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