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1 //===- PreISelIntrinsicLowering.cpp - Pre-ISel intrinsic lowering pass ----===//
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2 //
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3 // The LLVM Compiler Infrastructure
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4 //
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5 // This file is distributed under the University of Illinois Open Source
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6 // License. See LICENSE.TXT for details.
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7 //
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8 //===----------------------------------------------------------------------===//
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9 //
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10 // This pass implements IR lowering for the llvm.load.relative intrinsic.
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11 //
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12 //===----------------------------------------------------------------------===//
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13
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14 #include "llvm/CodeGen/PreISelIntrinsicLowering.h"
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15 #include "llvm/CodeGen/Passes.h"
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16 #include "llvm/IR/Function.h"
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17 #include "llvm/IR/IRBuilder.h"
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18 #include "llvm/IR/Instructions.h"
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19 #include "llvm/IR/Module.h"
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20 #include "llvm/IR/Type.h"
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21 #include "llvm/IR/User.h"
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22 #include "llvm/Pass.h"
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23 #include "llvm/Support/Casting.h"
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24
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25 using namespace llvm;
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26
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27 static bool lowerLoadRelative(Function &F) {
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28 if (F.use_empty())
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29 return false;
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30
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31 bool Changed = false;
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32 Type *Int32Ty = Type::getInt32Ty(F.getContext());
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33 Type *Int32PtrTy = Int32Ty->getPointerTo();
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34 Type *Int8Ty = Type::getInt8Ty(F.getContext());
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35
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36 for (auto I = F.use_begin(), E = F.use_end(); I != E;) {
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37 auto CI = dyn_cast<CallInst>(I->getUser());
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38 ++I;
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39 if (!CI || CI->getCalledValue() != &F)
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40 continue;
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41
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42 IRBuilder<> B(CI);
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43 Value *OffsetPtr =
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44 B.CreateGEP(Int8Ty, CI->getArgOperand(0), CI->getArgOperand(1));
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45 Value *OffsetPtrI32 = B.CreateBitCast(OffsetPtr, Int32PtrTy);
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46 Value *OffsetI32 = B.CreateAlignedLoad(OffsetPtrI32, 4);
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47
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48 Value *ResultPtr = B.CreateGEP(Int8Ty, CI->getArgOperand(0), OffsetI32);
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49
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50 CI->replaceAllUsesWith(ResultPtr);
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51 CI->eraseFromParent();
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52 Changed = true;
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53 }
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54
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55 return Changed;
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56 }
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57
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58 static bool lowerIntrinsics(Module &M) {
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59 bool Changed = false;
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60 for (Function &F : M) {
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61 if (F.getName().startswith("llvm.load.relative."))
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62 Changed |= lowerLoadRelative(F);
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63 }
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64 return Changed;
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65 }
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66
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67 namespace {
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68
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69 class PreISelIntrinsicLoweringLegacyPass : public ModulePass {
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70 public:
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71 static char ID;
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72
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73 PreISelIntrinsicLoweringLegacyPass() : ModulePass(ID) {}
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74
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75 bool runOnModule(Module &M) override { return lowerIntrinsics(M); }
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76 };
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77
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78 } // end anonymous namespace
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79
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80 char PreISelIntrinsicLoweringLegacyPass::ID;
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81
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82 INITIALIZE_PASS(PreISelIntrinsicLoweringLegacyPass,
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83 "pre-isel-intrinsic-lowering", "Pre-ISel Intrinsic Lowering",
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84 false, false)
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85
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86 ModulePass *llvm::createPreISelIntrinsicLoweringPass() {
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87 return new PreISelIntrinsicLoweringLegacyPass;
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88 }
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89
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90 PreservedAnalyses PreISelIntrinsicLoweringPass::run(Module &M,
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91 ModuleAnalysisManager &AM) {
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92 if (!lowerIntrinsics(M))
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93 return PreservedAnalyses::all();
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94 else
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95 return PreservedAnalyses::none();
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96 }
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