[libc-commits] [libc] [libc] Optimize BigInt→decimal in IntegerToString (PR #123580)

[Simon Tatham via libc-commits]

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@@ -164,6 +164,168 @@ template <size_t radix> using Custom = details::Fmt<radix>;
 
 } // namespace radix
 
+// Extract the low-order decimal digit from a value of integer type T. The
+// returned value is the digit itself, from 0 to 9. The input value is passed
+// by reference, and modified by dividing by 10, so that iterating this
+// function extracts all the digits of the original number one at a time from
+// low to high.
+template <typename T, cpp::enable_if_t<cpp::is_integral_v<T>, int> = 0>
+LIBC_INLINE uint8_t extract_decimal_digit(T &value) {
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statham-arm wrote:

Done. (I learned the alternative `enable_if` trick from another LLVM code review where the reviewer told me to switch in the opposite direction, but there we go :-)

https://github.com/llvm/llvm-project/pull/123580