Revert "VM: New calling convention for generated code."

runtime/vm/code_patcher.cc

 // 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.
 
 #include "vm/code_patcher.h"
 #include "vm/cpu.h"
 #include "vm/instructions.h"
 #include "vm/object.h"
 #include "vm/virtual_memory.h"
 
@@ skipping 17 matching lines @@
 WritableInstructionsScope::~WritableInstructionsScope() {
   if (FLAG_write_protect_code) {
     bool status = VirtualMemory::Protect(reinterpret_cast<void*>(address_),
                                          size_,
                                          VirtualMemory::kReadExecute);
     ASSERT(status);
   }
 }
 
 
+static void SwapCode(intptr_t num_bytes, char* code, char* buffer) {
+  uword code_address = reinterpret_cast<uword>(code);
+  for (intptr_t i = 0; i < num_bytes; i++) {
+    char tmp = *code;
+    *code = *buffer;
+    *buffer = tmp;
+    code++;
+    buffer++;
+  }
+  CPU::FlushICache(code_address, num_bytes);
+  // The buffer is not executed. No need to flush.
+}
+
+
 // The patch code buffer contains the jmp code which will be inserted at
 // entry point.
-void CodePatcher::PatchEntry(const Code& code, const Code& new_code) {
-  ASSERT(code.instructions() == code.active_instructions());
-  code.set_active_instructions(new_code.instructions());
+void CodePatcher::PatchEntry(const Code& code) {
+  ASSERT(!IsEntryPatched(code));
+  const uword patch_addr = code.GetEntryPatchPc();
+  ASSERT(patch_addr != 0);
+  JumpPattern jmp_entry(patch_addr, code);
+  ASSERT(!jmp_entry.IsValid());
+  const uword patch_buffer = code.GetPatchCodePc();
+  ASSERT(patch_buffer != 0);
+  JumpPattern jmp_patch(patch_buffer, code);
+  ASSERT(jmp_patch.IsValid());
+  const uword jump_target = jmp_patch.TargetAddress();
+  intptr_t length = jmp_patch.pattern_length_in_bytes();
+  {
+    WritableInstructionsScope writable_code(patch_addr, length);
+    WritableInstructionsScope writable_buffer(patch_buffer, length);
+    SwapCode(jmp_patch.pattern_length_in_bytes(),
+             reinterpret_cast<char*>(patch_addr),
+             reinterpret_cast<char*>(patch_buffer));
+    jmp_entry.SetTargetAddress(jump_target);
+  }
 }
 
 
 // The entry point is a jmp instruction, the patch code buffer contains
 // original code, the entry point contains the jump instruction.
 void CodePatcher::RestoreEntry(const Code& code) {
   if (!IsEntryPatched(code)) return;
-  ASSERT(code.instructions() != code.active_instructions());
-  code.set_active_instructions(code.instructions());
+  const uword patch_addr = code.GetEntryPatchPc();
+  ASSERT(patch_addr != 0);
+  JumpPattern jmp_entry(patch_addr, code);
+  ASSERT(jmp_entry.IsValid());
+  const uword jump_target = jmp_entry.TargetAddress();
+  const uword patch_buffer = code.GetPatchCodePc();
+  ASSERT(patch_buffer != 0);
+  // 'patch_buffer' contains original entry code.
+  JumpPattern jmp_patch(patch_buffer, code);
+  ASSERT(!jmp_patch.IsValid());
+  intptr_t length = jmp_patch.pattern_length_in_bytes();
+  {
+    WritableInstructionsScope writable_code(patch_addr, length);
+    WritableInstructionsScope writable_buffer(patch_buffer, length);
+    SwapCode(jmp_patch.pattern_length_in_bytes(),
+             reinterpret_cast<char*>(patch_addr),
+             reinterpret_cast<char*>(patch_buffer));
+    ASSERT(jmp_patch.IsValid());
+    jmp_patch.SetTargetAddress(jump_target);
+  }
 }
 
 
 bool CodePatcher::IsEntryPatched(const Code& code) {
-  return code.instructions() != code.active_instructions();
+  const uword patch_addr = code.GetEntryPatchPc();
+  if (patch_addr == 0) {
+    return false;
+  }
+  JumpPattern jmp_entry(patch_addr, code);
+  return jmp_entry.IsValid();
+}
+
+
+bool CodePatcher::CodeIsPatchable(const Code& code) {
+  const uword patch_addr = code.GetEntryPatchPc();
+  // Zero means means that the function is not patchable.
+  if (patch_addr == 0) {
+    return false;
+  }
+  JumpPattern jmp_entry(patch_addr, code);
+  if (code.Size() < (jmp_entry.pattern_length_in_bytes() * 2)) {
+    return false;
+  }
+  const uword limit = patch_addr + jmp_entry.pattern_length_in_bytes();
+  // Check no object stored between patch_addr .. limit.
+  for (intptr_t i = 0; i < code.pointer_offsets_length(); i++) {
+    const uword obj_start = code.GetPointerOffsetAt(i) + code.EntryPoint();
+    const uword obj_end  = obj_start + kWordSize;
+    if ((obj_start < limit) && (obj_end > patch_addr)) {
+      return false;
+    }
+  }
+  return true;
 }
 
 }  // namespace dart