Start adding an integrated assembler.

src/assembler.cpp

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Modified by the Subzero authors.
+//
+//===- subzero/src/assembler.cpp - Assembler base class -------------------===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Assembler class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "assembler.h"
+#include "IceMemoryRegion.h"
+
+namespace Ice {
+
+static uintptr_t NewContents(Assembler &assembler, intptr_t capacity) {
+  uintptr_t result = assembler.AllocateBytes(capacity);
+  return result;
+}
+
+#if defined(DEBUG)
+AssemblerBuffer::EnsureCapacity::EnsureCapacity(AssemblerBuffer *buffer) {
+  if (buffer->cursor() >= buffer->limit())
+    buffer->ExtendCapacity();
+  // In debug mode, we save the assembler buffer along with the gap
+  // size before we start emitting to the buffer. This allows us to
+  // check that any single generated instruction doesn't overflow the
+  // limit implied by the minimum gap size.
+  buffer_ = buffer;
+  gap_ = ComputeGap();
+  // Make sure that extending the capacity leaves a big enough gap
+  // for any kind of instruction.
+  assert(gap_ >= kMinimumGap);
+  // Mark the buffer as having ensured the capacity.
+  assert(!buffer->HasEnsuredCapacity()); // Cannot nest.
+  buffer->has_ensured_capacity_ = true;
+}
+
+AssemblerBuffer::EnsureCapacity::~EnsureCapacity() {
+  // Unmark the buffer, so we cannot emit after this.
+  buffer_->has_ensured_capacity_ = false;
+  // Make sure the generated instruction doesn't take up more
+  // space than the minimum gap.
+  intptr_t delta = gap_ - ComputeGap();
+  assert(delta <= kMinimumGap);
+}
+#endif
+
+AssemblerBuffer::AssemblerBuffer(Assembler &assembler) : assembler_(assembler) {
+  const intptr_t OneKB = 1024;
+  static const intptr_t kInitialBufferCapacity = 4 * OneKB;
+  contents_ = NewContents(assembler_, kInitialBufferCapacity);
+  cursor_ = contents_;
+  limit_ = ComputeLimit(contents_, kInitialBufferCapacity);
+  fixup_ = NULL;
+#if defined(DEBUG)
+  has_ensured_capacity_ = false;
+  fixups_processed_ = false;
+#endif
+
+  // Verify internal state.
+  assert(Capacity() == kInitialBufferCapacity);
+  assert(Size() == 0);
+}
+
+AssemblerBuffer::~AssemblerBuffer() {}
+
+void AssemblerBuffer::ProcessFixups(const MemoryRegion &region) {
+  AssemblerFixup *fixup = fixup_;
+  while (fixup != NULL) {
+    fixup->Process(region, fixup->position());
+    fixup = fixup->previous();
+  }
+}
+
+void AssemblerBuffer::FinalizeInstructions(const MemoryRegion &instructions) {
+  // Copy the instructions from the buffer.
+  MemoryRegion from(reinterpret_cast<void *>(contents()), Size());
+  instructions.CopyFrom(0, from);
+
+  // Process fixups in the instructions.
+  ProcessFixups(instructions);
+#if defined(DEBUG)
+  fixups_processed_ = true;
+#endif
+}
+
+void AssemblerBuffer::ExtendCapacity() {
+  intptr_t old_size = Size();
+  intptr_t old_capacity = Capacity();
+  const intptr_t OneMB = 1 << 20;
+  intptr_t new_capacity = std::min(old_capacity * 2, old_capacity + OneMB);
+  if (new_capacity < old_capacity) {
+    // FATAL
+    llvm_unreachable("Unexpected overflow in AssemblerBuffer::ExtendCapacity");
+  }
+
+  // Allocate the new data area and copy contents of the old one to it.
+  uintptr_t new_contents = NewContents(assembler_, new_capacity);
+  memmove(reinterpret_cast<void *>(new_contents),
+          reinterpret_cast<void *>(contents_), old_size);
+
+  // Compute the relocation delta and switch to the new contents area.
+  intptr_t delta = new_contents - contents_;
+  contents_ = new_contents;
+
+  // Update the cursor and recompute the limit.
+  cursor_ += delta;
+  limit_ = ComputeLimit(new_contents, new_capacity);
+
+  // Verify internal state.
+  assert(Capacity() == new_capacity);
+  assert(Size() == old_size);
+}
+
+} // end of namespace Ice