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      1 //===---- MipsOs16.cpp for Mips Option -Os16                       --------===//
      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 file defines an optimization phase for the MIPS target.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/IR/Instructions.h"
     15 #include "Mips.h"
     16 #include "llvm/IR/Module.h"
     17 #include "llvm/Support/CommandLine.h"
     18 #include "llvm/Support/Debug.h"
     19 #include "llvm/Support/raw_ostream.h"
     20 
     21 using namespace llvm;
     22 
     23 #define DEBUG_TYPE "mips-os16"
     24 
     25 static cl::opt<std::string> Mips32FunctionMask(
     26   "mips32-function-mask",
     27   cl::init(""),
     28   cl::desc("Force function to be mips32"),
     29   cl::Hidden);
     30 
     31 namespace {
     32   class MipsOs16 : public ModulePass {
     33   public:
     34     static char ID;
     35 
     36     MipsOs16() : ModulePass(ID) {}
     37 
     38     const char *getPassName() const override {
     39       return "MIPS Os16 Optimization";
     40     }
     41 
     42     bool runOnModule(Module &M) override;
     43   };
     44 
     45   char MipsOs16::ID = 0;
     46 }
     47 
     48 // Figure out if we need float point based on the function signature.
     49 // We need to move variables in and/or out of floating point
     50 // registers because of the ABI
     51 //
     52 static  bool needsFPFromSig(Function &F) {
     53   Type* RetType = F.getReturnType();
     54   switch (RetType->getTypeID()) {
     55   case Type::FloatTyID:
     56   case Type::DoubleTyID:
     57     return true;
     58   default:
     59     ;
     60   }
     61   if (F.arg_size() >=1) {
     62     Argument &Arg = F.getArgumentList().front();
     63     switch (Arg.getType()->getTypeID()) {
     64     case Type::FloatTyID:
     65     case Type::DoubleTyID:
     66       return true;
     67     default:
     68       ;
     69     }
     70   }
     71   return false;
     72 }
     73 
     74 // Figure out if the function will need floating point operations
     75 //
     76 static bool needsFP(Function &F) {
     77   if (needsFPFromSig(F))
     78     return true;
     79   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
     80     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
     81          I != E; ++I) {
     82       const Instruction &Inst = *I;
     83       switch (Inst.getOpcode()) {
     84       case Instruction::FAdd:
     85       case Instruction::FSub:
     86       case Instruction::FMul:
     87       case Instruction::FDiv:
     88       case Instruction::FRem:
     89       case Instruction::FPToUI:
     90       case Instruction::FPToSI:
     91       case Instruction::UIToFP:
     92       case Instruction::SIToFP:
     93       case Instruction::FPTrunc:
     94       case Instruction::FPExt:
     95       case Instruction::FCmp:
     96         return true;
     97       default:
     98         ;
     99       }
    100       if (const CallInst *CI = dyn_cast<CallInst>(I)) {
    101         DEBUG(dbgs() << "Working on call" << "\n");
    102         Function &F_ =  *CI->getCalledFunction();
    103         if (needsFPFromSig(F_))
    104           return true;
    105       }
    106     }
    107   return false;
    108 }
    109 
    110 
    111 bool MipsOs16::runOnModule(Module &M) {
    112   bool usingMask = Mips32FunctionMask.length() > 0;
    113   bool doneUsingMask = false; // this will make it stop repeating
    114 
    115   DEBUG(dbgs() << "Run on Module MipsOs16 \n" << Mips32FunctionMask << "\n");
    116   if (usingMask)
    117     DEBUG(dbgs() << "using mask \n" << Mips32FunctionMask << "\n");
    118 
    119   unsigned int functionIndex = 0;
    120   bool modified = false;
    121 
    122   for (auto &F : M) {
    123     if (F.isDeclaration())
    124       continue;
    125 
    126     DEBUG(dbgs() << "Working on " << F.getName() << "\n");
    127     if (usingMask) {
    128       if (!doneUsingMask) {
    129         if (functionIndex == Mips32FunctionMask.length())
    130           functionIndex = 0;
    131         switch (Mips32FunctionMask[functionIndex]) {
    132         case '1':
    133           DEBUG(dbgs() << "mask forced mips32: " << F.getName() << "\n");
    134           F.addFnAttr("nomips16");
    135           break;
    136         case '.':
    137           doneUsingMask = true;
    138           break;
    139         default:
    140           break;
    141         }
    142         functionIndex++;
    143       }
    144     }
    145     else {
    146       if (needsFP(F)) {
    147         DEBUG(dbgs() << "os16 forced mips32: " << F.getName() << "\n");
    148         F.addFnAttr("nomips16");
    149       }
    150       else {
    151         DEBUG(dbgs() << "os16 forced mips16: " << F.getName() << "\n");
    152         F.addFnAttr("mips16");
    153       }
    154     }
    155   }
    156 
    157   return modified;
    158 }
    159 
    160 ModulePass *llvm::createMipsOs16Pass(MipsTargetMachine &TM) {
    161   return new MipsOs16;
    162 }
    163