LLVM  3.7.0
LowerInvoke.cpp
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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/Scalar.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"
25 using namespace llvm;
26 
27 #define DEBUG_TYPE "lowerinvoke"
28 
29 STATISTIC(NumInvokes, "Number of invokes replaced");
30 
31 namespace {
32  class LowerInvoke : public FunctionPass {
33  public:
34  static char ID; // Pass identification, replacement for typeid
35  explicit LowerInvoke() : FunctionPass(ID) {
37  }
38  bool runOnFunction(Function &F) override;
39  };
40 }
41 
42 char LowerInvoke::ID = 0;
43 INITIALIZE_PASS(LowerInvoke, "lowerinvoke",
44  "Lower invoke and unwind, for unwindless code generators",
45  false, false)
46 
47 char &llvm::LowerInvokePassID = LowerInvoke::ID;
48 
49 // Public Interface To the LowerInvoke pass.
51  return new LowerInvoke();
52 }
53 
54 bool LowerInvoke::runOnFunction(Function &F) {
55  bool Changed = false;
56  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
57  if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
58  SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
59  // Insert a normal call instruction...
60  CallInst *NewCall = CallInst::Create(II->getCalledValue(),
61  CallArgs, "", II);
62  NewCall->takeName(II);
63  NewCall->setCallingConv(II->getCallingConv());
64  NewCall->setAttributes(II->getAttributes());
65  NewCall->setDebugLoc(II->getDebugLoc());
66  II->replaceAllUsesWith(NewCall);
67 
68  // Insert an unconditional branch to the normal destination.
69  BranchInst::Create(II->getNormalDest(), II);
70 
71  // Remove any PHI node entries from the exception destination.
72  II->getUnwindDest()->removePredecessor(BB);
73 
74  // Remove the invoke instruction now.
75  BB->getInstList().erase(II);
76 
77  ++NumInvokes; Changed = true;
78  }
79  return Changed;
80 }
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
STATISTIC(NumFunctions,"Total number of functions")
iterator end()
Definition: Function.h:459
CallInst - This class represents a function call, abstracting a target machine's calling convention...
F(f)
static CallInst * Create(Value *Func, ArrayRef< Value * > Args, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
iterator begin()
Definition: Function.h:457
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:294
char & LowerInvokePassID
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:56
void initializeLowerInvokePass(PassRegistry &)
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
Module.h This file contains the declarations for the Module class.
static BranchInst * Create(BasicBlock *IfTrue, Instruction *InsertBefore=nullptr)
FunctionPass * createLowerInvokePass()
InvokeInst - Invoke instruction.