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 "llvm/ADT/Twine.h"
15 #include <cstdint>
16 #ifdef LLVM_ENABLE_EXCEPTIONS
17 #include <stdexcept>
18 #endif
19 using namespace llvm;
20 
21 // Check that no bytes are wasted and everything is well-aligned.
22 namespace {
23 // These structures may cause binary compat warnings on AIX. Suppress the
24 // warning since we are only using these types for the static assertions below.
25 #if defined(_AIX)
26 #pragma GCC diagnostic push
27 #pragma GCC diagnostic ignored "-Waix-compat"
28 #endif
29 struct Struct16B {
30  alignas(16) void *X;
31 };
32 struct Struct32B {
33  alignas(32) void *X;
34 };
35 #if defined(_AIX)
36 #pragma GCC diagnostic pop
37 #endif
38 }
39 static_assert(sizeof(SmallVector<void *, 0>) ==
40  sizeof(unsigned) * 2 + sizeof(void *),
41  "wasted space in SmallVector size 0");
42 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
43  "wrong alignment for 16-byte aligned T");
44 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
45  "wrong alignment for 32-byte aligned T");
46 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
47  "missing padding for 16-byte aligned T");
48 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
49  "missing padding for 32-byte aligned T");
50 static_assert(sizeof(SmallVector<void *, 1>) ==
51  sizeof(unsigned) * 2 + sizeof(void *) * 2,
52  "wasted space in SmallVector size 1");
53 
54 static_assert(sizeof(SmallVector<char, 0>) ==
55  sizeof(void *) * 2 + sizeof(void *),
56  "1 byte elements have word-sized type for size and capacity");
57 
58 /// Report that MinSize doesn't fit into this vector's size type. Throws
59 /// std::length_error or calls report_fatal_error.
60 [[noreturn]] static void report_size_overflow(size_t MinSize, size_t MaxSize);
61 static void report_size_overflow(size_t MinSize, size_t MaxSize) {
62  std::string Reason = "SmallVector unable to grow. Requested capacity (" +
63  std::to_string(MinSize) +
64  ") is larger than maximum value for size type (" +
65  std::to_string(MaxSize) + ")";
66 #ifdef LLVM_ENABLE_EXCEPTIONS
67  throw std::length_error(Reason);
68 #else
69  report_fatal_error(Twine(Reason));
70 #endif
71 }
72 
73 /// Report that this vector is already at maximum capacity. Throws
74 /// std::length_error or calls report_fatal_error.
75 [[noreturn]] static void report_at_maximum_capacity(size_t MaxSize);
76 static void report_at_maximum_capacity(size_t MaxSize) {
77  std::string Reason =
78  "SmallVector capacity unable to grow. Already at maximum size " +
79  std::to_string(MaxSize);
80 #ifdef LLVM_ENABLE_EXCEPTIONS
81  throw std::length_error(Reason);
82 #else
83  report_fatal_error(Twine(Reason));
84 #endif
85 }
86 
87 // Note: Moving this function into the header may cause performance regression.
88 template <class Size_T>
89 static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
90  constexpr size_t MaxSize = std::numeric_limits<Size_T>::max();
91 
92  // Ensure we can fit the new capacity.
93  // This is only going to be applicable when the capacity is 32 bit.
94  if (MinSize > MaxSize)
95  report_size_overflow(MinSize, MaxSize);
96 
97  // Ensure we can meet the guarantee of space for at least one more element.
98  // The above check alone will not catch the case where grow is called with a
99  // default MinSize of 0, but the current capacity cannot be increased.
100  // This is only going to be applicable when the capacity is 32 bit.
101  if (OldCapacity == MaxSize)
103 
104  // In theory 2*capacity can overflow if the capacity is 64 bit, but the
105  // original capacity would never be large enough for this to be a problem.
106  size_t NewCapacity = 2 * OldCapacity + 1; // Always grow.
107  return std::min(std::max(NewCapacity, MinSize), MaxSize);
108 }
109 
110 // Note: Moving this function into the header may cause performance regression.
111 template <class Size_T>
112 void *SmallVectorBase<Size_T>::mallocForGrow(size_t MinSize, size_t TSize,
113  size_t &NewCapacity) {
114  NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
115  return llvm::safe_malloc(NewCapacity * TSize);
116 }
117 
118 // Note: Moving this function into the header may cause performance regression.
119 template <class Size_T>
120 void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize,
121  size_t TSize) {
122  size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
123  void *NewElts;
124  if (BeginX == FirstEl) {
125  NewElts = safe_malloc(NewCapacity * TSize);
126 
127  // Copy the elements over. No need to run dtors on PODs.
128  memcpy(NewElts, this->BeginX, size() * TSize);
129  } else {
130  // If this wasn't grown from the inline copy, grow the allocated space.
131  NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
132  }
133 
134  this->BeginX = NewElts;
135  this->Capacity = NewCapacity;
136 }
137 
138 template class llvm::SmallVectorBase<uint32_t>;
139 
140 // Disable the uint64_t instantiation for 32-bit builds.
141 // Both uint32_t and uint64_t instantiations are needed for 64-bit builds.
142 // This instantiation will never be used in 32-bit builds, and will cause
143 // warnings when sizeof(Size_T) > sizeof(size_t).
144 #if SIZE_MAX > UINT32_MAX
145 template class llvm::SmallVectorBase<uint64_t>;
146 
147 // Assertions to ensure this #if stays in sync with SmallVectorSizeType.
148 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
149  "Expected SmallVectorBase<uint64_t> variant to be in use.");
150 #else
151 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
152  "Expected SmallVectorBase<uint32_t> variant to be in use.");
153 #endif
llvm
This is an optimization pass for GlobalISel generic memory operations.
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:120
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:76
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
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:61
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:1562
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:89
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:112
llvm::safe_malloc
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_malloc(size_t Sz)
Definition: MemAlloc.h:25