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      1 //===-- SITypeRewriter.cpp - Remove unwanted types ------------------------===//
      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 /// \file
     11 /// This pass removes performs the following type substitution on all
     12 /// non-compute shaders:
     13 ///
     14 /// v16i8 => i128
     15 ///   - v16i8 is used for constant memory resource descriptors.  This type is
     16 ///      legal for some compute APIs, and we don't want to declare it as legal
     17 ///      in the backend, because we want the legalizer to expand all v16i8
     18 ///      operations.
     19 /// v1* => *
     20 ///   - Having v1* types complicates the legalizer and we can easily replace
     21 ///   - them with the element type.
     22 //===----------------------------------------------------------------------===//
     23 
     24 #include "AMDGPU.h"
     25 #include "Utils/AMDGPUBaseInfo.h"
     26 #include "llvm/IR/IRBuilder.h"
     27 #include "llvm/IR/InstVisitor.h"
     28 
     29 using namespace llvm;
     30 
     31 namespace {
     32 
     33 class SITypeRewriter : public FunctionPass,
     34                        public InstVisitor<SITypeRewriter> {
     35 
     36   static char ID;
     37   Module *Mod;
     38   Type *v16i8;
     39   Type *v4i32;
     40 
     41 public:
     42   SITypeRewriter() : FunctionPass(ID) { }
     43   bool doInitialization(Module &M) override;
     44   bool runOnFunction(Function &F) override;
     45   const char *getPassName() const override {
     46     return "SI Type Rewriter";
     47   }
     48   void visitLoadInst(LoadInst &I);
     49   void visitCallInst(CallInst &I);
     50   void visitBitCast(BitCastInst &I);
     51 };
     52 
     53 } // End anonymous namespace
     54 
     55 char SITypeRewriter::ID = 0;
     56 
     57 bool SITypeRewriter::doInitialization(Module &M) {
     58   Mod = &M;
     59   v16i8 = VectorType::get(Type::getInt8Ty(M.getContext()), 16);
     60   v4i32 = VectorType::get(Type::getInt32Ty(M.getContext()), 4);
     61   return false;
     62 }
     63 
     64 bool SITypeRewriter::runOnFunction(Function &F) {
     65   if (AMDGPU::getShaderType(F) == ShaderType::COMPUTE)
     66     return false;
     67 
     68   visit(F);
     69   visit(F);
     70 
     71   return false;
     72 }
     73 
     74 void SITypeRewriter::visitLoadInst(LoadInst &I) {
     75   Value *Ptr = I.getPointerOperand();
     76   Type *PtrTy = Ptr->getType();
     77   Type *ElemTy = PtrTy->getPointerElementType();
     78   IRBuilder<> Builder(&I);
     79   if (ElemTy == v16i8)  {
     80     Value *BitCast = Builder.CreateBitCast(Ptr,
     81         PointerType::get(v4i32,PtrTy->getPointerAddressSpace()));
     82     LoadInst *Load = Builder.CreateLoad(BitCast);
     83     SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
     84     I.getAllMetadataOtherThanDebugLoc(MD);
     85     for (unsigned i = 0, e = MD.size(); i != e; ++i) {
     86       Load->setMetadata(MD[i].first, MD[i].second);
     87     }
     88     Value *BitCastLoad = Builder.CreateBitCast(Load, I.getType());
     89     I.replaceAllUsesWith(BitCastLoad);
     90     I.eraseFromParent();
     91   }
     92 }
     93 
     94 void SITypeRewriter::visitCallInst(CallInst &I) {
     95   IRBuilder<> Builder(&I);
     96 
     97   SmallVector <Value*, 8> Args;
     98   SmallVector <Type*, 8> Types;
     99   bool NeedToReplace = false;
    100   Function *F = I.getCalledFunction();
    101   std::string Name = F->getName();
    102   for (unsigned i = 0, e = I.getNumArgOperands(); i != e; ++i) {
    103     Value *Arg = I.getArgOperand(i);
    104     if (Arg->getType() == v16i8) {
    105       Args.push_back(Builder.CreateBitCast(Arg, v4i32));
    106       Types.push_back(v4i32);
    107       NeedToReplace = true;
    108       Name = Name + ".v4i32";
    109     } else if (Arg->getType()->isVectorTy() &&
    110                Arg->getType()->getVectorNumElements() == 1 &&
    111                Arg->getType()->getVectorElementType() ==
    112                                               Type::getInt32Ty(I.getContext())){
    113       Type *ElementTy = Arg->getType()->getVectorElementType();
    114       std::string TypeName = "i32";
    115       InsertElementInst *Def = cast<InsertElementInst>(Arg);
    116       Args.push_back(Def->getOperand(1));
    117       Types.push_back(ElementTy);
    118       std::string VecTypeName = "v1" + TypeName;
    119       Name = Name.replace(Name.find(VecTypeName), VecTypeName.length(), TypeName);
    120       NeedToReplace = true;
    121     } else {
    122       Args.push_back(Arg);
    123       Types.push_back(Arg->getType());
    124     }
    125   }
    126 
    127   if (!NeedToReplace) {
    128     return;
    129   }
    130   Function *NewF = Mod->getFunction(Name);
    131   if (!NewF) {
    132     NewF = Function::Create(FunctionType::get(F->getReturnType(), Types, false), GlobalValue::ExternalLinkage, Name, Mod);
    133     NewF->setAttributes(F->getAttributes());
    134   }
    135   I.replaceAllUsesWith(Builder.CreateCall(NewF, Args));
    136   I.eraseFromParent();
    137 }
    138 
    139 void SITypeRewriter::visitBitCast(BitCastInst &I) {
    140   IRBuilder<> Builder(&I);
    141   if (I.getDestTy() != v4i32) {
    142     return;
    143   }
    144 
    145   if (BitCastInst *Op = dyn_cast<BitCastInst>(I.getOperand(0))) {
    146     if (Op->getSrcTy() == v4i32) {
    147       I.replaceAllUsesWith(Op->getOperand(0));
    148       I.eraseFromParent();
    149     }
    150   }
    151 }
    152 
    153 FunctionPass *llvm::createSITypeRewriter() {
    154   return new SITypeRewriter();
    155 }
    156