Use GPRs for mints

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index 648bc6e53f02694710ab365b40ecf5990a00ecc3..7da18183f150ef10fae39072aab59fb7cdbce9a7 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -567,7 +567,7 @@ void FlowGraphCompiler::RecordSafepoint(LocationSummary* locs) {
       for (intptr_t i = 0; i < kNumberOfCpuRegisters; ++i) {
         Register reg = static_cast<Register>(i);
         if (locs->live_registers()->ContainsRegister(reg)) {
-          bitmap->Set(bitmap->Length(), true);
+          bitmap->Set(bitmap->Length(), locs->live_registers()->IsTagged(reg));
         }
       }
     }
@@ -638,7 +638,6 @@ Environment* FlowGraphCompiler::SlowPathEnvironmentFor(
       Value* value = it.CurrentValue();
       switch (value->definition()->representation()) {
         case kUnboxedDouble:
-        case kUnboxedMint:
           it.SetCurrentLocation(Location::DoubleStackSlot(index));
           break;
         case kUnboxedFloat32x4:
@@ -649,6 +648,27 @@ Environment* FlowGraphCompiler::SlowPathEnvironmentFor(
         default:
           UNREACHABLE();
       }
+    } else if (loc.IsPairLocation()) {
+      intptr_t representation =
+          it.CurrentValue()->definition()->representation();
+      ASSERT(representation == kUnboxedMint);
+      PairLocation* value_pair = loc.AsPairLocation();
+      intptr_t index_lo;
+      intptr_t index_hi;
+      if (value_pair->At(0).IsRegister()) {
+        index_lo = cpu_reg_slots[value_pair->At(0).reg()];
+      } else {
+        ASSERT(value_pair->At(0).IsStackSlot());
+        index_lo = value_pair->At(0).stack_index();
+      }
+      if (value_pair->At(1).IsRegister()) {
+        index_hi = cpu_reg_slots[value_pair->At(1).reg()];
+      } else {
+        ASSERT(value_pair->At(1).IsStackSlot());
+        index_hi = value_pair->At(1).stack_index();
+      }
+      it.SetCurrentLocation(Location::Pair(Location::StackSlot(index_lo),
+                                           Location::StackSlot(index_hi)));
     } else if (loc.IsInvalid()) {
       Definition* def =
           it.CurrentValue()->definition();