ARROW-7631: return zero if there is an overflow while downscaling a d… (

apache#13) * ARROW-7631: return zero if there is an overflow while downscaling a decimal - also add castDecimalNullOnOverflow function * inline helper function
pprudhvi · Jan 21, 2020 · 6608e91 · 6608e91
1 parent 92f2900
commit 6608e91
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Showing 3 changed files with 40 additions and 4 deletions.
diff --git a/cpp/src/gandiva/function_registry_arithmetic.cc b/cpp/src/gandiva/function_registry_arithmetic.cc
@@ -56,6 +56,10 @@ std::vector<NativeFunction> GetArithmeticFunctionRegistry() {
       UNARY_SAFE_NULL_IF_NULL(castDECIMAL, {}, decimal128, decimal128),
       UNARY_UNSAFE_NULL_IF_NULL(castDECIMAL, {}, utf8, decimal128),
 
+      NativeFunction("castDECIMALNullOnOverflow", {}, DataTypeVector{decimal128()},
+                     decimal128(), kResultNullInternal,
+                     "castDECIMALNullOnOverflow_decimal128"),
+
       UNARY_SAFE_NULL_IF_NULL(castDATE, {}, int64, date64),
 
       // add/sub/multiply/divide/mod

diff --git a/cpp/src/gandiva/precompiled/decimal_ops.cc b/cpp/src/gandiva/precompiled/decimal_ops.cc
@@ -544,7 +544,10 @@ static BasicDecimal128 ModifyScaleAndPrecision(const BasicDecimalScalar128& x,
     return x.value().IncreaseScaleBy(delta_scale);
   } else {
     // Do not do any rounding, that is handled by the caller.
-    return x.value().ReduceScaleBy(-delta_scale, false);
+    auto result = x.value().ReduceScaleBy(-delta_scale, false);
+    DECIMAL_OVERFLOW_IF(BasicDecimal128::Abs(result) > GetMaxValue(out_precision),
+                        overflow);
+    return result;
   }
 }
 

diff --git a/cpp/src/gandiva/precompiled/decimal_wrapper.cc b/cpp/src/gandiva/precompiled/decimal_wrapper.cc
@@ -229,14 +229,43 @@ void castDECIMAL_float32(float in, int32_t x_precision, int32_t x_scale,
 }
 
 FORCE_INLINE
-void castDECIMAL_decimal128(int64_t x_high, uint64_t x_low, int32_t x_precision,
-                            int32_t x_scale, int32_t out_precision, int32_t out_scale,
-                            int64_t* out_high, int64_t* out_low) {
+boolean castDecimal_return_overflow(int64_t x_high, uint64_t x_low, int32_t x_precision,
+                                    int32_t x_scale, int32_t out_precision,
+                                    int32_t out_scale, int64_t* out_high,
+                                    int64_t* out_low) {
   gandiva::BasicDecimalScalar128 x({x_high, x_low}, x_precision, x_scale);
   bool overflow = false;
   auto out = gandiva::decimalops::Convert(x, out_precision, out_scale, &overflow);
   *out_high = out.high_bits();
   *out_low = out.low_bits();
+  return overflow;
+}
+
+FORCE_INLINE
+void castDECIMAL_decimal128(int64_t x_high, uint64_t x_low, int32_t x_precision,
+                            int32_t x_scale, int32_t out_precision, int32_t out_scale,
+                            int64_t* out_high, int64_t* out_low) {
+  castDecimal_return_overflow(x_high, x_low, x_precision, x_scale, out_precision,
+                              out_scale, out_high, out_low);
+}
+
+FORCE_INLINE
+void castDECIMALNullOnOverflow_decimal128(int64_t x_high, uint64_t x_low,
+                                          int32_t x_precision, int32_t x_scale,
+                                          boolean x_isvalid, bool* out_valid,
+                                          int32_t out_precision, int32_t out_scale,
+                                          int64_t* out_high, int64_t* out_low) {
+  *out_valid = true;
+
+  if (!x_isvalid) {
+    *out_valid = false;
+    return;
+  }
+
+  if (castDecimal_return_overflow(x_high, x_low, x_precision, x_scale, out_precision,
+                                  out_scale, out_high, out_low)) {
+    *out_valid = false;
+  }
 }
 
 FORCE_INLINE