https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109471
Bug ID: 109471
Summary: Missing loop unrolling for small std::vector?
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: stefano.d at posteo dot de
Target Milestone: ---
Hi,
I did some benchmarks where I wanted to bench a switch-case statement against a
small std::vector. In GCC 12.2 the result was as expected: The switch-case
statement was faster than the linear search in std::vector. But when I switched
to clang 13 or above, the std::vector implementation was much faster than the
switch-case statement!
You can the results here:
https://quick-bench.com/q/9DEDS7rQm0MnIFxwZt3A2iD86G0
Please switch here between GCC and clang.
Here an assembly output:
https://godbolt.org/z/j8oenP8x9
Kind regards
Stefano
