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 Set the alignment field of an attribute.
120 void setAlignment(unsigned Align);
122 /// \brief Returns the stack alignment field of an attribute as a byte
124 unsigned getStackAlignment() const;
126 /// \brief Set the stack alignment field of an attribute.
127 void setStackAlignment(unsigned Align);
129 /// \brief Equality and non-equality query methods.
130 bool operator==(AttrKind K) const;
131 bool operator!=(AttrKind K) const;
133 // FIXME: Remove these 'operator' methods.
134 bool operator==(const Attribute &A) const {
135 return pImpl == A.pImpl;
137 bool operator!=(const Attribute &A) const {
138 return pImpl != A.pImpl;
141 uint64_t getBitMask() const;
143 /// \brief Which attributes cannot be applied to a type.
144 static Attribute typeIncompatible(Type *Ty);
146 /// \brief This returns an integer containing an encoding of all the LLVM
147 /// attributes found in the given attribute bitset. Any change to this
148 /// encoding is a breaking change to bitcode compatibility.
149 static uint64_t encodeLLVMAttributesForBitcode(Attribute Attrs);
151 /// \brief This returns an attribute bitset containing the LLVM attributes
152 /// that have been decoded from the given integer. This function must stay in
153 /// sync with 'encodeLLVMAttributesForBitcode'.
154 static Attribute decodeLLVMAttributesForBitcode(LLVMContext &C,
155 uint64_t EncodedAttrs);
157 /// \brief The Attribute is converted to a string of equivalent mnemonic. This
158 /// is, presumably, for writing out the mnemonics for the assembly writer.
159 std::string getAsString() const;
162 //===----------------------------------------------------------------------===//
164 /// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by
166 template<> struct DenseMapInfo<Attribute::AttrKind> {
167 static inline Attribute::AttrKind getEmptyKey() {
168 return Attribute::AttrKind(~0U);
170 static inline Attribute::AttrKind getTombstoneKey() {
171 return Attribute::AttrKind(~0U - 1);
173 static unsigned getHashValue(const Attribute::AttrKind &Val) {
176 static bool isEqual(const Attribute::AttrKind &LHS,
177 const Attribute::AttrKind &RHS) {
182 //===----------------------------------------------------------------------===//
184 /// \brief This class is used in conjunction with the Attribute::get method to
185 /// create an Attribute object. The object itself is uniquified. The Builder's
186 /// value, however, is not. So this can be used as a quick way to test for
187 /// equality, presence of attributes, etc.
189 DenseSet<Attribute::AttrKind> Attrs;
191 uint64_t StackAlignment;
193 AttrBuilder() : Alignment(0), StackAlignment(0) {}
194 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) {
197 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) {
203 /// \brief Add an attribute to the builder.
204 AttrBuilder &addAttribute(Attribute::AttrKind Val);
206 /// \brief Remove an attribute from the builder.
207 AttrBuilder &removeAttribute(Attribute::AttrKind Val);
209 /// \brief Add the attributes from A to the builder.
210 AttrBuilder &addAttributes(const Attribute &A);
212 /// \brief Remove the attributes from A from the builder.
213 AttrBuilder &removeAttributes(const Attribute &A);
215 /// \brief Return true if the builder has the specified attribute.
216 bool contains(Attribute::AttrKind A) const;
218 /// \brief Return true if the builder has IR-level attributes.
219 bool hasAttributes() const;
221 /// \brief Return true if the builder has any attribute that's in the
222 /// specified attribute.
223 bool hasAttributes(const Attribute &A) const;
225 /// \brief Return true if the builder has an alignment attribute.
226 bool hasAlignmentAttr() const;
228 /// \brief Retrieve the alignment attribute, if it exists.
229 uint64_t getAlignment() const { return Alignment; }
231 /// \brief Retrieve the stack alignment attribute, if it exists.
232 uint64_t getStackAlignment() const { return StackAlignment; }
234 /// \brief This turns an int alignment (which must be a power of 2) into the
235 /// form used internally in Attribute.
236 AttrBuilder &addAlignmentAttr(unsigned Align);
238 /// \brief This turns an int stack alignment (which must be a power of 2) into
239 /// the form used internally in Attribute.
240 AttrBuilder &addStackAlignmentAttr(unsigned Align);
242 typedef DenseSet<Attribute::AttrKind>::iterator iterator;
243 typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator;
245 iterator begin() { return Attrs.begin(); }
246 iterator end() { return Attrs.end(); }
248 const_iterator begin() const { return Attrs.begin(); }
249 const_iterator end() const { return Attrs.end(); }
251 /// \brief Add the raw value to the internal representation.
253 /// N.B. This should be used ONLY for decoding LLVM bitcode!
254 AttrBuilder &addRawValue(uint64_t Val);
256 /// \brief Remove attributes that are used on functions only.
257 void removeFunctionOnlyAttrs() {
258 removeAttribute(Attribute::NoReturn)
259 .removeAttribute(Attribute::NoUnwind)
260 .removeAttribute(Attribute::ReadNone)
261 .removeAttribute(Attribute::ReadOnly)
262 .removeAttribute(Attribute::NoInline)
263 .removeAttribute(Attribute::AlwaysInline)
264 .removeAttribute(Attribute::OptimizeForSize)
265 .removeAttribute(Attribute::StackProtect)
266 .removeAttribute(Attribute::StackProtectReq)
267 .removeAttribute(Attribute::NoRedZone)
268 .removeAttribute(Attribute::NoImplicitFloat)
269 .removeAttribute(Attribute::Naked)
270 .removeAttribute(Attribute::InlineHint)
271 .removeAttribute(Attribute::StackAlignment)
272 .removeAttribute(Attribute::UWTable)
273 .removeAttribute(Attribute::NonLazyBind)
274 .removeAttribute(Attribute::ReturnsTwice)
275 .removeAttribute(Attribute::AddressSafety)
276 .removeAttribute(Attribute::MinSize)
277 .removeAttribute(Attribute::NoDuplicate);
280 uint64_t getBitMask() const;
282 bool operator==(const AttrBuilder &B);
283 bool operator!=(const AttrBuilder &B) {
284 return !(*this == B);
288 //===----------------------------------------------------------------------===//
290 /// \brief This is just a pair of values to associate a set of attributes with
292 struct AttributeWithIndex {
293 Attribute Attrs; ///< The attributes that are set, or'd together.
294 unsigned Index; ///< Index of the parameter for which the attributes apply.
295 ///< Index 0 is used for return value attributes.
296 ///< Index ~0U is used for function attributes.
298 static AttributeWithIndex get(LLVMContext &C, unsigned Idx,
299 ArrayRef<Attribute::AttrKind> Attrs) {
300 return get(Idx, Attribute::get(C, Attrs));
302 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) {
303 AttributeWithIndex P;
310 //===----------------------------------------------------------------------===//
311 // AttributeSet Smart Pointer
312 //===----------------------------------------------------------------------===//
314 class AttributeSetImpl;
316 //===----------------------------------------------------------------------===//
318 /// \brief This class manages the ref count for the opaque AttributeSetImpl
319 /// object and provides accessors for it.
327 /// \brief The attributes that we are managing. This can be null to represent
328 /// the empty attributes list.
329 AttributeSetImpl *AttrList;
331 /// \brief The attributes for the specified index are returned. Attributes
332 /// for the result are denoted with Idx = 0.
333 Attribute getAttributes(unsigned Idx) const;
335 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {}
337 AttributeSet() : AttrList(0) {}
338 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {}
339 const AttributeSet &operator=(const AttributeSet &RHS);
341 //===--------------------------------------------------------------------===//
342 // Attribute List Construction and Mutation
343 //===--------------------------------------------------------------------===//
345 /// \brief Return an AttributeSet with the specified parameters in it.
346 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs);
347 static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B);
349 /// \brief Add the specified attribute at the specified index to this
350 /// attribute list. Since attribute lists are immutable, this returns the new
352 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
354 /// \brief Remove the specified attribute at the specified index from this
355 /// attribute list. Since attribute lists are immutable, this returns the new
357 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
359 //===--------------------------------------------------------------------===//
360 // Attribute List Accessors
361 //===--------------------------------------------------------------------===//
363 /// \brief The attributes for the specified index are returned.
364 Attribute getParamAttributes(unsigned Idx) const {
365 return getAttributes(Idx);
368 /// \brief The attributes for the ret value are returned.
369 Attribute getRetAttributes() const {
370 return getAttributes(ReturnIndex);
373 /// \brief The function attributes are returned.
374 Attribute getFnAttributes() const {
375 return getAttributes(FunctionIndex);
378 /// \brief Return the alignment for the specified function parameter.
379 unsigned getParamAlignment(unsigned Idx) const {
380 return getAttributes(Idx).getAlignment();
383 /// \brief Return true if the attribute exists at the given index.
384 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
386 /// \brief Return true if attribute exists at the given index.
387 bool hasAttributes(unsigned Index) const;
389 /// \brief Get the stack alignment.
390 unsigned getStackAlignment(unsigned Index) const;
392 /// \brief Return the attributes at the index as a string.
393 std::string getAsString(unsigned Index) const;
395 uint64_t getBitMask(unsigned Index) const;
397 /// \brief Return true if the specified attribute is set for at least one
398 /// parameter or for the return value.
399 bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
401 /// operator==/!= - Provide equality predicates.
402 bool operator==(const AttributeSet &RHS) const {
403 return AttrList == RHS.AttrList;
405 bool operator!=(const AttributeSet &RHS) const {
406 return AttrList != RHS.AttrList;
409 //===--------------------------------------------------------------------===//
410 // Attribute List Introspection
411 //===--------------------------------------------------------------------===//
413 /// \brief Return a raw pointer that uniquely identifies this attribute list.
414 void *getRawPointer() const {
418 // Attributes are stored as a dense set of slots, where there is one slot for
419 // each argument that has an attribute. This allows walking over the dense
420 // set instead of walking the sparse list of attributes.
422 /// \brief Return true if there are no attributes.
423 bool isEmpty() const {
424 return AttrList == 0;
427 /// \brief Return the number of slots used in this attribute list. This is
428 /// the number of arguments that have an attribute set on them (including the
429 /// function itself).
430 unsigned getNumSlots() const;
432 /// \brief Return the AttributeWithIndex at the specified slot. This holds a
433 /// index number plus a set of attributes.
434 const AttributeWithIndex &getSlot(unsigned Slot) const;
439 } // end llvm namespace