First step in reducing the size of PC descriptors.

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 34 matching lines @@
     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 uword patch_addr = code.GetPcForDeoptId(Isolate::kNoDeoptId,
-                                                PcDescriptors::kEntryPatch);
+  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) {
-  const uword patch_addr = code.GetPcForDeoptId(Isolate::kNoDeoptId,
-                                                PcDescriptors::kEntryPatch);
+  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) {
-  const uword patch_addr = code.GetPcForDeoptId(Isolate::kNoDeoptId,
-                                                PcDescriptors::kEntryPatch);
+  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.GetPcForDeoptId(Isolate::kNoDeoptId,
-                                                PcDescriptors::kEntryPatch);
-  // kEntryPatch may not exist which means the function is not patchable.
+  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