MIPS: Optimize load/store with large offset on MIPSr6

src/mips64/assembler-mips64.cc

Index: src/mips64/assembler-mips64.cc
diff --git a/src/mips64/assembler-mips64.cc b/src/mips64/assembler-mips64.cc
index 09a19169d677454b241592a05424405c46729680..e26fc604244f2888be60908ae60e6b8a8611f48f 100644
--- a/src/mips64/assembler-mips64.cc
+++ b/src/mips64/assembler-mips64.cc
@@ -1965,8 +1965,12 @@ int32_t Assembler::LoadRegPlusUpperOffsetPartToAt(const MemOperand& src) {
     hi += 1;
   }
 
-  lui(at, hi);
-  daddu(at, at, src.rm());
+  if (kArchVariant == kMips64r6) {
+    daui(at, src.rm(), hi);
+  } else {
+    lui(at, hi);
+    daddu(at, at, src.rm());
+  }
   return (src.offset_ & kImm16Mask);
 }