VM: Fix umulh on simarm64 Windows.

runtime/vm/simulator_arm64.cc

Index: runtime/vm/simulator_arm64.cc
diff --git a/runtime/vm/simulator_arm64.cc b/runtime/vm/simulator_arm64.cc
index 4e8fde227829e2ce610d177a28560e77c516865c..f502c101623de3fb8ec6d1bb27eb523eb1e2b29c 100644
--- a/runtime/vm/simulator_arm64.cc
+++ b/runtime/vm/simulator_arm64.cc
@@ -2261,7 +2261,8 @@ int64_t Simulator::ShiftOperand(uint8_t reg_size,
         value &= kWRegMask;
       }
       return (static_cast<uint64_t>(value) >> amount) |
-             ((value & ((1L << amount) - 1L)) << (reg_size - amount));
+             ((static_cast<uint64_t>(value) & ((1ULL << amount) - 1ULL))
+              << (reg_size - amount));
     }
     default:
       UNIMPLEMENTED();
@@ -2673,8 +2674,8 @@ void Simulator::DecodeMiscDP3Source(Instr* instr) {
     const uint64_t rm_val = get_register(rm, R31IsZR);
 #if defined(TARGET_OS_WINDOWS)
     // Visual Studio does not support __int128.
-    int64_t alu_out;
-    Multiply128(rn_val, rm_val, &alu_out);
+    uint64_t alu_out;
+    UnsignedMultiply128(rn_val, rm_val, &alu_out);
 #else
     const __int128 res =
         static_cast<__int128>(rn_val) * static_cast<__int128>(rm_val);

[zra, 2017/01/17 20:18:04]

Is this one signed or unsigned?

[Florian Schneider, 2017/01/17 21:16:47]

I'll add unsigned here as well. The code generated by gcc is the same.