ARM mint cleanups

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 1429 matching lines @@
         // TOOD(regis): merge stores using vstmd instruction.
         __ vstrd(d1, Address(SP, offset));
         __ vstrd(d2, Address(SP, offset + 2 * kWordSize));
         offset += kFpuRegisterSize;
       }
     }
     ASSERT(offset == (fpu_regs_count * kFpuRegisterSize));
   }
 
   // Store general purpose registers with the highest register number at the
-  // lowest address.
+  // lowest address. The order in which the registers are pushed must match the
+  // order in which the registers are encoded in the safe point's stack map.
+  // NOTE: Using ARM's multi-register push, pushes the registers in the wrong
+  // order.
   for (intptr_t reg_idx = 0; reg_idx < kNumberOfCpuRegisters; ++reg_idx) {
     Register reg = static_cast<Register>(reg_idx);
     if (locs->live_registers()->ContainsRegister(reg)) {
       __ Push(reg);
     }
   }
 }
 
 
 void FlowGraphCompiler::RestoreLiveRegisters(LocationSummary* locs) {
   // General purpose registers have the highest register number at the
-  // lowest address.
+  // lowest address. The order in which the registers are popped must match the
+  // order in which the registers are pushed in SaveLiveRegisters.
   for (intptr_t reg_idx = kNumberOfCpuRegisters - 1; reg_idx >= 0; --reg_idx) {
     Register reg = static_cast<Register>(reg_idx);
     if (locs->live_registers()->ContainsRegister(reg)) {
       __ Pop(reg);
     }
   }
 
   const intptr_t fpu_regs_count = locs->live_registers()->FpuRegisterCount();
   if (fpu_regs_count > 0) {
     // Fpu registers have the lowest register number at the lowest address.
@@ skipping 344 matching lines @@
   DRegister dreg = EvenDRegisterOf(reg);
   __ vldrd(dreg, Address(SP, kDoubleSize, Address::PostIndex));
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM