lib/Support/SmallVector.cpp

   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 using namespace llvm;
  15
  16 // Check that no bytes are wasted and everything is well-aligned.
  17 namespace {
  18 struct Struct16B {
  19   alignas(16) void *X;
  20 };
  21 struct Struct32B {
  22   alignas(32) void *X;
  23 };
  24 }
  25 static_assert(sizeof(SmallVector<void *, 0>) ==
  26                   sizeof(unsigned) * 2 + sizeof(void *),
  27               "wasted space in SmallVector size 0");
  28 static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
  29               "wrong alignment for 16-byte aligned T");
  30 static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
  31               "wrong alignment for 32-byte aligned T");
  32 static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
  33               "missing padding for 16-byte aligned T");
  34 static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
  35               "missing padding for 32-byte aligned T");
  36 static_assert(sizeof(SmallVector<void *, 1>) ==
  37                   sizeof(unsigned) * 2 + sizeof(void *) * 2,
  38               "wasted space in SmallVector size 1");
  39
  40 /// grow_pod - This is an implementation of the grow() method which only works
  41 /// on POD-like datatypes and is out of line to reduce code duplication.
  42 void SmallVectorBase::grow_pod(void *FirstEl, size_t MinCapacity,
  43                                size_t TSize) {
  44   // Ensure we can fit the new capacity in 32 bits.
  45   if (MinCapacity > UINT32_MAX)
  46     report_bad_alloc_error("SmallVector capacity overflow during allocation");
  47
  48   size_t NewCapacity = 2 * capacity() + 1; // Always grow.
  49   NewCapacity =
  50       std::min(std::max(NewCapacity, MinCapacity), size_t(UINT32_MAX));
  51
  52   void *NewElts;
  53   if (BeginX == FirstEl) {
  54     NewElts = safe_malloc(NewCapacity * TSize);
  55
  56     // Copy the elements over.  No need to run dtors on PODs.
  57     memcpy(NewElts, this->BeginX, size() * TSize);
  58   } else {
  59     // If this wasn't grown from the inline copy, grow the allocated space.
  60     NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
  61   }
  62
  63   this->BeginX = NewElts;
  64   this->Capacity = NewCapacity;
  65 }