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 Attributes that are mutually incompatible.
126 const AttrConst MutuallyIncompatible[5] = {
127 {ByVal_i | Nest_i | StructRet_i},
128 {ByVal_i | Nest_i | InReg_i },
130 {ReadNone_i | ReadOnly_i},
131 {NoInline_i | AlwaysInline_i}
134 } // namespace Attribute
136 /// AttributeImpl - The internal representation of the Attributes class. This is
138 class AttributesImpl;
140 /// Attributes - A bitset of attributes.
144 None = 0, ///< No attributes have been set
145 ZExt = 1, ///< Zero extended before/after call
146 SExt = 2, ///< Sign extended before/after call
147 NoReturn = 3, ///< Mark the function as not returning
148 InReg = 4, ///< Force argument to be passed in register
149 StructRet = 5, ///< Hidden pointer to structure to return
150 NoUnwind = 6, ///< Function doesn't unwind stack
151 NoAlias = 7, ///< Considered to not alias after call
152 ByVal = 8, ///< Pass structure by value
153 Nest = 9, ///< Nested function static chain
154 ReadNone = 10, ///< Function does not access memory
155 ReadOnly = 11, ///< Function only reads from memory
156 NoInline = 12, ///< inline=never
157 AlwaysInline = 13, ///< inline=always
158 OptimizeForSize = 14, ///< opt_size
159 StackProtect = 15, ///< Stack protection.
160 StackProtectReq = 16, ///< Stack protection required.
161 Alignment = 17, ///< Alignment of parameter (5 bits)
162 ///< stored as log2 of alignment with +1 bias
163 ///< 0 means unaligned different from align 1
164 NoCapture = 18, ///< Function creates no aliases of pointer
165 NoRedZone = 19, ///< Disable redzone
166 NoImplicitFloat = 20, ///< Disable implicit floating point insts
167 Naked = 21, ///< Naked function
168 InlineHint = 22, ///< Source said inlining was desirable
169 StackAlignment = 23, ///< Alignment of stack for function (3 bits)
170 ///< stored as log2 of alignment with +1 bias 0
171 ///< means unaligned (different from
173 ReturnsTwice = 24, ///< Function can return twice
174 UWTable = 25, ///< Function must be in a unwind table
175 NonLazyBind = 26, ///< Function is called early and/or
176 ///< often, so lazy binding isn't worthwhile
177 AddressSafety = 27 ///< Address safety checking is on.
180 AttributesImpl Attrs;
182 explicit Attributes(AttributesImpl *A);
184 Attributes() : Attrs(0) {}
185 explicit Attributes(uint64_t Val);
186 /*implicit*/ Attributes(Attribute::AttrConst Val);
187 Attributes(const Attributes &A);
190 friend class Attributes;
193 Builder() : Bits(0) {}
194 Builder(const Attributes &A) : Bits(A.Raw()) {}
196 void clear() { Bits = 0; }
198 bool hasAttributes() const;
199 bool hasAttributes(const Attributes &A) const;
200 bool hasAlignmentAttr() const;
202 uint64_t getAlignment() const;
204 void addAttribute(Attributes::AttrVal Val);
205 void removeAttribute(Attributes::AttrVal Val);
207 void addAlignmentAttr(unsigned Align);
208 void addStackAlignmentAttr(unsigned Align);
210 void removeAttributes(const Attributes &A);
213 /// get - Return a uniquified Attributes object. This takes the uniquified
214 /// value from the Builder and wraps it in the Attributes class.
215 static Attributes get(Builder &B);
216 static Attributes get(LLVMContext &Context, Builder &B);
218 /// @brief Parameter attributes that do not apply to vararg call arguments.
219 bool hasIncompatibleWithVarArgsAttrs() const {
220 return hasAttribute(Attributes::StructRet);
223 /// @brief Return true if the attribute is present.
224 bool hasAttribute(AttrVal Val) const;
226 /// @brief Return true if attributes exist
227 bool hasAttributes() const {
228 return Attrs.hasAttributes();
231 /// @brief Return true if the attributes are a non-null intersection.
232 bool hasAttributes(const Attributes &A) const;
234 /// This returns the alignment field of an attribute as a byte alignment
236 unsigned getAlignment() const;
238 /// This returns the stack alignment field of an attribute as a byte alignment
240 unsigned getStackAlignment() const;
242 bool isEmptyOrSingleton() const;
244 // This is a "safe bool() operator".
245 operator const void *() const { return Attrs.Bits ? this : 0; }
246 bool operator == (const Attributes &A) const {
247 return Attrs.Bits == A.Attrs.Bits;
249 bool operator != (const Attributes &A) const {
250 return Attrs.Bits != A.Attrs.Bits;
253 Attributes operator | (const Attributes &A) const;
254 Attributes operator & (const Attributes &A) const;
255 Attributes operator ^ (const Attributes &A) const;
256 Attributes &operator |= (const Attributes &A);
257 Attributes &operator &= (const Attributes &A);
258 Attributes operator ~ () const;
260 uint64_t Raw() const;
262 /// constructAlignmentFromInt - This turns an int alignment (a power of 2,
263 /// normally) into the form used internally in Attributes.
264 static Attributes constructAlignmentFromInt(unsigned i) {
265 // Default alignment, allow the target to define how to align it.
267 return Attribute::None;
269 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
270 assert(i <= 0x40000000 && "Alignment too large.");
271 return Attributes((Log2_32(i)+1) << 16);
274 /// constructStackAlignmentFromInt - This turns an int stack alignment (which
275 /// must be a power of 2) into the form used internally in Attributes.
276 static Attributes constructStackAlignmentFromInt(unsigned i) {
277 // Default alignment, allow the target to define how to align it.
279 return Attribute::None;
281 assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
282 assert(i <= 0x100 && "Alignment too large.");
283 return Attributes((Log2_32(i)+1) << 26);
286 /// @brief Which attributes cannot be applied to a type.
287 static Attributes typeIncompatible(Type *Ty);
289 /// encodeLLVMAttributesForBitcode - This returns an integer containing an
290 /// encoding of all the LLVM attributes found in the given attribute bitset.
291 /// Any change to this encoding is a breaking change to bitcode compatibility.
292 static uint64_t encodeLLVMAttributesForBitcode(Attributes Attrs) {
293 // FIXME: It doesn't make sense to store the alignment information as an
294 // expanded out value, we should store it as a log2 value. However, we
295 // can't just change that here without breaking bitcode compatibility. If
296 // this ever becomes a problem in practice, we should introduce new tag
297 // numbers in the bitcode file and have those tags use a more efficiently
298 // encoded alignment field.
300 // Store the alignment in the bitcode as a 16-bit raw value instead of a
301 // 5-bit log2 encoded value. Shift the bits above the alignment up by 11
303 uint64_t EncodedAttrs = Attrs.Raw() & 0xffff;
304 if (Attrs.hasAttribute(Attributes::Alignment))
305 EncodedAttrs |= (1ULL << 16) <<
306 (((Attrs.Raw() & Attribute::Alignment_i) - 1) >> 16);
307 EncodedAttrs |= (Attrs.Raw() & (0xfffULL << 21)) << 11;
311 /// decodeLLVMAttributesForBitcode - This returns an attribute bitset
312 /// containing the LLVM attributes that have been decoded from the given
313 /// integer. This function must stay in sync with
314 /// 'encodeLLVMAttributesForBitcode'.
315 static Attributes decodeLLVMAttributesForBitcode(uint64_t EncodedAttrs) {
316 // The alignment is stored as a 16-bit raw value from bits 31--16. We shift
317 // the bits above 31 down by 11 bits.
318 unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
319 assert((!Alignment || isPowerOf2_32(Alignment)) &&
320 "Alignment must be a power of two.");
322 Attributes Attrs(EncodedAttrs & 0xffff);
324 Attrs |= Attributes::constructAlignmentFromInt(Alignment);
325 Attrs |= Attributes((EncodedAttrs & (0xfffULL << 32)) >> 11);
329 /// getAsString - The set of Attributes set in Attributes is converted to a
330 /// string of equivalent mnemonics. This is, presumably, for writing out the
331 /// mnemonics for the assembly writer.
332 /// @brief Convert attribute bits to text
333 std::string getAsString() const;
336 //===----------------------------------------------------------------------===//
337 // AttributeWithIndex
338 //===----------------------------------------------------------------------===//
340 /// AttributeWithIndex - This is just a pair of values to associate a set of
341 /// attributes with an index.
342 struct AttributeWithIndex {
343 Attributes Attrs; ///< The attributes that are set, or'd together.
344 unsigned Index; ///< Index of the parameter for which the attributes apply.
345 ///< Index 0 is used for return value attributes.
346 ///< Index ~0U is used for function attributes.
348 static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
349 AttributeWithIndex P;
356 //===----------------------------------------------------------------------===//
357 // AttrListPtr Smart Pointer
358 //===----------------------------------------------------------------------===//
360 class AttributeListImpl;
362 /// AttrListPtr - This class manages the ref count for the opaque
363 /// AttributeListImpl object and provides accessors for it.
365 /// AttrList - The attributes that we are managing. This can be null
366 /// to represent the empty attributes list.
367 AttributeListImpl *AttrList;
369 AttrListPtr() : AttrList(0) {}
370 AttrListPtr(const AttrListPtr &P);
371 const AttrListPtr &operator=(const AttrListPtr &RHS);
374 //===--------------------------------------------------------------------===//
375 // Attribute List Construction and Mutation
376 //===--------------------------------------------------------------------===//
378 /// get - Return a Attributes list with the specified parameters in it.
379 static AttrListPtr get(ArrayRef<AttributeWithIndex> Attrs);
381 /// addAttr - Add the specified attribute at the specified index to this
382 /// attribute list. Since attribute lists are immutable, this
383 /// returns the new list.
384 AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
386 /// removeAttr - Remove the specified attribute at the specified index from
387 /// this attribute list. Since attribute lists are immutable, this
388 /// returns the new list.
389 AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
391 //===--------------------------------------------------------------------===//
392 // Attribute List Accessors
393 //===--------------------------------------------------------------------===//
394 /// getParamAttributes - The attributes for the specified index are
396 Attributes getParamAttributes(unsigned Idx) const {
397 return getAttributes(Idx);
400 /// getRetAttributes - The attributes for the ret value are
402 Attributes getRetAttributes() const {
403 return getAttributes(0);
406 /// getFnAttributes - The function attributes are returned.
407 Attributes getFnAttributes() const {
408 return getAttributes(~0U);
411 /// paramHasAttr - Return true if the specified parameter index has the
412 /// specified attribute set.
413 bool paramHasAttr(unsigned Idx, Attributes Attr) const {
414 return getAttributes(Idx).hasAttributes(Attr);
417 /// getParamAlignment - Return the alignment for the specified function
419 unsigned getParamAlignment(unsigned Idx) const {
420 return getAttributes(Idx).getAlignment();
423 /// hasAttrSomewhere - Return true if the specified attribute is set for at
424 /// least one parameter or for the return value.
425 bool hasAttrSomewhere(Attributes Attr) const;
427 unsigned getNumAttrs() const;
428 Attributes &getAttributesAtIndex(unsigned i) const;
430 /// operator==/!= - Provide equality predicates.
431 bool operator==(const AttrListPtr &RHS) const
432 { return AttrList == RHS.AttrList; }
433 bool operator!=(const AttrListPtr &RHS) const
434 { return AttrList != RHS.AttrList; }
438 //===--------------------------------------------------------------------===//
439 // Attribute List Introspection
440 //===--------------------------------------------------------------------===//
442 /// getRawPointer - Return a raw pointer that uniquely identifies this
444 void *getRawPointer() const {
448 // Attributes are stored as a dense set of slots, where there is one
449 // slot for each argument that has an attribute. This allows walking over the
450 // dense set instead of walking the sparse list of attributes.
452 /// isEmpty - Return true if there are no attributes.
454 bool isEmpty() const {
455 return AttrList == 0;
458 /// getNumSlots - Return the number of slots used in this attribute list.
459 /// This is the number of arguments that have an attribute set on them
460 /// (including the function itself).
461 unsigned getNumSlots() const;
463 /// getSlot - Return the AttributeWithIndex at the specified slot. This
464 /// holds a index number plus a set of attributes.
465 const AttributeWithIndex &getSlot(unsigned Slot) const;
468 explicit AttrListPtr(AttributeListImpl *L);
470 /// getAttributes - The attributes for the specified index are
471 /// returned. Attributes for the result are denoted with Idx = 0.
472 Attributes getAttributes(unsigned Idx) const;
475 } // End llvm namespace