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 //===----------------------------------------------------------------------===//
10 // This file contains the simple types necessary to represent the
11 // attributes associated with functions and their calls.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ATTRIBUTES_H
16 #define LLVM_ATTRIBUTES_H
18 #include "llvm/Support/MathExtras.h"
19 #include "llvm/ADT/ArrayRef.h"
28 /// AttributeImpl - The internal representation of the Attributes class. This is
32 /// Attributes - A bitset of attributes.
35 /// Function parameters and results can have attributes to indicate how they
36 /// should be treated by optimizations and code generation. This enumeration
37 /// lists the attributes that can be associated with parameters, function
38 /// results or the function itself.
40 /// Note that uwtable is about the ABI or the user mandating an entry in the
41 /// unwind table. The nounwind attribute is about an exception passing by the
44 /// In a theoretical system that uses tables for profiling and sjlj for
45 /// exceptions, they would be fully independent. In a normal system that uses
46 /// tables for both, the semantics are:
48 /// nil = Needs an entry because an exception might pass by.
49 /// nounwind = No need for an entry
50 /// uwtable = Needs an entry because the ABI says so and because
51 /// an exception might pass by.
52 /// uwtable + nounwind = Needs an entry because the ABI says so.
55 None = 0, ///< No attributes have been set
56 AddressSafety = 1, ///< Address safety checking is on.
57 Alignment = 2, ///< Alignment of parameter (5 bits)
58 ///< stored as log2 of alignment with +1 bias
59 ///< 0 means unaligned different from align 1
60 AlwaysInline = 3, ///< inline=always
61 ByVal = 4, ///< Pass structure by value
62 InlineHint = 5, ///< Source said inlining was desirable
63 InReg = 6, ///< Force argument to be passed in register
64 Naked = 7, ///< Naked function
65 Nest = 8, ///< Nested function static chain
66 NoAlias = 9, ///< Considered to not alias after call
67 NoCapture = 10, ///< Function creates no aliases of pointer
68 NoImplicitFloat = 11, ///< Disable implicit floating point insts
69 NoInline = 12, ///< inline=never
70 NonLazyBind = 13, ///< Function is called early and/or
71 ///< often, so lazy binding isn't worthwhile
72 NoRedZone = 14, ///< Disable redzone
73 NoReturn = 15, ///< Mark the function as not returning
74 NoUnwind = 16, ///< Function doesn't unwind stack
75 OptimizeForSize = 17, ///< opt_size
76 ReadNone = 18, ///< Function does not access memory
77 ReadOnly = 19, ///< Function only reads from memory
78 ReturnsTwice = 20, ///< Function can return twice
79 SExt = 21, ///< Sign extended before/after call
80 StackAlignment = 22, ///< Alignment of stack for function (3 bits)
81 ///< stored as log2 of alignment with +1 bias 0
82 ///< means unaligned (different from
84 StackProtect = 23, ///< Stack protection.
85 StackProtectReq = 24, ///< Stack protection required.
86 StructRet = 25, ///< Hidden pointer to structure to return
87 UWTable = 26, ///< Function must be in a unwind table
88 ZExt = 27 ///< Zero extended before/after call
91 AttributesImpl *Attrs;
93 explicit Attributes(AttributesImpl *A);
95 Attributes() : Attrs(0) {}
96 explicit Attributes(LLVMContext &C, ArrayRef<AttrVal> Vals);
97 Attributes(const Attributes &A);
98 Attributes &operator=(const Attributes &A) {
104 friend class Attributes;
107 Builder() : Bits(0) {}
108 explicit Builder(uint64_t B) : Bits(B) {}
109 Builder(const Attributes &A) : Bits(A.Raw()) {}
110 Builder(const Builder &B) : Bits(B.Bits) {}
112 void clear() { Bits = 0; }
114 bool hasAttribute(Attributes::AttrVal A) const;
115 bool hasAttributes() const;
116 bool hasAttributes(const Attributes &A) const;
117 bool hasAlignmentAttr() const;
119 uint64_t getAlignment() const;
120 uint64_t getStackAlignment() const;
122 Builder &addAttribute(Attributes::AttrVal Val);
123 Builder &removeAttribute(Attributes::AttrVal Val);
125 /// addRawValue - Add the raw value to the internal representation. This
126 /// should be used ONLY for decoding bitcode!
127 Builder &addRawValue(uint64_t Val);
129 /// addAlignmentAttr - This turns an int alignment (which must be a power of
130 /// 2) into the form used internally in Attributes.
131 Builder &addAlignmentAttr(unsigned Align);
133 /// addStackAlignmentAttr - This turns an int stack alignment (which must be
134 /// a power of 2) into the form used internally in Attributes.
135 Builder &addStackAlignmentAttr(unsigned Align);
137 Builder &addAttributes(const Attributes &A);
138 Builder &removeAttributes(const Attributes &A);
140 /// @brief Remove attributes that are used on functions only.
141 void removeFunctionOnlyAttrs() {
142 removeAttribute(Attributes::NoReturn)
143 .removeAttribute(Attributes::NoUnwind)
144 .removeAttribute(Attributes::ReadNone)
145 .removeAttribute(Attributes::ReadOnly)
146 .removeAttribute(Attributes::NoInline)
147 .removeAttribute(Attributes::AlwaysInline)
148 .removeAttribute(Attributes::OptimizeForSize)
149 .removeAttribute(Attributes::StackProtect)
150 .removeAttribute(Attributes::StackProtectReq)
151 .removeAttribute(Attributes::NoRedZone)
152 .removeAttribute(Attributes::NoImplicitFloat)
153 .removeAttribute(Attributes::Naked)
154 .removeAttribute(Attributes::InlineHint)
155 .removeAttribute(Attributes::StackAlignment)
156 .removeAttribute(Attributes::UWTable)
157 .removeAttribute(Attributes::NonLazyBind)
158 .removeAttribute(Attributes::ReturnsTwice)
159 .removeAttribute(Attributes::AddressSafety);
162 bool operator==(const Builder &B) {
163 return Bits == B.Bits;
165 bool operator!=(const Builder &B) {
166 return Bits != B.Bits;
170 /// get - Return a uniquified Attributes object. This takes the uniquified
171 /// value from the Builder and wraps it in the Attributes class.
172 static Attributes get(LLVMContext &Context, Builder &B);
174 /// @brief Return true if the attribute is present.
175 bool hasAttribute(AttrVal Val) const;
177 /// @brief Return true if attributes exist
178 bool hasAttributes() const;
180 /// @brief Return true if the attributes are a non-null intersection.
181 bool hasAttributes(const Attributes &A) const;
183 /// @brief Returns the alignment field of an attribute as a byte alignment
185 unsigned getAlignment() const;
187 /// @brief Returns the stack alignment field of an attribute as a byte
189 unsigned getStackAlignment() const;
191 /// @brief Parameter attributes that do not apply to vararg call arguments.
192 bool hasIncompatibleWithVarArgsAttrs() const {
193 return hasAttribute(Attributes::StructRet);
196 /// @brief Attributes that only apply to function parameters.
197 bool hasParameterOnlyAttrs() const {
198 return hasAttribute(Attributes::ByVal) ||
199 hasAttribute(Attributes::Nest) ||
200 hasAttribute(Attributes::StructRet) ||
201 hasAttribute(Attributes::NoCapture);
204 /// @brief Attributes that may be applied to the function itself. These cannot
205 /// be used on return values or function parameters.
206 bool hasFunctionOnlyAttrs() const {
207 return hasAttribute(Attributes::NoReturn) ||
208 hasAttribute(Attributes::NoUnwind) ||
209 hasAttribute(Attributes::ReadNone) ||
210 hasAttribute(Attributes::ReadOnly) ||
211 hasAttribute(Attributes::NoInline) ||
212 hasAttribute(Attributes::AlwaysInline) ||
213 hasAttribute(Attributes::OptimizeForSize) ||
214 hasAttribute(Attributes::StackProtect) ||
215 hasAttribute(Attributes::StackProtectReq) ||
216 hasAttribute(Attributes::NoRedZone) ||
217 hasAttribute(Attributes::NoImplicitFloat) ||
218 hasAttribute(Attributes::Naked) ||
219 hasAttribute(Attributes::InlineHint) ||
220 hasAttribute(Attributes::StackAlignment) ||
221 hasAttribute(Attributes::UWTable) ||
222 hasAttribute(Attributes::NonLazyBind) ||
223 hasAttribute(Attributes::ReturnsTwice) ||
224 hasAttribute(Attributes::AddressSafety);
227 bool operator == (const Attributes &A) const {
228 return Attrs == A.Attrs;
230 bool operator != (const Attributes &A) const {
231 return Attrs != A.Attrs;
234 uint64_t Raw() const;
236 /// @brief Which attributes cannot be applied to a type.
237 static Attributes typeIncompatible(Type *Ty);
239 /// encodeLLVMAttributesForBitcode - This returns an integer containing an
240 /// encoding of all the LLVM attributes found in the given attribute bitset.
241 /// Any change to this encoding is a breaking change to bitcode compatibility.
242 static uint64_t encodeLLVMAttributesForBitcode(Attributes Attrs) {
243 // FIXME: It doesn't make sense to store the alignment information as an
244 // expanded out value, we should store it as a log2 value. However, we
245 // can't just change that here without breaking bitcode compatibility. If
246 // this ever becomes a problem in practice, we should introduce new tag
247 // numbers in the bitcode file and have those tags use a more efficiently
248 // encoded alignment field.
250 // Store the alignment in the bitcode as a 16-bit raw value instead of a
251 // 5-bit log2 encoded value. Shift the bits above the alignment up by 11
253 uint64_t EncodedAttrs = Attrs.Raw() & 0xffff;
254 if (Attrs.hasAttribute(Attributes::Alignment))
255 EncodedAttrs |= Attrs.getAlignment() << 16;
256 EncodedAttrs |= (Attrs.Raw() & (0xfffULL << 21)) << 11;
260 /// decodeLLVMAttributesForBitcode - This returns an attribute bitset
261 /// containing the LLVM attributes that have been decoded from the given
262 /// integer. This function must stay in sync with
263 /// 'encodeLLVMAttributesForBitcode'.
264 static Attributes decodeLLVMAttributesForBitcode(LLVMContext &C,
265 uint64_t EncodedAttrs) {
266 // The alignment is stored as a 16-bit raw value from bits 31--16. We shift
267 // the bits above 31 down by 11 bits.
268 unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
269 assert((!Alignment || isPowerOf2_32(Alignment)) &&
270 "Alignment must be a power of two.");
272 Attributes::Builder B(EncodedAttrs & 0xffff);
274 B.addAlignmentAttr(Alignment);
275 B.addRawValue((EncodedAttrs & (0xfffULL << 32)) >> 11);
276 return Attributes::get(C, B);
279 /// getAsString - The set of Attributes set in Attributes is converted to a
280 /// string of equivalent mnemonics. This is, presumably, for writing out the
281 /// mnemonics for the assembly writer.
282 /// @brief Convert attribute bits to text
283 std::string getAsString() const;
286 //===----------------------------------------------------------------------===//
287 // AttributeWithIndex
288 //===----------------------------------------------------------------------===//
290 /// AttributeWithIndex - This is just a pair of values to associate a set of
291 /// attributes with an index.
292 struct AttributeWithIndex {
293 Attributes 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<Attributes::AttrVal> Attrs) {
300 Attributes::Builder B;
302 for (ArrayRef<Attributes::AttrVal>::iterator I = Attrs.begin(),
303 E = Attrs.end(); I != E; ++I)
306 AttributeWithIndex P;
308 P.Attrs = Attributes::get(C, B);
311 static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
312 AttributeWithIndex P;
319 //===----------------------------------------------------------------------===//
320 // AttrListPtr Smart Pointer
321 //===----------------------------------------------------------------------===//
323 class AttributeListImpl;
325 /// AttrListPtr - This class manages the ref count for the opaque
326 /// AttributeListImpl object and provides accessors for it.
328 /// AttrList - The attributes that we are managing. This can be null
329 /// to represent the empty attributes list.
330 AttributeListImpl *AttrList;
332 AttrListPtr() : AttrList(0) {}
333 AttrListPtr(const AttrListPtr &P);
334 const AttrListPtr &operator=(const AttrListPtr &RHS);
337 //===--------------------------------------------------------------------===//
338 // Attribute List Construction and Mutation
339 //===--------------------------------------------------------------------===//
341 /// get - Return a Attributes list with the specified parameters in it.
342 static AttrListPtr get(ArrayRef<AttributeWithIndex> Attrs);
344 /// addAttr - Add the specified attribute at the specified index to this
345 /// attribute list. Since attribute lists are immutable, this
346 /// returns the new list.
347 AttrListPtr addAttr(LLVMContext &C, unsigned Idx, Attributes Attrs) const;
349 /// removeAttr - Remove the specified attribute at the specified index from
350 /// this attribute list. Since attribute lists are immutable, this
351 /// returns the new list.
352 AttrListPtr removeAttr(LLVMContext &C, unsigned Idx, Attributes Attrs) const;
354 //===--------------------------------------------------------------------===//
355 // Attribute List Accessors
356 //===--------------------------------------------------------------------===//
357 /// getParamAttributes - The attributes for the specified index are
359 Attributes getParamAttributes(unsigned Idx) const {
360 return getAttributes(Idx);
363 /// getRetAttributes - The attributes for the ret value are
365 Attributes getRetAttributes() const {
366 return getAttributes(0);
369 /// getFnAttributes - The function attributes are returned.
370 Attributes getFnAttributes() const {
371 return getAttributes(~0U);
374 /// paramHasAttr - Return true if the specified parameter index has the
375 /// specified attribute set.
376 bool paramHasAttr(unsigned Idx, Attributes Attr) const {
377 return getAttributes(Idx).hasAttributes(Attr);
380 /// getParamAlignment - Return the alignment for the specified function
382 unsigned getParamAlignment(unsigned Idx) const {
383 return getAttributes(Idx).getAlignment();
386 /// hasAttrSomewhere - Return true if the specified attribute is set for at
387 /// least one parameter or for the return value.
388 bool hasAttrSomewhere(Attributes::AttrVal Attr) const;
390 unsigned getNumAttrs() const;
391 Attributes &getAttributesAtIndex(unsigned i) const;
393 /// operator==/!= - Provide equality predicates.
394 bool operator==(const AttrListPtr &RHS) const
395 { return AttrList == RHS.AttrList; }
396 bool operator!=(const AttrListPtr &RHS) const
397 { return AttrList != RHS.AttrList; }
401 //===--------------------------------------------------------------------===//
402 // Attribute List Introspection
403 //===--------------------------------------------------------------------===//
405 /// getRawPointer - Return a raw pointer that uniquely identifies this
407 void *getRawPointer() const {
411 // Attributes are stored as a dense set of slots, where there is one
412 // slot for each argument that has an attribute. This allows walking over the
413 // dense set instead of walking the sparse list of attributes.
415 /// isEmpty - Return true if there are no attributes.
417 bool isEmpty() const {
418 return AttrList == 0;
421 /// getNumSlots - Return the number of slots used in this attribute list.
422 /// This is the number of arguments that have an attribute set on them
423 /// (including the function itself).
424 unsigned getNumSlots() const;
426 /// getSlot - Return the AttributeWithIndex at the specified slot. This
427 /// holds a index number plus a set of attributes.
428 const AttributeWithIndex &getSlot(unsigned Slot) const;
431 explicit AttrListPtr(AttributeListImpl *L);
433 /// getAttributes - The attributes for the specified index are
434 /// returned. Attributes for the result are denoted with Idx = 0.
435 Attributes getAttributes(unsigned Idx) const;
438 } // End llvm namespace