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_IR_ATTRIBUTES_H
17 #define LLVM_IR_ATTRIBUTES_H
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseSet.h"
21 #include "llvm/Support/MathExtras.h"
33 //===----------------------------------------------------------------------===//
35 /// \brief Functions, function parameters, and return types can have attributes
36 /// to indicate how they should be treated by optimizations and code
37 /// generation. This class represents one of those attributes. It's light-weight
38 /// and should be passed around by-value.
41 /// This enumeration lists the attributes that can be associated with
42 /// parameters, function results or the function itself.
44 /// Note: uwtable is about the ABI or the user mandating an entry in the
45 /// unwind table. The nounwind attribute is about an exception passing by the
48 /// In a theoretical system that uses tables for profiling and sjlj for
49 /// exceptions, they would be fully independent. In a normal system that uses
50 /// tables for both, the semantics are:
52 /// nil = Needs an entry because an exception might pass by.
53 /// nounwind = No need for an entry
54 /// uwtable = Needs an entry because the ABI says so and because
55 /// an exception might pass by.
56 /// uwtable + nounwind = Needs an entry because the ABI says so.
59 // IR-Level Attributes
60 None, ///< No attributes have been set
61 AddressSafety, ///< Address safety checking is on.
62 Alignment, ///< Alignment of parameter (5 bits)
63 ///< stored as log2 of alignment with +1 bias
64 ///< 0 means unaligned (different from align(1))
65 AlwaysInline, ///< inline=always
66 ByVal, ///< Pass structure by value
67 InlineHint, ///< Source said inlining was desirable
68 InReg, ///< Force argument to be passed in register
69 MinSize, ///< Function must be optimized for size first
70 Naked, ///< Naked function
71 Nest, ///< Nested function static chain
72 NoAlias, ///< Considered to not alias after call
73 NoCapture, ///< Function creates no aliases of pointer
74 NoDuplicate, ///< Call cannot be duplicated
75 NoImplicitFloat, ///< Disable implicit floating point insts
76 NoInline, ///< inline=never
77 NonLazyBind, ///< Function is called early and/or
78 ///< often, so lazy binding isn't worthwhile
79 NoRedZone, ///< Disable redzone
80 NoReturn, ///< Mark the function as not returning
81 NoUnwind, ///< Function doesn't unwind stack
82 OptimizeForSize, ///< opt_size
83 ReadNone, ///< Function does not access memory
84 ReadOnly, ///< Function only reads from memory
85 ReturnsTwice, ///< Function can return twice
86 SExt, ///< Sign extended before/after call
87 StackAlignment, ///< Alignment of stack for function (3 bits)
88 ///< stored as log2 of alignment with +1 bias 0
89 ///< means unaligned (different from
91 StackProtect, ///< Stack protection.
92 StackProtectReq, ///< Stack protection required.
93 StructRet, ///< Hidden pointer to structure to return
94 UWTable, ///< Function must be in a unwind table
95 ZExt, ///< Zero extended before/after call
97 EndAttrKinds, ///< Sentinal value useful for loops
99 AttrKindEmptyKey, ///< Empty key value for DenseMapInfo
100 AttrKindTombstoneKey ///< Tombstone key value for DenseMapInfo
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 Raw() 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::AttrKindEmptyKey;
174 static inline Attribute::AttrKind getTombstoneKey() {
175 return Attribute::AttrKindTombstoneKey;
177 static unsigned getHashValue(const Attribute::AttrKind &Val) {
180 static bool isEqual(const Attribute::AttrKind &LHS,
181 const Attribute::AttrKind &RHS) {
186 //===----------------------------------------------------------------------===//
187 // AttributeSet Smart Pointer
188 //===----------------------------------------------------------------------===//
191 class AttributeSetImpl;
192 struct AttributeWithIndex;
194 //===----------------------------------------------------------------------===//
196 /// \brief This class manages the ref count for the opaque AttributeSetImpl
197 /// object and provides accessors for it.
205 friend class AttrBuilder;
207 /// \brief The attributes that we are managing. This can be null to represent
208 /// the empty attributes list.
209 AttributeSetImpl *AttrList;
211 /// \brief The attributes for the specified index are returned. Attributes
212 /// for the result are denoted with Idx = 0.
213 Attribute getAttributes(unsigned Idx) const;
215 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {}
217 AttributeSet() : AttrList(0) {}
218 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {}
219 const AttributeSet &operator=(const AttributeSet &RHS);
221 //===--------------------------------------------------------------------===//
222 // Attribute List Construction and Mutation
223 //===--------------------------------------------------------------------===//
225 /// \brief Return an AttributeSet with the specified parameters in it.
226 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs);
227 static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B);
229 /// \brief Add the specified attribute at the specified index to this
230 /// attribute list. Since attribute lists are immutable, this returns the new
232 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
234 /// \brief Add return attributes to this attribute set. Since attribute sets
235 /// are immutable, this returns a new set.
236 AttributeSet addRetAttributes(LLVMContext &C, AttributeSet Attrs) const;
238 /// \brief Add function attributes to this attribute set. Since attribute sets
239 /// are immutable, this returns a new set.
240 AttributeSet addFnAttributes(LLVMContext &C, AttributeSet Attrs) const;
242 /// \brief Remove the specified attribute at the specified index from this
243 /// attribute list. Since attribute lists are immutable, this returns the new
245 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
247 //===--------------------------------------------------------------------===//
248 // Attribute List Accessors
249 //===--------------------------------------------------------------------===//
251 /// \brief The attributes for the specified index are returned.
252 Attribute getParamAttributes(unsigned Idx) const {
253 return getAttributes(Idx);
256 /// \brief The attributes for the ret value are returned.
257 Attribute getRetAttributes() const {
258 return getAttributes(ReturnIndex);
261 /// \brief The function attributes are returned.
262 AttributeSet getFnAttributes() const;
264 /// \brief Return the alignment for the specified function parameter.
265 unsigned getParamAlignment(unsigned Idx) const;
267 /// \brief Return true if the attribute exists at the given index.
268 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
270 /// \brief Return true if attribute exists at the given index.
271 bool hasAttributes(unsigned Index) const;
273 /// \brief Get the stack alignment.
274 unsigned getStackAlignment(unsigned Index) const;
276 /// \brief Return the attributes at the index as a string.
277 std::string getAsString(unsigned Index) const;
279 uint64_t Raw(unsigned Index) const;
281 /// \brief Return true if the specified attribute is set for at least one
282 /// parameter or for the return value.
283 bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
285 /// operator==/!= - Provide equality predicates.
286 bool operator==(const AttributeSet &RHS) const {
287 return AttrList == RHS.AttrList;
289 bool operator!=(const AttributeSet &RHS) const {
290 return AttrList != RHS.AttrList;
293 //===--------------------------------------------------------------------===//
294 // Attribute List Introspection
295 //===--------------------------------------------------------------------===//
297 /// \brief Return a raw pointer that uniquely identifies this attribute list.
298 void *getRawPointer() const {
302 // Attributes are stored as a dense set of slots, where there is one slot for
303 // each argument that has an attribute. This allows walking over the dense
304 // set instead of walking the sparse list of attributes.
306 /// \brief Return true if there are no attributes.
307 bool isEmpty() const {
308 return AttrList == 0;
311 /// \brief Return the number of slots used in this attribute list. This is
312 /// the number of arguments that have an attribute set on them (including the
313 /// function itself).
314 unsigned getNumSlots() const;
316 /// \brief Return the AttributeWithIndex at the specified slot. This holds a
317 /// index number plus a set of attributes.
318 const AttributeWithIndex &getSlot(unsigned Slot) const;
323 //===----------------------------------------------------------------------===//
325 /// \brief This is just a pair of values to associate a set of attributes with
327 struct AttributeWithIndex {
328 Attribute Attrs; ///< The attributes that are set, or'd together.
329 Constant *Val; ///< Value attached to attribute, e.g. alignment.
330 unsigned Index; ///< Index of the parameter for which the attributes apply.
331 ///< Index 0 is used for return value attributes.
332 ///< Index ~0U is used for function attributes.
334 // FIXME: These methods all need to be revised. The first one is temporary.
335 static AttributeWithIndex get(LLVMContext &C, unsigned Idx, AttributeSet AS);
336 static AttributeWithIndex get(LLVMContext &C, unsigned Idx,
337 ArrayRef<Attribute::AttrKind> Attrs) {
338 return get(Idx, Attribute::get(C, Attrs));
340 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) {
341 AttributeWithIndex P;
347 static AttributeWithIndex get(unsigned Idx, Attribute Attrs, Constant *Val) {
348 AttributeWithIndex P;
356 //===----------------------------------------------------------------------===//
358 /// \brief This class is used in conjunction with the Attribute::get method to
359 /// create an Attribute object. The object itself is uniquified. The Builder's
360 /// value, however, is not. So this can be used as a quick way to test for
361 /// equality, presence of attributes, etc.
363 DenseSet<Attribute::AttrKind> Attrs;
365 uint64_t StackAlignment;
367 AttrBuilder() : Alignment(0), StackAlignment(0) {}
368 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) {
371 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) {
374 AttrBuilder(AttributeSet AS, unsigned Idx);
378 /// \brief Add an attribute to the builder.
379 AttrBuilder &addAttribute(Attribute::AttrKind Val);
381 /// \brief Remove an attribute from the builder.
382 AttrBuilder &removeAttribute(Attribute::AttrKind Val);
384 /// \brief Add the attributes from A to the builder.
385 AttrBuilder &addAttributes(const Attribute &A);
387 /// \brief Remove the attributes from A from the builder.
388 AttrBuilder &removeAttributes(const Attribute &A);
390 /// \brief Return true if the builder has the specified attribute.
391 bool contains(Attribute::AttrKind A) const;
393 /// \brief Return true if the builder has IR-level attributes.
394 bool hasAttributes() const;
396 /// \brief Return true if the builder has any attribute that's in the
397 /// specified attribute.
398 bool hasAttributes(const Attribute &A) const;
400 /// \brief Return true if the builder has an alignment attribute.
401 bool hasAlignmentAttr() const;
403 /// \brief Retrieve the alignment attribute, if it exists.
404 uint64_t getAlignment() const { return Alignment; }
406 /// \brief Retrieve the stack alignment attribute, if it exists.
407 uint64_t getStackAlignment() const { return StackAlignment; }
409 /// \brief This turns an int alignment (which must be a power of 2) into the
410 /// form used internally in Attribute.
411 AttrBuilder &addAlignmentAttr(unsigned Align);
413 /// \brief This turns an int stack alignment (which must be a power of 2) into
414 /// the form used internally in Attribute.
415 AttrBuilder &addStackAlignmentAttr(unsigned Align);
417 typedef DenseSet<Attribute::AttrKind>::iterator iterator;
418 typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator;
420 iterator begin() { return Attrs.begin(); }
421 iterator end() { return Attrs.end(); }
423 const_iterator begin() const { return Attrs.begin(); }
424 const_iterator end() const { return Attrs.end(); }
426 /// \brief Add the raw value to the internal representation.
428 /// N.B. This should be used ONLY for decoding LLVM bitcode!
429 AttrBuilder &addRawValue(uint64_t Val);
431 /// \brief Remove attributes that are used on functions only.
432 void removeFunctionOnlyAttrs() {
433 removeAttribute(Attribute::NoReturn)
434 .removeAttribute(Attribute::NoUnwind)
435 .removeAttribute(Attribute::ReadNone)
436 .removeAttribute(Attribute::ReadOnly)
437 .removeAttribute(Attribute::NoInline)
438 .removeAttribute(Attribute::AlwaysInline)
439 .removeAttribute(Attribute::OptimizeForSize)
440 .removeAttribute(Attribute::StackProtect)
441 .removeAttribute(Attribute::StackProtectReq)
442 .removeAttribute(Attribute::NoRedZone)
443 .removeAttribute(Attribute::NoImplicitFloat)
444 .removeAttribute(Attribute::Naked)
445 .removeAttribute(Attribute::InlineHint)
446 .removeAttribute(Attribute::StackAlignment)
447 .removeAttribute(Attribute::UWTable)
448 .removeAttribute(Attribute::NonLazyBind)
449 .removeAttribute(Attribute::ReturnsTwice)
450 .removeAttribute(Attribute::AddressSafety)
451 .removeAttribute(Attribute::MinSize)
452 .removeAttribute(Attribute::NoDuplicate);
455 uint64_t Raw() const;
457 bool operator==(const AttrBuilder &B);
458 bool operator!=(const AttrBuilder &B) {
459 return !(*this == B);
463 } // end llvm namespace