First step in reducing the size of PC descriptors.

runtime/vm/flow_graph_compiler_arm.cc

 // Copyright (c) 2013, 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_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 955 matching lines @@
     // Preserve PP of caller.
     __ mov(R7, Operand(PP));
     // Temporarily setup pool pointer for this dart function.
     __ LoadPoolPointer();
     // Load function object from object pool.
     __ LoadObject(function_reg, function);  // Uses PP.
     // Restore PP of caller.
     __ mov(PP, Operand(R7));
 
     // Patch point is after the eventually inlined function object.
-    AddCurrentDescriptor(PcDescriptors::kEntryPatch,
-                         Isolate::kNoDeoptId,
-                         0);  // No token position.
+    entry_patch_pc_offset_ = assembler()->CodeSize();
+
     intptr_t threshold = FLAG_optimization_counter_threshold;
     __ ldr(R7, FieldAddress(function_reg,
                             Function::usage_counter_offset()));
     if (is_optimizing()) {
       // Reoptimization of an optimized function is triggered by counting in
       // IC stubs, but not at the entry of the function.
       threshold = FLAG_reoptimization_counter_threshold;
     } else {
       __ add(R7, R7, Operand(1));
       __ str(R7, FieldAddress(function_reg,
                               Function::usage_counter_offset()));
     }
     __ CompareImmediate(R7, threshold);
     ASSERT(function_reg == R6);
     __ Branch(&StubCode::OptimizeFunctionLabel(), GE);
   } else if (!flow_graph().IsCompiledForOsr()) {
-    AddCurrentDescriptor(PcDescriptors::kEntryPatch,
-                         Isolate::kNoDeoptId,
-                         0);  // No token position.
+    entry_patch_pc_offset_ = assembler()->CodeSize();
   }
   __ Comment("Enter frame");
   if (flow_graph().IsCompiledForOsr()) {
     intptr_t extra_slots = StackSize()
         - flow_graph().num_stack_locals()
         - flow_graph().num_copied_params();
     ASSERT(extra_slots >= 0);
     __ EnterOsrFrame(extra_slots * kWordSize);
   } else {
     ASSERT(StackSize() >= 0);
@@ skipping 82 matching lines @@
       __ str(R0, Address(FP, (slot_base - i) * kWordSize));
     }
   }
 
   VisitBlocks();
 
   __ bkpt(0);
   GenerateDeferredCode();
   // Emit function patching code. This will be swapped with the first 3
   // instructions at entry point.
-  AddCurrentDescriptor(PcDescriptors::kPatchCode,
-                       Isolate::kNoDeoptId,
-                       0);  // No token position.
+  patch_code_pc_offset_ = assembler()->CodeSize();
   __ BranchPatchable(&StubCode::FixCallersTargetLabel());
-  AddCurrentDescriptor(PcDescriptors::kLazyDeoptJump,
-                       Isolate::kNoDeoptId,
-                       0);  // No token position.
-  __ Branch(&StubCode::DeoptimizeLazyLabel());
+
+  if (is_optimizing()) {
+    lazy_deopt_pc_offset_ = assembler()->CodeSize();
+    __ Branch(&StubCode::DeoptimizeLazyLabel());
+  }
 }
 
 
 void FlowGraphCompiler::GenerateCall(intptr_t token_pos,
                                      const ExternalLabel* label,
                                      PcDescriptors::Kind kind,
                                      LocationSummary* locs) {
   __ BranchLinkPatchable(label);
   AddCurrentDescriptor(kind, Isolate::kNoDeoptId, token_pos);
   RecordSafepoint(locs);
@@ skipping 656 matching lines @@
   DRegister dreg = EvenDRegisterOf(reg);
   __ vldrd(dreg, Address(SP, kDoubleSize, Address::PostIndex));
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM