LLVM  12.0.0git
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 using namespace llvm;
16 
17 // Check that no bytes are wasted and everything is well-aligned.
18 namespace {
19 struct Struct16B {
20  alignas(16) void *X;
21 };
22 struct Struct32B {
23  alignas(32) void *X;
24 };
25 }
26 static_assert(sizeof(SmallVector<void *, 0>) ==
27  sizeof(unsigned) * 2 + sizeof(void *),
28  "wasted space in SmallVector size 0");
29 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
30  "wrong alignment for 16-byte aligned T");
31 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
32  "wrong alignment for 32-byte aligned T");
33 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
34  "missing padding for 16-byte aligned T");
35 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
36  "missing padding for 32-byte aligned T");
37 static_assert(sizeof(SmallVector<void *, 1>) ==
38  sizeof(unsigned) * 2 + sizeof(void *) * 2,
39  "wasted space in SmallVector size 1");
40 
41 static_assert(sizeof(SmallVector<char, 0>) ==
42  sizeof(void *) * 2 + sizeof(void *),
43  "1 byte elements have word-sized type for size and capacity");
44 
45 // Note: Moving this function into the header may cause performance regression.
46 template <class Size_T>
47 void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinCapacity,
48  size_t TSize) {
49  // Ensure we can fit the new capacity.
50  // This is only going to be applicable when the capacity is 32 bit.
51  if (MinCapacity > SizeTypeMax())
52  report_bad_alloc_error("SmallVector capacity overflow during allocation");
53 
54  // Ensure we can meet the guarantee of space for at least one more element.
55  // The above check alone will not catch the case where grow is called with a
56  // default MinCapacity of 0, but the current capacity cannot be increased.
57  // This is only going to be applicable when the capacity is 32 bit.
58  if (capacity() == SizeTypeMax())
59  report_bad_alloc_error("SmallVector capacity unable to grow");
60 
61  // In theory 2*capacity can overflow if the capacity is 64 bit, but the
62  // original capacity would never be large enough for this to be a problem.
63  size_t NewCapacity = 2 * capacity() + 1; // Always grow.
64  NewCapacity = std::min(std::max(NewCapacity, MinCapacity), SizeTypeMax());
65 
66  void *NewElts;
67  if (BeginX == FirstEl) {
68  NewElts = safe_malloc(NewCapacity * TSize);
69 
70  // Copy the elements over. No need to run dtors on PODs.
71  memcpy(NewElts, this->BeginX, size() * TSize);
72  } else {
73  // If this wasn't grown from the inline copy, grow the allocated space.
74  NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
75  }
76 
77  this->BeginX = NewElts;
78  this->Capacity = NewCapacity;
79 }
80 
81 template class llvm::SmallVectorBase<uint32_t>;
82 
83 // Disable the uint64_t instantiation for 32-bit builds.
84 // Both uint32_t and uint64_t instantations are needed for 64-bit builds.
85 // This instantiation will never be used in 32-bit builds, and will cause
86 // warnings when sizeof(Size_T) > sizeof(size_t).
87 #if SIZE_MAX > UINT32_MAX
88 template class llvm::SmallVectorBase<uint64_t>;
89 
90 // Assertions to ensure this #if stays in sync with SmallVectorSizeType.
91 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
92  "Expected SmallVectorBase<uint64_t> variant to be in use.");
93 #else
94 static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
95  "Expected SmallVectorBase<uint32_t> variant to be in use.");
96 #endif
void grow_pod(void *FirstEl, size_t MinCapacity, 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:47
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
This class represents lattice values for constants.
Definition: AllocatorList.h:23
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_realloc(void *Ptr, size_t Sz)
Definition: MemAlloc.h:52
Expected< ExpressionValue > min(const ExpressionValue &Lhs, const ExpressionValue &Rhs)
Definition: FileCheck.cpp:305
LLVM_ATTRIBUTE_NORETURN void report_bad_alloc_error(const char *Reason, bool GenCrashDiag=true)
Reports a bad alloc error, calling any user defined bad alloc error handler.
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_malloc(size_t Sz)
Definition: MemAlloc.h:25
Align max(MaybeAlign Lhs, Align Rhs)
Definition: Alignment.h:350
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:883
auto size(R &&Range, std::enable_if_t< std::is_same< typename std::iterator_traits< decltype(Range.begin())>::iterator_category, std::random_access_iterator_tag >::value, void > *=nullptr)
Get the size of a range.
Definition: STLExtras.h:1473
This is all the stuff common to all SmallVectors.
Definition: SmallVector.h:46
typename std::conditional< sizeof(T)< 4 &&sizeof(void *) >=8, uint64_t, uint32_t >::type SmallVectorSizeType
Definition: SmallVector.h:89