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 GuaranteedTailCallOpt;
44   unsigned StackAlignmentOverride;
45   bool RealignStack;
46   bool DisableJumpTables;
47   bool StrongPHIElim;
48   bool HasDivModLibcall;
49   bool AsmVerbosityDefault(false);
50 }
51 
52 static cl::opt<bool, true>
53 PrintCode("print-machineinstrs",
54   cl::desc("Print generated machine code"),
55   cl::location(PrintMachineCode), cl::init(false));
56 static cl::opt<bool, true>
57 DisableFPElim("disable-fp-elim",
58   cl::desc("Disable frame pointer elimination optimization"),
59   cl::location(NoFramePointerElim),
60   cl::init(false));
61 static cl::opt<bool, true>
62 DisableFPElimNonLeaf("disable-non-leaf-fp-elim",
63   cl::desc("Disable frame pointer elimination optimization for non-leaf funcs"),
64   cl::location(NoFramePointerElimNonLeaf),
65   cl::init(false));
66 static cl::opt<bool, true>
67 DisableExcessPrecision("disable-excess-fp-precision",
68   cl::desc("Disable optimizations that may increase FP precision"),
69   cl::location(NoExcessFPPrecision),
70   cl::init(false));
71 static cl::opt<bool, true>
72 EnableFPMAD("enable-fp-mad",
73   cl::desc("Enable less precise MAD instructions to be generated"),
74   cl::location(LessPreciseFPMADOption),
75   cl::init(false));
76 static cl::opt<bool, true>
77 EnableUnsafeFPMath("enable-unsafe-fp-math",
78   cl::desc("Enable optimizations that may decrease FP precision"),
79   cl::location(UnsafeFPMath),
80   cl::init(false));
81 static cl::opt<bool, true>
82 EnableNoInfsFPMath("enable-no-infs-fp-math",
83   cl::desc("Enable FP math optimizations that assume no +-Infs"),
84   cl::location(NoInfsFPMath),
85   cl::init(false));
86 static cl::opt<bool, true>
87 EnableNoNaNsFPMath("enable-no-nans-fp-math",
88   cl::desc("Enable FP math optimizations that assume no NaNs"),
89   cl::location(NoNaNsFPMath),
90   cl::init(false));
91 static cl::opt<bool, true>
92 EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
93   cl::Hidden,
94   cl::desc("Force codegen to assume rounding mode can change dynamically"),
95   cl::location(HonorSignDependentRoundingFPMathOption),
96   cl::init(false));
97 static cl::opt<bool, true>
98 GenerateSoftFloatCalls("soft-float",
99   cl::desc("Generate software floating point library calls"),
100   cl::location(UseSoftFloat),
101   cl::init(false));
102 static cl::opt<llvm::FloatABI::ABIType, true>
103 FloatABIForCalls("float-abi",
104   cl::desc("Choose float ABI type"),
105   cl::location(FloatABIType),
106   cl::init(FloatABI::Default),
107   cl::values(
108     clEnumValN(FloatABI::Default, "default",
109                "Target default float ABI type"),
110     clEnumValN(FloatABI::Soft, "soft",
111                "Soft float ABI (implied by -soft-float)"),
112     clEnumValN(FloatABI::Hard, "hard",
113                "Hard float ABI (uses FP registers)"),
114     clEnumValEnd));
115 static cl::opt<bool, true>
116 DontPlaceZerosInBSS("nozero-initialized-in-bss",
117   cl::desc("Don't place zero-initialized symbols into bss section"),
118   cl::location(NoZerosInBSS),
119   cl::init(false));
120 static cl::opt<bool, true>
121 EnableJITExceptionHandling("jit-enable-eh",
122   cl::desc("Emit exception handling information"),
123   cl::location(JITExceptionHandling),
124   cl::init(false));
125 // In debug builds, make this default to true.
126 #ifdef NDEBUG
127 #define EMIT_DEBUG false
128 #else
129 #define EMIT_DEBUG true
130 #endif
131 static cl::opt<bool, true>
132 EmitJitDebugInfo("jit-emit-debug",
133   cl::desc("Emit debug information to debugger"),
134   cl::location(JITEmitDebugInfo),
135   cl::init(EMIT_DEBUG));
136 #undef EMIT_DEBUG
137 static cl::opt<bool, true>
138 EmitJitDebugInfoToDisk("jit-emit-debug-to-disk",
139   cl::Hidden,
140   cl::desc("Emit debug info objfiles to disk"),
141   cl::location(JITEmitDebugInfoToDisk),
142   cl::init(false));
143 
144 static cl::opt<bool, true>
145 EnableGuaranteedTailCallOpt("tailcallopt",
146   cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
147   cl::location(GuaranteedTailCallOpt),
148   cl::init(false));
149 static cl::opt<unsigned, true>
150 OverrideStackAlignment("stack-alignment",
151   cl::desc("Override default stack alignment"),
152   cl::location(StackAlignmentOverride),
153   cl::init(0));
154 static cl::opt<bool, true>
155 EnableRealignStack("realign-stack",
156   cl::desc("Realign stack if needed"),
157   cl::location(RealignStack),
158   cl::init(true));
159 static cl::opt<bool, true>
160 DisableSwitchTables(cl::Hidden, "disable-jump-tables",
161   cl::desc("Do not generate jump tables."),
162   cl::location(DisableJumpTables),
163   cl::init(false));
164 static cl::opt<bool, true>
165 EnableStrongPHIElim(cl::Hidden, "strong-phi-elim",
166   cl::desc("Use strong PHI elimination."),
167   cl::location(StrongPHIElim),
168   cl::init(false));
169 static cl::opt<std::string>
170 TrapFuncName("trap-func", cl::Hidden,
171   cl::desc("Emit a call to trap function rather than a trap instruction"),
172   cl::init(""));
173 static cl::opt<bool>
174 DataSections("fdata-sections",
175   cl::desc("Emit data into separate sections"),
176   cl::init(false));
177 static cl::opt<bool>
178 FunctionSections("ffunction-sections",
179   cl::desc("Emit functions into separate sections"),
180   cl::init(false));
181 //---------------------------------------------------------------------------
182 // TargetMachine Class
183 //
184 
185 TargetMachine::TargetMachine(const Target &T,
186                              StringRef TT, StringRef CPU, StringRef FS)
187   : TheTarget(T), TargetTriple(TT), TargetCPU(CPU), TargetFS(FS),
188     CodeGenInfo(0), AsmInfo(0),
189     MCRelaxAll(false),
190     MCNoExecStack(false),
191     MCSaveTempLabels(false),
192     MCUseLoc(true),
193     MCUseCFI(true) {
194   // Typically it will be subtargets that will adjust FloatABIType from Default
195   // to Soft or Hard.
196   if (UseSoftFloat)
197     FloatABIType = FloatABI::Soft;
198 }
199 
200 TargetMachine::~TargetMachine() {
201   delete CodeGenInfo;
202   delete AsmInfo;
203 }
204 
205 /// getRelocationModel - Returns the code generation relocation model. The
206 /// choices are static, PIC, and dynamic-no-pic, and target default.
207 Reloc::Model TargetMachine::getRelocationModel() const {
208   if (!CodeGenInfo)
209     return Reloc::Default;
210   return CodeGenInfo->getRelocationModel();
211 }
212 
213 /// getCodeModel - Returns the code model. The choices are small, kernel,
214 /// medium, large, and target default.
215 CodeModel::Model TargetMachine::getCodeModel() const {
216   if (!CodeGenInfo)
217     return CodeModel::Default;
218   return CodeGenInfo->getCodeModel();
219 }
220 
221 bool TargetMachine::getAsmVerbosityDefault() {
222   return AsmVerbosityDefault;
223 }
224 
225 void TargetMachine::setAsmVerbosityDefault(bool V) {
226   AsmVerbosityDefault = V;
227 }
228 
229 bool TargetMachine::getFunctionSections() {
230   return FunctionSections;
231 }
232 
233 bool TargetMachine::getDataSections() {
234   return DataSections;
235 }
236 
237 void TargetMachine::setFunctionSections(bool V) {
238   FunctionSections = V;
239 }
240 
241 void TargetMachine::setDataSections(bool V) {
242   DataSections = V;
243 }
244 
245 namespace llvm {
246   /// DisableFramePointerElim - This returns true if frame pointer elimination
247   /// optimization should be disabled for the given machine function.
248   bool DisableFramePointerElim(const MachineFunction &MF) {
249     // Check to see if we should eliminate non-leaf frame pointers and then
250     // check to see if we should eliminate all frame pointers.
251     if (NoFramePointerElimNonLeaf && !NoFramePointerElim) {
252       const MachineFrameInfo *MFI = MF.getFrameInfo();
253       return MFI->hasCalls();
254     }
255 
256     return NoFramePointerElim;
257   }
258 
259   /// LessPreciseFPMAD - This flag return true when -enable-fp-mad option
260   /// is specified on the command line.  When this flag is off(default), the
261   /// code generator is not allowed to generate mad (multiply add) if the
262   /// result is "less precise" than doing those operations individually.
263   bool LessPreciseFPMAD() { return UnsafeFPMath || LessPreciseFPMADOption; }
264 
265   /// HonorSignDependentRoundingFPMath - Return true if the codegen must assume
266   /// that the rounding mode of the FPU can change from its default.
267   bool HonorSignDependentRoundingFPMath() {
268     return !UnsafeFPMath && HonorSignDependentRoundingFPMathOption;
269   }
270 
271   /// getTrapFunctionName - If this returns a non-empty string, this means isel
272   /// should lower Intrinsic::trap to a call to the specified function name
273   /// instead of an ISD::TRAP node.
274   StringRef getTrapFunctionName() {
275     return TrapFuncName;
276   }
277 }
278