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"
27 /// We use this proxy POD type to allow constructing Attributes constants
28 /// using initializer lists. Do not use this class directly.
31 AttrConst operator | (const AttrConst Attrs) const {
32 AttrConst Res = {v | Attrs.v};
35 AttrConst operator ~ () const {
40 } // namespace Attribute
43 /// Attributes - A bitset of attributes.
46 Attributes() : Bits(0) { }
47 explicit Attributes(uint64_t Val) : Bits(Val) { }
48 /*implicit*/ Attributes(Attribute::AttrConst Val) : Bits(Val.v) { }
49 // This is a "safe bool() operator".
50 operator const void *() const { return Bits ? this : 0; }
51 bool isEmptyOrSingleton() const { return (Bits & (Bits - 1)) == 0; }
52 bool operator == (const Attributes &Attrs) const {
53 return Bits == Attrs.Bits;
55 bool operator != (const Attributes &Attrs) const {
56 return Bits != Attrs.Bits;
58 Attributes operator | (const Attributes &Attrs) const {
59 return Attributes(Bits | Attrs.Bits);
61 Attributes operator & (const Attributes &Attrs) const {
62 return Attributes(Bits & Attrs.Bits);
64 Attributes operator ^ (const Attributes &Attrs) const {
65 return Attributes(Bits ^ Attrs.Bits);
67 Attributes &operator |= (const Attributes &Attrs) {
71 Attributes &operator &= (const Attributes &Attrs) {
75 Attributes operator ~ () const { return Attributes(~Bits); }
76 uint64_t Raw() const { return Bits; }
78 // Currently, we need less than 64 bits.
84 /// Function parameters and results can have attributes to indicate how they
85 /// should be treated by optimizations and code generation. This enumeration
86 /// lists the attributes that can be associated with parameters, function
87 /// results or the function itself.
88 /// @brief Function attributes.
90 // We declare AttrConst objects that will be used throughout the code
91 // and also raw uint64_t objects with _i suffix to be used below for other
92 // constant declarations. This is done to avoid static CTORs and at the same
93 // time to keep type-safety of Attributes.
94 #define DECLARE_LLVM_ATTRIBUTE(name, value) \
95 const uint64_t name##_i = value; \
96 const AttrConst name = {value};
98 DECLARE_LLVM_ATTRIBUTE(None,0) ///< No attributes have been set
99 DECLARE_LLVM_ATTRIBUTE(ZExt,1<<0) ///< Zero extended before/after call
100 DECLARE_LLVM_ATTRIBUTE(SExt,1<<1) ///< Sign extended before/after call
101 DECLARE_LLVM_ATTRIBUTE(NoReturn,1<<2) ///< Mark the function as not returning
102 DECLARE_LLVM_ATTRIBUTE(InReg,1<<3) ///< Force argument to be passed in register
103 DECLARE_LLVM_ATTRIBUTE(StructRet,1<<4) ///< Hidden pointer to structure to return
104 DECLARE_LLVM_ATTRIBUTE(NoUnwind,1<<5) ///< Function doesn't unwind stack
105 DECLARE_LLVM_ATTRIBUTE(NoAlias,1<<6) ///< Considered to not alias after call
106 DECLARE_LLVM_ATTRIBUTE(ByVal,1<<7) ///< Pass structure by value
107 DECLARE_LLVM_ATTRIBUTE(Nest,1<<8) ///< Nested function static chain
108 DECLARE_LLVM_ATTRIBUTE(ReadNone,1<<9) ///< Function does not access memory
109 DECLARE_LLVM_ATTRIBUTE(ReadOnly,1<<10) ///< Function only reads from memory
110 DECLARE_LLVM_ATTRIBUTE(NoInline,1<<11) ///< inline=never
111 DECLARE_LLVM_ATTRIBUTE(AlwaysInline,1<<12) ///< inline=always
112 DECLARE_LLVM_ATTRIBUTE(OptimizeForSize,1<<13) ///< opt_size
113 DECLARE_LLVM_ATTRIBUTE(StackProtect,1<<14) ///< Stack protection.
114 DECLARE_LLVM_ATTRIBUTE(StackProtectReq,1<<15) ///< Stack protection required.
115 DECLARE_LLVM_ATTRIBUTE(Alignment,31<<16) ///< Alignment of parameter (5 bits)
116 // stored as log2 of alignment with +1 bias
117 // 0 means unaligned different from align 1
118 DECLARE_LLVM_ATTRIBUTE(NoCapture,1<<21) ///< Function creates no aliases of pointer
119 DECLARE_LLVM_ATTRIBUTE(NoRedZone,1<<22) /// disable redzone
120 DECLARE_LLVM_ATTRIBUTE(NoImplicitFloat,1<<23) /// disable implicit floating point
122 DECLARE_LLVM_ATTRIBUTE(Naked,1<<24) ///< Naked function
123 DECLARE_LLVM_ATTRIBUTE(InlineHint,1<<25) ///< source said inlining was
125 DECLARE_LLVM_ATTRIBUTE(StackAlignment,7<<26) ///< Alignment of stack for
126 ///function (3 bits) stored as log2
127 ///of alignment with +1 bias
128 ///0 means unaligned (different from
130 DECLARE_LLVM_ATTRIBUTE(ReturnsTwice,1<<29) ///< Function can return twice
131 DECLARE_LLVM_ATTRIBUTE(UWTable,1<<30) ///< Function must be in a unwind
133 DECLARE_LLVM_ATTRIBUTE(NonLazyBind,1U<<31) ///< Function is called early and/or
134 /// often, so lazy binding isn't
136 DECLARE_LLVM_ATTRIBUTE(AddressSafety,1ULL<<32) ///< Address safety checking is on.
138 #undef DECLARE_LLVM_ATTRIBUTE
140 /// Note that uwtable is about the ABI or the user mandating an entry in the
141 /// unwind table. The nounwind attribute is about an exception passing by the
143 /// In a theoretical system that uses tables for profiling and sjlj for
144 /// exceptions, they would be fully independent. In a normal system that
145 /// uses tables for both, the semantics are:
146 /// nil = Needs an entry because an exception might pass by.
147 /// nounwind = No need for an entry
148 /// uwtable = Needs an entry because the ABI says so and because
149 /// an exception might pass by.
150 /// uwtable + nounwind = Needs an entry because the ABI says so.
152 /// @brief Attributes that only apply to function parameters.
153 const AttrConst ParameterOnly = {ByVal_i | Nest_i |
154 StructRet_i | NoCapture_i};
156 /// @brief Attributes that may be applied to the function itself. These cannot
157 /// be used on return values or function parameters.
158 const AttrConst FunctionOnly = {NoReturn_i | NoUnwind_i | ReadNone_i |
159 ReadOnly_i | NoInline_i | AlwaysInline_i | OptimizeForSize_i |
160 StackProtect_i | StackProtectReq_i | NoRedZone_i | NoImplicitFloat_i |
161 Naked_i | InlineHint_i | StackAlignment_i |
162 UWTable_i | NonLazyBind_i | ReturnsTwice_i | AddressSafety_i};
164 /// @brief Parameter attributes that do not apply to vararg call arguments.
165 const AttrConst VarArgsIncompatible = {StructRet_i};
167 /// @brief Attributes that are mutually incompatible.
168 const AttrConst MutuallyIncompatible[5] = {
169 {ByVal_i | Nest_i | StructRet_i},
170 {ByVal_i | Nest_i | InReg_i },
172 {ReadNone_i | ReadOnly_i},
173 {NoInline_i | AlwaysInline_i}
176 /// @brief Which attributes cannot be applied to a type.
177 Attributes typeIncompatible(Type *Ty);
179 /// This turns an int alignment (a power of 2, normally) into the
180 /// form used internally in Attributes.
181 inline Attributes constructAlignmentFromInt(unsigned i) {
182 // Default alignment, allow the target to define how to align it.
186 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
187 assert(i <= 0x40000000 && "Alignment too large.");
188 return Attributes((Log2_32(i)+1) << 16);
191 /// This returns the alignment field of an attribute as a byte alignment value.
192 inline unsigned getAlignmentFromAttrs(Attributes A) {
193 Attributes Align = A & Attribute::Alignment;
197 return 1U << ((Align.Raw() >> 16) - 1);
200 /// This turns an int stack alignment (which must be a power of 2) into
201 /// the form used internally in Attributes.
202 inline Attributes constructStackAlignmentFromInt(unsigned i) {
203 // Default alignment, allow the target to define how to align it.
207 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
208 assert(i <= 0x100 && "Alignment too large.");
209 return Attributes((Log2_32(i)+1) << 26);
212 /// This returns the stack alignment field of an attribute as a byte alignment
214 inline unsigned getStackAlignmentFromAttrs(Attributes A) {
215 Attributes StackAlign = A & Attribute::StackAlignment;
219 return 1U << ((StackAlign.Raw() >> 26) - 1);
222 /// This returns an integer containing an encoding of all the
223 /// LLVM attributes found in the given attribute bitset. Any
224 /// change to this encoding is a breaking change to bitcode
226 inline uint64_t encodeLLVMAttributesForBitcode(Attributes Attrs) {
227 // FIXME: It doesn't make sense to store the alignment information as an
228 // expanded out value, we should store it as a log2 value. However, we can't
229 // just change that here without breaking bitcode compatibility. If this ever
230 // becomes a problem in practice, we should introduce new tag numbers in the
231 // bitcode file and have those tags use a more efficiently encoded alignment
234 // Store the alignment in the bitcode as a 16-bit raw value instead of a
235 // 5-bit log2 encoded value. Shift the bits above the alignment up by
238 uint64_t EncodedAttrs = Attrs.Raw() & 0xffff;
239 if (Attrs & Attribute::Alignment)
240 EncodedAttrs |= (1ull << 16) <<
241 (((Attrs & Attribute::Alignment).Raw()-1) >> 16);
242 EncodedAttrs |= (Attrs.Raw() & (0xfffull << 21)) << 11;
247 /// This returns an attribute bitset containing the LLVM attributes
248 /// that have been decoded from the given integer. This function
249 /// must stay in sync with 'encodeLLVMAttributesForBitcode'.
250 inline Attributes decodeLLVMAttributesForBitcode(uint64_t EncodedAttrs) {
251 // The alignment is stored as a 16-bit raw value from bits 31--16.
252 // We shift the bits above 31 down by 11 bits.
254 unsigned Alignment = (EncodedAttrs & (0xffffull << 16)) >> 16;
255 assert((!Alignment || isPowerOf2_32(Alignment)) &&
256 "Alignment must be a power of two.");
258 Attributes Attrs(EncodedAttrs & 0xffff);
260 Attrs |= Attribute::constructAlignmentFromInt(Alignment);
261 Attrs |= Attributes((EncodedAttrs & (0xfffull << 32)) >> 11);
267 /// The set of Attributes set in Attributes is converted to a
268 /// string of equivalent mnemonics. This is, presumably, for writing out
269 /// the mnemonics for the assembly writer.
270 /// @brief Convert attribute bits to text
271 std::string getAsString(Attributes Attrs);
272 } // end namespace Attribute
274 /// This is just a pair of values to associate a set of attributes
276 struct AttributeWithIndex {
277 Attributes Attrs; ///< The attributes that are set, or'd together.
278 unsigned Index; ///< Index of the parameter for which the attributes apply.
279 ///< Index 0 is used for return value attributes.
280 ///< Index ~0U is used for function attributes.
282 static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
283 AttributeWithIndex P;
290 //===----------------------------------------------------------------------===//
291 // AttrListPtr Smart Pointer
292 //===----------------------------------------------------------------------===//
294 class AttributeListImpl;
296 /// AttrListPtr - This class manages the ref count for the opaque
297 /// AttributeListImpl object and provides accessors for it.
299 /// AttrList - The attributes that we are managing. This can be null
300 /// to represent the empty attributes list.
301 AttributeListImpl *AttrList;
303 AttrListPtr() : AttrList(0) {}
304 AttrListPtr(const AttrListPtr &P);
305 const AttrListPtr &operator=(const AttrListPtr &RHS);
308 //===--------------------------------------------------------------------===//
309 // Attribute List Construction and Mutation
310 //===--------------------------------------------------------------------===//
312 /// get - Return a Attributes list with the specified parameters in it.
313 static AttrListPtr get(ArrayRef<AttributeWithIndex> Attrs);
315 /// addAttr - Add the specified attribute at the specified index to this
316 /// attribute list. Since attribute lists are immutable, this
317 /// returns the new list.
318 AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
320 /// removeAttr - Remove the specified attribute at the specified index from
321 /// this attribute list. Since attribute lists are immutable, this
322 /// returns the new list.
323 AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
325 //===--------------------------------------------------------------------===//
326 // Attribute List Accessors
327 //===--------------------------------------------------------------------===//
328 /// getParamAttributes - The attributes for the specified index are
330 Attributes getParamAttributes(unsigned Idx) const {
331 assert (Idx && Idx != ~0U && "Invalid parameter index!");
332 return getAttributes(Idx);
335 /// getRetAttributes - The attributes for the ret value are
337 Attributes getRetAttributes() const {
338 return getAttributes(0);
341 /// getFnAttributes - The function attributes are returned.
342 Attributes getFnAttributes() const {
343 return getAttributes(~0U);
346 /// paramHasAttr - Return true if the specified parameter index has the
347 /// specified attribute set.
348 bool paramHasAttr(unsigned Idx, Attributes Attr) const {
349 return getAttributes(Idx) & Attr;
352 /// getParamAlignment - Return the alignment for the specified function
354 unsigned getParamAlignment(unsigned Idx) const {
355 return Attribute::getAlignmentFromAttrs(getAttributes(Idx));
358 /// hasAttrSomewhere - Return true if the specified attribute is set for at
359 /// least one parameter or for the return value.
360 bool hasAttrSomewhere(Attributes Attr) const;
362 /// operator==/!= - Provide equality predicates.
363 bool operator==(const AttrListPtr &RHS) const
364 { return AttrList == RHS.AttrList; }
365 bool operator!=(const AttrListPtr &RHS) const
366 { return AttrList != RHS.AttrList; }
370 //===--------------------------------------------------------------------===//
371 // Attribute List Introspection
372 //===--------------------------------------------------------------------===//
374 /// getRawPointer - Return a raw pointer that uniquely identifies this
376 void *getRawPointer() const {
380 // Attributes are stored as a dense set of slots, where there is one
381 // slot for each argument that has an attribute. This allows walking over the
382 // dense set instead of walking the sparse list of attributes.
384 /// isEmpty - Return true if there are no attributes.
386 bool isEmpty() const {
387 return AttrList == 0;
390 /// getNumSlots - Return the number of slots used in this attribute list.
391 /// This is the number of arguments that have an attribute set on them
392 /// (including the function itself).
393 unsigned getNumSlots() const;
395 /// getSlot - Return the AttributeWithIndex at the specified slot. This
396 /// holds a index number plus a set of attributes.
397 const AttributeWithIndex &getSlot(unsigned Slot) const;
400 explicit AttrListPtr(AttributeListImpl *L);
402 /// getAttributes - The attributes for the specified index are
403 /// returned. Attributes for the result are denoted with Idx = 0.
404 Attributes getAttributes(unsigned Idx) const;
408 } // End llvm namespace