llvm-project/llvm/lib/Support/SmallVector.cpp

//===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the SmallVector class.
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/SmallVector.h"
using namespace llvm;

// Check that no bytes are wasted and everything is well-aligned.
namespace {
struct Struct16B {
  alignas(16) void *X;
};
struct Struct32B {
  alignas(32) void *X;
};
}
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");

/// grow_pod - This is an implementation of the grow() method which only works
/// on POD-like datatypes and is out of line to reduce code duplication.
void SmallVectorBase::grow_pod(void *FirstEl, size_t MinCapacity,
                               size_t TSize) {
  // Ensure we can fit the new capacity in 32 bits.
  if (MinCapacity > UINT32_MAX)
    report_bad_alloc_error("SmallVector capacity overflow during allocation");

  size_t NewCapacity = 2 * capacity() + 1; // Always grow.
  NewCapacity =
      std::min(std::max(NewCapacity, MinCapacity), size_t(UINT32_MAX));

  void *NewElts;
  if (BeginX == FirstEl) {
    NewElts = safe_malloc(NewCapacity * TSize);

    // 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 = safe_realloc(this->BeginX, NewCapacity * TSize);
  }

  this->BeginX = NewElts;
  this->Capacity = NewCapacity;
}