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/AttributesImpl.h"
19 #include "llvm/Support/MathExtras.h"
20 #include "llvm/ADT/ArrayRef.h"
31 /// AttrConst - We use this proxy POD type to allow constructing Attributes
32 /// constants using initializer lists. Do not use this class directly.
35 AttrConst operator | (const AttrConst Attrs) const {
36 AttrConst Res = {v | Attrs.v};
39 AttrConst operator ~ () const {
45 /// Function parameters and results can have attributes to indicate how they
46 /// should be treated by optimizations and code generation. This enumeration
47 /// lists the attributes that can be associated with parameters, function
48 /// results or the function itself.
49 /// @brief Function attributes.
51 /// We declare AttrConst objects that will be used throughout the code and also
52 /// raw uint64_t objects with _i suffix to be used below for other constant
53 /// declarations. This is done to avoid static CTORs and at the same time to
54 /// keep type-safety of Attributes.
55 #define DECLARE_LLVM_ATTRIBUTE(name, value) \
56 const uint64_t name##_i = value; \
57 const AttrConst name = {value};
59 DECLARE_LLVM_ATTRIBUTE(None,0) ///< No attributes have been set
60 DECLARE_LLVM_ATTRIBUTE(ZExt,1<<0) ///< Zero extended before/after call
61 DECLARE_LLVM_ATTRIBUTE(SExt,1<<1) ///< Sign extended before/after call
62 DECLARE_LLVM_ATTRIBUTE(NoReturn,1<<2) ///< Mark the function as not returning
63 DECLARE_LLVM_ATTRIBUTE(InReg,1<<3) ///< Force argument to be passed in register
64 DECLARE_LLVM_ATTRIBUTE(StructRet,1<<4) ///< Hidden pointer to structure to return
65 DECLARE_LLVM_ATTRIBUTE(NoUnwind,1<<5) ///< Function doesn't unwind stack
66 DECLARE_LLVM_ATTRIBUTE(NoAlias,1<<6) ///< Considered to not alias after call
67 DECLARE_LLVM_ATTRIBUTE(ByVal,1<<7) ///< Pass structure by value
68 DECLARE_LLVM_ATTRIBUTE(Nest,1<<8) ///< Nested function static chain
69 DECLARE_LLVM_ATTRIBUTE(ReadNone,1<<9) ///< Function does not access memory
70 DECLARE_LLVM_ATTRIBUTE(ReadOnly,1<<10) ///< Function only reads from memory
71 DECLARE_LLVM_ATTRIBUTE(NoInline,1<<11) ///< inline=never
72 DECLARE_LLVM_ATTRIBUTE(AlwaysInline,1<<12) ///< inline=always
73 DECLARE_LLVM_ATTRIBUTE(OptimizeForSize,1<<13) ///< opt_size
74 DECLARE_LLVM_ATTRIBUTE(StackProtect,1<<14) ///< Stack protection.
75 DECLARE_LLVM_ATTRIBUTE(StackProtectReq,1<<15) ///< Stack protection required.
76 DECLARE_LLVM_ATTRIBUTE(Alignment,31<<16) ///< Alignment of parameter (5 bits)
77 // stored as log2 of alignment with +1 bias
78 // 0 means unaligned different from align 1
79 DECLARE_LLVM_ATTRIBUTE(NoCapture,1<<21) ///< Function creates no aliases of pointer
80 DECLARE_LLVM_ATTRIBUTE(NoRedZone,1<<22) /// disable redzone
81 DECLARE_LLVM_ATTRIBUTE(NoImplicitFloat,1<<23) /// disable implicit floating point
83 DECLARE_LLVM_ATTRIBUTE(Naked,1<<24) ///< Naked function
84 DECLARE_LLVM_ATTRIBUTE(InlineHint,1<<25) ///< source said inlining was
86 DECLARE_LLVM_ATTRIBUTE(StackAlignment,7<<26) ///< Alignment of stack for
87 ///function (3 bits) stored as log2
88 ///of alignment with +1 bias
89 ///0 means unaligned (different from
91 DECLARE_LLVM_ATTRIBUTE(ReturnsTwice,1<<29) ///< Function can return twice
92 DECLARE_LLVM_ATTRIBUTE(UWTable,1<<30) ///< Function must be in a unwind
94 DECLARE_LLVM_ATTRIBUTE(NonLazyBind,1U<<31) ///< Function is called early and/or
95 /// often, so lazy binding isn't
97 DECLARE_LLVM_ATTRIBUTE(AddressSafety,1ULL<<32) ///< Address safety checking is on.
99 #undef DECLARE_LLVM_ATTRIBUTE
101 /// Note that uwtable is about the ABI or the user mandating an entry in the
102 /// unwind table. The nounwind attribute is about an exception passing by the
104 /// In a theoretical system that uses tables for profiling and sjlj for
105 /// exceptions, they would be fully independent. In a normal system that
106 /// uses tables for both, the semantics are:
107 /// nil = Needs an entry because an exception might pass by.
108 /// nounwind = No need for an entry
109 /// uwtable = Needs an entry because the ABI says so and because
110 /// an exception might pass by.
111 /// uwtable + nounwind = Needs an entry because the ABI says so.
113 /// @brief Attributes that only apply to function parameters.
114 const AttrConst ParameterOnly = {ByVal_i | Nest_i |
115 StructRet_i | NoCapture_i};
117 /// @brief Attributes that may be applied to the function itself. These cannot
118 /// be used on return values or function parameters.
119 const AttrConst FunctionOnly = {NoReturn_i | NoUnwind_i | ReadNone_i |
120 ReadOnly_i | NoInline_i | AlwaysInline_i | OptimizeForSize_i |
121 StackProtect_i | StackProtectReq_i | NoRedZone_i | NoImplicitFloat_i |
122 Naked_i | InlineHint_i | StackAlignment_i |
123 UWTable_i | NonLazyBind_i | ReturnsTwice_i | AddressSafety_i};
125 /// @brief Parameter attributes that do not apply to vararg call arguments.
126 const AttrConst VarArgsIncompatible = {StructRet_i};
128 /// @brief Attributes that are mutually incompatible.
129 const AttrConst MutuallyIncompatible[5] = {
130 {ByVal_i | Nest_i | StructRet_i},
131 {ByVal_i | Nest_i | InReg_i },
133 {ReadNone_i | ReadOnly_i},
134 {NoInline_i | AlwaysInline_i}
137 } // namespace Attribute
139 /// AttributeImpl - The internal representation of the Attributes class. This is
141 class AttributesImpl;
143 /// Attributes - A bitset of attributes.
145 // Currently, we need less than 64 bits.
146 AttributesImpl Attrs;
147 explicit Attributes(AttributesImpl *A);
149 Attributes() : Attrs(0) {}
150 explicit Attributes(uint64_t Val);
151 /*implicit*/ Attributes(Attribute::AttrConst Val);
152 Attributes(const Attributes &A);
155 friend class Attributes;
158 Builder() : Bits(0) {}
159 Builder(const Attributes &A) : Bits(A.Raw()) {}
161 void clear() { Bits = 0; }
163 bool hasAttributes() const;
164 bool hasAttributes(const Attributes &A) const;
165 bool hasAlignmentAttr() const;
167 uint64_t getAlignment() const;
169 void addAddressSafetyAttr();
170 void addAlwaysInlineAttr();
172 void addInlineHintAttr();
176 void addNoAliasAttr();
177 void addNoCaptureAttr();
178 void addNoImplicitFloatAttr();
179 void addNoInlineAttr();
180 void addNonLazyBindAttr();
181 void addNoRedZoneAttr();
182 void addNoReturnAttr();
183 void addNoUnwindAttr();
184 void addOptimizeForSizeAttr();
185 void addReadNoneAttr();
186 void addReadOnlyAttr();
187 void addReturnsTwiceAttr();
189 void addStackProtectAttr();
190 void addStackProtectReqAttr();
191 void addStructRetAttr();
192 void addUWTableAttr();
195 void addAlignmentAttr(unsigned Align);
196 void addStackAlignmentAttr(unsigned Align);
198 void removeAttributes(const Attributes &A);
200 void removeAddressSafetyAttr();
201 void removeAlwaysInlineAttr();
202 void removeByValAttr();
203 void removeInlineHintAttr();
204 void removeInRegAttr();
205 void removeNakedAttr();
206 void removeNestAttr();
207 void removeNoAliasAttr();
208 void removeNoCaptureAttr();
209 void removeNoImplicitFloatAttr();
210 void removeNoInlineAttr();
211 void removeNonLazyBindAttr();
212 void removeNoRedZoneAttr();
213 void removeNoReturnAttr();
214 void removeNoUnwindAttr();
215 void removeOptimizeForSizeAttr();
216 void removeReadNoneAttr();
217 void removeReadOnlyAttr();
218 void removeReturnsTwiceAttr();
219 void removeSExtAttr();
220 void removeStackProtectAttr();
221 void removeStackProtectReqAttr();
222 void removeStructRetAttr();
223 void removeUWTableAttr();
224 void removeZExtAttr();
226 void removeAlignmentAttr();
227 void removeStackAlignmentAttr();
230 /// get - Return a uniquified Attributes object. This takes the uniquified
231 /// value from the Builder and wraps it in the Attributes class.
232 static Attributes get(Builder &B);
233 static Attributes get(LLVMContext &Context, Builder &B);
235 /// @brief Parameter attributes that do not apply to vararg call arguments.
236 bool hasIncompatibleWithVarArgsAttrs() const {
237 return hasStructRetAttr();
240 // Attribute query methods.
241 // FIXME: StackAlignment & Alignment attributes have no predicate methods.
242 bool hasAttributes() const {
243 return Attrs.hasAttributes();
245 bool hasAttributes(const Attributes &A) const;
246 bool hasAddressSafetyAttr() const;
247 bool hasAlignmentAttr() const;
248 bool hasAlwaysInlineAttr() const;
249 bool hasByValAttr() const;
250 bool hasInRegAttr() const;
251 bool hasInlineHintAttr() const;
252 bool hasNakedAttr() const;
253 bool hasNestAttr() const;
254 bool hasNoAliasAttr() const;
255 bool hasNoCaptureAttr() const;
256 bool hasNoImplicitFloatAttr() const;
257 bool hasNoInlineAttr() const;
258 bool hasNonLazyBindAttr() const;
259 bool hasNoRedZoneAttr() const;
260 bool hasNoReturnAttr() const;
261 bool hasNoUnwindAttr() const;
262 bool hasOptimizeForSizeAttr() const;
263 bool hasReadNoneAttr() const;
264 bool hasReadOnlyAttr() const;
265 bool hasReturnsTwiceAttr() const;
266 bool hasSExtAttr() const;
267 bool hasStackAlignmentAttr() const;
268 bool hasStackProtectAttr() const;
269 bool hasStackProtectReqAttr() const;
270 bool hasStructRetAttr() const;
271 bool hasUWTableAttr() const;
272 bool hasZExtAttr() const;
274 /// This returns the alignment field of an attribute as a byte alignment
276 unsigned getAlignment() const;
278 /// This returns the stack alignment field of an attribute as a byte alignment
280 unsigned getStackAlignment() const;
282 bool isEmptyOrSingleton() const;
284 // This is a "safe bool() operator".
285 operator const void *() const { return Attrs.Bits ? this : 0; }
286 bool operator == (const Attributes &A) const {
287 return Attrs.Bits == A.Attrs.Bits;
289 bool operator != (const Attributes &A) const {
290 return Attrs.Bits != A.Attrs.Bits;
293 Attributes operator | (const Attributes &A) const;
294 Attributes operator & (const Attributes &A) const;
295 Attributes operator ^ (const Attributes &A) const;
296 Attributes &operator |= (const Attributes &A);
297 Attributes &operator &= (const Attributes &A);
298 Attributes operator ~ () const;
300 uint64_t Raw() const;
302 /// constructAlignmentFromInt - This turns an int alignment (a power of 2,
303 /// normally) into the form used internally in Attributes.
304 static Attributes constructAlignmentFromInt(unsigned i) {
305 // Default alignment, allow the target to define how to align it.
307 return Attribute::None;
309 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
310 assert(i <= 0x40000000 && "Alignment too large.");
311 return Attributes((Log2_32(i)+1) << 16);
314 /// constructStackAlignmentFromInt - This turns an int stack alignment (which
315 /// must be a power of 2) into the form used internally in Attributes.
316 static Attributes constructStackAlignmentFromInt(unsigned i) {
317 // Default alignment, allow the target to define how to align it.
319 return Attribute::None;
321 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
322 assert(i <= 0x100 && "Alignment too large.");
323 return Attributes((Log2_32(i)+1) << 26);
326 /// @brief Which attributes cannot be applied to a type.
327 static Attributes typeIncompatible(Type *Ty);
329 /// encodeLLVMAttributesForBitcode - This returns an integer containing an
330 /// encoding of all the LLVM attributes found in the given attribute bitset.
331 /// Any change to this encoding is a breaking change to bitcode compatibility.
332 static uint64_t encodeLLVMAttributesForBitcode(Attributes Attrs) {
333 // FIXME: It doesn't make sense to store the alignment information as an
334 // expanded out value, we should store it as a log2 value. However, we
335 // can't just change that here without breaking bitcode compatibility. If
336 // this ever becomes a problem in practice, we should introduce new tag
337 // numbers in the bitcode file and have those tags use a more efficiently
338 // encoded alignment field.
340 // Store the alignment in the bitcode as a 16-bit raw value instead of a
341 // 5-bit log2 encoded value. Shift the bits above the alignment up by 11
343 uint64_t EncodedAttrs = Attrs.Raw() & 0xffff;
344 if (Attrs.hasAlignmentAttr())
345 EncodedAttrs |= (1ULL << 16) <<
346 (((Attrs.Raw() & Attribute::Alignment_i) - 1) >> 16);
347 EncodedAttrs |= (Attrs.Raw() & (0xfffULL << 21)) << 11;
351 /// decodeLLVMAttributesForBitcode - This returns an attribute bitset
352 /// containing the LLVM attributes that have been decoded from the given
353 /// integer. This function must stay in sync with
354 /// 'encodeLLVMAttributesForBitcode'.
355 static Attributes decodeLLVMAttributesForBitcode(uint64_t EncodedAttrs) {
356 // The alignment is stored as a 16-bit raw value from bits 31--16. We shift
357 // the bits above 31 down by 11 bits.
358 unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
359 assert((!Alignment || isPowerOf2_32(Alignment)) &&
360 "Alignment must be a power of two.");
362 Attributes Attrs(EncodedAttrs & 0xffff);
364 Attrs |= Attributes::constructAlignmentFromInt(Alignment);
365 Attrs |= Attributes((EncodedAttrs & (0xfffULL << 32)) >> 11);
369 /// getAsString - The set of Attributes set in Attributes is converted to a
370 /// string of equivalent mnemonics. This is, presumably, for writing out the
371 /// mnemonics for the assembly writer.
372 /// @brief Convert attribute bits to text
373 std::string getAsString() const;
376 //===----------------------------------------------------------------------===//
377 // AttributeWithIndex
378 //===----------------------------------------------------------------------===//
380 /// AttributeWithIndex - This is just a pair of values to associate a set of
381 /// attributes with an index.
382 struct AttributeWithIndex {
383 Attributes Attrs; ///< The attributes that are set, or'd together.
384 unsigned Index; ///< Index of the parameter for which the attributes apply.
385 ///< Index 0 is used for return value attributes.
386 ///< Index ~0U is used for function attributes.
388 static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
389 AttributeWithIndex P;
396 //===----------------------------------------------------------------------===//
397 // AttrListPtr Smart Pointer
398 //===----------------------------------------------------------------------===//
400 class AttributeListImpl;
402 /// AttrListPtr - This class manages the ref count for the opaque
403 /// AttributeListImpl object and provides accessors for it.
405 /// AttrList - The attributes that we are managing. This can be null
406 /// to represent the empty attributes list.
407 AttributeListImpl *AttrList;
409 AttrListPtr() : AttrList(0) {}
410 AttrListPtr(const AttrListPtr &P);
411 const AttrListPtr &operator=(const AttrListPtr &RHS);
414 //===--------------------------------------------------------------------===//
415 // Attribute List Construction and Mutation
416 //===--------------------------------------------------------------------===//
418 /// get - Return a Attributes list with the specified parameters in it.
419 static AttrListPtr get(ArrayRef<AttributeWithIndex> Attrs);
421 /// addAttr - Add the specified attribute at the specified index to this
422 /// attribute list. Since attribute lists are immutable, this
423 /// returns the new list.
424 AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
426 /// removeAttr - Remove the specified attribute at the specified index from
427 /// this attribute list. Since attribute lists are immutable, this
428 /// returns the new list.
429 AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
431 //===--------------------------------------------------------------------===//
432 // Attribute List Accessors
433 //===--------------------------------------------------------------------===//
434 /// getParamAttributes - The attributes for the specified index are
436 Attributes getParamAttributes(unsigned Idx) const {
437 return getAttributes(Idx);
440 /// getRetAttributes - The attributes for the ret value are
442 Attributes getRetAttributes() const {
443 return getAttributes(0);
446 /// getFnAttributes - The function attributes are returned.
447 Attributes getFnAttributes() const {
448 return getAttributes(~0U);
451 /// paramHasAttr - Return true if the specified parameter index has the
452 /// specified attribute set.
453 bool paramHasAttr(unsigned Idx, Attributes Attr) const {
454 return getAttributes(Idx).hasAttributes(Attr);
457 /// getParamAlignment - Return the alignment for the specified function
459 unsigned getParamAlignment(unsigned Idx) const {
460 return getAttributes(Idx).getAlignment();
463 /// hasAttrSomewhere - Return true if the specified attribute is set for at
464 /// least one parameter or for the return value.
465 bool hasAttrSomewhere(Attributes Attr) const;
467 unsigned getNumAttrs() const;
468 Attributes &getAttributesAtIndex(unsigned i) const;
470 /// operator==/!= - Provide equality predicates.
471 bool operator==(const AttrListPtr &RHS) const
472 { return AttrList == RHS.AttrList; }
473 bool operator!=(const AttrListPtr &RHS) const
474 { return AttrList != RHS.AttrList; }
478 //===--------------------------------------------------------------------===//
479 // Attribute List Introspection
480 //===--------------------------------------------------------------------===//
482 /// getRawPointer - Return a raw pointer that uniquely identifies this
484 void *getRawPointer() const {
488 // Attributes are stored as a dense set of slots, where there is one
489 // slot for each argument that has an attribute. This allows walking over the
490 // dense set instead of walking the sparse list of attributes.
492 /// isEmpty - Return true if there are no attributes.
494 bool isEmpty() const {
495 return AttrList == 0;
498 /// getNumSlots - Return the number of slots used in this attribute list.
499 /// This is the number of arguments that have an attribute set on them
500 /// (including the function itself).
501 unsigned getNumSlots() const;
503 /// getSlot - Return the AttributeWithIndex at the specified slot. This
504 /// holds a index number plus a set of attributes.
505 const AttributeWithIndex &getSlot(unsigned Slot) const;
508 explicit AttrListPtr(AttributeListImpl *L);
510 /// getAttributes - The attributes for the specified index are
511 /// returned. Attributes for the result are denoted with Idx = 0.
512 Attributes getAttributes(unsigned Idx) const;
515 } // End llvm namespace