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 "llvm/ADT/STLExtras.h"
18 #include "llvm/IR/Instructions.h"
19 #include <iterator>
20 #include <vector>
21
22 using namespace llvm;
23
24 /// Removes all the Defined Functions
25 /// that aren't inside any of the desired Chunks.
extractFunctionsFromModule(const std::vector<Chunk> & ChunksToKeep,Module * Program)26 static void extractFunctionsFromModule(const std::vector<Chunk> &ChunksToKeep,
27 Module *Program) {
28 Oracle O(ChunksToKeep);
29
30 // Record all out-of-chunk functions.
31 std::vector<std::reference_wrapper<Function>> FuncsToRemove;
32 copy_if(Program->functions(), std::back_inserter(FuncsToRemove),
33 [&O](Function &F) {
34 // Intrinsics don't have function bodies that are useful to
35 // reduce. Additionally, intrinsics may have additional operand
36 // constraints. But, do drop intrinsics that are not referenced.
37 return (!F.isIntrinsic() || F.use_empty()) && !O.shouldKeep();
38 });
39
40 // Then, drop body of each of them. We want to batch this and do nothing else
41 // here so that minimal number of remaining exteranal uses will remain.
42 for (Function &F : FuncsToRemove)
43 F.dropAllReferences();
44
45 // And finally, we can actually delete them.
46 for (Function &F : FuncsToRemove) {
47 // Replace all *still* remaining uses with undef.
48 F.replaceAllUsesWith(UndefValue::get(F.getType()));
49 // And finally, fully drop it.
50 F.eraseFromParent();
51 }
52 }
53
54 /// Counts the amount of functions and prints their
55 /// respective name & index
countFunctions(Module * Program)56 static int countFunctions(Module *Program) {
57 // TODO: Silence index with --quiet flag
58 errs() << "----------------------------\n";
59 errs() << "Function Index Reference:\n";
60 int FunctionCount = 0;
61 for (auto &F : *Program) {
62 if (F.isIntrinsic() && !F.use_empty())
63 continue;
64
65 errs() << '\t' << ++FunctionCount << ": " << F.getName() << '\n';
66 }
67
68 errs() << "----------------------------\n";
69 return FunctionCount;
70 }
71
reduceFunctionsDeltaPass(TestRunner & Test)72 void llvm::reduceFunctionsDeltaPass(TestRunner &Test) {
73 errs() << "*** Reducing Functions...\n";
74 int Functions = countFunctions(Test.getProgram());
75 runDeltaPass(Test, Functions, extractFunctionsFromModule);
76 errs() << "----------------------------\n";
77 }
78