s390x: fix high 32-bit word corruption issue

R=joransiu@ca.ibm.com

Change-Id: I9a2cf0f3e4a33dc4b86c83acfefcd27968bbcdb4
Reviewed-on: https://chromium-review.googlesource.com/1176424Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#55143}

src/compiler/s390/instruction-selector-s390.cc

@@ -329,12 +329,12 @@ ArchOpcode SelectLoadOpcode(Node* node) {
   /* Float unary op*/              \
   V(BitcastFloat32ToInt32)         \
   /* V(TruncateFloat64ToWord32) */ \
-  /* V(RoundFloat64ToInt32)     */ \
-  /* V(TruncateFloat32ToInt32)  */ \
-  /* V(TruncateFloat32ToUint32) */ \
-  /* V(TruncateFloat64ToUint32) */ \
-  /* V(ChangeFloat64ToInt32)    */ \
-  /* V(ChangeFloat64ToUint32)   */ \
+  V(RoundFloat64ToInt32)           \
+  V(TruncateFloat32ToInt32)        \
+  V(TruncateFloat32ToUint32)       \
+  V(TruncateFloat64ToUint32)       \
+  V(ChangeFloat64ToInt32)          \
+  V(ChangeFloat64ToUint32)         \
   /* Word32 unary op */            \
   V(Word32Clz)                     \
   V(Word32Popcnt)                  \

src/s390/macro-assembler-s390.cc

@@ -796,6 +796,9 @@ void TurboAssembler::ConvertDoubleToInt32(const Register dst,
       UNIMPLEMENTED();
       break;
   }
+#ifdef V8_TARGET_ARCH_S390X
+  lghi(dst, Operand::Zero());
+#endif
   cfdbr(m, dst, double_input);
 }
 
@@ -820,6 +823,9 @@ void TurboAssembler::ConvertFloat32ToInt32(const Register result,
       UNIMPLEMENTED();
       break;
   }
+#ifdef V8_TARGET_ARCH_S390X
+  lghi(result, Operand::Zero());
+#endif
   cfebr(m, result, double_input);
 }
 
@@ -844,6 +850,9 @@ void TurboAssembler::ConvertFloat32ToUnsignedInt32(
       UNIMPLEMENTED();
       break;
   }
+#ifdef V8_TARGET_ARCH_S390X
+  lghi(result, Operand::Zero());
+#endif
   clfebr(m, Condition(0), result, double_input);
 }
 
@@ -916,6 +925,9 @@ void TurboAssembler::ConvertDoubleToUnsignedInt32(
       UNIMPLEMENTED();
       break;
   }
+#ifdef V8_TARGET_ARCH_S390X
+  lghi(dst, Operand::Zero());
+#endif
   clfdbr(m, Condition(0), dst, double_input);
 }