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/Support/MathExtras.h"
31 //===----------------------------------------------------------------------===//
33 /// \brief Functions, function parameters, and return types can have attributes
34 /// to indicate how they should be treated by optimizations and code
35 /// generation. This class represents one of those attributes. It's light-weight
36 /// and should be passed around by-value.
39 /// This enumeration lists the attributes that can be associated with
40 /// parameters, function results or the function itself.
42 /// Note: uwtable is about the ABI or the user mandating an entry in the
43 /// unwind table. The nounwind attribute is about an exception passing by the
46 /// In a theoretical system that uses tables for profiling and sjlj for
47 /// exceptions, they would be fully independent. In a normal system that uses
48 /// tables for both, the semantics are:
50 /// nil = Needs an entry because an exception might pass by.
51 /// nounwind = No need for an entry
52 /// uwtable = Needs an entry because the ABI says so and because
53 /// an exception might pass by.
54 /// uwtable + nounwind = Needs an entry because the ABI says so.
57 // IR-Level Attributes
58 None, ///< No attributes have been set
59 AddressSafety, ///< Address safety checking is on.
60 Alignment, ///< Alignment of parameter (5 bits)
61 ///< stored as log2 of alignment with +1 bias
62 ///< 0 means unaligned (different from align(1))
63 AlwaysInline, ///< inline=always
64 ByVal, ///< Pass structure by value
65 InlineHint, ///< Source said inlining was desirable
66 InReg, ///< Force argument to be passed in register
67 MinSize, ///< Function must be optimized for size first
68 Naked, ///< Naked function
69 Nest, ///< Nested function static chain
70 NoAlias, ///< Considered to not alias after call
71 NoCapture, ///< Function creates no aliases of pointer
72 NoDuplicate, ///< Call cannot be duplicated
73 NoImplicitFloat, ///< Disable implicit floating point insts
74 NoInline, ///< inline=never
75 NonLazyBind, ///< Function is called early and/or
76 ///< often, so lazy binding isn't worthwhile
77 NoRedZone, ///< Disable redzone
78 NoReturn, ///< Mark the function as not returning
79 NoUnwind, ///< Function doesn't unwind stack
80 OptimizeForSize, ///< opt_size
81 ReadNone, ///< Function does not access memory
82 ReadOnly, ///< Function only reads from memory
83 ReturnsTwice, ///< Function can return twice
84 SExt, ///< Sign extended before/after call
85 StackAlignment, ///< Alignment of stack for function (3 bits)
86 ///< stored as log2 of alignment with +1 bias 0
87 ///< means unaligned (different from
89 StackProtect, ///< Stack protection.
90 StackProtectReq, ///< Stack protection required.
91 StructRet, ///< Hidden pointer to structure to return
92 UWTable, ///< Function must be in a unwind table
93 ZExt ///< Zero extended before/after call
97 Attribute(AttributeImpl *A) : pImpl(A) {}
99 Attribute() : pImpl(0) {}
101 /// \brief Return a uniquified Attribute object. This takes the uniquified
102 /// value from the Builder and wraps it in the Attribute class.
103 static Attribute get(LLVMContext &Context, ArrayRef<AttrKind> Vals);
104 static Attribute get(LLVMContext &Context, AttrBuilder &B);
106 /// \brief Return true if the attribute is present.
107 bool hasAttribute(AttrKind Val) const;
109 /// \brief Return true if attributes exist
110 bool hasAttributes() const;
112 /// \brief Returns the alignment field of an attribute as a byte alignment
114 unsigned getAlignment() const;
116 /// \brief Returns the stack alignment field of an attribute as a byte
118 unsigned getStackAlignment() const;
120 /// \brief Equality and non-equality query methods.
121 bool operator==(AttrKind K) const;
122 bool operator!=(AttrKind K) const;
124 // FIXME: Remove these 'operator' methods.
125 bool operator==(const Attribute &A) const {
126 return pImpl == A.pImpl;
128 bool operator!=(const Attribute &A) const {
129 return pImpl != A.pImpl;
132 uint64_t getBitMask() const;
134 /// \brief Which attributes cannot be applied to a type.
135 static Attribute typeIncompatible(Type *Ty);
137 /// \brief This returns an integer containing an encoding of all the LLVM
138 /// attributes found in the given attribute bitset. Any change to this
139 /// encoding is a breaking change to bitcode compatibility.
140 static uint64_t encodeLLVMAttributesForBitcode(Attribute Attrs);
142 /// \brief This returns an attribute bitset containing the LLVM attributes
143 /// that have been decoded from the given integer. This function must stay in
144 /// sync with 'encodeLLVMAttributesForBitcode'.
145 static Attribute decodeLLVMAttributesForBitcode(LLVMContext &C,
146 uint64_t EncodedAttrs);
148 /// \brief The Attribute is converted to a string of equivalent mnemonic. This
149 /// is, presumably, for writing out the mnemonics for the assembly writer.
150 std::string getAsString() const;
153 //===----------------------------------------------------------------------===//
155 /// \brief This class is used in conjunction with the Attribute::get method to
156 /// create an Attribute object. The object itself is uniquified. The Builder's
157 /// value, however, is not. So this can be used as a quick way to test for
158 /// equality, presence of attributes, etc.
162 AttrBuilder() : Bits(0) {}
163 explicit AttrBuilder(uint64_t B) : Bits(B) {}
164 AttrBuilder(const Attribute &A) : Bits(A.getBitMask()) {}
166 void clear() { Bits = 0; }
168 /// \brief Add an attribute to the builder.
169 AttrBuilder &addAttribute(Attribute::AttrKind Val);
171 /// \brief Remove an attribute from the builder.
172 AttrBuilder &removeAttribute(Attribute::AttrKind Val);
174 /// \brief Add the attributes from A to the builder.
175 AttrBuilder &addAttributes(const Attribute &A);
177 /// \brief Remove the attributes from A from the builder.
178 AttrBuilder &removeAttributes(const Attribute &A);
180 /// \brief Return true if the builder has the specified attribute.
181 bool contains(Attribute::AttrKind A) const;
183 /// \brief Return true if the builder has IR-level attributes.
184 bool hasAttributes() const;
186 /// \brief Return true if the builder has any attribute that's in the
187 /// specified attribute.
188 bool hasAttributes(const Attribute &A) const;
190 /// \brief Return true if the builder has an alignment attribute.
191 bool hasAlignmentAttr() const;
193 /// \brief Retrieve the alignment attribute, if it exists.
194 uint64_t getAlignment() const;
196 /// \brief Retrieve the stack alignment attribute, if it exists.
197 uint64_t getStackAlignment() const;
199 /// \brief This turns an int alignment (which must be a power of 2) into the
200 /// form used internally in Attribute.
201 AttrBuilder &addAlignmentAttr(unsigned Align);
203 /// \brief This turns an int stack alignment (which must be a power of 2) into
204 /// the form used internally in Attribute.
205 AttrBuilder &addStackAlignmentAttr(unsigned Align);
207 /// \brief Add the raw value to the internal representation.
209 /// N.B. This should be used ONLY for decoding LLVM bitcode!
210 AttrBuilder &addRawValue(uint64_t Val);
212 /// \brief Remove attributes that are used on functions only.
213 void removeFunctionOnlyAttrs() {
214 removeAttribute(Attribute::NoReturn)
215 .removeAttribute(Attribute::NoUnwind)
216 .removeAttribute(Attribute::ReadNone)
217 .removeAttribute(Attribute::ReadOnly)
218 .removeAttribute(Attribute::NoInline)
219 .removeAttribute(Attribute::AlwaysInline)
220 .removeAttribute(Attribute::OptimizeForSize)
221 .removeAttribute(Attribute::StackProtect)
222 .removeAttribute(Attribute::StackProtectReq)
223 .removeAttribute(Attribute::NoRedZone)
224 .removeAttribute(Attribute::NoImplicitFloat)
225 .removeAttribute(Attribute::Naked)
226 .removeAttribute(Attribute::InlineHint)
227 .removeAttribute(Attribute::StackAlignment)
228 .removeAttribute(Attribute::UWTable)
229 .removeAttribute(Attribute::NonLazyBind)
230 .removeAttribute(Attribute::ReturnsTwice)
231 .removeAttribute(Attribute::AddressSafety)
232 .removeAttribute(Attribute::MinSize)
233 .removeAttribute(Attribute::NoDuplicate);
236 uint64_t getBitMask() const { return Bits; }
238 bool operator==(const AttrBuilder &B) {
239 return Bits == B.Bits;
241 bool operator!=(const AttrBuilder &B) {
242 return Bits != B.Bits;
246 //===----------------------------------------------------------------------===//
248 /// \brief This is just a pair of values to associate a set of attributes with
250 struct AttributeWithIndex {
251 Attribute Attrs; ///< The attributes that are set, or'd together.
252 unsigned Index; ///< Index of the parameter for which the attributes apply.
253 ///< Index 0 is used for return value attributes.
254 ///< Index ~0U is used for function attributes.
256 static AttributeWithIndex get(LLVMContext &C, unsigned Idx,
257 ArrayRef<Attribute::AttrKind> Attrs) {
258 return get(Idx, Attribute::get(C, Attrs));
260 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) {
261 AttributeWithIndex P;
268 //===----------------------------------------------------------------------===//
269 // AttributeSet Smart Pointer
270 //===----------------------------------------------------------------------===//
272 class AttributeSetImpl;
274 //===----------------------------------------------------------------------===//
276 /// \brief This class manages the ref count for the opaque AttributeSetImpl
277 /// object and provides accessors for it.
285 /// \brief The attributes that we are managing. This can be null to represent
286 /// the empty attributes list.
287 AttributeSetImpl *AttrList;
289 /// \brief The attributes for the specified index are returned. Attributes
290 /// for the result are denoted with Idx = 0.
291 Attribute getAttributes(unsigned Idx) const;
293 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {}
295 AttributeSet() : AttrList(0) {}
296 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {}
297 const AttributeSet &operator=(const AttributeSet &RHS);
299 //===--------------------------------------------------------------------===//
300 // Attribute List Construction and Mutation
301 //===--------------------------------------------------------------------===//
303 /// \brief Return an AttributeSet with the specified parameters in it.
304 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs);
306 /// \brief Add the specified attribute at the specified index to this
307 /// attribute list. Since attribute lists are immutable, this returns the new
309 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
311 /// \brief Remove the specified attribute at the specified index from this
312 /// attribute list. Since attribute lists are immutable, this returns the new
314 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
316 //===--------------------------------------------------------------------===//
317 // Attribute List Accessors
318 //===--------------------------------------------------------------------===//
320 /// \brief The attributes for the specified index are returned.
321 Attribute getParamAttributes(unsigned Idx) const {
322 return getAttributes(Idx);
325 /// \brief The attributes for the ret value are returned.
326 Attribute getRetAttributes() const {
327 return getAttributes(ReturnIndex);
330 /// \brief The function attributes are returned.
331 Attribute getFnAttributes() const {
332 return getAttributes(FunctionIndex);
335 /// \brief Return the alignment for the specified function parameter.
336 unsigned getParamAlignment(unsigned Idx) const {
337 return getAttributes(Idx).getAlignment();
340 /// \brief Return true if the attribute exists at the given index.
341 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
343 /// \brief Return true if attribute exists at the given index.
344 bool hasAttributes(unsigned Index) const;
346 /// \brief Get the stack alignment.
347 unsigned getStackAlignment(unsigned Index) const;
349 /// \brief Return the attributes at the index as a string.
350 std::string getAsString(unsigned Index) const;
352 uint64_t getBitMask(unsigned Index) const;
354 /// \brief Return true if the specified attribute is set for at least one
355 /// parameter or for the return value.
356 bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
358 /// operator==/!= - Provide equality predicates.
359 bool operator==(const AttributeSet &RHS) const {
360 return AttrList == RHS.AttrList;
362 bool operator!=(const AttributeSet &RHS) const {
363 return AttrList != RHS.AttrList;
366 //===--------------------------------------------------------------------===//
367 // Attribute List Introspection
368 //===--------------------------------------------------------------------===//
370 /// \brief Return a raw pointer that uniquely identifies this attribute list.
371 void *getRawPointer() const {
375 // Attributes are stored as a dense set of slots, where there is one slot for
376 // each argument that has an attribute. This allows walking over the dense
377 // set instead of walking the sparse list of attributes.
379 /// \brief Return true if there are no attributes.
380 bool isEmpty() const {
381 return AttrList == 0;
384 /// \brief Return the number of slots used in this attribute list. This is
385 /// the number of arguments that have an attribute set on them (including the
386 /// function itself).
387 unsigned getNumSlots() const;
389 /// \brief Return the AttributeWithIndex at the specified slot. This holds a
390 /// index number plus a set of attributes.
391 const AttributeWithIndex &getSlot(unsigned Slot) const;
396 } // end llvm namespace