lib/Support/SmallVector.cpp

   1 //===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the SmallVector class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/SmallVector.h"
  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 /// grow_pod - This is an implementation of the grow() method which only works
  42 /// on POD-like datatypes and is out of line to reduce code duplication.
  43 void SmallVectorBase::grow_pod(void *FirstEl, size_t MinCapacity,
  44                                size_t TSize) {
  45   // Ensure we can fit the new capacity in 32 bits.
  46   if (MinCapacity > UINT32_MAX)
  47     report_bad_alloc_error("SmallVector capacity overflow during allocation");
  48
  49   size_t NewCapacity = 2 * capacity() + 1; // Always grow.
  50   NewCapacity =
  51       std::min(std::max(NewCapacity, MinCapacity), size_t(UINT32_MAX));
  52
  53   void *NewElts;
  54   if (BeginX == FirstEl) {
  55     NewElts = safe_malloc(NewCapacity * TSize);
  56
  57     // Copy the elements over.  No need to run dtors on PODs.
  58     memcpy(NewElts, this->BeginX, size() * TSize);
  59   } else {
  60     // If this wasn't grown from the inline copy, grow the allocated space.
  61     NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
  62   }
  63
  64   this->BeginX = NewElts;
  65   this->Capacity = NewCapacity;
  66 }