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 GuaranteedTailCallOpt;
44   unsigned StackAlignment;
45   bool RealignStack;
46   bool DisableJumpTables;
47   bool StrongPHIElim;
48   bool AsmVerbosityDefault(false);
49 }
50 
51 static cl::opt<bool, true>
52 PrintCode("print-machineinstrs",
53   cl::desc("Print generated machine code"),
54   cl::location(PrintMachineCode), cl::init(false));
55 static cl::opt<bool, true>
56 DisableFPElim("disable-fp-elim",
57   cl::desc("Disable frame pointer elimination optimization"),
58   cl::location(NoFramePointerElim),
59   cl::init(false));
60 static cl::opt<bool, true>
61 DisableExcessPrecision("disable-excess-fp-precision",
62   cl::desc("Disable optimizations that may increase FP precision"),
63   cl::location(NoExcessFPPrecision),
64   cl::init(false));
65 static cl::opt<bool, true>
66 EnableFPMAD("enable-fp-mad",
67   cl::desc("Enable less precise MAD instructions to be generated"),
68   cl::location(LessPreciseFPMADOption),
69   cl::init(false));
70 static cl::opt<bool, true>
71 EnableUnsafeFPMath("enable-unsafe-fp-math",
72   cl::desc("Enable optimizations that may decrease FP precision"),
73   cl::location(UnsafeFPMath),
74   cl::init(false));
75 static cl::opt<bool, true>
76 EnableFiniteOnlyFPMath("enable-finite-only-fp-math",
77   cl::desc("Enable optimizations that assumes non- NaNs / +-Infs"),
78   cl::location(FiniteOnlyFPMathOption),
79   cl::init(false));
80 static cl::opt<bool, true>
81 EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
82   cl::Hidden,
83   cl::desc("Force codegen to assume rounding mode can change dynamically"),
84   cl::location(HonorSignDependentRoundingFPMathOption),
85   cl::init(false));
86 static cl::opt<bool, true>
87 GenerateSoftFloatCalls("soft-float",
88   cl::desc("Generate software floating point library calls"),
89   cl::location(UseSoftFloat),
90   cl::init(false));
91 static cl::opt<llvm::FloatABI::ABIType, true>
92 FloatABIForCalls("float-abi",
93   cl::desc("Choose float ABI type"),
94   cl::location(FloatABIType),
95   cl::init(FloatABI::Default),
96   cl::values(
97     clEnumValN(FloatABI::Default, "default",
98                "Target default float ABI type"),
99     clEnumValN(FloatABI::Soft, "soft",
100                "Soft float ABI (implied by -soft-float)"),
101     clEnumValN(FloatABI::Hard, "hard",
102                "Hard float ABI (uses FP registers)"),
103     clEnumValEnd));
104 static cl::opt<bool, true>
105 DontPlaceZerosInBSS("nozero-initialized-in-bss",
106   cl::desc("Don't place zero-initialized symbols into bss section"),
107   cl::location(NoZerosInBSS),
108   cl::init(false));
109 static cl::opt<bool, true>
110 EnableDwarfExceptionHandling("enable-eh",
111   cl::desc("Emit DWARF exception handling (default if target supports)"),
112   cl::location(DwarfExceptionHandling),
113   cl::init(false));
114 static cl::opt<bool, true>
115 EnableSjLjExceptionHandling("enable-sjlj-eh",
116   cl::desc("Emit SJLJ exception handling (default if target supports)"),
117   cl::location(SjLjExceptionHandling),
118   cl::init(false));
119 // In debug builds, make this default to true.
120 #ifdef NDEBUG
121 #define EMIT_DEBUG false
122 #else
123 #define EMIT_DEBUG true
124 #endif
125 static cl::opt<bool, true>
126 EmitJitDebugInfo("jit-emit-debug",
127   cl::desc("Emit debug information to debugger"),
128   cl::location(JITEmitDebugInfo),
129   cl::init(EMIT_DEBUG));
130 #undef EMIT_DEBUG
131 static cl::opt<bool, true>
132 EmitJitDebugInfoToDisk("jit-emit-debug-to-disk",
133   cl::Hidden,
134   cl::desc("Emit debug info objfiles to disk"),
135   cl::location(JITEmitDebugInfoToDisk),
136   cl::init(false));
137 static cl::opt<bool, true>
138 EnableUnwindTables("unwind-tables",
139   cl::desc("Generate unwinding tables for all functions"),
140   cl::location(UnwindTablesMandatory),
141   cl::init(false));
142 
143 static cl::opt<llvm::Reloc::Model, true>
144 DefRelocationModel("relocation-model",
145   cl::desc("Choose relocation model"),
146   cl::location(RelocationModel),
147   cl::init(Reloc::Default),
148   cl::values(
149     clEnumValN(Reloc::Default, "default",
150                "Target default relocation model"),
151     clEnumValN(Reloc::Static, "static",
152                "Non-relocatable code"),
153     clEnumValN(Reloc::PIC_, "pic",
154                "Fully relocatable, position independent code"),
155     clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
156                "Relocatable external references, non-relocatable code"),
157     clEnumValEnd));
158 static cl::opt<llvm::CodeModel::Model, true>
159 DefCodeModel("code-model",
160   cl::desc("Choose code model"),
161   cl::location(CMModel),
162   cl::init(CodeModel::Default),
163   cl::values(
164     clEnumValN(CodeModel::Default, "default",
165                "Target default code model"),
166     clEnumValN(CodeModel::Small, "small",
167                "Small code model"),
168     clEnumValN(CodeModel::Kernel, "kernel",
169                "Kernel code model"),
170     clEnumValN(CodeModel::Medium, "medium",
171                "Medium code model"),
172     clEnumValN(CodeModel::Large, "large",
173                "Large code model"),
174     clEnumValEnd));
175 static cl::opt<bool, true>
176 EnableGuaranteedTailCallOpt("tailcallopt",
177   cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
178   cl::location(GuaranteedTailCallOpt),
179   cl::init(false));
180 static cl::opt<unsigned, true>
181 OverrideStackAlignment("stack-alignment",
182   cl::desc("Override default stack alignment"),
183   cl::location(StackAlignment),
184   cl::init(0));
185 static cl::opt<bool, true>
186 EnableRealignStack("realign-stack",
187   cl::desc("Realign stack if needed"),
188   cl::location(RealignStack),
189   cl::init(true));
190 static cl::opt<bool, true>
191 DisableSwitchTables(cl::Hidden, "disable-jump-tables",
192   cl::desc("Do not generate jump tables."),
193   cl::location(DisableJumpTables),
194   cl::init(false));
195 static cl::opt<bool, true>
196 EnableStrongPHIElim(cl::Hidden, "strong-phi-elim",
197   cl::desc("Use strong PHI elimination."),
198   cl::location(StrongPHIElim),
199   cl::init(false));
200 
201 //---------------------------------------------------------------------------
202 // TargetMachine Class
203 //
204 
205 TargetMachine::TargetMachine(const Target &T)
206   : TheTarget(T), AsmInfo(0) {
207   // Typically it will be subtargets that will adjust FloatABIType from Default
208   // to Soft or Hard.
209   if (UseSoftFloat)
210     FloatABIType = FloatABI::Soft;
211 }
212 
213 TargetMachine::~TargetMachine() {
214   delete AsmInfo;
215 }
216 
217 /// getRelocationModel - Returns the code generation relocation model. The
218 /// choices are static, PIC, and dynamic-no-pic, and target default.
219 Reloc::Model TargetMachine::getRelocationModel() {
220   return RelocationModel;
221 }
222 
223 /// setRelocationModel - Sets the code generation relocation model.
224 void TargetMachine::setRelocationModel(Reloc::Model Model) {
225   RelocationModel = Model;
226 }
227 
228 /// getCodeModel - Returns the code model. The choices are small, kernel,
229 /// medium, large, and target default.
230 CodeModel::Model TargetMachine::getCodeModel() {
231   return CMModel;
232 }
233 
234 /// setCodeModel - Sets the code model.
235 void TargetMachine::setCodeModel(CodeModel::Model Model) {
236   CMModel = Model;
237 }
238 
239 bool TargetMachine::getAsmVerbosityDefault() {
240   return AsmVerbosityDefault;
241 }
242 
243 void TargetMachine::setAsmVerbosityDefault(bool V) {
244   AsmVerbosityDefault = V;
245 }
246 
247 namespace llvm {
248   /// LessPreciseFPMAD - This flag return true when -enable-fp-mad option
249   /// is specified on the command line.  When this flag is off(default), the
250   /// code generator is not allowed to generate mad (multiply add) if the
251   /// result is "less precise" than doing those operations individually.
252   bool LessPreciseFPMAD() { return UnsafeFPMath || LessPreciseFPMADOption; }
253 
254   /// FiniteOnlyFPMath - This returns true when the -enable-finite-only-fp-math
255   /// option is specified on the command line. If this returns false (default),
256   /// the code generator is not allowed to assume that FP arithmetic arguments
257   /// and results are never NaNs or +-Infs.
258   bool FiniteOnlyFPMath() { return UnsafeFPMath || FiniteOnlyFPMathOption; }
259 
260   /// HonorSignDependentRoundingFPMath - Return true if the codegen must assume
261   /// that the rounding mode of the FPU can change from its default.
262   bool HonorSignDependentRoundingFPMath() {
263     return !UnsafeFPMath && HonorSignDependentRoundingFPMathOption;
264   }
265 }
266