillInst Simplifying the uses for some contexts in passes
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supported_ref_ptrs_.insert(ptrId);
return true;
}
return false;
}
bool LocalSingleBlockLoadStoreElimPass::LocalSingleBlockLoadStoreElim(
Function* func) {
// Perform local store/load, load/load and store/store elimination
// on each block
bool modified = false;
std::vector<Instruction*> instructions_to_kill;
std::unordered_set<Instruction*> instructions_to_save;
for (auto bi = func->begin(); bi != func->end(); ++bi) {
var2store_.clear();
var2load_.clear();
auto next = bi->begin();
for (auto ii = next; ii != bi->end(); ii = next) {
++next;
switch (ii->opcode()) {
case SpvOpStore: {
// Verify store variable is target type
uint32_t varId;
Instruction* ptrInst = GetPtr(&*ii, &varId);
if (!IsTargetVar(varId)) continue;
if (!HasOnlySupportedRefs(varId)) continue;
// If a store to the whole variable, remember it for succeeding
// loads and stores. Otherwise forget any previous store to that
// variable.
if (ptrInst->opcode() == SpvOpVariable) {
// If a previous store to same variable, mark the store
// for deletion if not still used. Don't delete store
// if debugging; let ssa-rewrite and DCE handle it
auto prev_store = var2store_.find(varId);
if (prev_store != var2store_.end() &&
instructions_to_save.count(prev_store->second) == 0 &&
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!context()->get_debug_info_mgr()->IsDebugDeclared(varId)) {
instructions_to_kill.push_back(prev_store->second);
modified = true;
}
bool kill_store = false;
auto li = var2load_.find(varId);
if (li != var2load_.end()) {
if (ii->GetSingleWordInOperand(kStoreValIdInIdx) ==
li->second->result_id()) {
// We are storing the same value that already exists in the
// memory location. The store does nothing.
kill_store = true;
}
}
if (!kill_store) {
var2store_[varId] = &*ii;
var2load_.erase(varId);
} else {
instructions_to_kill.push_back(&*ii);
modified = true;
}
} else {
assert(IsNonPtrAccessChain(ptrInst->opcode()));
var2store_.erase(varId);
var2load_.erase(varId);
}
} break;
case SpvOpLoad: {
// Verify store variable is target type
uint32_t varId;
Instruction* ptrInst = GetPtr(&*ii, &varId);
if (!IsTargetVar(varId)) continue;
if (!HasOnlySupportedRefs(varId)) continue;
uint32_t replId = 0;
if (ptrInst->opcode() == SpvOpVariable) {
// If a load from a variable, look for a previous store or
// load from that variable and use its value.
auto si = var2store_.find(varId);
if (si != var2store_.end()) {
replId = si->second->GetSingleWordInOperand(kStoreValIdInIdx);
} else {
auto li = var2load_.find(varId);
if (li != var2load_.end()) {
replId = li->second->result_id();
}
}
} else {
// If a partial load of a previously seen store, remember
// not to delete the store.
auto si = var2store_.find(varId);
if (si != var2store_.end()) instructions_to_save.insert(si->second);
}
if (replId != 0) {
// replace load's result id and delete load
context()->KillNamesAndDecorates(&*ii);
context()->ReplaceAllUsesWith(ii->result_id(), replId);
instructions_to_kill.push_back(&*ii);
modified = true;
} else {
if (ptrInst->opcode() == SpvOpVariable)
var2load_[varId] = &*ii; // register load
}
} break;
case SpvOpFunctionCall: {
// Conservatively assume all locals are redefined for now.
// TODO(): Handle more optimally
var2store_.clear();
var2load_.clear();
} break;
default:
break;
}
}
}
for (Instruction* inst : instructions_to_kill) {
context()->KillInst(inst);
}
return modified;
}
void LocalSingleBlockLoadStoreElimPass::Initialize() {
// Initialize Target Type Caches
seen_target_vars_.clear();
seen_non_target_vars_.clear();
// Clear collections
supported_ref_ptrs_.clear();
// Initialize extensions allowlist
InitExtensions();
}
bool LocalSingleBlockLoadStoreElimPass::AllExtensionsSupported() const {
// If any extension not in allowlist, return false
for (auto& ei : get_module()->extensions()) {
const char* extName =
reinterpret_cast<const char*>(&ei.GetInOperand(0).words[0]);
if (extensions_allowlist_.find(extName) == extensions_allowlist_.end())
return false;
}
return true;
}
Pass::Status LocalSingleBlockLoadStoreElimPass::ProcessImpl() {
// Assumes relaxed logical addressing only (see instruction.h).
if (context()->get_feature_mgr()->HasCapability(SpvCapabilityAddresses))
return Status::SuccessWithoutChange;
// Do not process if module contains OpGroupDecorate. Additional
// support required in KillNamesAndDecorates().
// TODO(greg-lunarg): Add support for OpGroupDecorate
for (auto& ai : get_module()->annotations())
if (ai.opcode() == SpvOpGroupDecorate) return Status::SuccessWithoutChange;
// If any extensions in the module are not explicitly supported,
// return unmodified.
if (!AllExtensionsSupported()) return Status::SuccessWithoutChange;
// Process all entry point functions
ProcessFunction pfn = [this](Function* fp) {
return LocalSingleBlockLoadStoreElim(fp);
};
bool modified = context()->ProcessEntryPointCallTree(pfn);
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
LocalSingleBlockLoadStoreElimPass::LocalSingleBlockLoadStoreElimPass() =
default;
Pass::Status LocalSingleBlockLoadStoreElimPass::Process() {
Initialize();
return ProcessImpl();
}
void LocalSingleBlockLoadStoreElimPass::InitExtensions() {
extensions_allowlist_.clear();
extensions_allowlist_.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",
"SPV_AMD_gpu_shader_int16",
"SPV_KHR_post_depth_coverage",
"SPV_KHR_shader_atomic_counter_ops",
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"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_demote_to_helper_invocation",
"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",
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"SPV_KHR_ray_tracing",
"SPV_KHR_ray_query",
"SPV_EXT_fragment_invocation_density",
"SPV_EXT_physical_storage_buffer",
"SPV_KHR_terminate_invocation",
});
}
} // namespace opt
} // namespace spvtools