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     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.getArgumentList().front();
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         DEBUG(dbgs() << "Working on call" << "\n");
100         Function &F_ =  *CI->getCalledFunction();
101         if (needsFPFromSig(F_))
102           return true;
103       }
104     }
105   return false;
106 }
107 
108 
109 bool MipsOs16::runOnModule(Module &M) {
110   bool usingMask = Mips32FunctionMask.length() > 0;
111   bool doneUsingMask = false; // this will make it stop repeating
112 
113   DEBUG(dbgs() << "Run on Module MipsOs16 \n" << Mips32FunctionMask << "\n");
114   if (usingMask)
115     DEBUG(dbgs() << "using mask \n" << Mips32FunctionMask << "\n");
116 
117   unsigned int functionIndex = 0;
118   bool modified = false;
119 
120   for (auto &F : M) {
121     if (F.isDeclaration())
122       continue;
123 
124     DEBUG(dbgs() << "Working on " << F.getName() << "\n");
125     if (usingMask) {
126       if (!doneUsingMask) {
127         if (functionIndex == Mips32FunctionMask.length())
128           functionIndex = 0;
129         switch (Mips32FunctionMask[functionIndex]) {
130         case '1':
131           DEBUG(dbgs() << "mask forced mips32: " << F.getName() << "\n");
132           F.addFnAttr("nomips16");
133           break;
134         case '.':
135           doneUsingMask = true;
136           break;
137         default:
138           break;
139         }
140         functionIndex++;
141       }
142     }
143     else {
144       if (needsFP(F)) {
145         DEBUG(dbgs() << "os16 forced mips32: " << F.getName() << "\n");
146         F.addFnAttr("nomips16");
147       }
148       else {
149         DEBUG(dbgs() << "os16 forced mips16: " << F.getName() << "\n");
150         F.addFnAttr("mips16");
151       }
152     }
153   }
154 
155   return modified;
156 }
157 
158 ModulePass *llvm::createMipsOs16Pass(MipsTargetMachine &TM) {
159   return new MipsOs16;
160 }
161