1 //===- PreISelIntrinsicLowering.cpp - Pre-ISel intrinsic lowering pass ----===//
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 pass implements IR lowering for the llvm.load.relative intrinsic.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/CodeGen/PreISelIntrinsicLowering.h"
15 #include "llvm/CodeGen/Passes.h"
16 #include "llvm/IR/Function.h"
17 #include "llvm/IR/IRBuilder.h"
18 #include "llvm/IR/Instructions.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/IR/Type.h"
21 #include "llvm/IR/User.h"
22 #include "llvm/Pass.h"
23 #include "llvm/Support/Casting.h"
24
25 using namespace llvm;
26
lowerLoadRelative(Function & F)27 static bool lowerLoadRelative(Function &F) {
28 if (F.use_empty())
29 return false;
30
31 bool Changed = false;
32 Type *Int32Ty = Type::getInt32Ty(F.getContext());
33 Type *Int32PtrTy = Int32Ty->getPointerTo();
34 Type *Int8Ty = Type::getInt8Ty(F.getContext());
35
36 for (auto I = F.use_begin(), E = F.use_end(); I != E;) {
37 auto CI = dyn_cast<CallInst>(I->getUser());
38 ++I;
39 if (!CI || CI->getCalledValue() != &F)
40 continue;
41
42 IRBuilder<> B(CI);
43 Value *OffsetPtr =
44 B.CreateGEP(Int8Ty, CI->getArgOperand(0), CI->getArgOperand(1));
45 Value *OffsetPtrI32 = B.CreateBitCast(OffsetPtr, Int32PtrTy);
46 Value *OffsetI32 = B.CreateAlignedLoad(OffsetPtrI32, 4);
47
48 Value *ResultPtr = B.CreateGEP(Int8Ty, CI->getArgOperand(0), OffsetI32);
49
50 CI->replaceAllUsesWith(ResultPtr);
51 CI->eraseFromParent();
52 Changed = true;
53 }
54
55 return Changed;
56 }
57
lowerIntrinsics(Module & M)58 static bool lowerIntrinsics(Module &M) {
59 bool Changed = false;
60 for (Function &F : M) {
61 if (F.getName().startswith("llvm.load.relative."))
62 Changed |= lowerLoadRelative(F);
63 }
64 return Changed;
65 }
66
67 namespace {
68
69 class PreISelIntrinsicLoweringLegacyPass : public ModulePass {
70 public:
71 static char ID;
72
PreISelIntrinsicLoweringLegacyPass()73 PreISelIntrinsicLoweringLegacyPass() : ModulePass(ID) {}
74
runOnModule(Module & M)75 bool runOnModule(Module &M) override { return lowerIntrinsics(M); }
76 };
77
78 } // end anonymous namespace
79
80 char PreISelIntrinsicLoweringLegacyPass::ID;
81
82 INITIALIZE_PASS(PreISelIntrinsicLoweringLegacyPass,
83 "pre-isel-intrinsic-lowering", "Pre-ISel Intrinsic Lowering",
84 false, false)
85
createPreISelIntrinsicLoweringPass()86 ModulePass *llvm::createPreISelIntrinsicLoweringPass() {
87 return new PreISelIntrinsicLoweringLegacyPass;
88 }
89
run(Module & M,ModuleAnalysisManager & AM)90 PreservedAnalyses PreISelIntrinsicLoweringPass::run(Module &M,
91 ModuleAnalysisManager &AM) {
92 if (!lowerIntrinsics(M))
93 return PreservedAnalyses::all();
94 else
95 return PreservedAnalyses::none();
96 }
97