1 // Copyright (c) 2019 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "source/reduce/remove_block_reduction_opportunity.h"
16
17 #include "source/opt/ir_context.h"
18
19 namespace spvtools {
20 namespace reduce {
21
RemoveBlockReductionOpportunity(opt::IRContext * context,opt::Function * function,opt::BasicBlock * block)22 RemoveBlockReductionOpportunity::RemoveBlockReductionOpportunity(
23 opt::IRContext* context, opt::Function* function, opt::BasicBlock* block)
24 : context_(context), function_(function), block_(block) {
25 // precondition:
26 assert(block_->begin() != block_->end() &&
27 context_->get_def_use_mgr()->NumUsers(block_->id()) == 0 &&
28 "RemoveBlockReductionOpportunity block must have 0 references");
29 }
30
PreconditionHolds()31 bool RemoveBlockReductionOpportunity::PreconditionHolds() {
32 // Removing other blocks cannot disable this opportunity.
33 return true;
34 }
35
Apply()36 void RemoveBlockReductionOpportunity::Apply() {
37 // We need an iterator pointing to the block, hence the loop.
38 for (auto bi = function_->begin(); bi != function_->end(); ++bi) {
39 if (bi->id() == block_->id()) {
40 bi.Erase();
41 context_->InvalidateAnalysesExceptFor(opt::IRContext::kAnalysisNone);
42 return;
43 }
44 }
45
46 assert(false &&
47 "Unreachable: we should have found a block with the desired id.");
48 }
49
50 } // namespace reduce
51 } // namespace spvtools
52