From 0e36681b8eeeb0671ef701f7ff9a18bb23244f7f Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Mon, 7 Jun 2021 07:42:22 -0700
Subject: [PATCH] Cleanup digit count

---
 include/fmt/format.h | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index 536bd377..f6853ef5 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -897,10 +897,8 @@ FMT_CONSTEXPR inline auto count_digits(uint128_t n) -> int {
 // Returns the number of decimal digits in n. Leading zeros are not counted
 // except for n == 0 in which case count_digits returns 1.
 FMT_CONSTEXPR20 inline auto count_digits(uint64_t n) -> int {
-  if (is_constant_evaluated()) {
-    return count_digits_fallback(n);
-  }
 #ifdef FMT_BUILTIN_CLZLL
+  if (!is_constant_evaluated()) {
   // https://github.com/fmtlib/format-benchmark/blob/master/digits10
   // Maps bsr(n) to ceil(log10(pow(2, bsr(n) + 1) - 1)).
   FMT_STATIC_CONSTEXPR uint16_t bsr2log10[] = {
@@ -913,9 +911,9 @@ FMT_CONSTEXPR20 inline auto count_digits(uint64_t n) -> int {
       0, 0, FMT_POWERS_OF_10(1U), FMT_POWERS_OF_10(1000000000ULL),
       10000000000000000000ULL};
   return t - (n < zero_or_powers_of_10[t]);
-#else
-  return count_digits_fallback(n);
+  }
 #endif
+  return count_digits_fallback(n);
 }
 
 // Counts the number of digits in n. BITS = log2(radix).
@@ -934,14 +932,12 @@ FMT_CONSTEXPR auto count_digits(UInt n) -> int {
 
 template <> auto count_digits<4>(detail::fallback_uintptr n) -> int;
 
-#ifdef FMT_BUILTIN_CLZ
-
 // It is a separate function rather than a part of count_digits to workaround
 // the lack of static constexpr in constexpr functions.
 FMT_INLINE uint64_t count_digits_inc(int n) {
   // An optimization by Kendall Willets from https://bit.ly/3uOIQrB.
   // This increments the upper 32 bits (log10(T) - 1) when >= T is added.
-#  define FMT_INC(T) (((sizeof(#  T) - 1ull) << 32) - T)
+#define FMT_INC(T) (((sizeof(#T) - 1ull) << 32) - T)
   static constexpr uint64_t table[] = {
       FMT_INC(0),          FMT_INC(0),          FMT_INC(0),           // 8
       FMT_INC(10),         FMT_INC(10),         FMT_INC(10),          // 64
@@ -960,11 +956,14 @@ FMT_INLINE uint64_t count_digits_inc(int n) {
 
 // Optional version of count_digits for better performance on 32-bit platforms.
 FMT_CONSTEXPR20 inline auto count_digits(uint32_t n) -> int {
-  if (is_constant_evaluated()) return count_digits_fallback(n);
-  auto inc = count_digits_inc(FMT_BUILTIN_CLZ(n | 1) ^ 31);
-  return static_cast<int>((n + inc) >> 32);
-}
+#ifdef FMT_BUILTIN_CLZ
+  if (!is_constant_evaluated()) {
+    auto inc = count_digits_inc(FMT_BUILTIN_CLZ(n | 1) ^ 31);
+    return static_cast<int>((n + inc) >> 32);
+  }
 #endif
+  return count_digits_fallback(n);
+}
 
 template <typename Int> constexpr auto digits10() FMT_NOEXCEPT -> int {
   return std::numeric_limits<Int>::digits10;