src/vixl/code-buffer.cc

// Copyright 2014, ARM Limited
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
//
//   * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright notice,
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//     used to endorse or promote products derived from this software without
//     specific prior written permission.
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#include "vixl/code-buffer.h"
#include "vixl/utils.h"

namespace vixl {


CodeBuffer::CodeBuffer(size_t capacity) : managed_(true), capacity_(capacity) {
  VIXL_CHECK(capacity_ != 0);
  buffer_ = reinterpret_cast<byte*>(malloc(capacity_));
  VIXL_CHECK(buffer_ != NULL);
  // A64 instructions must be word aligned, we assert the default allocator
  // always returns word align memory.
  VIXL_ASSERT(IsWordAligned(buffer_));

  cursor_ = buffer_;
  dirty_ = false;
}


CodeBuffer::CodeBuffer(void* buffer, size_t capacity)
    : buffer_(reinterpret_cast<byte*>(buffer)),
      managed_(false),
      cursor_(reinterpret_cast<byte*>(buffer)),
      dirty_(false),
      capacity_(capacity) {
  VIXL_ASSERT(buffer_ != NULL);
}


CodeBuffer::~CodeBuffer() {
  VIXL_ASSERT(!IsDirty());
  if (managed_) {
    free(buffer_);
  }
}


void CodeBuffer::EmitString(const char* string) {
  VIXL_ASSERT(RemainingBytes() > strlen(string));
  char* dst = reinterpret_cast<char*>(cursor_);
  dirty_ = true;
  char* null_char = stpcpy(dst, string);
  cursor_ = reinterpret_cast<byte*>(null_char) + 1;
}


void CodeBuffer::Align() {
  byte* end = AlignUp(cursor_, 4);
  VIXL_ASSERT(end >= cursor_);
  const size_t padding_size = end - cursor_;
  VIXL_ASSERT(RemainingBytes() >= padding_size);
  VIXL_ASSERT(padding_size <= 4);
  const byte padding[] = { 0, 0, 0, 0};
  dirty_ = true;
  memcpy(cursor_, padding, padding_size);
  cursor_ = end;
}


void CodeBuffer::Reset() {
#ifdef VIXL_DEBUG
  if (managed_) {
    // TODO(all): Consider allowing for custom default values, e.g. HLT.
    memset(buffer_, 0, capacity_);
  }
#endif
  cursor_ = buffer_;
  SetClean();
}


void CodeBuffer::Grow(size_t new_capacity) {
  VIXL_ASSERT(managed_);
  VIXL_ASSERT(new_capacity > capacity_);
  size_t size = CursorOffset();
  buffer_ = static_cast<byte*>(realloc(buffer_, new_capacity));
  VIXL_CHECK(buffer_ != NULL);

  cursor_ = buffer_ + size;
  capacity_ = new_capacity;
}


}  // namespace vixl