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/MC/MCAsmInfo.h"
15 #include "llvm/Target/TargetMachine.h"
16 #include "llvm/Target/TargetOptions.h"
17 #include "llvm/Support/CommandLine.h"
18 using namespace llvm;
19 
20 //---------------------------------------------------------------------------
21 // Command-line options that tend to be useful on more than one back-end.
22 //
23 
24 namespace llvm {
25   bool LessPreciseFPMADOption;
26   bool PrintMachineCode;
27   bool NoFramePointerElim;
28   bool NoExcessFPPrecision;
29   bool UnsafeFPMath;
30   bool FiniteOnlyFPMathOption;
31   bool HonorSignDependentRoundingFPMathOption;
32   bool UseSoftFloat;
33   FloatABI::ABIType FloatABIType;
34   bool NoImplicitFloat;
35   bool NoZerosInBSS;
36   bool DwarfExceptionHandling;
37   bool SjLjExceptionHandling;
38   bool JITEmitDebugInfo;
39   bool JITEmitDebugInfoToDisk;
40   bool UnwindTablesMandatory;
41   Reloc::Model RelocationModel;
42   CodeModel::Model CMModel;
43   bool PerformTailCallOpt;
44   unsigned StackAlignment;
45   bool RealignStack;
46   bool DisableJumpTables;
47   bool StrongPHIElim;
48   bool AsmVerbosityDefault(false);
49   bool DisableScheduling;
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 DisableExcessPrecision("disable-excess-fp-precision",
63   cl::desc("Disable optimizations that may increase FP precision"),
64   cl::location(NoExcessFPPrecision),
65   cl::init(false));
66 static cl::opt<bool, true>
67 EnableFPMAD("enable-fp-mad",
68   cl::desc("Enable less precise MAD instructions to be generated"),
69   cl::location(LessPreciseFPMADOption),
70   cl::init(false));
71 static cl::opt<bool, true>
72 EnableUnsafeFPMath("enable-unsafe-fp-math",
73   cl::desc("Enable optimizations that may decrease FP precision"),
74   cl::location(UnsafeFPMath),
75   cl::init(false));
76 static cl::opt<bool, true>
77 EnableFiniteOnlyFPMath("enable-finite-only-fp-math",
78   cl::desc("Enable optimizations that assumes non- NaNs / +-Infs"),
79   cl::location(FiniteOnlyFPMathOption),
80   cl::init(false));
81 static cl::opt<bool, true>
82 EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
83   cl::Hidden,
84   cl::desc("Force codegen to assume rounding mode can change dynamically"),
85   cl::location(HonorSignDependentRoundingFPMathOption),
86   cl::init(false));
87 static cl::opt<bool, true>
88 GenerateSoftFloatCalls("soft-float",
89   cl::desc("Generate software floating point library calls"),
90   cl::location(UseSoftFloat),
91   cl::init(false));
92 static cl::opt<llvm::FloatABI::ABIType, true>
93 FloatABIForCalls("float-abi",
94   cl::desc("Choose float ABI type"),
95   cl::location(FloatABIType),
96   cl::init(FloatABI::Default),
97   cl::values(
98     clEnumValN(FloatABI::Default, "default",
99                "Target default float ABI type"),
100     clEnumValN(FloatABI::Soft, "soft",
101                "Soft float ABI (implied by -soft-float)"),
102     clEnumValN(FloatABI::Hard, "hard",
103                "Hard float ABI (uses FP registers)"),
104     clEnumValEnd));
105 static cl::opt<bool, true>
106 DontPlaceZerosInBSS("nozero-initialized-in-bss",
107   cl::desc("Don't place zero-initialized symbols into bss section"),
108   cl::location(NoZerosInBSS),
109   cl::init(false));
110 static cl::opt<bool, true>
111 EnableDwarfExceptionHandling("enable-eh",
112   cl::desc("Emit DWARF exception handling (default if target supports)"),
113   cl::location(DwarfExceptionHandling),
114   cl::init(false));
115 static cl::opt<bool, true>
116 EnableSjLjExceptionHandling("enable-sjlj-eh",
117   cl::desc("Emit SJLJ exception handling (default if target supports)"),
118   cl::location(SjLjExceptionHandling),
119   cl::init(false));
120 // In debug builds, make this default to true.
121 #ifdef NDEBUG
122 #define EMIT_DEBUG false
123 #else
124 #define EMIT_DEBUG true
125 #endif
126 static cl::opt<bool, true>
127 EmitJitDebugInfo("jit-emit-debug",
128   cl::desc("Emit debug information to debugger"),
129   cl::location(JITEmitDebugInfo),
130   cl::init(EMIT_DEBUG));
131 #undef EMIT_DEBUG
132 static cl::opt<bool, true>
133 EmitJitDebugInfoToDisk("jit-emit-debug-to-disk",
134   cl::Hidden,
135   cl::desc("Emit debug info objfiles to disk"),
136   cl::location(JITEmitDebugInfoToDisk),
137   cl::init(false));
138 static cl::opt<bool, true>
139 EnableUnwindTables("unwind-tables",
140   cl::desc("Generate unwinding tables for all functions"),
141   cl::location(UnwindTablesMandatory),
142   cl::init(false));
143 
144 static cl::opt<llvm::Reloc::Model, true>
145 DefRelocationModel("relocation-model",
146   cl::desc("Choose relocation model"),
147   cl::location(RelocationModel),
148   cl::init(Reloc::Default),
149   cl::values(
150     clEnumValN(Reloc::Default, "default",
151                "Target default relocation model"),
152     clEnumValN(Reloc::Static, "static",
153                "Non-relocatable code"),
154     clEnumValN(Reloc::PIC_, "pic",
155                "Fully relocatable, position independent code"),
156     clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
157                "Relocatable external references, non-relocatable code"),
158     clEnumValEnd));
159 static cl::opt<llvm::CodeModel::Model, true>
160 DefCodeModel("code-model",
161   cl::desc("Choose code model"),
162   cl::location(CMModel),
163   cl::init(CodeModel::Default),
164   cl::values(
165     clEnumValN(CodeModel::Default, "default",
166                "Target default code model"),
167     clEnumValN(CodeModel::Small, "small",
168                "Small code model"),
169     clEnumValN(CodeModel::Kernel, "kernel",
170                "Kernel code model"),
171     clEnumValN(CodeModel::Medium, "medium",
172                "Medium code model"),
173     clEnumValN(CodeModel::Large, "large",
174                "Large code model"),
175     clEnumValEnd));
176 static cl::opt<bool, true>
177 EnablePerformTailCallOpt("tailcallopt",
178   cl::desc("Turn on tail call optimization."),
179   cl::location(PerformTailCallOpt),
180   cl::init(false));
181 static cl::opt<unsigned, true>
182 OverrideStackAlignment("stack-alignment",
183   cl::desc("Override default stack alignment"),
184   cl::location(StackAlignment),
185   cl::init(0));
186 static cl::opt<bool, true>
187 EnableRealignStack("realign-stack",
188   cl::desc("Realign stack if needed"),
189   cl::location(RealignStack),
190   cl::init(true));
191 static cl::opt<bool, true>
192 DisableSwitchTables(cl::Hidden, "disable-jump-tables",
193   cl::desc("Do not generate jump tables."),
194   cl::location(DisableJumpTables),
195   cl::init(false));
196 static cl::opt<bool, true>
197 EnableStrongPHIElim(cl::Hidden, "strong-phi-elim",
198   cl::desc("Use strong PHI elimination."),
199   cl::location(StrongPHIElim),
200   cl::init(false));
201 static cl::opt<bool, true>
202 DisableInstScheduling("disable-scheduling",
203   cl::desc("Disable instruction scheduling"),
204   cl::location(DisableScheduling),
205   cl::init(false));
206 
207 //---------------------------------------------------------------------------
208 // TargetMachine Class
209 //
210 
211 TargetMachine::TargetMachine(const Target &T)
212   : TheTarget(T), AsmInfo(0) {
213   // Typically it will be subtargets that will adjust FloatABIType from Default
214   // to Soft or Hard.
215   if (UseSoftFloat)
216     FloatABIType = FloatABI::Soft;
217 }
218 
219 TargetMachine::~TargetMachine() {
220   delete AsmInfo;
221 }
222 
223 /// getRelocationModel - Returns the code generation relocation model. The
224 /// choices are static, PIC, and dynamic-no-pic, and target default.
225 Reloc::Model TargetMachine::getRelocationModel() {
226   return RelocationModel;
227 }
228 
229 /// setRelocationModel - Sets the code generation relocation model.
230 void TargetMachine::setRelocationModel(Reloc::Model Model) {
231   RelocationModel = Model;
232 }
233 
234 /// getCodeModel - Returns the code model. The choices are small, kernel,
235 /// medium, large, and target default.
236 CodeModel::Model TargetMachine::getCodeModel() {
237   return CMModel;
238 }
239 
240 /// setCodeModel - Sets the code model.
241 void TargetMachine::setCodeModel(CodeModel::Model Model) {
242   CMModel = Model;
243 }
244 
245 bool TargetMachine::getAsmVerbosityDefault() {
246   return AsmVerbosityDefault;
247 }
248 
249 void TargetMachine::setAsmVerbosityDefault(bool V) {
250   AsmVerbosityDefault = V;
251 }
252 
253 namespace llvm {
254   /// LessPreciseFPMAD - This flag return true when -enable-fp-mad option
255   /// is specified on the command line.  When this flag is off(default), the
256   /// code generator is not allowed to generate mad (multiply add) if the
257   /// result is "less precise" than doing those operations individually.
258   bool LessPreciseFPMAD() { return UnsafeFPMath || LessPreciseFPMADOption; }
259 
260   /// FiniteOnlyFPMath - This returns true when the -enable-finite-only-fp-math
261   /// option is specified on the command line. If this returns false (default),
262   /// the code generator is not allowed to assume that FP arithmetic arguments
263   /// and results are never NaNs or +-Infs.
264   bool FiniteOnlyFPMath() { return UnsafeFPMath || FiniteOnlyFPMathOption; }
265 
266   /// HonorSignDependentRoundingFPMath - Return true if the codegen must assume
267   /// that the rounding mode of the FPU can change from its default.
268   bool HonorSignDependentRoundingFPMath() {
269     return !UnsafeFPMath && HonorSignDependentRoundingFPMathOption;
270   }
271 }
272