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) { }
110 // Attribute query methods.
111 // FIXME: StackAlignment & Alignment attributes have no predicate methods.
112 bool hasAttributes() const {
115 bool hasAttributes(const Attributes &A) const {
116 return Bits & A.Bits;
119 bool hasZExtAttr() const {
120 return Bits & Attribute::ZExt_i;
122 bool hasSExtAttr() const {
123 return Bits & Attribute::SExt_i;
125 bool hasNoReturnAttr() const {
126 return Bits & Attribute::NoReturn_i;
128 bool hasInRegAttr() const {
129 return Bits & Attribute::InReg_i;
131 bool hasStructRetAttr() const {
132 return Bits & Attribute::StructRet_i;
134 bool hasNoUnwindAttr() const {
135 return Bits & Attribute::NoUnwind_i;
137 bool hasNoAliasAttr() const {
138 return Bits & Attribute::NoAlias_i;
140 bool hasByValAttr() const {
141 return Bits & Attribute::ByVal_i;
143 bool hasNestAttr() const {
144 return Bits & Attribute::Nest_i;
146 bool hasReadNoneAttr() const {
147 return Bits & Attribute::ReadNone_i;
149 bool hasReadOnlyAttr() const {
150 return Bits & Attribute::ReadOnly_i;
152 bool hasNoInlineAttr() const {
153 return Bits & Attribute::NoInline_i;
155 bool hasAlwaysInlineAttr() const {
156 return Bits & Attribute::AlwaysInline_i;
158 bool hasOptimizeForSizeAttr() const {
159 return Bits & Attribute::OptimizeForSize_i;
161 bool hasStackProtectAttr() const {
162 return Bits & Attribute::StackProtect_i;
164 bool hasStackProtectReqAttr() const {
165 return Bits & Attribute::StackProtectReq_i;
167 bool hasAlignmentAttr() const {
168 return Bits & Attribute::Alignment_i;
170 bool hasNoCaptureAttr() const {
171 return Bits & Attribute::NoCapture_i;
173 bool hasNoRedZoneAttr() const {
174 return Bits & Attribute::NoRedZone_i;
176 bool hasNoImplicitFloatAttr() const {
177 return Bits & Attribute::NoImplicitFloat_i;
179 bool hasNakedAttr() const {
180 return Bits & Attribute::Naked_i;
182 bool hasInlineHintAttr() const {
183 return Bits & Attribute::InlineHint_i;
185 bool hasReturnsTwiceAttr() const {
186 return Bits & Attribute::ReturnsTwice_i;
188 bool hasStackAlignmentAttr() const {
189 return Bits & Attribute::StackAlignment_i;
191 bool hasUWTableAttr() const {
192 return Bits & Attribute::UWTable_i;
194 bool hasNonLazyBindAttr() const {
195 return Bits & Attribute::NonLazyBind_i;
197 bool hasAddressSafetyAttr() const {
198 return Bits & Attribute::AddressSafety_i;
201 uint64_t getRawAlignment() const {
202 return Bits & Attribute::Alignment_i;
204 uint64_t getRawStackAlignment() const {
205 return Bits & Attribute::StackAlignment_i;
208 /// This returns the alignment field of an attribute as a byte alignment
210 unsigned getAlignment() const {
211 if (!hasAlignmentAttr())
214 return 1U << ((getRawAlignment() >> 16) - 1);
217 /// This returns the stack alignment field of an attribute as a byte alignment
219 unsigned getStackAlignment() const {
220 if (!hasStackAlignmentAttr())
223 return 1U << ((getRawStackAlignment() >> 26) - 1);
226 /// This turns an int alignment (a power of 2, normally) into the form used
227 /// internally in Attributes.
228 static Attributes constructAlignmentFromInt(unsigned i) {
229 // Default alignment, allow the target to define how to align it.
231 return Attribute::None;
233 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
234 assert(i <= 0x40000000 && "Alignment too large.");
235 return Attributes((Log2_32(i)+1) << 16);
238 /// This turns an int stack alignment (which must be a power of 2) into the
239 /// form used internally in Attributes.
240 static Attributes constructStackAlignmentFromInt(unsigned i) {
241 // Default alignment, allow the target to define how to align it.
243 return Attribute::None;
245 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
246 assert(i <= 0x100 && "Alignment too large.");
247 return Attributes((Log2_32(i)+1) << 26);
250 // This is a "safe bool() operator".
251 operator const void *() const { return Bits ? this : 0; }
252 bool isEmptyOrSingleton() const { return (Bits & (Bits - 1)) == 0; }
253 bool operator == (const Attributes &Attrs) const {
254 return Bits == Attrs.Bits;
256 bool operator != (const Attributes &Attrs) const {
257 return Bits != Attrs.Bits;
259 Attributes operator | (const Attributes &Attrs) const {
260 return Attributes(Bits | Attrs.Bits);
262 Attributes operator & (const Attributes &Attrs) const {
263 return Attributes(Bits & Attrs.Bits);
265 Attributes operator ^ (const Attributes &Attrs) const {
266 return Attributes(Bits ^ Attrs.Bits);
268 Attributes &operator |= (const Attributes &Attrs) {
272 Attributes &operator &= (const Attributes &Attrs) {
276 Attributes operator ~ () const { return Attributes(~Bits); }
277 uint64_t Raw() const { return Bits; }
279 /// @brief Which attributes cannot be applied to a type.
280 static Attributes typeIncompatible(Type *Ty);
282 /// The set of Attributes set in Attributes is converted to a string of
283 /// equivalent mnemonics. This is, presumably, for writing out the mnemonics
284 /// for the assembly writer.
285 /// @brief Convert attribute bits to text
286 std::string getAsString() const;
289 namespace Attribute {
291 /// Note that uwtable is about the ABI or the user mandating an entry in the
292 /// unwind table. The nounwind attribute is about an exception passing by the
294 /// In a theoretical system that uses tables for profiling and sjlj for
295 /// exceptions, they would be fully independent. In a normal system that
296 /// uses tables for both, the semantics are:
297 /// nil = Needs an entry because an exception might pass by.
298 /// nounwind = No need for an entry
299 /// uwtable = Needs an entry because the ABI says so and because
300 /// an exception might pass by.
301 /// uwtable + nounwind = Needs an entry because the ABI says so.
303 /// @brief Attributes that only apply to function parameters.
304 const AttrConst ParameterOnly = {ByVal_i | Nest_i |
305 StructRet_i | NoCapture_i};
307 /// @brief Attributes that may be applied to the function itself. These cannot
308 /// be used on return values or function parameters.
309 const AttrConst FunctionOnly = {NoReturn_i | NoUnwind_i | ReadNone_i |
310 ReadOnly_i | NoInline_i | AlwaysInline_i | OptimizeForSize_i |
311 StackProtect_i | StackProtectReq_i | NoRedZone_i | NoImplicitFloat_i |
312 Naked_i | InlineHint_i | StackAlignment_i |
313 UWTable_i | NonLazyBind_i | ReturnsTwice_i | AddressSafety_i};
315 /// @brief Parameter attributes that do not apply to vararg call arguments.
316 const AttrConst VarArgsIncompatible = {StructRet_i};
318 /// @brief Attributes that are mutually incompatible.
319 const AttrConst MutuallyIncompatible[5] = {
320 {ByVal_i | Nest_i | StructRet_i},
321 {ByVal_i | Nest_i | InReg_i },
323 {ReadNone_i | ReadOnly_i},
324 {NoInline_i | AlwaysInline_i}
327 /// This returns an integer containing an encoding of all the
328 /// LLVM attributes found in the given attribute bitset. Any
329 /// change to this encoding is a breaking change to bitcode
331 inline uint64_t encodeLLVMAttributesForBitcode(Attributes Attrs) {
332 // FIXME: It doesn't make sense to store the alignment information as an
333 // expanded out value, we should store it as a log2 value. However, we can't
334 // just change that here without breaking bitcode compatibility. If this ever
335 // becomes a problem in practice, we should introduce new tag numbers in the
336 // bitcode file and have those tags use a more efficiently encoded alignment
339 // Store the alignment in the bitcode as a 16-bit raw value instead of a
340 // 5-bit log2 encoded value. Shift the bits above the alignment up by
343 uint64_t EncodedAttrs = Attrs.Raw() & 0xffff;
344 if (Attrs.hasAlignmentAttr())
345 EncodedAttrs |= (1ull << 16) <<
346 ((Attrs.getRawAlignment() - 1) >> 16);
347 EncodedAttrs |= (Attrs.Raw() & (0xfffull << 21)) << 11;
352 /// This returns an attribute bitset containing the LLVM attributes
353 /// that have been decoded from the given integer. This function
354 /// must stay in sync with 'encodeLLVMAttributesForBitcode'.
355 inline Attributes decodeLLVMAttributesForBitcode(uint64_t EncodedAttrs) {
356 // The alignment is stored as a 16-bit raw value from bits 31--16.
357 // We shift the bits above 31 down by 11 bits.
359 unsigned Alignment = (EncodedAttrs & (0xffffull << 16)) >> 16;
360 assert((!Alignment || isPowerOf2_32(Alignment)) &&
361 "Alignment must be a power of two.");
363 Attributes Attrs(EncodedAttrs & 0xffff);
365 Attrs |= Attributes::constructAlignmentFromInt(Alignment);
366 Attrs |= Attributes((EncodedAttrs & (0xfffull << 32)) >> 11);
371 } // end namespace Attribute
373 /// This is just a pair of values to associate a set of attributes
375 struct AttributeWithIndex {
376 Attributes Attrs; ///< The attributes that are set, or'd together.
377 unsigned Index; ///< Index of the parameter for which the attributes apply.
378 ///< Index 0 is used for return value attributes.
379 ///< Index ~0U is used for function attributes.
381 static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
382 AttributeWithIndex P;
389 //===----------------------------------------------------------------------===//
390 // AttrListPtr Smart Pointer
391 //===----------------------------------------------------------------------===//
393 class AttributeListImpl;
395 /// AttrListPtr - This class manages the ref count for the opaque
396 /// AttributeListImpl object and provides accessors for it.
398 /// AttrList - The attributes that we are managing. This can be null
399 /// to represent the empty attributes list.
400 AttributeListImpl *AttrList;
402 AttrListPtr() : AttrList(0) {}
403 AttrListPtr(const AttrListPtr &P);
404 const AttrListPtr &operator=(const AttrListPtr &RHS);
407 //===--------------------------------------------------------------------===//
408 // Attribute List Construction and Mutation
409 //===--------------------------------------------------------------------===//
411 /// get - Return a Attributes list with the specified parameters in it.
412 static AttrListPtr get(ArrayRef<AttributeWithIndex> Attrs);
414 /// addAttr - Add the specified attribute at the specified index to this
415 /// attribute list. Since attribute lists are immutable, this
416 /// returns the new list.
417 AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
419 /// removeAttr - Remove the specified attribute at the specified index from
420 /// this attribute list. Since attribute lists are immutable, this
421 /// returns the new list.
422 AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
424 //===--------------------------------------------------------------------===//
425 // Attribute List Accessors
426 //===--------------------------------------------------------------------===//
427 /// getParamAttributes - The attributes for the specified index are
429 Attributes getParamAttributes(unsigned Idx) const {
430 assert (Idx && Idx != ~0U && "Invalid parameter index!");
431 return getAttributes(Idx);
434 /// getRetAttributes - The attributes for the ret value are
436 Attributes getRetAttributes() const {
437 return getAttributes(0);
440 /// getFnAttributes - The function attributes are returned.
441 Attributes getFnAttributes() const {
442 return getAttributes(~0U);
445 /// paramHasAttr - Return true if the specified parameter index has the
446 /// specified attribute set.
447 bool paramHasAttr(unsigned Idx, Attributes Attr) const {
448 return getAttributes(Idx).hasAttributes(Attr);
451 /// getParamAlignment - Return the alignment for the specified function
453 unsigned getParamAlignment(unsigned Idx) const {
454 return getAttributes(Idx).getAlignment();
457 /// hasAttrSomewhere - Return true if the specified attribute is set for at
458 /// least one parameter or for the return value.
459 bool hasAttrSomewhere(Attributes Attr) const;
461 /// operator==/!= - Provide equality predicates.
462 bool operator==(const AttrListPtr &RHS) const
463 { return AttrList == RHS.AttrList; }
464 bool operator!=(const AttrListPtr &RHS) const
465 { return AttrList != RHS.AttrList; }
469 //===--------------------------------------------------------------------===//
470 // Attribute List Introspection
471 //===--------------------------------------------------------------------===//
473 /// getRawPointer - Return a raw pointer that uniquely identifies this
475 void *getRawPointer() const {
479 // Attributes are stored as a dense set of slots, where there is one
480 // slot for each argument that has an attribute. This allows walking over the
481 // dense set instead of walking the sparse list of attributes.
483 /// isEmpty - Return true if there are no attributes.
485 bool isEmpty() const {
486 return AttrList == 0;
489 /// getNumSlots - Return the number of slots used in this attribute list.
490 /// This is the number of arguments that have an attribute set on them
491 /// (including the function itself).
492 unsigned getNumSlots() const;
494 /// getSlot - Return the AttributeWithIndex at the specified slot. This
495 /// holds a index number plus a set of attributes.
496 const AttributeWithIndex &getSlot(unsigned Slot) const;
499 explicit AttrListPtr(AttributeListImpl *L);
501 /// getAttributes - The attributes for the specified index are
502 /// returned. Attributes for the result are denoted with Idx = 0.
503 Attributes getAttributes(unsigned Idx) const;
507 } // End llvm namespace