xref: /freebsd/contrib/llvm-project/llvm/lib/Transforms/Utils/LowerInvoke.cpp (revision d500a85e640d1cd270747c12e17c511b53864436)
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
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 
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->getCalledOperand(),
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 
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.
87 FunctionPass *createLowerInvokePass() { return new LowerInvokeLegacyPass(); }
88 
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