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.
147 None = 0, ///< No attributes have been set
148 ZExt = 1, ///< Zero extended before/after call
149 SExt = 2, ///< Sign extended before/after call
150 NoReturn = 3, ///< Mark the function as not returning
151 InReg = 4, ///< Force argument to be passed in register
152 StructRet = 5, ///< Hidden pointer to structure to return
153 NoUnwind = 6, ///< Function doesn't unwind stack
154 NoAlias = 7, ///< Considered to not alias after call
155 ByVal = 8, ///< Pass structure by value
156 Nest = 9, ///< Nested function static chain
157 ReadNone = 10, ///< Function does not access memory
158 ReadOnly = 11, ///< Function only reads from memory
159 NoInline = 12, ///< inline=never
160 AlwaysInline = 13, ///< inline=always
161 OptimizeForSize = 14, ///< opt_size
162 StackProtect = 15, ///< Stack protection.
163 StackProtectReq = 16, ///< Stack protection required.
164 Alignment = 17, ///< Alignment of parameter (5 bits)
165 ///< stored as log2 of alignment with +1 bias
166 ///< 0 means unaligned different from align 1
167 NoCapture = 18, ///< Function creates no aliases of pointer
168 NoRedZone = 19, ///< Disable redzone
169 NoImplicitFloat = 20, ///< Disable implicit floating point insts
170 Naked = 21, ///< Naked function
171 InlineHint = 22, ///< Source said inlining was desirable
172 StackAlignment = 23, ///< Alignment of stack for function (3 bits)
173 ///< stored as log2 of alignment with +1 bias 0
174 ///< means unaligned (different from
176 ReturnsTwice = 24, ///< Function can return twice
177 UWTable = 25, ///< Function must be in a unwind table
178 NonLazyBind = 26, ///< Function is called early and/or
179 ///< often, so lazy binding isn't worthwhile
180 AddressSafety = 27 ///< Address safety checking is on.
183 // Currently, we need less than 64 bits.
184 AttributesImpl Attrs;
186 explicit Attributes(AttributesImpl *A);
188 Attributes() : Attrs(0) {}
189 explicit Attributes(uint64_t Val);
190 /*implicit*/ Attributes(Attribute::AttrConst Val);
191 Attributes(const Attributes &A);
194 friend class Attributes;
197 Builder() : Bits(0) {}
198 Builder(const Attributes &A) : Bits(A.Raw()) {}
200 void clear() { Bits = 0; }
202 bool hasAttributes() const;
203 bool hasAttributes(const Attributes &A) const;
204 bool hasAlignmentAttr() const;
206 uint64_t getAlignment() const;
208 void addAttribute(Attributes::AttrVal Val);
209 void removeAttribute(Attributes::AttrVal Val);
211 void addAlignmentAttr(unsigned Align);
212 void addStackAlignmentAttr(unsigned Align);
214 void removeAttributes(const Attributes &A);
216 void removeAddressSafetyAttr();
217 void removeAlwaysInlineAttr();
218 void removeByValAttr();
219 void removeInlineHintAttr();
220 void removeInRegAttr();
221 void removeNakedAttr();
222 void removeNestAttr();
223 void removeNoAliasAttr();
224 void removeNoCaptureAttr();
225 void removeNoImplicitFloatAttr();
226 void removeNoInlineAttr();
227 void removeNonLazyBindAttr();
228 void removeNoRedZoneAttr();
229 void removeNoReturnAttr();
230 void removeNoUnwindAttr();
231 void removeOptimizeForSizeAttr();
232 void removeReadNoneAttr();
233 void removeReadOnlyAttr();
234 void removeReturnsTwiceAttr();
235 void removeSExtAttr();
236 void removeStackProtectAttr();
237 void removeStackProtectReqAttr();
238 void removeStructRetAttr();
239 void removeUWTableAttr();
240 void removeZExtAttr();
242 void removeAlignmentAttr();
243 void removeStackAlignmentAttr();
246 /// get - Return a uniquified Attributes object. This takes the uniquified
247 /// value from the Builder and wraps it in the Attributes class.
248 static Attributes get(Builder &B);
249 static Attributes get(LLVMContext &Context, Builder &B);
251 /// @brief Parameter attributes that do not apply to vararg call arguments.
252 bool hasIncompatibleWithVarArgsAttrs() const {
253 return hasAttribute(Attributes::StructRet);
256 /// @brief Return true if the attribute is present.
257 bool hasAttribute(AttrVal Val) const;
259 /// @brief Return true if attributes exist
260 bool hasAttributes() const {
261 return Attrs.hasAttributes();
264 /// @brief Return true if the attributes are a non-null intersection.
265 bool hasAttributes(const Attributes &A) const;
267 /// This returns the alignment field of an attribute as a byte alignment
269 unsigned getAlignment() const;
271 /// This returns the stack alignment field of an attribute as a byte alignment
273 unsigned getStackAlignment() const;
275 bool isEmptyOrSingleton() const;
277 // This is a "safe bool() operator".
278 operator const void *() const { return Attrs.Bits ? this : 0; }
279 bool operator == (const Attributes &A) const {
280 return Attrs.Bits == A.Attrs.Bits;
282 bool operator != (const Attributes &A) const {
283 return Attrs.Bits != A.Attrs.Bits;
286 Attributes operator | (const Attributes &A) const;
287 Attributes operator & (const Attributes &A) const;
288 Attributes operator ^ (const Attributes &A) const;
289 Attributes &operator |= (const Attributes &A);
290 Attributes &operator &= (const Attributes &A);
291 Attributes operator ~ () const;
293 uint64_t Raw() const;
295 /// constructAlignmentFromInt - This turns an int alignment (a power of 2,
296 /// normally) into the form used internally in Attributes.
297 static Attributes constructAlignmentFromInt(unsigned i) {
298 // Default alignment, allow the target to define how to align it.
300 return Attribute::None;
302 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
303 assert(i <= 0x40000000 && "Alignment too large.");
304 return Attributes((Log2_32(i)+1) << 16);
307 /// constructStackAlignmentFromInt - This turns an int stack alignment (which
308 /// must be a power of 2) into the form used internally in Attributes.
309 static Attributes constructStackAlignmentFromInt(unsigned i) {
310 // Default alignment, allow the target to define how to align it.
312 return Attribute::None;
314 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
315 assert(i <= 0x100 && "Alignment too large.");
316 return Attributes((Log2_32(i)+1) << 26);
319 /// @brief Which attributes cannot be applied to a type.
320 static Attributes typeIncompatible(Type *Ty);
322 /// encodeLLVMAttributesForBitcode - This returns an integer containing an
323 /// encoding of all the LLVM attributes found in the given attribute bitset.
324 /// Any change to this encoding is a breaking change to bitcode compatibility.
325 static uint64_t encodeLLVMAttributesForBitcode(Attributes Attrs) {
326 // FIXME: It doesn't make sense to store the alignment information as an
327 // expanded out value, we should store it as a log2 value. However, we
328 // can't just change that here without breaking bitcode compatibility. If
329 // this ever becomes a problem in practice, we should introduce new tag
330 // numbers in the bitcode file and have those tags use a more efficiently
331 // encoded alignment field.
333 // Store the alignment in the bitcode as a 16-bit raw value instead of a
334 // 5-bit log2 encoded value. Shift the bits above the alignment up by 11
336 uint64_t EncodedAttrs = Attrs.Raw() & 0xffff;
337 if (Attrs.hasAttribute(Attributes::Alignment))
338 EncodedAttrs |= (1ULL << 16) <<
339 (((Attrs.Raw() & Attribute::Alignment_i) - 1) >> 16);
340 EncodedAttrs |= (Attrs.Raw() & (0xfffULL << 21)) << 11;
344 /// decodeLLVMAttributesForBitcode - This returns an attribute bitset
345 /// containing the LLVM attributes that have been decoded from the given
346 /// integer. This function must stay in sync with
347 /// 'encodeLLVMAttributesForBitcode'.
348 static Attributes decodeLLVMAttributesForBitcode(uint64_t EncodedAttrs) {
349 // The alignment is stored as a 16-bit raw value from bits 31--16. We shift
350 // the bits above 31 down by 11 bits.
351 unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
352 assert((!Alignment || isPowerOf2_32(Alignment)) &&
353 "Alignment must be a power of two.");
355 Attributes Attrs(EncodedAttrs & 0xffff);
357 Attrs |= Attributes::constructAlignmentFromInt(Alignment);
358 Attrs |= Attributes((EncodedAttrs & (0xfffULL << 32)) >> 11);
362 /// getAsString - The set of Attributes set in Attributes is converted to a
363 /// string of equivalent mnemonics. This is, presumably, for writing out the
364 /// mnemonics for the assembly writer.
365 /// @brief Convert attribute bits to text
366 std::string getAsString() const;
369 //===----------------------------------------------------------------------===//
370 // AttributeWithIndex
371 //===----------------------------------------------------------------------===//
373 /// AttributeWithIndex - This is just a pair of values to associate a set of
374 /// attributes with an index.
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 return getAttributes(Idx);
433 /// getRetAttributes - The attributes for the ret value are
435 Attributes getRetAttributes() const {
436 return getAttributes(0);
439 /// getFnAttributes - The function attributes are returned.
440 Attributes getFnAttributes() const {
441 return getAttributes(~0U);
444 /// paramHasAttr - Return true if the specified parameter index has the
445 /// specified attribute set.
446 bool paramHasAttr(unsigned Idx, Attributes Attr) const {
447 return getAttributes(Idx).hasAttributes(Attr);
450 /// getParamAlignment - Return the alignment for the specified function
452 unsigned getParamAlignment(unsigned Idx) const {
453 return getAttributes(Idx).getAlignment();
456 /// hasAttrSomewhere - Return true if the specified attribute is set for at
457 /// least one parameter or for the return value.
458 bool hasAttrSomewhere(Attributes Attr) const;
460 unsigned getNumAttrs() const;
461 Attributes &getAttributesAtIndex(unsigned i) const;
463 /// operator==/!= - Provide equality predicates.
464 bool operator==(const AttrListPtr &RHS) const
465 { return AttrList == RHS.AttrList; }
466 bool operator!=(const AttrListPtr &RHS) const
467 { return AttrList != RHS.AttrList; }
471 //===--------------------------------------------------------------------===//
472 // Attribute List Introspection
473 //===--------------------------------------------------------------------===//
475 /// getRawPointer - Return a raw pointer that uniquely identifies this
477 void *getRawPointer() const {
481 // Attributes are stored as a dense set of slots, where there is one
482 // slot for each argument that has an attribute. This allows walking over the
483 // dense set instead of walking the sparse list of attributes.
485 /// isEmpty - Return true if there are no attributes.
487 bool isEmpty() const {
488 return AttrList == 0;
491 /// getNumSlots - Return the number of slots used in this attribute list.
492 /// This is the number of arguments that have an attribute set on them
493 /// (including the function itself).
494 unsigned getNumSlots() const;
496 /// getSlot - Return the AttributeWithIndex at the specified slot. This
497 /// holds a index number plus a set of attributes.
498 const AttributeWithIndex &getSlot(unsigned Slot) const;
501 explicit AttrListPtr(AttributeListImpl *L);
503 /// getAttributes - The attributes for the specified index are
504 /// returned. Attributes for the result are denoted with Idx = 0.
505 Attributes getAttributes(unsigned Idx) const;
508 } // End llvm namespace