cyb70289 commented on a change in pull request #9841:
URL: https://github.com/apache/arrow/pull/9841#discussion_r608292204
##########
File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
##########
@@ -233,6 +236,104 @@ struct DivideChecked {
}
};
+template <typename T>
+inline T integer_power(KernelContext* ctx, T left, T right) {
+ if (right < 0) {
+ ctx->SetStatus(
+ Status::Invalid("integers to negative integer powers are not
allowed"));
+ }
+ T result = 1;
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ while (true) {
+ if (right % 2) {
+ result *= left;
+ }
+ right /= 2;
+ if (!right) {
+ break;
+ }
+ left *= left;
+ }
+ return result;
+}
+
+template <typename T, typename Arg0, typename Arg1>
+inline T integer_power_checked(KernelContext* ctx, Arg0 left, Arg1 right) {
+ if (right < 0) {
+ ctx->SetStatus(
+ Status::Invalid("integers to negative integer powers are not
allowed"));
+ }
+ T result = 1;
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ while (true) {
+ if (right % 2) {
+ if (ARROW_PREDICT_FALSE(MultiplyWithOverflow(result, left, &result))) {
+ ctx->SetStatus(Status::Invalid("overflow"));
+ }
+ }
+ right /= 2;
+ if (!right) {
+ break;
+ }
+ if (ARROW_PREDICT_FALSE(MultiplyWithOverflow(left, left, &left))) {
+ ctx->SetStatus(Status::Invalid("overflow"));
+ }
+ }
+ return result;
+}
+
+template <typename T, typename Arg0, typename Arg1>
+inline T power(KernelContext* ctx, Arg0 left, Arg1 right) {
+ if (left == 0 && right < 0) {
+ ctx->SetStatus(Status::Invalid("divide by zero"));
+ }
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ return pow(left, right);
Review comment:
Just call `std::pow(left, right)`, leave the decision to the standard
library.
It says `0^-1 = inf`, `0^0 = 1`. It's fine. Our invention is no better than
that.
##########
File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
##########
@@ -233,6 +236,104 @@ struct DivideChecked {
}
};
+template <typename T>
+inline T integer_power(KernelContext* ctx, T left, T right) {
+ if (right < 0) {
+ ctx->SetStatus(
+ Status::Invalid("integers to negative integer powers are not
allowed"));
+ }
+ T result = 1;
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ while (true) {
+ if (right % 2) {
+ result *= left;
Review comment:
Please do check the UBSAN CI failure. I think it's caused by signed
integer overflow in this function. You can enable UBSAN check on your local
host with `cmake -DARROW_USE_UBSAN=ON ....`.
##########
File path: cpp/src/arrow/compute/api_scalar.cc
##########
@@ -44,14 +44,16 @@ namespace compute {
#define SCALAR_ARITHMETIC_BINARY(NAME, REGISTRY_NAME, REGISTRY_CHECKED_NAME)
\
Result<Datum> NAME(const Datum& left, const Datum& right, ArithmeticOptions
options, \
ExecContext* ctx) {
\
- auto func_name = (options.check_overflow) ? REGISTRY_CHECKED_NAME :
REGISTRY_NAME; \
+ std::string func_name =
\
+ (options.check_overflow) ? REGISTRY_CHECKED_NAME : REGISTRY_NAME;
\
Review comment:
Please restore this line
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