MIPS: Fixed FPU rounding checks and related errors in the Simulator.

src/mips/simulator-mips.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1141 matching lines @@
 
 
 bool Simulator::test_fcsr_bit(uint32_t cc) {
   return FCSR_ & (1 << cc);
 }
 
 
 // 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_round_error(double original, double rounded) {
-  if (!isfinite(original) ||
-      rounded > LONG_MAX ||
-      rounded < LONG_MIN) {
-    set_fcsr_bit(6, true);  // Invalid operation.
-    return true;
-  } else if (original != static_cast<double>(rounded)) {
-    set_fcsr_bit(2, true);  // Inexact.
+  bool ret = false;
+
+  if (!isfinite(original) || !isfinite(rounded)) {
+    set_fcsr_bit(kFCSRInvalidOpFlagBit, true);
+    ret = true;
   }
-  return false;
+
+  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 > INT_MAX || rounded < INT_MIN) {
+    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;
 }
 
 
 // Raw access to the PC register.
 void Simulator::set_pc(int32_t value) {
   pc_modified_ = true;
   registers_[pc] = value;
 }
 
 
@@ skipping 866 matching lines @@
                 double rounded = fs > 0 ? floor(fs + 0.5) : ceil(fs - 0.5);
                 int32_t result = static_cast<int32_t>(rounded);
                 set_fpu_register(fd_reg, result);
                 if (set_fcsr_round_error(fs, rounded)) {
                   set_fpu_register(fd_reg, kFPUInvalidResult);
                 }
               }
               break;
             case TRUNC_W_D:  // Truncate double to word (round towards 0).
               {
-                int32_t result = static_cast<int32_t>(fs);
+                double rounded = trunc(fs);
+                int32_t result = static_cast<int32_t>(rounded);
                 set_fpu_register(fd_reg, result);
-                if (set_fcsr_round_error(fs, static_cast<double>(result))) {
+                if (set_fcsr_round_error(fs, rounded)) {
                   set_fpu_register(fd_reg, kFPUInvalidResult);
                 }
               }
               break;
             case FLOOR_W_D:  // Round double to word towards negative infinity.
               {
                 double rounded = floor(fs);
                 int32_t result = static_cast<int32_t>(rounded);
                 set_fpu_register(fd_reg, result);
                 if (set_fcsr_round_error(fs, rounded)) {
                   set_fpu_register(fd_reg, kFPUInvalidResult);
                 }
               }
               break;
             case CEIL_W_D:  // Round double to word towards positive infinity.
               {
                 double rounded = ceil(fs);
                 int32_t result = static_cast<int32_t>(rounded);
                 set_fpu_register(fd_reg, result);
                 if (set_fcsr_round_error(fs, rounded)) {
                   set_fpu_register(fd_reg, kFPUInvalidResult);
                 }
               }
               break;
             case CVT_S_D:  // Convert double to float (single).
               set_fpu_register_float(fd_reg, static_cast<float>(fs));
               break;
-            case CVT_L_D:  // Mips32r2: Truncate double to 64-bit long-word.
-              i64 = static_cast<int64_t>(fs);
+            case CVT_L_D: {  // Mips32r2: Truncate double to 64-bit long-word.
+              double rounded = trunc(fs);
+              i64 = static_cast<int64_t>(rounded);
               set_fpu_register(fd_reg, i64 & 0xffffffff);
               set_fpu_register(fd_reg + 1, i64 >> 32);
               break;
-            case TRUNC_L_D:  // Mips32r2 instruction.
-              i64 = static_cast<int64_t>(fs);
+            }
+            case TRUNC_L_D: {  // Mips32r2 instruction.
+              double rounded = trunc(fs);
+              i64 = static_cast<int64_t>(rounded);
               set_fpu_register(fd_reg, i64 & 0xffffffff);
               set_fpu_register(fd_reg + 1, i64 >> 32);
               break;
+            }
             case ROUND_L_D: {  // Mips32r2 instruction.
               double rounded = fs > 0 ? floor(fs + 0.5) : ceil(fs - 0.5);
               i64 = static_cast<int64_t>(rounded);
               set_fpu_register(fd_reg, i64 & 0xffffffff);
               set_fpu_register(fd_reg + 1, i64 >> 32);
               break;
             }
             case FLOOR_L_D:  // Mips32r2 instruction.
               i64 = static_cast<int64_t>(floor(fs));
               set_fpu_register(fd_reg, i64 & 0xffffffff);
@@ skipping 694 matching lines @@
 }
 
 
 #undef UNSUPPORTED
 
 } }  // namespace v8::internal
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_MIPS