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
98 // Values for DenseMapInfo
99 EmptyKey = 0x7FFFFFFF,
100 TombstoneKey = -0x7FFFFFFF - 1
103 AttributeImpl *pImpl;
104 Attribute(AttributeImpl *A) : pImpl(A) {}
106 Attribute() : pImpl(0) {}
108 /// \brief Return a uniquified Attribute object. This takes the uniquified
109 /// value from the Builder and wraps it in the Attribute class.
110 static Attribute get(LLVMContext &Context, ArrayRef<AttrKind> Vals);
111 static Attribute get(LLVMContext &Context, AttrBuilder &B);
113 /// \brief Return true if the attribute is present.
114 bool hasAttribute(AttrKind Val) const;
116 /// \brief Return true if attributes exist
117 bool hasAttributes() const;
119 /// \brief Returns the alignment field of an attribute as a byte alignment
121 unsigned getAlignment() const;
123 /// \brief Set the alignment field of an attribute.
124 void setAlignment(unsigned Align);
126 /// \brief Returns the stack alignment field of an attribute as a byte
128 unsigned getStackAlignment() const;
130 /// \brief Set the stack alignment field of an attribute.
131 void setStackAlignment(unsigned Align);
133 /// \brief Equality and non-equality query methods.
134 bool operator==(AttrKind K) const;
135 bool operator!=(AttrKind K) const;
137 // FIXME: Remove these 'operator' methods.
138 bool operator==(const Attribute &A) const {
139 return pImpl == A.pImpl;
141 bool operator!=(const Attribute &A) const {
142 return pImpl != A.pImpl;
145 uint64_t getBitMask() const;
147 /// \brief Which attributes cannot be applied to a type.
148 static Attribute typeIncompatible(Type *Ty);
150 /// \brief This returns an integer containing an encoding of all the LLVM
151 /// attributes found in the given attribute bitset. Any change to this
152 /// encoding is a breaking change to bitcode compatibility.
153 static uint64_t encodeLLVMAttributesForBitcode(Attribute Attrs);
155 /// \brief This returns an attribute bitset containing the LLVM attributes
156 /// that have been decoded from the given integer. This function must stay in
157 /// sync with 'encodeLLVMAttributesForBitcode'.
158 static Attribute decodeLLVMAttributesForBitcode(LLVMContext &C,
159 uint64_t EncodedAttrs);
161 /// \brief The Attribute is converted to a string of equivalent mnemonic. This
162 /// is, presumably, for writing out the mnemonics for the assembly writer.
163 std::string getAsString() const;
166 //===----------------------------------------------------------------------===//
168 /// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by
170 template<> struct DenseMapInfo<Attribute::AttrKind> {
171 static inline Attribute::AttrKind getEmptyKey() {
172 return Attribute::EmptyKey;
174 static inline Attribute::AttrKind getTombstoneKey() {
175 return Attribute::TombstoneKey;
177 static unsigned getHashValue(const Attribute::AttrKind &Val) {
180 static bool isEqual(const Attribute::AttrKind &LHS,
181 const Attribute::AttrKind &RHS) {
186 //===----------------------------------------------------------------------===//
188 /// \brief This class is used in conjunction with the Attribute::get method to
189 /// create an Attribute object. The object itself is uniquified. The Builder's
190 /// value, however, is not. So this can be used as a quick way to test for
191 /// equality, presence of attributes, etc.
193 DenseSet<Attribute::AttrKind> Attrs;
195 uint64_t StackAlignment;
197 AttrBuilder() : Alignment(0), StackAlignment(0) {}
198 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) {
201 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) {
207 /// \brief Add an attribute to the builder.
208 AttrBuilder &addAttribute(Attribute::AttrKind Val);
210 /// \brief Remove an attribute from the builder.
211 AttrBuilder &removeAttribute(Attribute::AttrKind Val);
213 /// \brief Add the attributes from A to the builder.
214 AttrBuilder &addAttributes(const Attribute &A);
216 /// \brief Remove the attributes from A from the builder.
217 AttrBuilder &removeAttributes(const Attribute &A);
219 /// \brief Return true if the builder has the specified attribute.
220 bool contains(Attribute::AttrKind A) const;
222 /// \brief Return true if the builder has IR-level attributes.
223 bool hasAttributes() const;
225 /// \brief Return true if the builder has any attribute that's in the
226 /// specified attribute.
227 bool hasAttributes(const Attribute &A) const;
229 /// \brief Return true if the builder has an alignment attribute.
230 bool hasAlignmentAttr() const;
232 /// \brief Retrieve the alignment attribute, if it exists.
233 uint64_t getAlignment() const { return Alignment; }
235 /// \brief Retrieve the stack alignment attribute, if it exists.
236 uint64_t getStackAlignment() const { return StackAlignment; }
238 /// \brief This turns an int alignment (which must be a power of 2) into the
239 /// form used internally in Attribute.
240 AttrBuilder &addAlignmentAttr(unsigned Align);
242 /// \brief This turns an int stack alignment (which must be a power of 2) into
243 /// the form used internally in Attribute.
244 AttrBuilder &addStackAlignmentAttr(unsigned Align);
246 typedef DenseSet<Attribute::AttrKind>::iterator iterator;
247 typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator;
249 iterator begin() { return Attrs.begin(); }
250 iterator end() { return Attrs.end(); }
252 const_iterator begin() const { return Attrs.begin(); }
253 const_iterator end() const { return Attrs.end(); }
255 /// \brief Add the raw value to the internal representation.
257 /// N.B. This should be used ONLY for decoding LLVM bitcode!
258 AttrBuilder &addRawValue(uint64_t Val);
260 /// \brief Remove attributes that are used on functions only.
261 void removeFunctionOnlyAttrs() {
262 removeAttribute(Attribute::NoReturn)
263 .removeAttribute(Attribute::NoUnwind)
264 .removeAttribute(Attribute::ReadNone)
265 .removeAttribute(Attribute::ReadOnly)
266 .removeAttribute(Attribute::NoInline)
267 .removeAttribute(Attribute::AlwaysInline)
268 .removeAttribute(Attribute::OptimizeForSize)
269 .removeAttribute(Attribute::StackProtect)
270 .removeAttribute(Attribute::StackProtectReq)
271 .removeAttribute(Attribute::NoRedZone)
272 .removeAttribute(Attribute::NoImplicitFloat)
273 .removeAttribute(Attribute::Naked)
274 .removeAttribute(Attribute::InlineHint)
275 .removeAttribute(Attribute::StackAlignment)
276 .removeAttribute(Attribute::UWTable)
277 .removeAttribute(Attribute::NonLazyBind)
278 .removeAttribute(Attribute::ReturnsTwice)
279 .removeAttribute(Attribute::AddressSafety)
280 .removeAttribute(Attribute::MinSize)
281 .removeAttribute(Attribute::NoDuplicate);
284 uint64_t getBitMask() const;
286 bool operator==(const AttrBuilder &B);
287 bool operator!=(const AttrBuilder &B) {
288 return !(*this == B);
292 //===----------------------------------------------------------------------===//
294 /// \brief This is just a pair of values to associate a set of attributes with
296 struct AttributeWithIndex {
297 Attribute Attrs; ///< The attributes that are set, or'd together.
298 unsigned Index; ///< Index of the parameter for which the attributes apply.
299 ///< Index 0 is used for return value attributes.
300 ///< Index ~0U is used for function attributes.
302 static AttributeWithIndex get(LLVMContext &C, unsigned Idx,
303 ArrayRef<Attribute::AttrKind> Attrs) {
304 return get(Idx, Attribute::get(C, Attrs));
306 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) {
307 AttributeWithIndex P;
314 //===----------------------------------------------------------------------===//
315 // AttributeSet Smart Pointer
316 //===----------------------------------------------------------------------===//
318 class AttributeSetImpl;
320 //===----------------------------------------------------------------------===//
322 /// \brief This class manages the ref count for the opaque AttributeSetImpl
323 /// object and provides accessors for it.
331 /// \brief The attributes that we are managing. This can be null to represent
332 /// the empty attributes list.
333 AttributeSetImpl *AttrList;
335 /// \brief The attributes for the specified index are returned. Attributes
336 /// for the result are denoted with Idx = 0.
337 Attribute getAttributes(unsigned Idx) const;
339 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {}
341 AttributeSet() : AttrList(0) {}
342 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {}
343 const AttributeSet &operator=(const AttributeSet &RHS);
345 //===--------------------------------------------------------------------===//
346 // Attribute List Construction and Mutation
347 //===--------------------------------------------------------------------===//
349 /// \brief Return an AttributeSet with the specified parameters in it.
350 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs);
351 static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B);
353 /// \brief Add the specified attribute at the specified index to this
354 /// attribute list. Since attribute lists are immutable, this returns the new
356 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
358 /// \brief Remove the specified attribute at the specified index from this
359 /// attribute list. Since attribute lists are immutable, this returns the new
361 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
363 //===--------------------------------------------------------------------===//
364 // Attribute List Accessors
365 //===--------------------------------------------------------------------===//
367 /// \brief The attributes for the specified index are returned.
368 Attribute getParamAttributes(unsigned Idx) const {
369 return getAttributes(Idx);
372 /// \brief The attributes for the ret value are returned.
373 Attribute getRetAttributes() const {
374 return getAttributes(ReturnIndex);
377 /// \brief The function attributes are returned.
378 Attribute getFnAttributes() const {
379 return getAttributes(FunctionIndex);
382 /// \brief Return the alignment for the specified function parameter.
383 unsigned getParamAlignment(unsigned Idx) const {
384 return getAttributes(Idx).getAlignment();
387 /// \brief Return true if the attribute exists at the given index.
388 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
390 /// \brief Return true if attribute exists at the given index.
391 bool hasAttributes(unsigned Index) const;
393 /// \brief Get the stack alignment.
394 unsigned getStackAlignment(unsigned Index) const;
396 /// \brief Return the attributes at the index as a string.
397 std::string getAsString(unsigned Index) const;
399 uint64_t getBitMask(unsigned Index) const;
401 /// \brief Return true if the specified attribute is set for at least one
402 /// parameter or for the return value.
403 bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
405 /// operator==/!= - Provide equality predicates.
406 bool operator==(const AttributeSet &RHS) const {
407 return AttrList == RHS.AttrList;
409 bool operator!=(const AttributeSet &RHS) const {
410 return AttrList != RHS.AttrList;
413 //===--------------------------------------------------------------------===//
414 // Attribute List Introspection
415 //===--------------------------------------------------------------------===//
417 /// \brief Return a raw pointer that uniquely identifies this attribute list.
418 void *getRawPointer() const {
422 // Attributes are stored as a dense set of slots, where there is one slot for
423 // each argument that has an attribute. This allows walking over the dense
424 // set instead of walking the sparse list of attributes.
426 /// \brief Return true if there are no attributes.
427 bool isEmpty() const {
428 return AttrList == 0;
431 /// \brief Return the number of slots used in this attribute list. This is
432 /// the number of arguments that have an attribute set on them (including the
433 /// function itself).
434 unsigned getNumSlots() const;
436 /// \brief Return the AttributeWithIndex at the specified slot. This holds a
437 /// index number plus a set of attributes.
438 const AttributeWithIndex &getSlot(unsigned Slot) const;
443 } // end llvm namespace