1//===- LowerInvoke.cpp - Eliminate Invoke instructions --------------------===//
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 transformation is designed for use by code generators which do not yet
10// support stack unwinding. This pass converts 'invoke' instructions to 'call'
11// instructions, so that any exception-handling 'landingpad' blocks become dead
12// code (which can be removed by running the '-simplifycfg' pass afterwards).
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/Transforms/Utils/LowerInvoke.h"
17#include "llvm/ADT/SmallVector.h"
18#include "llvm/ADT/Statistic.h"
19#include "llvm/IR/Instructions.h"
20#include "llvm/InitializePasses.h"
21#include "llvm/Pass.h"
22#include "llvm/Transforms/Utils.h"
23using namespace llvm;
24
25#define DEBUG_TYPE "lower-invoke"
26
27STATISTIC(NumInvokes, "Number of invokes replaced");
28
29namespace {
30 class LowerInvokeLegacyPass : public FunctionPass {
31 public:
32 static char ID; // Pass identification, replacement for typeid
33 explicit LowerInvokeLegacyPass() : FunctionPass(ID) {
34 initializeLowerInvokeLegacyPassPass(*PassRegistry::getPassRegistry());
35 }
36 bool runOnFunction(Function &F) override;
37 };
38}
39
40char LowerInvokeLegacyPass::ID = 0;
41INITIALIZE_PASS(LowerInvokeLegacyPass, "lowerinvoke",
42 "Lower invoke and unwind, for unwindless code generators",
43 false, false)
44
45static bool runImpl(Function &F) {
46 bool Changed = false;
47 for (BasicBlock &BB : F)
48 if (InvokeInst *II = dyn_cast<InvokeInst>(Val: BB.getTerminator())) {
49 SmallVector<Value *, 16> CallArgs(II->args());
50 SmallVector<OperandBundleDef, 1> OpBundles;
51 II->getOperandBundlesAsDefs(Defs&: OpBundles);
52 // Insert a normal call instruction...
53 CallInst *NewCall =
54 CallInst::Create(Ty: II->getFunctionType(), Func: II->getCalledOperand(),
55 Args: CallArgs, Bundles: OpBundles, NameStr: "", InsertBefore: II->getIterator());
56 NewCall->takeName(V: II);
57 NewCall->setCallingConv(II->getCallingConv());
58 NewCall->setAttributes(II->getAttributes());
59 NewCall->setDebugLoc(II->getDebugLoc());
60 II->replaceAllUsesWith(V: NewCall);
61
62 // Insert an unconditional branch to the normal destination.
63 BranchInst::Create(IfTrue: II->getNormalDest(), InsertBefore: II->getIterator());
64
65 // Remove any PHI node entries from the exception destination.
66 II->getUnwindDest()->removePredecessor(Pred: &BB);
67
68 // Remove the invoke instruction now.
69 II->eraseFromParent();
70
71 ++NumInvokes;
72 Changed = true;
73 }
74 return Changed;
75}
76
77bool LowerInvokeLegacyPass::runOnFunction(Function &F) {
78 return runImpl(F);
79}
80
81namespace llvm {
82char &LowerInvokePassID = LowerInvokeLegacyPass::ID;
83
84// Public Interface To the LowerInvoke pass.
85FunctionPass *createLowerInvokePass() { return new LowerInvokeLegacyPass(); }
86
87PreservedAnalyses LowerInvokePass::run(Function &F,
88 FunctionAnalysisManager &AM) {
89 bool Changed = runImpl(F);
90 if (!Changed)
91 return PreservedAnalyses::all();
92
93 return PreservedAnalyses::none();
94}
95}
96