Reland of [turbofan] ARM: Implement vswp and use in gap resolver

src/arm/simulator-arm.cc

Index: src/arm/simulator-arm.cc
diff --git a/src/arm/simulator-arm.cc b/src/arm/simulator-arm.cc
index d456548c10cc4e177f05f91ff71ba88f1d0398c0..3b7dec08314f8fc0bdf6e7ceb2ecf19a169d253e 100644
--- a/src/arm/simulator-arm.cc
+++ b/src/arm/simulator-arm.cc
@@ -3783,6 +3783,21 @@ void Simulator::DecodeSpecialCondition(Instruction* instr) {
           e++;
         }
         set_q_register(Vd, reinterpret_cast<uint64_t*>(to));
+      } else if ((instr->Bits(21, 16) == 0x32) && (instr->Bits(11, 7) == 0) &&
+                 (instr->Bit(4) == 0)) {
+        int vd = instr->VFPDRegValue(kDoublePrecision);
+        int vm = instr->VFPMRegValue(kDoublePrecision);
+        if (instr->Bit(6) == 0) {
+          // vswp Dd, Dm.
+          uint64_t dval, mval;
+          get_d_register(vd, &dval);
+          get_d_register(vm, &mval);
+          set_d_register(vm, &dval);
+          set_d_register(vd, &mval);
+        } else {
+          // Q register vswp unimplemented.
+          UNIMPLEMENTED();
+        }
       } else {
         UNIMPLEMENTED();
       }