Remove the first_right_arg hack for HMod.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index ba8ccc5cc995ceade12a62eb68048aa4b5a0d726..0c957459739377a6ce544a9e2963321d0954c1ff 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1013,36 +1013,6 @@ void LCodeGen::DoModI(LModI* instr) {
     __ bind(&left_is_not_negative);
     __ andl(left_reg, Immediate(divisor - 1));
     __ bind(&done);
-
-  } else if (hmod->fixed_right_arg().has_value) {
-    Register left_reg = ToRegister(instr->left());
-    ASSERT(left_reg.is(ToRegister(instr->result())));
-    Register right_reg = ToRegister(instr->right());
-
-    int32_t divisor = hmod->fixed_right_arg().value;
-    ASSERT(IsPowerOf2(divisor));
-
-    // Check if our assumption of a fixed right operand still holds.
-    __ cmpl(right_reg, Immediate(divisor));
-    DeoptimizeIf(not_equal, instr->environment());
-
-    Label left_is_not_negative, done;
-    if (left->CanBeNegative()) {
-      __ testl(left_reg, left_reg);
-      __ j(not_sign, &left_is_not_negative, Label::kNear);
-      __ negl(left_reg);
-      __ andl(left_reg, Immediate(divisor - 1));
-      __ negl(left_reg);
-      if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
-        DeoptimizeIf(zero, instr->environment());
-      }
-      __ jmp(&done, Label::kNear);
-    }
-
-    __ bind(&left_is_not_negative);
-    __ andl(left_reg, Immediate(divisor - 1));
-    __ bind(&done);
-
   } else {
     Register left_reg = ToRegister(instr->left());
     ASSERT(left_reg.is(rax));