1//===- ReduceInstructions.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 uninteresting Instructions from defined functions.
11//
12//===----------------------------------------------------------------------===//
13
14#include "ReduceInstructions.h"
15#include "Utils.h"
16#include "llvm/IR/Constants.h"
17#include "llvm/IR/Instructions.h"
18
19using namespace llvm;
20
21/// Filter out cases where deleting the instruction will likely cause the
22/// user/def of the instruction to fail the verifier.
23//
24// TODO: Technically the verifier only enforces preallocated token usage and
25// there is a none token.
26static bool shouldAlwaysKeep(const Instruction &I) {
27 return I.isEHPad() || I.getType()->isTokenTy() || I.isSwiftError();
28}
29
30/// Removes out-of-chunk arguments from functions, and modifies their calls
31/// accordingly. It also removes allocations of out-of-chunk arguments.
32void llvm::reduceInstructionsDeltaPass(Oracle &O, ReducerWorkItem &WorkItem) {
33 Module &Program = WorkItem.getModule();
34
35 for (auto &F : Program) {
36 for (auto &BB : F) {
37 // Removing the terminator would make the block invalid. Only iterate over
38 // instructions before the terminator.
39 for (auto &Inst :
40 make_early_inc_range(Range: make_range(x: BB.begin(), y: std::prev(x: BB.end())))) {
41 if (!shouldAlwaysKeep(I: Inst) && !O.shouldKeep()) {
42 Inst.replaceAllUsesWith(V: isa<AllocaInst>(Val: Inst)
43 ? PoisonValue::get(T: Inst.getType())
44 : getDefaultValue(T: Inst.getType()));
45 Inst.eraseFromParent();
46 }
47 }
48 }
49 }
50}
51