lib/Target/TargetMachine.cpp

   1 //===-- TargetMachine.cpp - General Target Information ---------------------==//
   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 describes the general parts of a Target machine.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/CodeGen/MachineFunction.h"
  15 #include "llvm/CodeGen/MachineFrameInfo.h"
  16 #include "llvm/MC/MCAsmInfo.h"
  17 #include "llvm/Target/TargetMachine.h"
  18 #include "llvm/Target/TargetOptions.h"
  19 #include "llvm/Support/CommandLine.h"
  20 using namespace llvm;
  21
  22 //---------------------------------------------------------------------------
  23 // Command-line options that tend to be useful on more than one back-end.
  24 //
  25
  26 namespace llvm {
  27   bool LessPreciseFPMADOption;
  28   bool PrintMachineCode;
  29   bool NoFramePointerElim;
  30   bool NoFramePointerElimNonLeaf;
  31   bool NoExcessFPPrecision;
  32   bool UnsafeFPMath;
  33   bool NoInfsFPMath;
  34   bool NoNaNsFPMath;
  35   bool HonorSignDependentRoundingFPMathOption;
  36   bool UseSoftFloat;
  37   FloatABI::ABIType FloatABIType;
  38   bool NoImplicitFloat;
  39   bool NoZerosInBSS;
  40   bool JITExceptionHandling;
  41   bool JITEmitDebugInfo;
  42   bool JITEmitDebugInfoToDisk;
  43   bool UnwindTablesMandatory;
  44   Reloc::Model RelocationModel;
  45   CodeModel::Model CMModel;
  46   bool GuaranteedTailCallOpt;
  47   unsigned StackAlignment;
  48   bool RealignStack;
  49   bool DisableJumpTables;
  50   bool StrongPHIElim;
  51   bool AsmVerbosityDefault(false);
  52 }
  53
  54 static cl::opt<bool, true>
  55 PrintCode("print-machineinstrs",
  56   cl::desc("Print generated machine code"),
  57   cl::location(PrintMachineCode), cl::init(false));
  58 static cl::opt<bool, true>
  59 DisableFPElim("disable-fp-elim",
  60   cl::desc("Disable frame pointer elimination optimization"),
  61   cl::location(NoFramePointerElim),
  62   cl::init(false));
  63 static cl::opt<bool, true>
  64 DisableFPElimNonLeaf("disable-non-leaf-fp-elim",
  65   cl::desc("Disable frame pointer elimination optimization for non-leaf funcs"),
  66   cl::location(NoFramePointerElimNonLeaf),
  67   cl::init(false));
  68 static cl::opt<bool, true>
  69 DisableExcessPrecision("disable-excess-fp-precision",
  70   cl::desc("Disable optimizations that may increase FP precision"),
  71   cl::location(NoExcessFPPrecision),
  72   cl::init(false));
  73 static cl::opt<bool, true>
  74 EnableFPMAD("enable-fp-mad",
  75   cl::desc("Enable less precise MAD instructions to be generated"),
  76   cl::location(LessPreciseFPMADOption),
  77   cl::init(false));
  78 static cl::opt<bool, true>
  79 EnableUnsafeFPMath("enable-unsafe-fp-math",
  80   cl::desc("Enable optimizations that may decrease FP precision"),
  81   cl::location(UnsafeFPMath),
  82   cl::init(false));
  83 static cl::opt<bool, true>
  84 EnableNoInfsFPMath("enable-no-infs-fp-math",
  85   cl::desc("Enable FP math optimizations that assume no +-Infs"),
  86   cl::location(NoInfsFPMath),
  87   cl::init(false));
  88 static cl::opt<bool, true>
  89 EnableNoNaNsFPMath("enable-no-nans-fp-math",
  90   cl::desc("Enable FP math optimizations that assume no NaNs"),
  91   cl::location(NoNaNsFPMath),
  92   cl::init(false));
  93 static cl::opt<bool, true>
  94 EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
  95   cl::Hidden,
  96   cl::desc("Force codegen to assume rounding mode can change dynamically"),
  97   cl::location(HonorSignDependentRoundingFPMathOption),
  98   cl::init(false));
  99 static cl::opt<bool, true>
 100 GenerateSoftFloatCalls("soft-float",
 101   cl::desc("Generate software floating point library calls"),
 102   cl::location(UseSoftFloat),
 103   cl::init(false));
 104 static cl::opt<llvm::FloatABI::ABIType, true>
 105 FloatABIForCalls("float-abi",
 106   cl::desc("Choose float ABI type"),
 107   cl::location(FloatABIType),
 108   cl::init(FloatABI::Default),
 109   cl::values(
 110     clEnumValN(FloatABI::Default, "default",
 111                "Target default float ABI type"),
 112     clEnumValN(FloatABI::Soft, "soft",
 113                "Soft float ABI (implied by -soft-float)"),
 114     clEnumValN(FloatABI::Hard, "hard",
 115                "Hard float ABI (uses FP registers)"),
 116     clEnumValEnd));
 117 static cl::opt<bool, true>
 118 DontPlaceZerosInBSS("nozero-initialized-in-bss",
 119   cl::desc("Don't place zero-initialized symbols into bss section"),
 120   cl::location(NoZerosInBSS),
 121   cl::init(false));
 122 static cl::opt<bool, true>
 123 EnableJITExceptionHandling("jit-enable-eh",
 124   cl::desc("Emit exception handling information"),
 125   cl::location(JITExceptionHandling),
 126   cl::init(false));
 127 // In debug builds, make this default to true.
 128 #ifdef NDEBUG
 129 #define EMIT_DEBUG false
 130 #else
 131 #define EMIT_DEBUG true
 132 #endif
 133 static cl::opt<bool, true>
 134 EmitJitDebugInfo("jit-emit-debug",
 135   cl::desc("Emit debug information to debugger"),
 136   cl::location(JITEmitDebugInfo),
 137   cl::init(EMIT_DEBUG));
 138 #undef EMIT_DEBUG
 139 static cl::opt<bool, true>
 140 EmitJitDebugInfoToDisk("jit-emit-debug-to-disk",
 141   cl::Hidden,
 142   cl::desc("Emit debug info objfiles to disk"),
 143   cl::location(JITEmitDebugInfoToDisk),
 144   cl::init(false));
 145 static cl::opt<bool, true>
 146 EnableUnwindTables("unwind-tables",
 147   cl::desc("Generate unwinding tables for all functions"),
 148   cl::location(UnwindTablesMandatory),
 149   cl::init(false));
 150
 151 static cl::opt<llvm::Reloc::Model, true>
 152 DefRelocationModel("relocation-model",
 153   cl::desc("Choose relocation model"),
 154   cl::location(RelocationModel),
 155   cl::init(Reloc::Default),
 156   cl::values(
 157     clEnumValN(Reloc::Default, "default",
 158                "Target default relocation model"),
 159     clEnumValN(Reloc::Static, "static",
 160                "Non-relocatable code"),
 161     clEnumValN(Reloc::PIC_, "pic",
 162                "Fully relocatable, position independent code"),
 163     clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
 164                "Relocatable external references, non-relocatable code"),
 165     clEnumValEnd));
 166 static cl::opt<llvm::CodeModel::Model, true>
 167 DefCodeModel("code-model",
 168   cl::desc("Choose code model"),
 169   cl::location(CMModel),
 170   cl::init(CodeModel::Default),
 171   cl::values(
 172     clEnumValN(CodeModel::Default, "default",
 173                "Target default code model"),
 174     clEnumValN(CodeModel::Small, "small",
 175                "Small code model"),
 176     clEnumValN(CodeModel::Kernel, "kernel",
 177                "Kernel code model"),
 178     clEnumValN(CodeModel::Medium, "medium",
 179                "Medium code model"),
 180     clEnumValN(CodeModel::Large, "large",
 181                "Large code model"),
 182     clEnumValEnd));
 183 static cl::opt<bool, true>
 184 EnableGuaranteedTailCallOpt("tailcallopt",
 185   cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
 186   cl::location(GuaranteedTailCallOpt),
 187   cl::init(false));
 188 static cl::opt<unsigned, true>
 189 OverrideStackAlignment("stack-alignment",
 190   cl::desc("Override default stack alignment"),
 191   cl::location(StackAlignment),
 192   cl::init(0));
 193 static cl::opt<bool, true>
 194 EnableRealignStack("realign-stack",
 195   cl::desc("Realign stack if needed"),
 196   cl::location(RealignStack),
 197   cl::init(true));
 198 static cl::opt<bool, true>
 199 DisableSwitchTables(cl::Hidden, "disable-jump-tables",
 200   cl::desc("Do not generate jump tables."),
 201   cl::location(DisableJumpTables),
 202   cl::init(false));
 203 static cl::opt<bool, true>
 204 EnableStrongPHIElim(cl::Hidden, "strong-phi-elim",
 205   cl::desc("Use strong PHI elimination."),
 206   cl::location(StrongPHIElim),
 207   cl::init(false));
 208 static cl::opt<bool>
 209 DataSections("fdata-sections",
 210   cl::desc("Emit data into separate sections"),
 211   cl::init(false));
 212 static cl::opt<bool>
 213 FunctionSections("ffunction-sections",
 214   cl::desc("Emit functions into separate sections"),
 215   cl::init(false));
 216 //---------------------------------------------------------------------------
 217 // TargetMachine Class
 218 //
 219
 220 TargetMachine::TargetMachine(const Target &T)
 221   : TheTarget(T), AsmInfo(0),
 222     MCRelaxAll(false),
 223     MCUseLoc(true) {
 224   // Typically it will be subtargets that will adjust FloatABIType from Default
 225   // to Soft or Hard.
 226   if (UseSoftFloat)
 227     FloatABIType = FloatABI::Soft;
 228 }
 229
 230 TargetMachine::~TargetMachine() {
 231   delete AsmInfo;
 232 }
 233
 234 /// getRelocationModel - Returns the code generation relocation model. The
 235 /// choices are static, PIC, and dynamic-no-pic, and target default.
 236 Reloc::Model TargetMachine::getRelocationModel() {
 237   return RelocationModel;
 238 }
 239
 240 /// setRelocationModel - Sets the code generation relocation model.
 241 void TargetMachine::setRelocationModel(Reloc::Model Model) {
 242   RelocationModel = Model;
 243 }
 244
 245 /// getCodeModel - Returns the code model. The choices are small, kernel,
 246 /// medium, large, and target default.
 247 CodeModel::Model TargetMachine::getCodeModel() {
 248   return CMModel;
 249 }
 250
 251 /// setCodeModel - Sets the code model.
 252 void TargetMachine::setCodeModel(CodeModel::Model Model) {
 253   CMModel = Model;
 254 }
 255
 256 bool TargetMachine::getAsmVerbosityDefault() {
 257   return AsmVerbosityDefault;
 258 }
 259
 260 void TargetMachine::setAsmVerbosityDefault(bool V) {
 261   AsmVerbosityDefault = V;
 262 }
 263
 264 bool TargetMachine::getFunctionSections() {
 265   return FunctionSections;
 266 }
 267
 268 bool TargetMachine::getDataSections() {
 269   return DataSections;
 270 }
 271
 272 void TargetMachine::setFunctionSections(bool V) {
 273   FunctionSections = V;
 274 }
 275
 276 void TargetMachine::setDataSections(bool V) {
 277   DataSections = V;
 278 }
 279
 280 namespace llvm {
 281   /// DisableFramePointerElim - This returns true if frame pointer elimination
 282   /// optimization should be disabled for the given machine function.
 283   bool DisableFramePointerElim(const MachineFunction &MF) {
 284     // Check to see if we should eliminate non-leaf frame pointers and then
 285     // check to see if we should eliminate all frame pointers.
 286     if (NoFramePointerElimNonLeaf && !NoFramePointerElim) {
 287       const MachineFrameInfo *MFI = MF.getFrameInfo();
 288       return MFI->hasCalls();
 289     }
 290
 291     return NoFramePointerElim;
 292   }
 293
 294   /// LessPreciseFPMAD - This flag return true when -enable-fp-mad option
 295   /// is specified on the command line.  When this flag is off(default), the
 296   /// code generator is not allowed to generate mad (multiply add) if the
 297   /// result is "less precise" than doing those operations individually.
 298   bool LessPreciseFPMAD() { return UnsafeFPMath || LessPreciseFPMADOption; }
 299
 300   /// HonorSignDependentRoundingFPMath - Return true if the codegen must assume
 301   /// that the rounding mode of the FPU can change from its default.
 302   bool HonorSignDependentRoundingFPMath() {
 303     return !UnsafeFPMath && HonorSignDependentRoundingFPMathOption;
 304   }
 305 }