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::Function * function,opt::BasicBlock * block)22 RemoveBlockReductionOpportunity::RemoveBlockReductionOpportunity(
23 opt::Function* function, opt::BasicBlock* block)
24 : function_(function), block_(block) {
25 // precondition:
26 assert(block_->begin() != block_->end() &&
27 block_->begin()->context()->get_def_use_mgr()->NumUsers(
28 block_->id()) == 0 &&
29 "RemoveBlockReductionOpportunity block must have 0 references");
30 }
31
PreconditionHolds()32 bool RemoveBlockReductionOpportunity::PreconditionHolds() {
33 // Removing other blocks cannot disable this opportunity.
34 return true;
35 }
36
Apply()37 void RemoveBlockReductionOpportunity::Apply() {
38 // We need an iterator pointing to the block, hence the loop.
39 for (auto bi = function_->begin(); bi != function_->end(); ++bi) {
40 if (bi->id() == block_->id()) {
41 bi->KillAllInsts(true);
42 bi.Erase();
43 // Block removal changes the function, but we don't use analyses, so no
44 // need to invalidate them.
45 return;
46 }
47 }
48
49 assert(false &&
50 "Unreachable: we should have found a block with the desired id.");
51 }
52
53 } // namespace reduce
54 } // namespace spvtools
55