Optimize function at its entry instead of at exit.

runtime/vm/code_patcher_ia32.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/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/assembler.h"
 #include "vm/code_patcher.h"
 #include "vm/cpu.h"
@@ skipping 142 matching lines @@
   call.set_target(new_target);
 }
 
 
 void CodePatcher::PatchInstanceCallAt(uword return_address, uword new_target) {
   InstanceCall call(return_address);
   call.set_target(new_target);
 }
 
 
-static void SwapCode(intptr_t num_bytes, char* a, char* b) {
-  for (intptr_t i = 0; i < num_bytes; i++) {
-    char tmp = *a;
-    *a = *b;
-    *b = tmp;
-    a++;
-    b++;
-  }
-}
 
-
-// The patch code buffer contains the jmp code which will be inserted at
-// entry point.
-void CodePatcher::PatchEntry(const Code& code) {
-  JumpPattern jmp_entry(code.EntryPoint());
-  ASSERT(!jmp_entry.IsValid());
-  const uword patch_buffer = code.GetPatchCodePc();
-  ASSERT(patch_buffer != 0);
-  JumpPattern jmp_patch(patch_buffer);
-  ASSERT(jmp_patch.IsValid());
-  const uword jump_target = jmp_patch.TargetAddress();
-  SwapCode(jmp_patch.pattern_length_in_bytes(),
-           reinterpret_cast<char*>(code.EntryPoint()),
-           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) {
-  JumpPattern jmp_entry(code.EntryPoint());
-  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);
-  ASSERT(!jmp_patch.IsValid());
-  SwapCode(jmp_patch.pattern_length_in_bytes(),
-           reinterpret_cast<char*>(code.EntryPoint()),
-           reinterpret_cast<char*>(patch_buffer));
-  ASSERT(jmp_patch.IsValid());
-  jmp_patch.SetTargetAddress(jump_target);
-}
-
-
-bool CodePatcher::CodeIsPatchable(const Code& code) {
-  JumpPattern jmp_entry(code.EntryPoint());
-  if (code.Size() < (jmp_entry.pattern_length_in_bytes() * 2)) {
-    return false;
-  }
-  uword limit = code.EntryPoint() + jmp_entry.pattern_length_in_bytes();
-  for (intptr_t i = 0; i < code.pointer_offsets_length(); i++) {
-    const uword addr = code.GetPointerOffsetAt(i) + code.EntryPoint();
-    if (addr < limit) {
-      return false;
-    }
-  }
-  return true;
+void CodePatcher::InsertCallAt(uword start, uword target) {
+  *reinterpret_cast<uint8_t*>(start) = 0xE8;
+  CallPattern call(start);
+  call.SetTargetAddress(target);
+  CPU::FlushICache(start, CallPattern::InstructionLength());
 }
 
 
 bool CodePatcher::IsDartCall(uword return_address) {
   return DartCallPattern::IsValid(return_address);
 }
 
 
 uword CodePatcher::GetInstanceCallAt(uword return_address,
                                      ICData* ic_data,
                                      Array* arguments_descriptor) {
   InstanceCall call(return_address);
   if (ic_data != NULL) {
     *ic_data ^= call.ic_data();
   }
   if (arguments_descriptor != NULL) {
     *arguments_descriptor ^= call.arguments_descriptor();
   }
   return call.target();
 }
 
 
 intptr_t CodePatcher::InstanceCallSizeInBytes() {
   return DartCallPattern::kNumInstructions * DartCallPattern::kInstructionSize;
 }
 
-
-void CodePatcher::InsertCallAt(uword start, uword target) {
-  *reinterpret_cast<uint8_t*>(start) = 0xE8;
-  CallPattern call(start);
-  call.SetTargetAddress(target);
-  CPU::FlushICache(start, CallPattern::InstructionLength());
-}
-
-
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32