1//===- LowerWidenableCondition.cpp - Lower the guard intrinsic ---------------===//
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 pass lowers the llvm.widenable.condition intrinsic to default value
10// which is i1 true.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Transforms/Scalar/LowerWidenableCondition.h"
15#include "llvm/ADT/SmallVector.h"
16#include "llvm/IR/Function.h"
17#include "llvm/IR/InstIterator.h"
18#include "llvm/IR/Instructions.h"
19#include "llvm/IR/Intrinsics.h"
20#include "llvm/IR/Module.h"
21#include "llvm/IR/PatternMatch.h"
22#include "llvm/Transforms/Scalar.h"
23
24using namespace llvm;
25
26static bool lowerWidenableCondition(Function &F) {
27 // Check if we can cheaply rule out the possibility of not having any work to
28 // do.
29 auto *WCDecl = F.getParent()->getFunction(
30 Name: Intrinsic::getName(id: Intrinsic::experimental_widenable_condition));
31 if (!WCDecl || WCDecl->use_empty())
32 return false;
33
34 using namespace llvm::PatternMatch;
35 SmallVector<CallInst *, 8> ToLower;
36 // Traverse through the users of WCDecl.
37 // This is presumably cheaper than traversing all instructions in the
38 // function.
39 for (auto *U : WCDecl->users())
40 if (auto *CI = dyn_cast<CallInst>(Val: U))
41 if (CI->getFunction() == &F)
42 ToLower.push_back(Elt: CI);
43
44 if (ToLower.empty())
45 return false;
46
47 for (auto *CI : ToLower) {
48 CI->replaceAllUsesWith(V: ConstantInt::getTrue(Context&: CI->getContext()));
49 CI->eraseFromParent();
50 }
51 return true;
52}
53
54PreservedAnalyses LowerWidenableConditionPass::run(Function &F,
55 FunctionAnalysisManager &AM) {
56 if (lowerWidenableCondition(F))
57 return PreservedAnalyses::none();
58
59 return PreservedAnalyses::all();
60}
61