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script: actually trigger the optimization in BuildScript

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The counter is an optimization over calling `ret.empty()`. It was
suggested that the compiler would realize `cnt` is only `0` on the first
iteration, and not actually emit the check and conditional.

This optimization was actually not triggered at all, since we
incremented `cnt` at the beginning of the first iteration. Fix it by
incrementing at the end instead.

This was reported by Github user "Janus".
This commit is contained in:
Antoine Poinsot 2022-07-26 13:02:48 +02:00
parent 31c1b14754
commit 00897d0677
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GPG key ID: E13FC145CD3F4304
1 changed files with 1 additions and 1 deletions
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src/script/script.h
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@ -588,7 +588,6 @@ CScript BuildScript(Ts&&... inputs)
int cnt{0}; int cnt{0};
([&ret, &cnt] (Ts&& input) { ([&ret, &cnt] (Ts&& input) {
cnt++;
if constexpr (std::is_same_v<std::remove_cv_t<std::remove_reference_t<Ts>>, CScript>) { if constexpr (std::is_same_v<std::remove_cv_t<std::remove_reference_t<Ts>>, CScript>) {
// If it is a CScript, extend ret with it. Move or copy the first element instead. // If it is a CScript, extend ret with it. Move or copy the first element instead.
if (cnt == 0) { if (cnt == 0) {
@ -600,6 +599,7 @@ CScript BuildScript(Ts&&... inputs)
// Otherwise invoke CScript::operator<<. // Otherwise invoke CScript::operator<<.
ret << input; ret << input;
} }
cnt++;
} (std::forward<Ts>(inputs)), ...); } (std::forward<Ts>(inputs)), ...);
return ret; return ret;