s390x: Fix the logic to detect INT_MIN in simulator

src/s390/simulator-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 <stdarg.h>
 #include <stdlib.h>
 #include <cmath>
 
 #if V8_TARGET_ARCH_S390
 
@@ skipping 6486 matching lines @@
   int32_t r2_val = get_low_register<int32_t>(r2);
   SetS390ConditionCode<int32_t>(r2_val, 0);
   set_low_register(r1, r2_val);
   return length;
 }
 
 EVALUATE(LCR) {
   DCHECK_OPCODE(LCR);
   DECODE_RR_INSTRUCTION(r1, r2);
   int32_t r2_val = get_low_register<int32_t>(r2);
-  int32_t original_r2_val = r2_val;
   r2_val = ~r2_val;
   r2_val = r2_val + 1;
   set_low_register(r1, r2_val);
   SetS390ConditionCode<int32_t>(r2_val, 0);
   // Checks for overflow where r2_val = -2147483648.
   // Cannot do int comparison due to GCC 4.8 bug on x86.
   // Detect INT_MIN alternatively, as it is the only value where both
   // original and result are negative due to overflow.
-  if (r2_val < 0 && original_r2_val < 0) {
+  if (r2_val == (static_cast<int32_t>(1) << 31)) {
     SetS390OverflowCode(true);
   }
   return length;
 }
 
 EVALUATE(NR) {
   DCHECK_OPCODE(NR);
   DECODE_RR_INSTRUCTION(r1, r2);
   int32_t r1_val = get_low_register<int32_t>(r1);
   int32_t r2_val = get_low_register<int32_t>(r2);
@@ skipping 3303 matching lines @@
 
 EVALUATE(LCGR) {
   DCHECK_OPCODE(LCGR);
   DECODE_RRE_INSTRUCTION(r1, r2);
   int64_t r2_val = get_register(r2);
   r2_val = ~r2_val;
   r2_val = r2_val + 1;
   set_register(r1, r2_val);
   SetS390ConditionCode<int64_t>(r2_val, 0);
   // if the input is INT_MIN, loading its compliment would be overflowing
-  if (r2_val < 0 && (r2_val + 1) > 0) {
+  if (r2_val == (static_cast<int64_t>(1) << 63)) {
     SetS390OverflowCode(true);
   }
   return length;
 }
 
 EVALUATE(SGR) {
   DCHECK_OPCODE(SGR);
   DECODE_RRE_INSTRUCTION(r1, r2);
   int64_t r1_val = get_register(r1);
   int64_t r2_val = get_register(r2);
@@ skipping 2787 matching lines @@
   return 0;
 }
 
 #undef EVALUATE
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // USE_SIMULATOR
 #endif  // V8_TARGET_ARCH_S390