llvm/lib/Target/Mips/MipsOs16.cpp

   1 //===---- MipsOs16.cpp for Mips Option -Os16                       --------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines an optimization phase for the MIPS target.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "Mips.h"
  14 #include "llvm/IR/Instructions.h"
  15 #include "llvm/IR/Module.h"
  16 #include "llvm/Pass.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     StringRef getPassName() const override { return "MIPS Os16 Optimization"; }
  39
  40     bool runOnModule(Module &M) override;
  41   };
  42
  43   char MipsOs16::ID = 0;
  44 }
  45
  46 // Figure out if we need float point based on the function signature.
  47 // We need to move variables in and/or out of floating point
  48 // registers because of the ABI
  49 //
  50 static  bool needsFPFromSig(Function &F) {
  51   Type* RetType = F.getReturnType();
  52   switch (RetType->getTypeID()) {
  53   case Type::FloatTyID:
  54   case Type::DoubleTyID:
  55     return true;
  56   default:
  57     ;
  58   }
  59   if (F.arg_size() >=1) {
  60     Argument &Arg = *F.arg_begin();
  61     switch (Arg.getType()->getTypeID()) {
  62     case Type::FloatTyID:
  63     case Type::DoubleTyID:
  64       return true;
  65     default:
  66       ;
  67     }
  68   }
  69   return false;
  70 }
  71
  72 // Figure out if the function will need floating point operations
  73 //
  74 static bool needsFP(Function &F) {
  75   if (needsFPFromSig(F))
  76     return true;
  77   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
  78     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
  79          I != E; ++I) {
  80       const Instruction &Inst = *I;
  81       switch (Inst.getOpcode()) {
  82       case Instruction::FAdd:
  83       case Instruction::FSub:
  84       case Instruction::FMul:
  85       case Instruction::FDiv:
  86       case Instruction::FRem:
  87       case Instruction::FPToUI:
  88       case Instruction::FPToSI:
  89       case Instruction::UIToFP:
  90       case Instruction::SIToFP:
  91       case Instruction::FPTrunc:
  92       case Instruction::FPExt:
  93       case Instruction::FCmp:
  94         return true;
  95       default:
  96         ;
  97       }
  98       if (const CallInst *CI = dyn_cast<CallInst>(I)) {
  99         LLVM_DEBUG(dbgs() << "Working on call"
 100                           << "\n");
 101         Function &F_ =  *CI->getCalledFunction();
 102         if (needsFPFromSig(F_))
 103           return true;
 104       }
 105     }
 106   return false;
 107 }
 108
 109
 110 bool MipsOs16::runOnModule(Module &M) {
 111   bool usingMask = Mips32FunctionMask.length() > 0;
 112   bool doneUsingMask = false; // this will make it stop repeating
 113
 114   LLVM_DEBUG(dbgs() << "Run on Module MipsOs16 \n"
 115                     << Mips32FunctionMask << "\n");
 116   if (usingMask)
 117     LLVM_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     LLVM_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           LLVM_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         LLVM_DEBUG(dbgs() << "os16 forced mips32: " << F.getName() << "\n");
 148         F.addFnAttr("nomips16");
 149       }
 150       else {
 151         LLVM_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() { return new MipsOs16(); }