Avoiding __builtin_strlen #4429
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vitaut
requested changes
Apr 26, 2025
Makes sense, done. |
mwinterb
reviewed
Apr 26, 2025
| @@ -539,7 +539,7 @@ template <typename Char> class basic_string_view { | |||
| #endif | |||
| FMT_CONSTEXPR20 basic_string_view(const Char* s) : data_(s) { | |||
| #if FMT_HAS_BUILTIN(__builtin_strlen) || FMT_GCC_VERSION || FMT_CLANG_VERSION | |||
| if (std::is_same<Char, char>::value) { | |||
| if (std::is_same<Char, char>::value && !detail::is_constant_evaluated()) { | |||
| size_ = __builtin_strlen(detail::narrow(s)); | |||
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What's the advantage of still using __builtin_strlen? Will gcc or clang still end up producing a constant in some scenarios that they wouldn't if just strlen was used?
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Well... libstdc++ __builtin_strlen in char_traits, so I guess there's that.
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There was some benefit to the debug codegen at some point but probably no longer matters on newer compilers.
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More importantly, strlen is not constexpr.
vitaut
reviewed
Apr 27, 2025
|
Merged, thanks! |
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The added test fails on gcc 14 because of the call to
__builtin_strlen, so just avoiding it during constant evaluation. Fixed #4423.