Implement a variation of scalar replacement for non-escaping allocations.

runtime/vm/stub_code_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"
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 376 matching lines @@
   __ LeaveStubFrame();
   __ mov(FP, ShifterOperand(R0));
 
   // Frame is fully rewritten at this point and it is safe to perform a GC.
   // Materialize any objects that were deferred by FillFrame because they
   // require allocation.
   __ EnterStubFrame();
   if (preserve_result) {
     __ Push(R1);  // Preserve result, it will be GC-d here.
   }
-  __ CallRuntime(kDeoptimizeMaterializeDoublesRuntimeEntry);
+  __ PushObject(Smi::ZoneHandle());  // Space for the result.
+  __ CallRuntime(kDeoptimizeMaterializeRuntimeEntry);
+  // Result tells stub how many bytes to remove from the expression stack
+  // of the bottom-most frame. They were used as materialization arguments.
+  __ Pop(R1);
   if (preserve_result) {
     __ Pop(R0);  // Restore result.
   }
   __ LeaveStubFrame();
+  // Remove materialization arguments.
+  __ add(SP, SP, ShifterOperand(R1, ASR, kSmiTagSize));
   __ Ret();
 }
 
 
 void StubCode::GenerateDeoptimizeLazyStub(Assembler* assembler) {
   // Correct return address to point just after the call that is being
   // deoptimized.
   __ AddImmediate(LR, -CallPattern::kFixedLengthInBytes);
   GenerateDeoptimizationSequence(assembler, true);  // Preserve R0.
 }
@@ skipping 1511 matching lines @@
   __ Bind(&reference_compare);
   __ cmp(left, ShifterOperand(right));
   __ Bind(&done);
   __ PopList((1 << R0) | (1 << R1) | (1 << R2));
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM