S390: Fixed condition code handling on FP->INT and FP rounding in simulator.

src/s390/simulator-s390.h

Index: src/s390/simulator-s390.h
diff --git a/src/s390/simulator-s390.h b/src/s390/simulator-s390.h
index 1da49ed279189436bd95824fccdd7260e6e719dd..f8d0d565896c7ac2e5796b35955d492d73af42bf 100644
--- a/src/s390/simulator-s390.h
+++ b/src/s390/simulator-s390.h
@@ -317,6 +317,66 @@ class Simulator {
   bool DecodeSixByteArithmetic(Instruction* instr);
   bool S390InstructionDecode(Instruction* instr);
 
+  // Used by the CL**BR instructions.
+  template <typename T1, typename T2>
+  void SetS390RoundConditionCode(T1 r2_val, T2 max, T2 min) {
+    condition_reg_ = 0;
+    double r2_dval = static_cast<double>(r2_val);
+    double dbl_min = static_cast<double>(min);
+    double dbl_max = static_cast<double>(max);
+
+    if (r2_dval == 0.0)
+      condition_reg_ = 8;
+    else if (r2_dval < 0.0 && r2_dval >= dbl_min && std::isfinite(r2_dval))
+      condition_reg_ = 4;
+    else if (r2_dval > 0.0 && r2_dval <= dbl_max && std::isfinite(r2_dval))
+      condition_reg_ = 2;
+    else
+      condition_reg_ = 1;
+  }
+
+  template <typename T1>
+  void SetS390RoundConditionCode(T1 r2_val, int64_t max, int64_t min) {
+    condition_reg_ = 0;
+    double r2_dval = static_cast<double>(r2_val);
+    double dbl_min = static_cast<double>(min);
+    double dbl_max = static_cast<double>(max);
+
+    // Note that the IEEE 754 floating-point representations (both 32 and
+    // 64 bit) cannot exactly represent INT64_MAX. The closest it can get
+    // is INT64_max + 1. IEEE 754 FP can, though, represent INT64_MIN
+    // exactly.
+
+    // This is not an issue for INT32, as IEEE754 64-bit can represent
+    // INT32_MAX and INT32_MIN with exact precision.
+
+    if (r2_dval == 0.0)
+      condition_reg_ = 8;
+    else if (r2_dval < 0.0 && r2_dval >= dbl_min && std::isfinite(r2_dval))
+      condition_reg_ = 4;
+    else if (r2_dval > 0.0 && r2_dval < dbl_max && std::isfinite(r2_dval))
+      condition_reg_ = 2;
+    else
+      condition_reg_ = 1;
+  }
+
+  // Used by the CL**BR instructions.
+  template <typename T1, typename T2, typename T3>
+  void SetS390ConvertConditionCode(T1 src, T2 dst, T3 max) {
+    condition_reg_ = 0;
+    if (src == static_cast<T1>(0.0)) {
+      condition_reg_ |= 8;
+    } else if (src < static_cast<T1>(0.0) && static_cast<T2>(src) == 0 &&
+               std::isfinite(src)) {
+      condition_reg_ |= 4;
+    } else if (src > static_cast<T1>(0.0) && std::isfinite(src) &&
+               src < static_cast<T1>(max)) {
+      condition_reg_ |= 2;
+    } else {
+      condition_reg_ |= 1;
+    }
+  }
+
   template <typename T>
   void SetS390ConditionCode(T lhs, T rhs) {
     condition_reg_ = 0;