LLVM  14.0.0git
SmallVector.cpp
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1 //===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the SmallVector class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/ADT/SmallVector.h"
14 #include <cstdint>
15 #ifdef LLVM_ENABLE_EXCEPTIONS
16 #include <stdexcept>
17 #endif
18 using namespace llvm;
19 
20 // Check that no bytes are wasted and everything is well-aligned.
21 namespace {
22 // These structures may cause binary compat warnings on AIX. Suppress the
23 // warning since we are only using these types for the static assertions below.
24 #if defined(_AIX)
25 #pragma GCC diagnostic push
26 #pragma GCC diagnostic ignored "-Waix-compat"
27 #endif
28 struct Struct16B {
29  alignas(16) void *X;
30 };
31 struct Struct32B {
32  alignas(32) void *X;
33 };
34 #if defined(_AIX)
35 #pragma GCC diagnostic pop
36 #endif
37 }
38 static_assert(sizeof(SmallVector<void *, 0>) ==
39  sizeof(unsigned) * 2 + sizeof(void *),
40  "wasted space in SmallVector size 0");
41 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
42  "wrong alignment for 16-byte aligned T");
43 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
44  "wrong alignment for 32-byte aligned T");
45 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
46  "missing padding for 16-byte aligned T");
47 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
48  "missing padding for 32-byte aligned T");
49 static_assert(sizeof(SmallVector<void *, 1>) ==
50  sizeof(unsigned) * 2 + sizeof(void *) * 2,
51  "wasted space in SmallVector size 1");
52 
53 static_assert(sizeof(SmallVector<char, 0>) ==
54  sizeof(void *) * 2 + sizeof(void *),
55  "1 byte elements have word-sized type for size and capacity");
56 
57 /// Report that MinSize doesn't fit into this vector's size type. Throws
58 /// std::length_error or calls report_fatal_error.
59 [[noreturn]] static void report_size_overflow(size_t MinSize, size_t MaxSize);
60 static void report_size_overflow(size_t MinSize, size_t MaxSize) {
61  std::string Reason = "SmallVector unable to grow. Requested capacity (" +
62  std::to_string(MinSize) +
63  ") is larger than maximum value for size type (" +
64  std::to_string(MaxSize) + ")";
65 #ifdef LLVM_ENABLE_EXCEPTIONS
66  throw std::length_error(Reason);
67 #else
68  report_fatal_error(Reason);
69 #endif
70 }
71 
72 /// Report that this vector is already at maximum capacity. Throws
73 /// std::length_error or calls report_fatal_error.
74 [[noreturn]] static void report_at_maximum_capacity(size_t MaxSize);
75 static void report_at_maximum_capacity(size_t MaxSize) {
76  std::string Reason =
77  "SmallVector capacity unable to grow. Already at maximum size " +
78  std::to_string(MaxSize);
79 #ifdef LLVM_ENABLE_EXCEPTIONS
80  throw std::length_error(Reason);
81 #else
82  report_fatal_error(Reason);
83 #endif
84 }
85 
86 // Note: Moving this function into the header may cause performance regression.
87 template <class Size_T>
88 static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
89  constexpr size_t MaxSize = std::numeric_limits<Size_T>::max();
90 
91  // Ensure we can fit the new capacity.
92  // This is only going to be applicable when the capacity is 32 bit.
93  if (MinSize > MaxSize)
94  report_size_overflow(MinSize, MaxSize);
95 
96  // Ensure we can meet the guarantee of space for at least one more element.
97  // The above check alone will not catch the case where grow is called with a
98  // default MinSize of 0, but the current capacity cannot be increased.
99  // This is only going to be applicable when the capacity is 32 bit.
100  if (OldCapacity == MaxSize)
102 
103  // In theory 2*capacity can overflow if the capacity is 64 bit, but the
104  // original capacity would never be large enough for this to be a problem.
105  size_t NewCapacity = 2 * OldCapacity + 1; // Always grow.
106  return std::min(std::max(NewCapacity, MinSize), MaxSize);
107 }
108 
109 // Note: Moving this function into the header may cause performance regression.
110 template <class Size_T>
111 void *SmallVectorBase<Size_T>::mallocForGrow(size_t MinSize, size_t TSize,
112  size_t &NewCapacity) {
113  NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
114  return llvm::safe_malloc(NewCapacity * TSize);
115 }
116 
117 // Note: Moving this function into the header may cause performance regression.
118 template <class Size_T>
119 void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize,
120  size_t TSize) {
121  size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
122  void *NewElts;
123  if (BeginX == FirstEl) {
124  NewElts = safe_malloc(NewCapacity * TSize);
125 
126  // Copy the elements over. No need to run dtors on PODs.
127  memcpy(NewElts, this->BeginX, size() * TSize);
128  } else {
129  // If this wasn't grown from the inline copy, grow the allocated space.
130  NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
131  }
132 
133  this->BeginX = NewElts;
134  this->Capacity = NewCapacity;
135 }
136 
137 template class llvm::SmallVectorBase<uint32_t>;
138 
139 // Disable the uint64_t instantiation for 32-bit builds.
140 // Both uint32_t and uint64_t instantiations are needed for 64-bit builds.
141 // This instantiation will never be used in 32-bit builds, and will cause
142 // warnings when sizeof(Size_T) > sizeof(size_t).
143 #if SIZE_MAX > UINT32_MAX
144 template class llvm::SmallVectorBase<uint64_t>;
145 
146 // Assertions to ensure this #if stays in sync with SmallVectorSizeType.
147 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
148  "Expected SmallVectorBase<uint64_t> variant to be in use.");
149 #else
150 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
151  "Expected SmallVectorBase<uint32_t> variant to be in use.");
152 #endif
llvm
---------------------— PointerInfo ------------------------------------—
Definition: AllocatorList.h:23
llvm::SmallVector
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1168
llvm::SmallVectorBase::grow_pod
void grow_pod(void *FirstEl, size_t MinSize, size_t TSize)
This is an implementation of the grow() method which only works on POD-like data types and is out of ...
Definition: SmallVector.cpp:119
report_at_maximum_capacity
static void report_at_maximum_capacity(size_t MaxSize)
Report that this vector is already at maximum capacity.
Definition: SmallVector.cpp:75
llvm::report_fatal_error
void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:140
report_size_overflow
static void report_size_overflow(size_t MinSize, size_t MaxSize)
Report that MinSize doesn't fit into this vector's size type.
Definition: SmallVector.cpp:60
X
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
llvm::SmallVectorSizeType
typename std::conditional< sizeof(T)< 4 &&sizeof(void *) >=8, uint64_t, uint32_t >::type SmallVectorSizeType
Definition: SmallVector.h:93
uint64_t
memcpy
<%struct.s * > cast struct s *S to sbyte *< sbyte * > sbyte uint cast struct s *agg result to sbyte *< sbyte * > sbyte uint cast struct s *memtmp to sbyte *< sbyte * > sbyte uint ret void llc ends up issuing two memcpy or custom lower memcpy(of small size) to be ldmia/stmia. I think option 2 is better but the current register allocator cannot allocate a chunk of registers at a time. A feasible temporary solution is to use specific physical registers at the lowering time for small(<
llvm::size
auto size(R &&Range, std::enable_if_t< std::is_base_of< std::random_access_iterator_tag, typename std::iterator_traits< decltype(Range.begin())>::iterator_category >::value, void > *=nullptr)
Get the size of a range.
Definition: STLExtras.h:1532
llvm::min
Expected< ExpressionValue > min(const ExpressionValue &Lhs, const ExpressionValue &Rhs)
Definition: FileCheck.cpp:357
uint32_t
getNewCapacity
static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity)
Definition: SmallVector.cpp:88
llvm::safe_realloc
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_realloc(void *Ptr, size_t Sz)
Definition: MemAlloc.h:52
SmallVector.h
llvm::to_string
std::string to_string(const T &Value)
Definition: ScopedPrinter.h:63
llvm::max
Align max(MaybeAlign Lhs, Align Rhs)
Definition: Alignment.h:340
llvm::SmallVectorBase
This is all the stuff common to all SmallVectors.
Definition: SmallVector.h:45
llvm::SmallVectorBase::mallocForGrow
void * mallocForGrow(size_t MinSize, size_t TSize, size_t &NewCapacity)
This is a helper for grow() that's out of line to reduce code duplication.
Definition: SmallVector.cpp:111
llvm::safe_malloc
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_malloc(size_t Sz)
Definition: MemAlloc.h:25