1 //===-- llvm/Attributes.h - Container for Attributes ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the simple types necessary to represent the
11 // attributes associated with functions and their calls.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ATTRIBUTES_H
16 #define LLVM_ATTRIBUTES_H
18 #include "llvm/Support/MathExtras.h"
19 #include "llvm/ADT/ArrayRef.h"
29 /// We use this proxy POD type to allow constructing Attributes constants using
30 /// initializer lists. Do not use this class directly.
33 AttrConst operator | (const AttrConst Attrs) const {
34 AttrConst Res = {v | Attrs.v};
37 AttrConst operator ~ () const {
43 /// Function parameters and results can have attributes to indicate how they
44 /// should be treated by optimizations and code generation. This enumeration
45 /// lists the attributes that can be associated with parameters, function
46 /// results or the function itself.
47 /// @brief Function attributes.
49 /// We declare AttrConst objects that will be used throughout the code and also
50 /// raw uint64_t objects with _i suffix to be used below for other constant
51 /// declarations. This is done to avoid static CTORs and at the same time to
52 /// keep type-safety of Attributes.
53 #define DECLARE_LLVM_ATTRIBUTE(name, value) \
54 const uint64_t name##_i = value; \
55 const AttrConst name = {value};
57 DECLARE_LLVM_ATTRIBUTE(None,0) ///< No attributes have been set
58 DECLARE_LLVM_ATTRIBUTE(ZExt,1<<0) ///< Zero extended before/after call
59 DECLARE_LLVM_ATTRIBUTE(SExt,1<<1) ///< Sign extended before/after call
60 DECLARE_LLVM_ATTRIBUTE(NoReturn,1<<2) ///< Mark the function as not returning
61 DECLARE_LLVM_ATTRIBUTE(InReg,1<<3) ///< Force argument to be passed in register
62 DECLARE_LLVM_ATTRIBUTE(StructRet,1<<4) ///< Hidden pointer to structure to return
63 DECLARE_LLVM_ATTRIBUTE(NoUnwind,1<<5) ///< Function doesn't unwind stack
64 DECLARE_LLVM_ATTRIBUTE(NoAlias,1<<6) ///< Considered to not alias after call
65 DECLARE_LLVM_ATTRIBUTE(ByVal,1<<7) ///< Pass structure by value
66 DECLARE_LLVM_ATTRIBUTE(Nest,1<<8) ///< Nested function static chain
67 DECLARE_LLVM_ATTRIBUTE(ReadNone,1<<9) ///< Function does not access memory
68 DECLARE_LLVM_ATTRIBUTE(ReadOnly,1<<10) ///< Function only reads from memory
69 DECLARE_LLVM_ATTRIBUTE(NoInline,1<<11) ///< inline=never
70 DECLARE_LLVM_ATTRIBUTE(AlwaysInline,1<<12) ///< inline=always
71 DECLARE_LLVM_ATTRIBUTE(OptimizeForSize,1<<13) ///< opt_size
72 DECLARE_LLVM_ATTRIBUTE(StackProtect,1<<14) ///< Stack protection.
73 DECLARE_LLVM_ATTRIBUTE(StackProtectReq,1<<15) ///< Stack protection required.
74 DECLARE_LLVM_ATTRIBUTE(Alignment,31<<16) ///< Alignment of parameter (5 bits)
75 // stored as log2 of alignment with +1 bias
76 // 0 means unaligned different from align 1
77 DECLARE_LLVM_ATTRIBUTE(NoCapture,1<<21) ///< Function creates no aliases of pointer
78 DECLARE_LLVM_ATTRIBUTE(NoRedZone,1<<22) /// disable redzone
79 DECLARE_LLVM_ATTRIBUTE(NoImplicitFloat,1<<23) /// disable implicit floating point
81 DECLARE_LLVM_ATTRIBUTE(Naked,1<<24) ///< Naked function
82 DECLARE_LLVM_ATTRIBUTE(InlineHint,1<<25) ///< source said inlining was
84 DECLARE_LLVM_ATTRIBUTE(StackAlignment,7<<26) ///< Alignment of stack for
85 ///function (3 bits) stored as log2
86 ///of alignment with +1 bias
87 ///0 means unaligned (different from
89 DECLARE_LLVM_ATTRIBUTE(ReturnsTwice,1<<29) ///< Function can return twice
90 DECLARE_LLVM_ATTRIBUTE(UWTable,1<<30) ///< Function must be in a unwind
92 DECLARE_LLVM_ATTRIBUTE(NonLazyBind,1U<<31) ///< Function is called early and/or
93 /// often, so lazy binding isn't
95 DECLARE_LLVM_ATTRIBUTE(AddressSafety,1ULL<<32) ///< Address safety checking is on.
97 #undef DECLARE_LLVM_ATTRIBUTE
99 } // namespace Attribute
101 /// Attributes - A bitset of attributes.
103 // Currently, we need less than 64 bits.
106 Attributes() : Bits(0) { }
107 explicit Attributes(uint64_t Val) : Bits(Val) { }
108 /*implicit*/ Attributes(Attribute::AttrConst Val) : Bits(Val.v) { }
109 // This is a "safe bool() operator".
110 operator const void *() const { return Bits ? this : 0; }
111 bool isEmptyOrSingleton() const { return (Bits & (Bits - 1)) == 0; }
112 bool operator == (const Attributes &Attrs) const {
113 return Bits == Attrs.Bits;
115 bool operator != (const Attributes &Attrs) const {
116 return Bits != Attrs.Bits;
118 Attributes operator | (const Attributes &Attrs) const {
119 return Attributes(Bits | Attrs.Bits);
121 Attributes operator & (const Attributes &Attrs) const {
122 return Attributes(Bits & Attrs.Bits);
124 Attributes operator ^ (const Attributes &Attrs) const {
125 return Attributes(Bits ^ Attrs.Bits);
127 Attributes &operator |= (const Attributes &Attrs) {
131 Attributes &operator &= (const Attributes &Attrs) {
135 Attributes operator ~ () const { return Attributes(~Bits); }
136 uint64_t Raw() const { return Bits; }
139 namespace Attribute {
141 /// Note that uwtable is about the ABI or the user mandating an entry in the
142 /// unwind table. The nounwind attribute is about an exception passing by the
144 /// In a theoretical system that uses tables for profiling and sjlj for
145 /// exceptions, they would be fully independent. In a normal system that
146 /// uses tables for both, the semantics are:
147 /// nil = Needs an entry because an exception might pass by.
148 /// nounwind = No need for an entry
149 /// uwtable = Needs an entry because the ABI says so and because
150 /// an exception might pass by.
151 /// uwtable + nounwind = Needs an entry because the ABI says so.
153 /// @brief Attributes that only apply to function parameters.
154 const AttrConst ParameterOnly = {ByVal_i | Nest_i |
155 StructRet_i | NoCapture_i};
157 /// @brief Attributes that may be applied to the function itself. These cannot
158 /// be used on return values or function parameters.
159 const AttrConst FunctionOnly = {NoReturn_i | NoUnwind_i | ReadNone_i |
160 ReadOnly_i | NoInline_i | AlwaysInline_i | OptimizeForSize_i |
161 StackProtect_i | StackProtectReq_i | NoRedZone_i | NoImplicitFloat_i |
162 Naked_i | InlineHint_i | StackAlignment_i |
163 UWTable_i | NonLazyBind_i | ReturnsTwice_i | AddressSafety_i};
165 /// @brief Parameter attributes that do not apply to vararg call arguments.
166 const AttrConst VarArgsIncompatible = {StructRet_i};
168 /// @brief Attributes that are mutually incompatible.
169 const AttrConst MutuallyIncompatible[5] = {
170 {ByVal_i | Nest_i | StructRet_i},
171 {ByVal_i | Nest_i | InReg_i },
173 {ReadNone_i | ReadOnly_i},
174 {NoInline_i | AlwaysInline_i}
177 /// @brief Which attributes cannot be applied to a type.
178 Attributes typeIncompatible(Type *Ty);
180 /// This turns an int alignment (a power of 2, normally) into the
181 /// form used internally in Attributes.
182 inline Attributes constructAlignmentFromInt(unsigned i) {
183 // Default alignment, allow the target to define how to align it.
187 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
188 assert(i <= 0x40000000 && "Alignment too large.");
189 return Attributes((Log2_32(i)+1) << 16);
192 /// This returns the alignment field of an attribute as a byte alignment value.
193 inline unsigned getAlignmentFromAttrs(Attributes A) {
194 Attributes Align = A & Attribute::Alignment;
198 return 1U << ((Align.Raw() >> 16) - 1);
201 /// This turns an int stack alignment (which must be a power of 2) into
202 /// the form used internally in Attributes.
203 inline Attributes constructStackAlignmentFromInt(unsigned i) {
204 // Default alignment, allow the target to define how to align it.
208 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
209 assert(i <= 0x100 && "Alignment too large.");
210 return Attributes((Log2_32(i)+1) << 26);
213 /// This returns the stack alignment field of an attribute as a byte alignment
215 inline unsigned getStackAlignmentFromAttrs(Attributes A) {
216 Attributes StackAlign = A & Attribute::StackAlignment;
220 return 1U << ((StackAlign.Raw() >> 26) - 1);
223 /// This returns an integer containing an encoding of all the
224 /// LLVM attributes found in the given attribute bitset. Any
225 /// change to this encoding is a breaking change to bitcode
227 inline uint64_t encodeLLVMAttributesForBitcode(Attributes Attrs) {
228 // FIXME: It doesn't make sense to store the alignment information as an
229 // expanded out value, we should store it as a log2 value. However, we can't
230 // just change that here without breaking bitcode compatibility. If this ever
231 // becomes a problem in practice, we should introduce new tag numbers in the
232 // bitcode file and have those tags use a more efficiently encoded alignment
235 // Store the alignment in the bitcode as a 16-bit raw value instead of a
236 // 5-bit log2 encoded value. Shift the bits above the alignment up by
239 uint64_t EncodedAttrs = Attrs.Raw() & 0xffff;
240 if (Attrs & Attribute::Alignment)
241 EncodedAttrs |= (1ull << 16) <<
242 (((Attrs & Attribute::Alignment).Raw()-1) >> 16);
243 EncodedAttrs |= (Attrs.Raw() & (0xfffull << 21)) << 11;
248 /// This returns an attribute bitset containing the LLVM attributes
249 /// that have been decoded from the given integer. This function
250 /// must stay in sync with 'encodeLLVMAttributesForBitcode'.
251 inline Attributes decodeLLVMAttributesForBitcode(uint64_t EncodedAttrs) {
252 // The alignment is stored as a 16-bit raw value from bits 31--16.
253 // We shift the bits above 31 down by 11 bits.
255 unsigned Alignment = (EncodedAttrs & (0xffffull << 16)) >> 16;
256 assert((!Alignment || isPowerOf2_32(Alignment)) &&
257 "Alignment must be a power of two.");
259 Attributes Attrs(EncodedAttrs & 0xffff);
261 Attrs |= Attribute::constructAlignmentFromInt(Alignment);
262 Attrs |= Attributes((EncodedAttrs & (0xfffull << 32)) >> 11);
268 /// The set of Attributes set in Attributes is converted to a
269 /// string of equivalent mnemonics. This is, presumably, for writing out
270 /// the mnemonics for the assembly writer.
271 /// @brief Convert attribute bits to text
272 std::string getAsString(Attributes Attrs);
273 } // end namespace Attribute
275 /// This is just a pair of values to associate a set of attributes
277 struct AttributeWithIndex {
278 Attributes Attrs; ///< The attributes that are set, or'd together.
279 unsigned Index; ///< Index of the parameter for which the attributes apply.
280 ///< Index 0 is used for return value attributes.
281 ///< Index ~0U is used for function attributes.
283 static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
284 AttributeWithIndex P;
291 //===----------------------------------------------------------------------===//
292 // AttrListPtr Smart Pointer
293 //===----------------------------------------------------------------------===//
295 class AttributeListImpl;
297 /// AttrListPtr - This class manages the ref count for the opaque
298 /// AttributeListImpl object and provides accessors for it.
300 /// AttrList - The attributes that we are managing. This can be null
301 /// to represent the empty attributes list.
302 AttributeListImpl *AttrList;
304 AttrListPtr() : AttrList(0) {}
305 AttrListPtr(const AttrListPtr &P);
306 const AttrListPtr &operator=(const AttrListPtr &RHS);
309 //===--------------------------------------------------------------------===//
310 // Attribute List Construction and Mutation
311 //===--------------------------------------------------------------------===//
313 /// get - Return a Attributes list with the specified parameters in it.
314 static AttrListPtr get(ArrayRef<AttributeWithIndex> Attrs);
316 /// addAttr - Add the specified attribute at the specified index to this
317 /// attribute list. Since attribute lists are immutable, this
318 /// returns the new list.
319 AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
321 /// removeAttr - Remove the specified attribute at the specified index from
322 /// this attribute list. Since attribute lists are immutable, this
323 /// returns the new list.
324 AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
326 //===--------------------------------------------------------------------===//
327 // Attribute List Accessors
328 //===--------------------------------------------------------------------===//
329 /// getParamAttributes - The attributes for the specified index are
331 Attributes getParamAttributes(unsigned Idx) const {
332 assert (Idx && Idx != ~0U && "Invalid parameter index!");
333 return getAttributes(Idx);
336 /// getRetAttributes - The attributes for the ret value are
338 Attributes getRetAttributes() const {
339 return getAttributes(0);
342 /// getFnAttributes - The function attributes are returned.
343 Attributes getFnAttributes() const {
344 return getAttributes(~0U);
347 /// paramHasAttr - Return true if the specified parameter index has the
348 /// specified attribute set.
349 bool paramHasAttr(unsigned Idx, Attributes Attr) const {
350 return getAttributes(Idx) & Attr;
353 /// getParamAlignment - Return the alignment for the specified function
355 unsigned getParamAlignment(unsigned Idx) const {
356 return Attribute::getAlignmentFromAttrs(getAttributes(Idx));
359 /// hasAttrSomewhere - Return true if the specified attribute is set for at
360 /// least one parameter or for the return value.
361 bool hasAttrSomewhere(Attributes Attr) const;
363 /// operator==/!= - Provide equality predicates.
364 bool operator==(const AttrListPtr &RHS) const
365 { return AttrList == RHS.AttrList; }
366 bool operator!=(const AttrListPtr &RHS) const
367 { return AttrList != RHS.AttrList; }
371 //===--------------------------------------------------------------------===//
372 // Attribute List Introspection
373 //===--------------------------------------------------------------------===//
375 /// getRawPointer - Return a raw pointer that uniquely identifies this
377 void *getRawPointer() const {
381 // Attributes are stored as a dense set of slots, where there is one
382 // slot for each argument that has an attribute. This allows walking over the
383 // dense set instead of walking the sparse list of attributes.
385 /// isEmpty - Return true if there are no attributes.
387 bool isEmpty() const {
388 return AttrList == 0;
391 /// getNumSlots - Return the number of slots used in this attribute list.
392 /// This is the number of arguments that have an attribute set on them
393 /// (including the function itself).
394 unsigned getNumSlots() const;
396 /// getSlot - Return the AttributeWithIndex at the specified slot. This
397 /// holds a index number plus a set of attributes.
398 const AttributeWithIndex &getSlot(unsigned Slot) const;
401 explicit AttrListPtr(AttributeListImpl *L);
403 /// getAttributes - The attributes for the specified index are
404 /// returned. Attributes for the result are denoted with Idx = 0.
405 Attributes getAttributes(unsigned Idx) const;
409 } // End llvm namespace