LLVM  15.0.0git
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 "llvm/ADT/Twine.h"
15 #include "llvm/Support/MemAlloc.h"
16 #include <cstdint>
17 #ifdef LLVM_ENABLE_EXCEPTIONS
18 #include <stdexcept>
19 #endif
20 using namespace llvm;
21 
22 // Check that no bytes are wasted and everything is well-aligned.
23 namespace {
24 // These structures may cause binary compat warnings on AIX. Suppress the
25 // warning since we are only using these types for the static assertions below.
26 #if defined(_AIX)
27 #pragma GCC diagnostic push
28 #pragma GCC diagnostic ignored "-Waix-compat"
29 #endif
30 struct Struct16B {
31  alignas(16) void *X;
32 };
33 struct Struct32B {
34  alignas(32) void *X;
35 };
36 #if defined(_AIX)
37 #pragma GCC diagnostic pop
38 #endif
39 }
40 static_assert(sizeof(SmallVector<void *, 0>) ==
41  sizeof(unsigned) * 2 + sizeof(void *),
42  "wasted space in SmallVector size 0");
43 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
44  "wrong alignment for 16-byte aligned T");
45 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
46  "wrong alignment for 32-byte aligned T");
47 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
48  "missing padding for 16-byte aligned T");
49 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
50  "missing padding for 32-byte aligned T");
51 static_assert(sizeof(SmallVector<void *, 1>) ==
52  sizeof(unsigned) * 2 + sizeof(void *) * 2,
53  "wasted space in SmallVector size 1");
54 
55 static_assert(sizeof(SmallVector<char, 0>) ==
56  sizeof(void *) * 2 + sizeof(void *),
57  "1 byte elements have word-sized type for size and capacity");
58 
59 /// Report that MinSize doesn't fit into this vector's size type. Throws
60 /// std::length_error or calls report_fatal_error.
61 [[noreturn]] static void report_size_overflow(size_t MinSize, size_t MaxSize);
62 static void report_size_overflow(size_t MinSize, size_t MaxSize) {
63  std::string Reason = "SmallVector unable to grow. Requested capacity (" +
64  std::to_string(MinSize) +
65  ") is larger than maximum value for size type (" +
66  std::to_string(MaxSize) + ")";
67 #ifdef LLVM_ENABLE_EXCEPTIONS
68  throw std::length_error(Reason);
69 #else
70  report_fatal_error(Twine(Reason));
71 #endif
72 }
73 
74 /// Report that this vector is already at maximum capacity. Throws
75 /// std::length_error or calls report_fatal_error.
76 [[noreturn]] static void report_at_maximum_capacity(size_t MaxSize);
77 static void report_at_maximum_capacity(size_t MaxSize) {
78  std::string Reason =
79  "SmallVector capacity unable to grow. Already at maximum size " +
80  std::to_string(MaxSize);
81 #ifdef LLVM_ENABLE_EXCEPTIONS
82  throw std::length_error(Reason);
83 #else
84  report_fatal_error(Twine(Reason));
85 #endif
86 }
87 
88 // Note: Moving this function into the header may cause performance regression.
89 template <class Size_T>
90 static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
91  constexpr size_t MaxSize = std::numeric_limits<Size_T>::max();
92 
93  // Ensure we can fit the new capacity.
94  // This is only going to be applicable when the capacity is 32 bit.
95  if (MinSize > MaxSize)
96  report_size_overflow(MinSize, MaxSize);
97 
98  // Ensure we can meet the guarantee of space for at least one more element.
99  // The above check alone will not catch the case where grow is called with a
100  // default MinSize of 0, but the current capacity cannot be increased.
101  // This is only going to be applicable when the capacity is 32 bit.
102  if (OldCapacity == MaxSize)
104 
105  // In theory 2*capacity can overflow if the capacity is 64 bit, but the
106  // original capacity would never be large enough for this to be a problem.
107  size_t NewCapacity = 2 * OldCapacity + 1; // Always grow.
108  return std::min(std::max(NewCapacity, MinSize), MaxSize);
109 }
110 
111 // Note: Moving this function into the header may cause performance regression.
112 template <class Size_T>
113 void *SmallVectorBase<Size_T>::mallocForGrow(size_t MinSize, size_t TSize,
114  size_t &NewCapacity) {
115  NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
116  return llvm::safe_malloc(NewCapacity * TSize);
117 }
118 
119 // Note: Moving this function into the header may cause performance regression.
120 template <class Size_T>
121 void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize,
122  size_t TSize) {
123  size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
124  void *NewElts;
125  if (BeginX == FirstEl) {
126  NewElts = safe_malloc(NewCapacity * TSize);
127 
128  // Copy the elements over. No need to run dtors on PODs.
129  memcpy(NewElts, this->BeginX, size() * TSize);
130  } else {
131  // If this wasn't grown from the inline copy, grow the allocated space.
132  NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
133  }
134 
135  this->BeginX = NewElts;
136  this->Capacity = NewCapacity;
137 }
138 
139 template class llvm::SmallVectorBase<uint32_t>;
140 
141 // Disable the uint64_t instantiation for 32-bit builds.
142 // Both uint32_t and uint64_t instantiations are needed for 64-bit builds.
143 // This instantiation will never be used in 32-bit builds, and will cause
144 // warnings when sizeof(Size_T) > sizeof(size_t).
145 #if SIZE_MAX > UINT32_MAX
146 template class llvm::SmallVectorBase<uint64_t>;
147 
148 // Assertions to ensure this #if stays in sync with SmallVectorSizeType.
149 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
150  "Expected SmallVectorBase<uint64_t> variant to be in use.");
151 #else
152 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
153  "Expected SmallVectorBase<uint32_t> variant to be in use.");
154 #endif
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:17
llvm::SmallVector
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1185
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:121
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:77
Twine.h
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:143
MemAlloc.h
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:62
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:89
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:1588
llvm::min
Expected< ExpressionValue > min(const ExpressionValue &Lhs, const ExpressionValue &Rhs)
Definition: FileCheck.cpp:357
uint32_t
llvm::Twine
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:83
getNewCapacity
static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity)
Definition: SmallVector.cpp:90
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:86
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:113
llvm::safe_malloc
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_malloc(size_t Sz)
Definition: MemAlloc.h:25