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/IR/LLVMContext.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/InitializePasses.h"
23 #include "llvm/Pass.h"
24 #include "llvm/Transforms/Utils.h"
25 using namespace llvm;
26
27 #define DEBUG_TYPE "lowerinvoke"
28
29 STATISTIC(NumInvokes, "Number of invokes replaced");
30
31 namespace {
32 class LowerInvokeLegacyPass : public FunctionPass {
33 public:
34 static char ID; // Pass identification, replacement for typeid
LowerInvokeLegacyPass()35 explicit LowerInvokeLegacyPass() : FunctionPass(ID) {
36 initializeLowerInvokeLegacyPassPass(*PassRegistry::getPassRegistry());
37 }
38 bool runOnFunction(Function &F) override;
39 };
40 }
41
42 char LowerInvokeLegacyPass::ID = 0;
43 INITIALIZE_PASS(LowerInvokeLegacyPass, "lowerinvoke",
44 "Lower invoke and unwind, for unwindless code generators",
45 false, false)
46
runImpl(Function & F)47 static bool runImpl(Function &F) {
48 bool Changed = false;
49 for (BasicBlock &BB : F)
50 if (InvokeInst *II = dyn_cast<InvokeInst>(BB.getTerminator())) {
51 SmallVector<Value *, 16> CallArgs(II->arg_begin(), II->arg_end());
52 SmallVector<OperandBundleDef, 1> OpBundles;
53 II->getOperandBundlesAsDefs(OpBundles);
54 // Insert a normal call instruction...
55 CallInst *NewCall =
56 CallInst::Create(II->getFunctionType(), II->getCalledValue(),
57 CallArgs, OpBundles, "", II);
58 NewCall->takeName(II);
59 NewCall->setCallingConv(II->getCallingConv());
60 NewCall->setAttributes(II->getAttributes());
61 NewCall->setDebugLoc(II->getDebugLoc());
62 II->replaceAllUsesWith(NewCall);
63
64 // Insert an unconditional branch to the normal destination.
65 BranchInst::Create(II->getNormalDest(), II);
66
67 // Remove any PHI node entries from the exception destination.
68 II->getUnwindDest()->removePredecessor(&BB);
69
70 // Remove the invoke instruction now.
71 BB.getInstList().erase(II);
72
73 ++NumInvokes;
74 Changed = true;
75 }
76 return Changed;
77 }
78
runOnFunction(Function & F)79 bool LowerInvokeLegacyPass::runOnFunction(Function &F) {
80 return runImpl(F);
81 }
82
83 namespace llvm {
84 char &LowerInvokePassID = LowerInvokeLegacyPass::ID;
85
86 // Public Interface To the LowerInvoke pass.
createLowerInvokePass()87 FunctionPass *createLowerInvokePass() { return new LowerInvokeLegacyPass(); }
88
run(Function & F,FunctionAnalysisManager & AM)89 PreservedAnalyses LowerInvokePass::run(Function &F,
90 FunctionAnalysisManager &AM) {
91 bool Changed = runImpl(F);
92 if (!Changed)
93 return PreservedAnalyses::all();
94
95 return PreservedAnalyses::none();
96 }
97 }
98