1 //===- ReduceFunctions.cpp - Specialized Delta Pass -----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements a function which calls the Generic Delta pass in order
10 // to reduce functions (and any instruction that calls it) in the provided
11 // Module.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "ReduceFunctions.h"
16 #include "Delta.h"
17 #include "Utils.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/Transforms/Utils/ModuleUtils.h"
20 #include <iterator>
21
22 using namespace llvm;
23
24 /// Removes all the Defined Functions
25 /// that aren't inside any of the desired Chunks.
extractFunctionsFromModule(Oracle & O,ReducerWorkItem & WorkItem)26 static void extractFunctionsFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
27 Module &Program = WorkItem.getModule();
28
29 // Record all out-of-chunk functions.
30 SmallPtrSet<Constant *, 8> FuncsToRemove;
31 for (Function &F : Program.functions()) {
32 // Intrinsics don't have function bodies that are useful to
33 // reduce. Additionally, intrinsics may have additional operand
34 // constraints. But, do drop intrinsics that are not referenced.
35 if ((!F.isIntrinsic() || F.use_empty()) && !hasAliasOrBlockAddressUse(F) &&
36 !O.shouldKeep())
37 FuncsToRemove.insert(&F);
38 }
39
40 removeFromUsedLists(Program, [&FuncsToRemove](Constant *C) {
41 return FuncsToRemove.count(C);
42 });
43
44 // Then, drop body of each of them. We want to batch this and do nothing else
45 // here so that minimal number of remaining exteranal uses will remain.
46 for (Constant *F : FuncsToRemove)
47 F->dropAllReferences();
48
49 // And finally, we can actually delete them.
50 for (Constant *F : FuncsToRemove) {
51 // Replace all *still* remaining uses with the default value.
52 F->replaceAllUsesWith(getDefaultValue(F->getType()));
53 // And finally, fully drop it.
54 cast<Function>(F)->eraseFromParent();
55 }
56 }
57
reduceFunctionsDeltaPass(TestRunner & Test)58 void llvm::reduceFunctionsDeltaPass(TestRunner &Test) {
59 runDeltaPass(Test, extractFunctionsFromModule, "Reducing Functions");
60 }
61