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 Return true if the attributes are a non-null intersection.
113 bool hasAttributes(const Attribute &A) 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 bool operator==(const Attribute &A) const {
124 return pImpl == A.pImpl;
126 bool operator!=(const Attribute &A) const {
127 return pImpl != A.pImpl;
130 uint64_t getBitMask() const;
132 /// \brief Which attributes cannot be applied to a type.
133 static Attribute typeIncompatible(Type *Ty);
135 /// \brief This returns an integer containing an encoding of all the LLVM
136 /// attributes found in the given attribute bitset. Any change to this
137 /// encoding is a breaking change to bitcode compatibility.
138 static uint64_t encodeLLVMAttributesForBitcode(Attribute Attrs);
140 /// \brief This returns an attribute bitset containing the LLVM attributes
141 /// that have been decoded from the given integer. This function must stay in
142 /// sync with 'encodeLLVMAttributesForBitcode'.
143 static Attribute decodeLLVMAttributesForBitcode(LLVMContext &C,
144 uint64_t EncodedAttrs);
146 /// \brief The Attribute is converted to a string of equivalent mnemonic. This
147 /// is, presumably, for writing out the mnemonics for the assembly writer.
148 std::string getAsString() const;
151 //===----------------------------------------------------------------------===//
153 /// \brief This class is used in conjunction with the Attribute::get method to
154 /// create an Attribute object. The object itself is uniquified. The Builder's
155 /// value, however, is not. So this can be used as a quick way to test for
156 /// equality, presence of attributes, etc.
160 AttrBuilder() : Bits(0) {}
161 explicit AttrBuilder(uint64_t B) : Bits(B) {}
162 AttrBuilder(const Attribute &A) : Bits(A.getBitMask()) {}
164 void clear() { Bits = 0; }
166 /// addAttribute - Add an attribute to the builder.
167 AttrBuilder &addAttribute(Attribute::AttrKind Val);
169 /// removeAttribute - Remove an attribute from the builder.
170 AttrBuilder &removeAttribute(Attribute::AttrKind Val);
172 /// addAttribute - Add the attributes from A to the builder.
173 AttrBuilder &addAttributes(const Attribute &A);
175 /// removeAttribute - Remove the attributes from A from the builder.
176 AttrBuilder &removeAttributes(const Attribute &A);
178 /// \brief Return true if the builder has the specified attribute.
179 bool contains(Attribute::AttrKind A) const;
181 /// hasAttributes - Return true if the builder has IR-level attributes.
182 bool hasAttributes() const;
184 /// hasAttributes - Return true if the builder has any attribute that's in the
185 /// specified attribute.
186 bool hasAttributes(const Attribute &A) const;
188 /// hasAlignmentAttr - Return true if the builder has an alignment attribute.
189 bool hasAlignmentAttr() const;
191 /// getAlignment - Retrieve the alignment attribute, if it exists.
192 uint64_t getAlignment() const;
194 /// getStackAlignment - Retrieve the stack alignment attribute, if it exists.
195 uint64_t getStackAlignment() const;
197 /// addAlignmentAttr - This turns an int alignment (which must be a power of
198 /// 2) into the form used internally in Attribute.
199 AttrBuilder &addAlignmentAttr(unsigned Align);
201 /// addStackAlignmentAttr - This turns an int stack alignment (which must be a
202 /// power of 2) into the form used internally in Attribute.
203 AttrBuilder &addStackAlignmentAttr(unsigned Align);
205 /// addRawValue - Add the raw value to the internal representation.
206 /// N.B. This should be used ONLY for decoding LLVM bitcode!
207 AttrBuilder &addRawValue(uint64_t Val);
209 /// @brief Remove attributes that are used on functions only.
210 void removeFunctionOnlyAttrs() {
211 removeAttribute(Attribute::NoReturn)
212 .removeAttribute(Attribute::NoUnwind)
213 .removeAttribute(Attribute::ReadNone)
214 .removeAttribute(Attribute::ReadOnly)
215 .removeAttribute(Attribute::NoInline)
216 .removeAttribute(Attribute::AlwaysInline)
217 .removeAttribute(Attribute::OptimizeForSize)
218 .removeAttribute(Attribute::StackProtect)
219 .removeAttribute(Attribute::StackProtectReq)
220 .removeAttribute(Attribute::NoRedZone)
221 .removeAttribute(Attribute::NoImplicitFloat)
222 .removeAttribute(Attribute::Naked)
223 .removeAttribute(Attribute::InlineHint)
224 .removeAttribute(Attribute::StackAlignment)
225 .removeAttribute(Attribute::UWTable)
226 .removeAttribute(Attribute::NonLazyBind)
227 .removeAttribute(Attribute::ReturnsTwice)
228 .removeAttribute(Attribute::AddressSafety)
229 .removeAttribute(Attribute::MinSize)
230 .removeAttribute(Attribute::NoDuplicate);
233 uint64_t getBitMask() const { return Bits; }
235 bool operator==(const AttrBuilder &B) {
236 return Bits == B.Bits;
238 bool operator!=(const AttrBuilder &B) {
239 return Bits != B.Bits;
243 //===----------------------------------------------------------------------===//
245 /// \brief This is just a pair of values to associate a set of attributes with
247 struct AttributeWithIndex {
248 Attribute Attrs; ///< The attributes that are set, or'd together.
249 unsigned Index; ///< Index of the parameter for which the attributes apply.
250 ///< Index 0 is used for return value attributes.
251 ///< Index ~0U is used for function attributes.
253 static AttributeWithIndex get(LLVMContext &C, unsigned Idx,
254 ArrayRef<Attribute::AttrKind> Attrs) {
255 return get(Idx, Attribute::get(C, Attrs));
257 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) {
258 AttributeWithIndex P;
265 //===----------------------------------------------------------------------===//
266 // AttributeSet Smart Pointer
267 //===----------------------------------------------------------------------===//
269 class AttributeSetImpl;
271 //===----------------------------------------------------------------------===//
273 /// \brief This class manages the ref count for the opaque AttributeSetImpl
274 /// object and provides accessors for it.
282 /// \brief The attributes that we are managing. This can be null to represent
283 /// the empty attributes list.
284 AttributeSetImpl *AttrList;
286 /// \brief The attributes for the specified index are returned. Attributes
287 /// for the result are denoted with Idx = 0.
288 Attribute getAttributes(unsigned Idx) const;
290 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {}
292 AttributeSet() : AttrList(0) {}
293 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {}
294 const AttributeSet &operator=(const AttributeSet &RHS);
296 //===--------------------------------------------------------------------===//
297 // Attribute List Construction and Mutation
298 //===--------------------------------------------------------------------===//
300 /// \brief Return an AttributeSet with the specified parameters in it.
301 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs);
303 /// \brief Add the specified attribute at the specified index to this
304 /// attribute list. Since attribute lists are immutable, this returns the new
306 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
308 /// \brief Remove the specified attribute at the specified index from this
309 /// attribute list. Since attribute lists are immutable, this returns the new
311 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const;
313 //===--------------------------------------------------------------------===//
314 // Attribute List Accessors
315 //===--------------------------------------------------------------------===//
317 /// \brief The attributes for the specified index are returned.
318 Attribute getParamAttributes(unsigned Idx) const {
319 return getAttributes(Idx);
322 /// \brief The attributes for the ret value are returned.
323 Attribute getRetAttributes() const {
324 return getAttributes(ReturnIndex);
327 /// \brief The function attributes are returned.
328 Attribute getFnAttributes() const {
329 return getAttributes(FunctionIndex);
332 /// \brief Return true if the specified parameter index has the specified
334 bool paramHasAttr(unsigned Idx, Attribute Attr) const {
335 return getAttributes(Idx).hasAttributes(Attr);
338 /// \brief Return the alignment for the specified function parameter.
339 unsigned getParamAlignment(unsigned Idx) const {
340 return getAttributes(Idx).getAlignment();
343 /// \brief Return true if the attribute exists at the given index.
344 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
346 /// \brief Return true if attribute exists at the given index.
347 bool hasAttributes(unsigned Index) const;
349 /// \brief Get the stack alignment.
350 unsigned getStackAlignment(unsigned Index) const;
352 /// \brief Return the attributes at the index as a string.
353 std::string getAsString(unsigned Index) const;
355 uint64_t getBitMask(unsigned Index) const;
357 /// \brief Return true if the specified attribute is set for at least one
358 /// parameter or for the return value.
359 bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
361 /// operator==/!= - Provide equality predicates.
362 bool operator==(const AttributeSet &RHS) const {
363 return AttrList == RHS.AttrList;
365 bool operator!=(const AttributeSet &RHS) const {
366 return AttrList != RHS.AttrList;
369 //===--------------------------------------------------------------------===//
370 // Attribute List Introspection
371 //===--------------------------------------------------------------------===//
373 /// \brief Return a raw pointer that uniquely identifies this attribute list.
374 void *getRawPointer() const {
378 // Attributes are stored as a dense set of slots, where there is one slot for
379 // each argument that has an attribute. This allows walking over the dense
380 // set instead of walking the sparse list of attributes.
382 /// \brief Return true if there are no attributes.
383 bool isEmpty() const {
384 return AttrList == 0;
387 /// \brief Return the number of slots used in this attribute list. This is
388 /// the number of arguments that have an attribute set on them (including the
389 /// function itself).
390 unsigned getNumSlots() const;
392 /// \brief Return the AttributeWithIndex at the specified slot. This holds a
393 /// index number plus a set of attributes.
394 const AttributeWithIndex &getSlot(unsigned Slot) const;
399 } // end llvm namespace