[arm] Add support for SMMLA, SMMLS and SMMUL.

src/base/bits.cc

Index: src/base/bits.cc
diff --git a/src/base/bits.cc b/src/base/bits.cc
index 6daee532a74cf7e5a0e0022afe70f453eb0e3ad3..7a3fb6d33159dfd64c88fb16683aabf2248f05a8 100644
--- a/src/base/bits.cc
+++ b/src/base/bits.cc
@@ -20,6 +20,25 @@ uint32_t RoundUpToPowerOfTwo32(uint32_t value) {
   return value + 1;
 }
 
+
+int32_t SignedMulHigh32(int32_t lhs, int32_t rhs) {
+  int64_t const value = static_cast<int64_t>(lhs) * static_cast<int64_t>(rhs);
+  return bit_cast<int32_t, uint32_t>(bit_cast<uint64_t>(value) >> 32u);
+}
+
+
+int32_t SignedMulHighAndAdd32(int32_t lhs, int32_t rhs, int32_t acc) {
+  return bit_cast<int32_t>(bit_cast<uint32_t>(acc) +
+                           bit_cast<uint32_t>(SignedMulHigh32(lhs, rhs)));
+}
+
+
+int32_t SignedMulHighAndSub32(int32_t lhs, int32_t rhs, int32_t acc) {
+  return bit_cast<int32_t>(bit_cast<uint32_t>(acc) -
+                           bit_cast<uint32_t>(SignedMulHigh32(lhs, rhs)));
+}
+
+
 }  // namespace bits
 }  // namespace base
 }  // namespace v8