mirror of
https://github.com/KhronosGroup/SPIRV-Tools
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329 lines
11 KiB
C++
329 lines
11 KiB
C++
// Copyright (c) 2015-2016 The Khronos Group Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and/or associated documentation files (the
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// "Materials"), to deal in the Materials without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Materials, and to
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// permit persons to whom the Materials are furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Materials.
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//
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// MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS
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// KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS
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// SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT
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// https://www.khronos.org/registry/
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//
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// THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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// MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
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#include "validate.h"
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#include "validate_passes.h"
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#include <algorithm>
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#include <cassert>
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#include <unordered_map>
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#include <unordered_set>
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#include <utility>
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#include <vector>
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using std::find;
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using std::get;
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using std::make_pair;
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using std::numeric_limits;
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using std::pair;
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using std::transform;
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using std::unordered_map;
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using std::unordered_set;
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using std::vector;
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using libspirv::BasicBlock;
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namespace libspirv {
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namespace {
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using bb_ptr = BasicBlock*;
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using cbb_ptr = const BasicBlock*;
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using bb_iter = vector<BasicBlock*>::const_iterator;
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/// @brief Sorts the blocks in a CFG given the entry node
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///
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/// Returns a vector of basic block pointers in a Control Flow Graph(CFG) which
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/// are sorted in the order they were accessed in a post order traversal.
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///
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/// @param[in] entry the first block of a CFG
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/// @param[in] depth_hint a hint about the depth of the CFG
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///
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/// @return A vector of pointers in the order they were access in a post order
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/// traversal
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vector<const BasicBlock*> PostOrderSort(const BasicBlock& entry, size_t size) {
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struct block_info {
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cbb_ptr block;
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bb_iter iter;
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};
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vector<cbb_ptr> out;
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vector<block_info> staged;
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unordered_set<uint32_t> processed;
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staged.reserve(size);
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staged.emplace_back(block_info{&entry, begin(entry.get_successors())});
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processed.insert(entry.get_id());
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while (!staged.empty()) {
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block_info& top = staged.back();
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if (top.iter == end(top.block->get_successors())) {
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out.push_back(top.block);
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staged.pop_back();
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} else {
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BasicBlock* child = *top.iter;
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if (processed.find(child->get_id()) == end(processed)) {
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staged.emplace_back(block_info{child, begin(child->get_successors())});
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processed.insert(child->get_id());
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}
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top.iter++;
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}
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}
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return out;
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}
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} // namespace
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vector<pair<BasicBlock*, BasicBlock*>> CalculateDominators(
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const BasicBlock& first_block) {
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struct block_detail {
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size_t dominator; ///< The index of blocks's dominator in post order array
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size_t postorder_index; ///< The index of the block in the post order array
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};
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vector<cbb_ptr> postorder = PostOrderSort(first_block, 10);
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const size_t undefined_dom = static_cast<size_t>(postorder.size());
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unordered_map<cbb_ptr, block_detail> idoms;
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for (size_t i = 0; i < postorder.size(); i++) {
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idoms[postorder[i]] = {undefined_dom, i};
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}
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idoms[postorder.back()].dominator = idoms[postorder.back()].postorder_index;
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bool changed = true;
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while (changed) {
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changed = false;
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for (auto b = postorder.rbegin() + 1; b != postorder.rend(); b++) {
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size_t& b_dom = idoms[*b].dominator;
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const vector<BasicBlock*>& predecessors = (*b)->get_predecessors();
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// first processed predecessor
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auto res = find_if(begin(predecessors), end(predecessors),
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[&idoms, undefined_dom](BasicBlock* pred) {
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return idoms[pred].dominator != undefined_dom;
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});
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assert(res != end(predecessors));
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BasicBlock* idom = *res;
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size_t idom_idx = idoms[idom].postorder_index;
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// all other predecessors
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for (auto p : predecessors) {
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if (idom == p || p->is_reachable() == false) {
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continue;
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}
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if (idoms[p].dominator != undefined_dom) {
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size_t finger1 = idoms[p].postorder_index;
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size_t finger2 = idom_idx;
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while (finger1 != finger2) {
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while (finger1 < finger2) {
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finger1 = idoms[postorder[finger1]].dominator;
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}
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while (finger2 < finger1) {
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finger2 = idoms[postorder[finger2]].dominator;
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}
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}
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idom_idx = finger1;
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}
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}
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if (b_dom != idom_idx) {
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b_dom = idom_idx;
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changed = true;
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}
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}
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}
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vector<pair<bb_ptr, bb_ptr>> out;
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for (auto idom : idoms) {
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// NOTE: performing a const cast for convenient usage with
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// UpdateImmediateDominators
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out.push_back({const_cast<BasicBlock*>(get<0>(idom)),
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const_cast<BasicBlock*>(postorder[get<1>(idom).dominator])});
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}
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return out;
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}
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void UpdateImmediateDominators(vector<pair<bb_ptr, bb_ptr>>& dom_edges) {
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for (auto& edge : dom_edges) {
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get<0>(edge)->SetImmediateDominator(get<1>(edge));
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}
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}
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void printDominatorList(BasicBlock& b) {
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std::cout << b.get_id() << " is dominated by: ";
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const BasicBlock* bb = &b;
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while (bb->GetImmediateDominator() != bb) {
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bb = bb->GetImmediateDominator();
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std::cout << bb->get_id() << " ";
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}
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}
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#define CFG_ASSERT(ASSERT_FUNC, TARGET) \
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if (spv_result_t rcode = ASSERT_FUNC(_, TARGET)) return rcode
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spv_result_t FirstBlockAssert(ValidationState_t& _, uint32_t target) {
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if (_.get_current_function().IsFirstBlock(target)) {
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return _.diag(SPV_ERROR_INVALID_CFG)
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<< "First block " << _.getIdName(target) << " of funciton "
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<< _.getIdName(_.get_current_function().get_id())
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<< " is targeted by block "
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<< _.getIdName(
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_.get_current_function().get_current_block().get_id());
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}
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return SPV_SUCCESS;
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}
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spv_result_t MergeBlockAssert(ValidationState_t& _, uint32_t merge_block) {
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if (_.get_current_function().IsMergeBlock(merge_block)) {
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return _.diag(SPV_ERROR_INVALID_CFG)
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<< "Block " << _.getIdName(merge_block)
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<< " is already a merge block for another header";
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}
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return SPV_SUCCESS;
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}
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spv_result_t PerformCfgChecks(ValidationState_t& _) {
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for (auto& function : _.get_functions()) {
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// Updates each blocks immediate dominators
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if (auto* first_block = function.get_first_block()) {
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auto edges = libspirv::CalculateDominators(*first_block);
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libspirv::UpdateImmediateDominators(edges);
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}
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// Check if the order of blocks in the binary appear before the blocks they
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// dominate
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auto& blocks = function.get_blocks();
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if (blocks.empty() == false) {
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for (auto block = begin(blocks) + 1; block != end(blocks); block++) {
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if (auto idom = (*block)->GetImmediateDominator()) {
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if (block == std::find(begin(blocks), block, idom)) {
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return _.diag(SPV_ERROR_INVALID_CFG)
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<< "Block " << _.getIdName((*block)->get_id())
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<< " appears in the binary before its dominator "
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<< _.getIdName(idom->get_id());
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}
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}
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}
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}
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// Check all referenced blocks are defined within a function
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if (function.get_undefined_block_count() != 0) {
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std::stringstream ss;
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ss << "{";
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for (auto undefined_block : function.get_undefined_blocks()) {
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ss << _.getIdName(undefined_block) << " ";
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}
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return _.diag(SPV_ERROR_INVALID_CFG)
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<< "Block(s) " << ss.str() << "\b}"
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<< " are referenced but not defined in function "
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<< _.getIdName(function.get_id());
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}
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// Check all headers dominate their merge blocks
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for (CFConstruct& construct : function.get_constructs()) {
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auto header = construct.get_header();
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auto merge = construct.get_merge();
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// auto cont = construct.get_continue();
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if (merge->is_reachable() &&
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find(merge->dom_begin(), merge->dom_end(), header) ==
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merge->dom_end()) {
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return _.diag(SPV_ERROR_INVALID_CFG)
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<< "Header block " << _.getIdName(header->get_id())
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<< " doesn't dominate its merge block "
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<< _.getIdName(merge->get_id());
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}
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}
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// TODO(umar): All CFG back edges must branch to a loop header, with each
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// loop header having exactly one back edge branching to it
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// TODO(umar): For a given loop, its back-edge block must post dominate the
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// OpLoopMerge's Continue Target, and that Continue Target must dominate the
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// back-edge block
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}
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return SPV_SUCCESS;
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}
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spv_result_t CfgPass(ValidationState_t& _,
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const spv_parsed_instruction_t* inst) {
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SpvOp opcode = static_cast<SpvOp>(inst->opcode);
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switch (opcode) {
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case SpvOpLabel:
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spvCheckReturn(_.get_current_function().RegisterBlock(inst->result_id));
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break;
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case SpvOpLoopMerge: {
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// TODO(umar): mark current block as a loop header
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uint32_t merge_block = inst->words[inst->operands[0].offset];
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uint32_t continue_block = inst->words[inst->operands[1].offset];
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CFG_ASSERT(MergeBlockAssert, merge_block);
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spvCheckReturn(_.get_current_function().RegisterLoopMerge(
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merge_block, continue_block));
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} break;
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case SpvOpSelectionMerge: {
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uint32_t merge_block = inst->words[inst->operands[0].offset];
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CFG_ASSERT(MergeBlockAssert, merge_block);
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spvCheckReturn(
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_.get_current_function().RegisterSelectionMerge(merge_block));
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} break;
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case SpvOpBranch: {
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uint32_t target = inst->words[inst->operands[0].offset];
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CFG_ASSERT(FirstBlockAssert, target);
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_.get_current_function().RegisterBlockEnd({target}, opcode);
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} break;
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case SpvOpBranchConditional: {
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uint32_t tlabel = inst->words[inst->operands[1].offset];
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uint32_t flabel = inst->words[inst->operands[2].offset];
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CFG_ASSERT(FirstBlockAssert, tlabel);
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CFG_ASSERT(FirstBlockAssert, flabel);
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_.get_current_function().RegisterBlockEnd({tlabel, flabel}, opcode);
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} break;
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case SpvOpSwitch: {
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vector<uint32_t> cases;
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for (int i = 1; i < inst->num_operands; i += 2) {
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uint32_t target = inst->words[inst->operands[i].offset];
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CFG_ASSERT(FirstBlockAssert, target);
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cases.push_back(target);
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}
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_.get_current_function().RegisterBlockEnd({cases}, opcode);
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} break;
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case SpvOpKill:
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case SpvOpReturn:
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case SpvOpReturnValue:
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case SpvOpUnreachable:
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_.get_current_function().RegisterBlockEnd({}, opcode);
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break;
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default:
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break;
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}
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return SPV_SUCCESS;
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}
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} // namespace libspirv
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