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[rustc.git] / src / llvm / lib / Transforms / Utils / LowerInvoke.cpp
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1a4d82fc 1//===- LowerInvoke.cpp - Eliminate Invoke instructions --------------------===//
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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
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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).
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14//
15//===----------------------------------------------------------------------===//
16
223e47cc 17#include "llvm/Transforms/Scalar.h"
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18#include "llvm/ADT/SmallVector.h"
19#include "llvm/ADT/Statistic.h"
970d7e83 20#include "llvm/IR/Instructions.h"
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21#include "llvm/IR/LLVMContext.h"
22#include "llvm/IR/Module.h"
23#include "llvm/Pass.h"
223e47cc 24#include "llvm/Support/CommandLine.h"
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25using namespace llvm;
26
1a4d82fc 27#define DEBUG_TYPE "lowerinvoke"
223e47cc 28
1a4d82fc 29STATISTIC(NumInvokes, "Number of invokes replaced");
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30
31namespace {
32 class LowerInvoke : public FunctionPass {
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33 public:
34 static char ID; // Pass identification, replacement for typeid
1a4d82fc 35 explicit LowerInvoke() : FunctionPass(ID) {
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36 initializeLowerInvokePass(*PassRegistry::getPassRegistry());
37 }
1a4d82fc 38 bool runOnFunction(Function &F) override;
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39 };
40}
41
42char LowerInvoke::ID = 0;
43INITIALIZE_PASS(LowerInvoke, "lowerinvoke",
44 "Lower invoke and unwind, for unwindless code generators",
45 false, false)
46
47char &llvm::LowerInvokePassID = LowerInvoke::ID;
48
49// Public Interface To the LowerInvoke pass.
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50FunctionPass *llvm::createLowerInvokePass() {
51 return new LowerInvoke();
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52}
53
1a4d82fc 54bool LowerInvoke::runOnFunction(Function &F) {
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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}