Remove the first_right_arg hack for HMod.

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 8699 matching lines @@
     switch (op) {
       case Token::ADD:
         instr = AddUncasted<HAdd>(left, right);
         break;
       case Token::SUB:
         instr = AddUncasted<HSub>(left, right);
         break;
       case Token::MUL:
         instr = AddUncasted<HMul>(left, right);
         break;
-      case Token::MOD:
-        instr = AddUncasted<HMod>(left, right, fixed_right_arg);
+      case Token::MOD: {
+        if (fixed_right_arg.has_value) {
+          if (right->IsConstant()) {
+            ASSERT_EQ(fixed_right_arg.value,
+                      HConstant::cast(right)->Integer32Value());
+          } else {
+            HConstant* fixed_right = Add<HConstant>(
+                static_cast<int>(fixed_right_arg.value));
+            IfBuilder if_same(this);
+            if_same.If<HCompareNumericAndBranch>(right, fixed_right, Token::EQ);
+            if_same.Then();
+            if_same.ElseDeopt("Unexpected RHS of binary operation");
+            right = fixed_right;
+          }
+        }
+        instr = AddUncasted<HMod>(left, right);
         break;
+      }
       case Token::DIV:
         instr = AddUncasted<HDiv>(left, right);
         break;
       case Token::BIT_XOR:
       case Token::BIT_AND:
         instr = AddUncasted<HBitwise>(op, left, right);
         break;
       case Token::BIT_OR: {
         HValue* operand, *shift_amount;
         if (left_type->Is(Type::Signed32()) &&
@@ skipping 1915 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal