1 //===- LowerInvoke.cpp - Eliminate Invoke instructions --------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This transformation is designed for use by code generators which do not yet
11 // support stack unwinding. This pass converts 'invoke' instructions to 'call'
12 // instructions, so that any exception-handling 'landingpad' blocks become dead
13 // code (which can be removed by running the '-simplifycfg' pass afterwards).
14 //
15 //===----------------------------------------------------------------------===//
16
17 #include "llvm/Transforms/Utils/LowerInvoke.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/IR/Instructions.h"
21 #include "llvm/IR/LLVMContext.h"
22 #include "llvm/IR/Module.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->getCalledValue(), CallArgs, OpBundles, "", II);
57 NewCall->takeName(II);
58 NewCall->setCallingConv(II->getCallingConv());
59 NewCall->setAttributes(II->getAttributes());
60 NewCall->setDebugLoc(II->getDebugLoc());
61 II->replaceAllUsesWith(NewCall);
62
63 // Insert an unconditional branch to the normal destination.
64 BranchInst::Create(II->getNormalDest(), II);
65
66 // Remove any PHI node entries from the exception destination.
67 II->getUnwindDest()->removePredecessor(&BB);
68
69 // Remove the invoke instruction now.
70 BB.getInstList().erase(II);
71
72 ++NumInvokes;
73 Changed = true;
74 }
75 return Changed;
76 }
77
runOnFunction(Function & F)78 bool LowerInvokeLegacyPass::runOnFunction(Function &F) {
79 return runImpl(F);
80 }
81
82 namespace llvm {
83 char &LowerInvokePassID = LowerInvokeLegacyPass::ID;
84
85 // Public Interface To the LowerInvoke pass.
createLowerInvokePass()86 FunctionPass *createLowerInvokePass() { return new LowerInvokeLegacyPass(); }
87
run(Function & F,FunctionAnalysisManager & AM)88 PreservedAnalyses LowerInvokePass::run(Function &F,
89 FunctionAnalysisManager &AM) {
90 bool Changed = runImpl(F);
91 if (!Changed)
92 return PreservedAnalyses::all();
93
94 return PreservedAnalyses::none();
95 }
96 }
97