TargetOptions.h revision 769951f6cc6323821ce1e9f46a37817a541c884f 
1//===-- llvm/Target/TargetOptions.h - Target Options ------------*- C++ -*-===//
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 defines command line option flags that are shared across various
11// targets.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_TARGET_TARGETOPTIONS_H
16#define LLVM_TARGET_TARGETOPTIONS_H
17
18#include <string>
19
20namespace llvm {
21  class MachineFunction;
22  class StringRef;
23
24  // Possible float ABI settings. Used with FloatABIType in TargetOptions.h.
25  namespace FloatABI {
26    enum ABIType {
27      Default, // Target-specific (either soft or hard depending on triple, etc).
28      Soft, // Soft float.
29      Hard  // Hard float.
30    };
31  }
32
33  namespace FPOpFusion {
34    enum FPOpFusionMode {
35      Fast,     // Enable fusion of FP ops wherever it's profitable.
36      Standard, // Only allow fusion of 'blessed' ops (currently just fmuladd).
37      Strict    // Never fuse FP-ops.
38    };
39  }
40
41  class TargetOptions {
42  public:
43    TargetOptions()
44        : PrintMachineCode(false), NoFramePointerElim(false),
45          NoFramePointerElimNonLeaf(false), LessPreciseFPMADOption(false),
46          UnsafeFPMath(false), NoInfsFPMath(false),
47          NoNaNsFPMath(false), HonorSignDependentRoundingFPMathOption(false),
48          UseSoftFloat(false), NoZerosInBSS(false), JITExceptionHandling(false),
49          JITEmitDebugInfo(false), JITEmitDebugInfoToDisk(false),
50          GuaranteedTailCallOpt(false), DisableTailCalls(false),
51          StackAlignmentOverride(0), RealignStack(true), EnableFastISel(false),
52          PositionIndependentExecutable(false), EnableSegmentedStacks(false),
53          UseInitArray(false), TrapFuncName(""), FloatABIType(FloatABI::Default),
54          AllowFPOpFusion(FPOpFusion::Standard)
55    {}
56
57    /// PrintMachineCode - This flag is enabled when the -print-machineinstrs
58    /// option is specified on the command line, and should enable debugging
59    /// output from the code generator.
60    unsigned PrintMachineCode : 1;
61
62    /// NoFramePointerElim - This flag is enabled when the -disable-fp-elim is
63    /// specified on the command line.  If the target supports the frame pointer
64    /// elimination optimization, this option should disable it.
65    unsigned NoFramePointerElim : 1;
66
67    /// NoFramePointerElimNonLeaf - This flag is enabled when the
68    /// -disable-non-leaf-fp-elim is specified on the command line. If the
69    /// target supports the frame pointer elimination optimization, this option
70    /// should disable it for non-leaf functions.
71    unsigned NoFramePointerElimNonLeaf : 1;
72
73    /// DisableFramePointerElim - This returns true if frame pointer elimination
74    /// optimization should be disabled for the given machine function.
75    bool DisableFramePointerElim(const MachineFunction &MF) const;
76
77    /// LessPreciseFPMAD - This flag is enabled when the
78    /// -enable-fp-mad is specified on the command line.  When this flag is off
79    /// (the default), the code generator is not allowed to generate mad
80    /// (multiply add) if the result is "less precise" than doing those
81    /// operations individually.
82    unsigned LessPreciseFPMADOption : 1;
83    bool LessPreciseFPMAD() const;
84
85    /// UnsafeFPMath - This flag is enabled when the
86    /// -enable-unsafe-fp-math flag is specified on the command line.  When
87    /// this flag is off (the default), the code generator is not allowed to
88    /// produce results that are "less precise" than IEEE allows.  This includes
89    /// use of X86 instructions like FSIN and FCOS instead of libcalls.
90    /// UnsafeFPMath implies LessPreciseFPMAD.
91    unsigned UnsafeFPMath : 1;
92
93    /// NoInfsFPMath - This flag is enabled when the
94    /// -enable-no-infs-fp-math flag is specified on the command line. When
95    /// this flag is off (the default), the code generator is not allowed to
96    /// assume the FP arithmetic arguments and results are never +-Infs.
97    unsigned NoInfsFPMath : 1;
98
99    /// NoNaNsFPMath - This flag is enabled when the
100    /// -enable-no-nans-fp-math flag is specified on the command line. When
101    /// this flag is off (the default), the code generator is not allowed to
102    /// assume the FP arithmetic arguments and results are never NaNs.
103    unsigned NoNaNsFPMath : 1;
104
105    /// HonorSignDependentRoundingFPMath - This returns true when the
106    /// -enable-sign-dependent-rounding-fp-math is specified.  If this returns
107    /// false (the default), the code generator is allowed to assume that the
108    /// rounding behavior is the default (round-to-zero for all floating point
109    /// to integer conversions, and round-to-nearest for all other arithmetic
110    /// truncations).  If this is enabled (set to true), the code generator must
111    /// assume that the rounding mode may dynamically change.
112    unsigned HonorSignDependentRoundingFPMathOption : 1;
113    bool HonorSignDependentRoundingFPMath() const;
114
115    /// UseSoftFloat - This flag is enabled when the -soft-float flag is
116    /// specified on the command line.  When this flag is on, the code generator
117    /// will generate libcalls to the software floating point library instead of
118    /// target FP instructions.
119    unsigned UseSoftFloat : 1;
120
121    /// NoZerosInBSS - By default some codegens place zero-initialized data to
122    /// .bss section. This flag disables such behaviour (necessary, e.g. for
123    /// crt*.o compiling).
124    unsigned NoZerosInBSS : 1;
125
126    /// JITExceptionHandling - This flag indicates that the JIT should emit
127    /// exception handling information.
128    unsigned JITExceptionHandling : 1;
129
130    /// JITEmitDebugInfo - This flag indicates that the JIT should try to emit
131    /// debug information and notify a debugger about it.
132    unsigned JITEmitDebugInfo : 1;
133
134    /// JITEmitDebugInfoToDisk - This flag indicates that the JIT should write
135    /// the object files generated by the JITEmitDebugInfo flag to disk.  This
136    /// flag is hidden and is only for debugging the debug info.
137    unsigned JITEmitDebugInfoToDisk : 1;
138
139    /// GuaranteedTailCallOpt - This flag is enabled when -tailcallopt is
140    /// specified on the commandline. When the flag is on, participating targets
141    /// will perform tail call optimization on all calls which use the fastcc
142    /// calling convention and which satisfy certain target-independent
143    /// criteria (being at the end of a function, having the same return type
144    /// as their parent function, etc.), using an alternate ABI if necessary.
145    unsigned GuaranteedTailCallOpt : 1;
146
147    /// DisableTailCalls - This flag controls whether we will use tail calls.
148    /// Disabling them may be useful to maintain a correct call stack.
149    unsigned DisableTailCalls : 1;
150
151    /// StackAlignmentOverride - Override default stack alignment for target.
152    unsigned StackAlignmentOverride;
153
154    /// RealignStack - This flag indicates whether the stack should be
155    /// automatically realigned, if needed.
156    unsigned RealignStack : 1;
157
158    /// EnableFastISel - This flag enables fast-path instruction selection
159    /// which trades away generated code quality in favor of reducing
160    /// compile time.
161    unsigned EnableFastISel : 1;
162
163    /// PositionIndependentExecutable - This flag indicates whether the code
164    /// will eventually be linked into a single executable, despite the PIC
165    /// relocation model being in use. It's value is undefined (and irrelevant)
166    /// if the relocation model is anything other than PIC.
167    unsigned PositionIndependentExecutable : 1;
168
169    unsigned EnableSegmentedStacks : 1;
170
171    /// UseInitArray - Use .init_array instead of .ctors for static
172    /// constructors.
173    unsigned UseInitArray : 1;
174
175    /// getTrapFunctionName - If this returns a non-empty string, this means
176    /// isel should lower Intrinsic::trap to a call to the specified function
177    /// name instead of an ISD::TRAP node.
178    std::string TrapFuncName;
179    StringRef getTrapFunctionName() const;
180
181    /// FloatABIType - This setting is set by -float-abi=xxx option is specfied
182    /// on the command line. This setting may either be Default, Soft, or Hard.
183    /// Default selects the target's default behavior. Soft selects the ABI for
184    /// UseSoftFloat, but does not indicate that FP hardware may not be used.
185    /// Such a combination is unfortunately popular (e.g. arm-apple-darwin).
186    /// Hard presumes that the normal FP ABI is used.
187    FloatABI::ABIType FloatABIType;
188
189    /// AllowFPOpFusion - This flag is set by the -fuse-fp-ops=xxx option.
190    /// This controls the creation of fused FP ops that store intermediate
191    /// results in higher precision than IEEE allows (E.g. FMAs).
192    ///
193    /// Fast mode - allows formation of fused FP ops whenever they're
194    /// profitable.
195    /// Standard mode - allow fusion only for 'blessed' FP ops. At present the
196    /// only blessed op is the fmuladd intrinsic. In the future more blessed ops
197    /// may be added.
198    /// Strict mode - allow fusion only if/when it can be proven that the excess
199    /// precision won't effect the result.
200    ///
201    /// Note: This option only controls formation of fused ops by the optimizers.
202    /// Fused operations that are explicitly specified (e.g. FMA via the
203    /// llvm.fma.* intrinsic) will always be honored, regardless of the value of
204    /// this option.
205    FPOpFusion::FPOpFusionMode AllowFPOpFusion;
206
207  };
208} // End llvm namespace
209
210#endif
211