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 //===----------------------------------------------------------------------===//
11 /// \brief This file contains the simple types necessary to represent the
12 /// attributes associated with functions and their calls.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_ATTRIBUTES_H
17 #define LLVM_ATTRIBUTES_H
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseSet.h"
21 #include "llvm/Support/MathExtras.h"
32 //===----------------------------------------------------------------------===//
34 /// \brief Functions, function parameters, and return types can have attributes
35 /// to indicate how they should be treated by optimizations and code
36 /// generation. This class represents one of those attributes. It's light-weight
37 /// and should be passed around by-value.
40 /// This enumeration lists the attributes that can be associated with
41 /// parameters, function results or the function itself.
43 /// Note: uwtable is about the ABI or the user mandating an entry in the
44 /// unwind table. The nounwind attribute is about an exception passing by the
47 /// In a theoretical system that uses tables for profiling and sjlj for
48 /// exceptions, they would be fully independent. In a normal system that uses
49 /// tables for both, the semantics are:
51 /// nil = Needs an entry because an exception might pass by.
52 /// nounwind = No need for an entry
53 /// uwtable = Needs an entry because the ABI says so and because
54 /// an exception might pass by.
55 /// uwtable + nounwind = Needs an entry because the ABI says so.
58 // IR-Level Attributes
59 None, ///< No attributes have been set
60 AddressSafety, ///< Address safety checking is on.
61 Alignment, ///< Alignment of parameter (5 bits)
62 ///< stored as log2 of alignment with +1 bias
63 ///< 0 means unaligned (different from align(1))
64 AlwaysInline, ///< inline=always
65 ByVal, ///< Pass structure by value
66 InlineHint, ///< Source said inlining was desirable
67 InReg, ///< Force argument to be passed in register
68 MinSize, ///< Function must be optimized for size first
69 Naked, ///< Naked function
70 Nest, ///< Nested function static chain
71 NoAlias, ///< Considered to not alias after call
72 NoCapture, ///< Function creates no aliases of pointer
73 NoDuplicate, ///< Call cannot be duplicated
74 NoImplicitFloat, ///< Disable implicit floating point insts
75 NoInline, ///< inline=never
76 NonLazyBind, ///< Function is called early and/or
77 ///< often, so lazy binding isn't worthwhile
78 NoRedZone, ///< Disable redzone
79 NoReturn, ///< Mark the function as not returning
80 NoUnwind, ///< Function doesn't unwind stack
81 OptimizeForSize, ///< opt_size
82 ReadNone, ///< Function does not access memory
83 ReadOnly, ///< Function only reads from memory
84 ReturnsTwice, ///< Function can return twice
85 SExt, ///< Sign extended before/after call
86 StackAlignment, ///< Alignment of stack for function (3 bits)
87 ///< stored as log2 of alignment with +1 bias 0
88 ///< means unaligned (different from
90 StackProtect, ///< Stack protection.
91 StackProtectReq, ///< Stack protection required.
92 StructRet, ///< Hidden pointer to structure to return
93 UWTable, ///< Function must be in a unwind table
94 ZExt, ///< Zero extended before/after call
96 EndAttrKinds ///< Sentinal value useful for loops
100 Attribute(AttributeImpl *A) : pImpl(A) {}
102 Attribute() : pImpl(0) {}
104 /// \brief Return a uniquified Attribute object. This takes the uniquified
105 /// value from the Builder and wraps it in the Attribute class.
106 static Attribute get(LLVMContext &Context, ArrayRef<AttrKind> Vals);
107 static Attribute get(LLVMContext &Context, AttrBuilder &B);
109 /// \brief Return true if the attribute is present.
110 bool hasAttribute(AttrKind Val) const;
112 /// \brief Return true if attributes exist
113 bool hasAttributes() const;
115 /// \brief Returns the alignment field of an attribute as a byte alignment
117 unsigned getAlignment() const;
119 /// \brief Returns the stack alignment field of an attribute as a byte
121 unsigned getStackAlignment() const;
123 /// \brief Equality and non-equality query methods.
124 bool operator==(AttrKind K) const;
125 bool operator!=(AttrKind K) const;
127 // FIXME: Remove these 'operator' methods.
128 bool operator==(const Attribute &A) const {
129 return pImpl == A.pImpl;
131 bool operator!=(const Attribute &A) const {
132 return pImpl != A.pImpl;
135 uint64_t getBitMask() const;
137 /// \brief Which attributes cannot be applied to a type.
138 static Attribute typeIncompatible(Type *Ty);
140 /// \brief This returns an integer containing an encoding of all the LLVM
141 /// attributes found in the given attribute bitset. Any change to this
142 /// encoding is a breaking change to bitcode compatibility.
143 static uint64_t encodeLLVMAttributesForBitcode(Attribute Attrs);
145 /// \brief This returns an attribute bitset containing the LLVM attributes
146 /// that have been decoded from the given integer. This function must stay in
147 /// sync with 'encodeLLVMAttributesForBitcode'.
148 static Attribute decodeLLVMAttributesForBitcode(LLVMContext &C,
149 uint64_t EncodedAttrs);
151 /// \brief The Attribute is converted to a string of equivalent mnemonic. This
152 /// is, presumably, for writing out the mnemonics for the assembly writer.
153 std::string getAsString() const;
156 //===----------------------------------------------------------------------===//
158 /// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by
160 template<> struct DenseMapInfo<Attribute::AttrKind> {
161 static inline Attribute::AttrKind getEmptyKey() {
162 return Attribute::AttrKind(~0U);
164 static inline Attribute::AttrKind getTombstoneKey() {
165 return Attribute::AttrKind(~0U - 1);
167 static unsigned getHashValue(const Attribute::AttrKind &Val) {
170 static bool isEqual(const Attribute::AttrKind &LHS,
171 const Attribute::AttrKind &RHS) {
176 //===----------------------------------------------------------------------===//
178 /// \brief This class is used in conjunction with the Attribute::get method to
179 /// create an Attribute object. The object itself is uniquified. The Builder's
180 /// value, however, is not. So this can be used as a quick way to test for
181 /// equality, presence of attributes, etc.
183 DenseSet<Attribute::AttrKind> Attrs;
185 uint64_t StackAlignment;
187 AttrBuilder() : Alignment(0), StackAlignment(0) {}
188 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) {
191 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) {
197 /// \brief Add an attribute to the builder.
198 AttrBuilder &addAttribute(Attribute::AttrKind Val);
200 /// \brief Remove an attribute from the builder.
201 AttrBuilder &removeAttribute(Attribute::AttrKind Val);
203 /// \brief Add the attributes from A to the builder.
204 AttrBuilder &addAttributes(const Attribute &A);
206 /// \brief Remove the attributes from A from the builder.
207 AttrBuilder &removeAttributes(const Attribute &A);
209 /// \brief Return true if the builder has the specified attribute.
210 bool contains(Attribute::AttrKind A) const;
212 /// \brief Return true if the builder has IR-level attributes.
213 bool hasAttributes() const;
215 /// \brief Return true if the builder has any attribute that's in the
216 /// specified attribute.
217 bool hasAttributes(const Attribute &A) const;
219 /// \brief Return true if the builder has an alignment attribute.
220 bool hasAlignmentAttr() const;
222 /// \brief Retrieve the alignment attribute, if it exists.
223 uint64_t getAlignment() const { return Alignment; }
225 /// \brief Retrieve the stack alignment attribute, if it exists.
226 uint64_t getStackAlignment() const { return StackAlignment; }
228 /// \brief This turns an int alignment (which must be a power of 2) into the
229 /// form used internally in Attribute.
230 AttrBuilder &addAlignmentAttr(unsigned Align);
232 /// \brief This turns an int stack alignment (which must be a power of 2) into
233 /// the form used internally in Attribute.
234 AttrBuilder &addStackAlignmentAttr(unsigned Align);
236 /// \brief Add the raw value to the internal representation.
238 /// N.B. This should be used ONLY for decoding LLVM bitcode!
239 AttrBuilder &addRawValue(uint64_t Val);
241 /// \brief Remove attributes that are used on functions only.
242 void removeFunctionOnlyAttrs() {
243 removeAttribute(Attribute::NoReturn)
244 .removeAttribute(Attribute::NoUnwind)
245 .removeAttribute(Attribute::ReadNone)
246 .removeAttribute(Attribute::ReadOnly)
247 .removeAttribute(Attribute::NoInline)
248 .removeAttribute(Attribute::AlwaysInline)
249 .removeAttribute(Attribute::OptimizeForSize)
250 .removeAttribute(Attribute::StackProtect)
251 .removeAttribute(Attribute::StackProtectReq)
252 .removeAttribute(Attribute::NoRedZone)
253 .removeAttribute(Attribute::NoImplicitFloat)
254 .removeAttribute(Attribute::Naked)
255 .removeAttribute(Attribute::InlineHint)
256 .removeAttribute(Attribute::StackAlignment)
257 .removeAttribute(Attribute::UWTable)
258 .removeAttribute(Attribute::NonLazyBind)
259 .removeAttribute(Attribute::ReturnsTwice)
260 .removeAttribute(Attribute::AddressSafety)
261 .removeAttribute(Attribute::MinSize)
262 .removeAttribute(Attribute::NoDuplicate);
265 uint64_t getBitMask() const;
267 bool operator==(const AttrBuilder &B);
268 bool operator!=(const AttrBuilder &B) {
269 return !(*this == B);
273 //===----------------------------------------------------------------------===//
275 /// \brief This is just a pair of values to associate a set of attributes with
277 struct AttributeWithIndex {
278 Attribute Attrs; ///< The attributes that are set, or'd together.
279 unsigned Index; ///< Index of the parameter for which the attributes apply.
280 ///< Index 0 is used for return value attributes.
281 ///< Index ~0U is used for function attributes.
283 static AttributeWithIndex get(LLVMContext &C, unsigned Idx,
284 ArrayRef<Attribute::AttrKind> Attrs) {
285 return get(Idx, Attribute::get(C, Attrs));
287 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) {
288 AttributeWithIndex P;
295 //===----------------------------------------------------------------------===//
296 // AttributeSet Smart Pointer
297 //===----------------------------------------------------------------------===//
299 class AttributeSetImpl;
301 //===----------------------------------------------------------------------===//
303 /// \brief This class manages the ref count for the opaque AttributeSetImpl
304 /// object and provides accessors for it.
312 /// \brief The attributes that we are managing. This can be null to represent
313 /// the empty attributes list.
314 AttributeSetImpl *AttrList;
316 /// \brief The attributes for the specified index are returned. Attributes
317 /// for the result are denoted with Idx = 0.
318 Attribute getAttributes(unsigned Idx) const;
320 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {}
322 AttributeSet() : AttrList(0) {}
323 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {}
324 const AttributeSet &operator=(const AttributeSet &RHS);
326 //===--------------------------------------------------------------------===//
327 // Attribute List Construction and Mutation
328 //===--------------------------------------------------------------------===//
330 /// \brief Return an AttributeSet with the specified parameters in it.
331 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs);
333 /// \brief Add the specified attribute at the specified index to this
334 /// attribute list. Since attribute lists are immutable, this returns the new
336 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
338 /// \brief Remove the specified attribute at the specified index from this
339 /// attribute list. Since attribute lists are immutable, this returns the new
341 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
343 //===--------------------------------------------------------------------===//
344 // Attribute List Accessors
345 //===--------------------------------------------------------------------===//
347 /// \brief The attributes for the specified index are returned.
348 Attribute getParamAttributes(unsigned Idx) const {
349 return getAttributes(Idx);
352 /// \brief The attributes for the ret value are returned.
353 Attribute getRetAttributes() const {
354 return getAttributes(ReturnIndex);
357 /// \brief The function attributes are returned.
358 Attribute getFnAttributes() const {
359 return getAttributes(FunctionIndex);
362 /// \brief Return the alignment for the specified function parameter.
363 unsigned getParamAlignment(unsigned Idx) const {
364 return getAttributes(Idx).getAlignment();
367 /// \brief Return true if the attribute exists at the given index.
368 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
370 /// \brief Return true if attribute exists at the given index.
371 bool hasAttributes(unsigned Index) const;
373 /// \brief Get the stack alignment.
374 unsigned getStackAlignment(unsigned Index) const;
376 /// \brief Return the attributes at the index as a string.
377 std::string getAsString(unsigned Index) const;
379 uint64_t getBitMask(unsigned Index) const;
381 /// \brief Return true if the specified attribute is set for at least one
382 /// parameter or for the return value.
383 bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
385 /// operator==/!= - Provide equality predicates.
386 bool operator==(const AttributeSet &RHS) const {
387 return AttrList == RHS.AttrList;
389 bool operator!=(const AttributeSet &RHS) const {
390 return AttrList != RHS.AttrList;
393 //===--------------------------------------------------------------------===//
394 // Attribute List Introspection
395 //===--------------------------------------------------------------------===//
397 /// \brief Return a raw pointer that uniquely identifies this attribute list.
398 void *getRawPointer() const {
402 // Attributes are stored as a dense set of slots, where there is one slot for
403 // each argument that has an attribute. This allows walking over the dense
404 // set instead of walking the sparse list of attributes.
406 /// \brief Return true if there are no attributes.
407 bool isEmpty() const {
408 return AttrList == 0;
411 /// \brief Return the number of slots used in this attribute list. This is
412 /// the number of arguments that have an attribute set on them (including the
413 /// function itself).
414 unsigned getNumSlots() const;
416 /// \brief Return the AttributeWithIndex at the specified slot. This holds a
417 /// index number plus a set of attributes.
418 const AttributeWithIndex &getSlot(unsigned Slot) const;
423 } // end llvm namespace