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//===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the SmallVector class.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/MemAlloc.h"
#include <cstdint>
#ifdef LLVM_ENABLE_EXCEPTIONS
#include <stdexcept>
#endif
using namespace llvm;
// Check that no bytes are wasted and everything is well-aligned.
namespace {
// These structures may cause binary compat warnings on AIX. Suppress the
// warning since we are only using these types for the static assertions below.
#if defined(_AIX)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Waix-compat"
#endif
struct Struct16B {
alignas(16) void *X;
};
struct Struct32B {
alignas(32) void *X;
};
#if defined(_AIX)
#pragma GCC diagnostic pop
#endif
}
static_assert(sizeof(SmallVector<void *, 0>) ==
sizeof(unsigned) * 2 + sizeof(void *),
"wasted space in SmallVector size 0");
static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
"wrong alignment for 16-byte aligned T");
static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
"wrong alignment for 32-byte aligned T");
static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
"missing padding for 16-byte aligned T");
static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
"missing padding for 32-byte aligned T");
static_assert(sizeof(SmallVector<void *, 1>) ==
sizeof(unsigned) * 2 + sizeof(void *) * 2,
"wasted space in SmallVector size 1");
static_assert(sizeof(SmallVector<char, 0>) ==
sizeof(void *) * 2 + sizeof(void *),
"1 byte elements have word-sized type for size and capacity");
/// Report that MinSize doesn't fit into this vector's size type. Throws
/// std::length_error or calls report_fatal_error.
[[noreturn]] static void report_size_overflow(size_t MinSize, size_t MaxSize);
static void report_size_overflow(size_t MinSize, size_t MaxSize) {
std::string Reason = "SmallVector unable to grow. Requested capacity (" +
std::to_string(MinSize) +
") is larger than maximum value for size type (" +
std::to_string(MaxSize) + ")";
#ifdef LLVM_ENABLE_EXCEPTIONS
throw std::length_error(Reason);
#else
report_fatal_error(Twine(Reason));
#endif
}
/// Report that this vector is already at maximum capacity. Throws
/// std::length_error or calls report_fatal_error.
[[noreturn]] static void report_at_maximum_capacity(size_t MaxSize);
static void report_at_maximum_capacity(size_t MaxSize) {
std::string Reason =
"SmallVector capacity unable to grow. Already at maximum size " +
std::to_string(MaxSize);
#ifdef LLVM_ENABLE_EXCEPTIONS
throw std::length_error(Reason);
#else
report_fatal_error(Twine(Reason));
#endif
}
// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
constexpr size_t MaxSize = std::numeric_limits<Size_T>::max();
// Ensure we can fit the new capacity.
// This is only going to be applicable when the capacity is 32 bit.
if (MinSize > MaxSize)
report_size_overflow(MinSize, MaxSize);
// Ensure we can meet the guarantee of space for at least one more element.
// The above check alone will not catch the case where grow is called with a
// default MinSize of 0, but the current capacity cannot be increased.
// This is only going to be applicable when the capacity is 32 bit.
if (OldCapacity == MaxSize)
report_at_maximum_capacity(MaxSize);
// In theory 2*capacity can overflow if the capacity is 64 bit, but the
// original capacity would never be large enough for this to be a problem.
size_t NewCapacity = 2 * OldCapacity + 1; // Always grow.
return std::clamp(NewCapacity, MinSize, MaxSize);
}
template <class Size_T>
void *SmallVectorBase<Size_T>::replaceAllocation(void *NewElts, size_t TSize,
size_t NewCapacity,
size_t VSize) {
void *NewEltsReplace = llvm::safe_malloc(NewCapacity * TSize);
if (VSize)
memcpy(NewEltsReplace, NewElts, VSize * TSize);
free(NewElts);
return NewEltsReplace;
}
// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
void *SmallVectorBase<Size_T>::mallocForGrow(void *FirstEl, size_t MinSize,
size_t TSize,
size_t &NewCapacity) {
NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
// Even if capacity is not 0 now, if the vector was originally created with
// capacity 0, it's possible for the malloc to return FirstEl.
void *NewElts = llvm::safe_malloc(NewCapacity * TSize);
if (NewElts == FirstEl)
NewElts = replaceAllocation(NewElts, TSize, NewCapacity);
return NewElts;
}
// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize,
size_t TSize) {
size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
void *NewElts;
if (BeginX == FirstEl) {
NewElts = llvm::safe_malloc(NewCapacity * TSize);
if (NewElts == FirstEl)
NewElts = replaceAllocation(NewElts, TSize, NewCapacity);
// Copy the elements over. No need to run dtors on PODs.
memcpy(NewElts, this->BeginX, size() * TSize);
} else {
// If this wasn't grown from the inline copy, grow the allocated space.
NewElts = llvm::safe_realloc(this->BeginX, NewCapacity * TSize);
if (NewElts == FirstEl)
NewElts = replaceAllocation(NewElts, TSize, NewCapacity, size());
}
this->BeginX = NewElts;
this->Capacity = NewCapacity;
}
template class llvm::SmallVectorBase<uint32_t>;
// Disable the uint64_t instantiation for 32-bit builds.
// Both uint32_t and uint64_t instantiations are needed for 64-bit builds.
// This instantiation will never be used in 32-bit builds, and will cause
// warnings when sizeof(Size_T) > sizeof(size_t).
#if SIZE_MAX > UINT32_MAX
template class llvm::SmallVectorBase<uint64_t>;
// Assertions to ensure this #if stays in sync with SmallVectorSizeType.
static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
"Expected SmallVectorBase<uint64_t> variant to be in use.");
#else
static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
"Expected SmallVectorBase<uint32_t> variant to be in use.");
#endif
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