MIPS64: Use BOVC/BNVC for overflow checking on r6.

src/mips64/simulator-mips64.cc

 // Copyright 2011 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 <limits.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <cmath>
 
 #if V8_TARGET_ARCH_MIPS64
@@ skipping 4312 matching lines @@
     case BC:
       BranchCompactHelper(true, 26);
       break;
     case BALC:
       BranchAndLinkCompactHelper(true, 26);
       break;
     case POP10:  // BOVC, BEQZALC, BEQC / ADDI (pre-r6)
       if (kArchVariant == kMips64r6) {
         if (rs_reg >= rt_reg) {  // BOVC
           if (HaveSameSign(rs, rt)) {
-            if (rs > 0) {
-              BranchCompactHelper(rs > Registers::kMaxValue - rt, 16);
-            } else if (rs < 0) {
-              BranchCompactHelper(rs < Registers::kMinValue - rt, 16);
-            }
+            int64_t sum = rs + rt;
+            BranchCompactHelper(sum < INT32_MIN || sum > INT32_MAX, 16);
           }
         } else {
           if (rs_reg == 0) {  // BEQZALC
             BranchAndLinkCompactHelper(rt == 0, 16);
           } else {  // BEQC
             BranchCompactHelper(rt == rs, 16);
           }
         }
       } else {  // ADDI
         if (HaveSameSign(rs, se_imm16)) {
           if (rs > 0) {
             if (rs <= Registers::kMaxValue - se_imm16) {
               SignalException(kIntegerOverflow);
             }
           } else if (rs < 0) {
             if (rs >= Registers::kMinValue - se_imm16) {
               SignalException(kIntegerUnderflow);
             }
           }
         }
         SetResult(rt_reg, rs + se_imm16);
       }
       break;
     case POP30:  // BNVC, BNEZALC, BNEC / DADDI (pre-r6)
       if (kArchVariant == kMips64r6) {
         if (rs_reg >= rt_reg) {  // BNVC
           if (!HaveSameSign(rs, rt) || rs == 0 || rt == 0) {
             BranchCompactHelper(true, 16);
           } else {
-            if (rs > 0) {
-              BranchCompactHelper(rs <= Registers::kMaxValue - rt, 16);
-            } else if (rs < 0) {
-              BranchCompactHelper(rs >= Registers::kMinValue - rt, 16);
-            }
+            int64_t sum = rs + rt;
+            BranchCompactHelper(sum >= INT32_MIN && sum <= INT32_MAX, 16);
           }
         } else {
           if (rs_reg == 0) {  // BNEZALC
             BranchAndLinkCompactHelper(rt != 0, 16);
           } else {  // BNEC
             BranchCompactHelper(rt != rs, 16);
           }
         }
       }
       break;
@@ skipping 479 matching lines @@
 }
 
 
 #undef UNSUPPORTED
 }  // namespace internal
 }  // namespace v8
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_MIPS64