Custom stack for IVM. 2-3x faster.

src/alloy/backend/ivm/ivm_stack.cc

@@ -0,0 +1,79 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include <alloy/backend/ivm/ivm_stack.h>
+
+using namespace alloy;
+using namespace alloy::backend;
+using namespace alloy::backend::ivm;
+
+
+IVMStack::IVMStack() :
+    chunk_size_(2 * 1024 * 1024),
+    head_chunk_(NULL), active_chunk_(NULL) {
+}
+
+IVMStack::~IVMStack() {
+  Chunk* chunk = head_chunk_;
+  while (chunk) {
+    Chunk* next = chunk->next;
+    delete chunk;
+    chunk = next;
+  }
+  head_chunk_ = NULL;
+}
+
+Register* IVMStack::Alloc(size_t register_count) {
+  size_t size = register_count * sizeof(Register);
+  if (active_chunk_) {
+    if (active_chunk_->capacity - active_chunk_->offset < size) {
+      Chunk* next = active_chunk_->next;
+      if (!next) {
+        XEASSERT(size < chunk_size_); // need to support larger chunks
+        next = new Chunk(chunk_size_);
+        next->prev = active_chunk_;
+        active_chunk_->next = next;
+      }
+      next->offset = 0;
+      active_chunk_ = next;
+    }
+  } else {
+    head_chunk_ = active_chunk_ = new Chunk(chunk_size_);
+  }
+
+  uint8_t* p = active_chunk_->buffer + active_chunk_->offset;
+  active_chunk_->offset += size;
+  return (Register*)p;
+}
+
+void IVMStack::Free(size_t register_count) {
+  size_t size = register_count * sizeof(Register);
+  if (active_chunk_->offset == size) {
+    // Moving back a chunk.
+    active_chunk_->offset = 0;
+    if (active_chunk_->prev) {
+      active_chunk_ = active_chunk_->prev;
+    }
+  } else {
+    // Still in same chunk.
+    active_chunk_->offset -= size;
+  }
+}
+
+IVMStack::Chunk::Chunk(size_t chunk_size) :
+    prev(NULL), next(NULL),
+    capacity(chunk_size), buffer(0), offset(0) {
+  buffer = (uint8_t*)xe_malloc(capacity);
+}
+
+IVMStack::Chunk::~Chunk() {
+  if (buffer) {
+    xe_free(buffer);
+  }
+}