It is my understanding that this is precisely what recent Perl implementations do.

Then your understanding is flawed. There's a cache, but it only holds one value: the last regexp compiled for that operator instance. 

>perl -Mre=debug -e"qr/$_/ for qw( foo bar bar foo )" 2>&1 | find "Com
+piling"
Compiling REx `foo'
Compiling REx `bar'
Compiling REx `foo'

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In reply to Re^2: Precompiling qr/.../o question by ikegami
in thread Precompiling qr/.../o question by vit

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