s390: optimize for compares

src/s390/macro-assembler-s390.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <assert.h>  // For assert
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_S390
 
 #include "src/base/bits.h"
@@ skipping 3313 matching lines @@
 
 #define Generate_Mul32WithOverflowIfCCUnequal(instr) \
   {                                                  \
     lgfr(dst, src1);                                 \
     instr(dst, src2);                                \
     cgfr(dst, dst);                                  \
   }
 
 void MacroAssembler::Mul32WithOverflowIfCCUnequal(Register dst, Register src1,
                                                   const MemOperand& src2) {
+  Register result = dst;
+  if (src2.rx().is(dst) || src2.rb().is(dst)) dst = r0;
   Generate_Mul32WithOverflowIfCCUnequal(msgf);
+  if (!result.is(dst)) llgfr(result, dst);
 }
 
 void MacroAssembler::Mul32WithOverflowIfCCUnequal(Register dst, Register src1,
                                                   Register src2) {
   if (dst.is(src2)) {
     std::swap(src1, src2);
   }
   Generate_Mul32WithOverflowIfCCUnequal(msgfr);
 }
 
@@ skipping 2007 matching lines @@
   }
   if (mag.shift > 0) ShiftRightArith(result, result, Operand(mag.shift));
   ExtractBit(r0, dividend, 31);
   AddP(result, r0);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_S390