Reland of "MIPS64: Fix trunc_l_[s,d] in simulator."

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 1243 matching lines @@
   }
 
   return ret;
 }
 
 
 // Sets the rounding error codes in FCSR based on the result of the rounding.
 // Returns true if the operation was invalid.
 bool Simulator::set_fcsr_round64_error(double original, double rounded) {
   bool ret = false;
+  // The value of INT64_MAX (2^63-1) can't be represented as double exactly,
+  // loading the most accurate representation into max_int64, which is 2^63.
   double max_int64 = std::numeric_limits<int64_t>::max();
   double min_int64 = std::numeric_limits<int64_t>::min();
 
   if (!std::isfinite(original) || !std::isfinite(rounded)) {
     set_fcsr_bit(kFCSRInvalidOpFlagBit, true);
     ret = true;
   }
 
   if (original != rounded) {
     set_fcsr_bit(kFCSRInexactFlagBit, true);
   }
 
   if (rounded < DBL_MIN && rounded > -DBL_MIN && rounded != 0) {
     set_fcsr_bit(kFCSRUnderflowFlagBit, true);
     ret = true;
   }
 
-  if (rounded > max_int64 || rounded < min_int64) {
+  if (rounded >= max_int64 || rounded < min_int64) {
     set_fcsr_bit(kFCSROverflowFlagBit, true);
     // The reference is not really clear but it seems this is required:
     set_fcsr_bit(kFCSRInvalidOpFlagBit, true);
     ret = true;
   }
 
   return ret;
 }
 
 
@@ skipping 63 matching lines @@
     }
   } else {
     set_fpu_register(fd_reg(), kFPUInvalidResult);
   }
 }
 
 
 void Simulator::set_fpu_register_invalid_result64(float original,
                                                   float rounded) {
   if (FCSR_ & kFCSRNaN2008FlagMask) {
+    // The value of INT64_MAX (2^63-1) can't be represented as double exactly,
+    // loading the most accurate representation into max_int64, which is 2^63.
     double max_int64 = std::numeric_limits<int64_t>::max();
     double min_int64 = std::numeric_limits<int64_t>::min();
     if (std::isnan(original)) {
       set_fpu_register(fd_reg(), 0);
-    } else if (rounded > max_int64) {
+    } else if (rounded >= max_int64) {
       set_fpu_register(fd_reg(), kFPU64InvalidResult);
     } else if (rounded < min_int64) {
       set_fpu_register(fd_reg(), kFPU64InvalidResultNegative);
     } else {
       UNREACHABLE();
     }
   } else {
     set_fpu_register(fd_reg(), kFPU64InvalidResult);
   }
 }
@@ skipping 35 matching lines @@
     }
   } else {
     set_fpu_register(fd_reg(), kFPUInvalidResult);
   }
 }
 
 
 void Simulator::set_fpu_register_invalid_result64(double original,
                                                   double rounded) {
   if (FCSR_ & kFCSRNaN2008FlagMask) {
+    // The value of INT64_MAX (2^63-1) can't be represented as double exactly,
+    // loading the most accurate representation into max_int64, which is 2^63.
     double max_int64 = std::numeric_limits<int64_t>::max();
     double min_int64 = std::numeric_limits<int64_t>::min();
     if (std::isnan(original)) {
       set_fpu_register(fd_reg(), 0);
-    } else if (rounded > max_int64) {
+    } else if (rounded >= max_int64) {
       set_fpu_register(fd_reg(), kFPU64InvalidResult);
     } else if (rounded < min_int64) {
       set_fpu_register(fd_reg(), kFPU64InvalidResultNegative);
     } else {
       UNREACHABLE();
     }
   } else {
     set_fpu_register(fd_reg(), kFPU64InvalidResult);
   }
 }
 
 
 // Sets the rounding error codes in FCSR based on the result of the rounding.
 // Returns true if the operation was invalid.
 bool Simulator::set_fcsr_round64_error(float original, float rounded) {
   bool ret = false;
+  // The value of INT64_MAX (2^63-1) can't be represented as double exactly,
+  // loading the most accurate representation into max_int64, which is 2^63.
   double max_int64 = std::numeric_limits<int64_t>::max();
   double min_int64 = std::numeric_limits<int64_t>::min();
 
   if (!std::isfinite(original) || !std::isfinite(rounded)) {
     set_fcsr_bit(kFCSRInvalidOpFlagBit, true);
     ret = true;
   }
 
   if (original != rounded) {
     set_fcsr_bit(kFCSRInexactFlagBit, true);
   }
 
   if (rounded < FLT_MIN && rounded > -FLT_MIN && rounded != 0) {
     set_fcsr_bit(kFCSRUnderflowFlagBit, true);
     ret = true;
   }
 
-  if (rounded > max_int64 || rounded < min_int64) {
+  if (rounded >= max_int64 || rounded < min_int64) {
     set_fcsr_bit(kFCSROverflowFlagBit, true);
     // The reference is not really clear but it seems this is required:
     set_fcsr_bit(kFCSRInvalidOpFlagBit, true);
     ret = true;
   }
 
   return ret;
 }
 
 
@@ skipping 3258 matching lines @@
 }
 
 
 #undef UNSUPPORTED
 }  // namespace internal
 }  // namespace v8
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_MIPS64