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From: "pskocik at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/93487] Missed tail-call optimizations
Date: Sun, 26 May 2024 20:41:35 +0000	[thread overview]
Message-ID: <bug-93487-4-Ua9KieE21k@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-93487-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93487

--- Comment #5 from Petr Skocik <pskocik at gmail dot com> ---
Another case of a missed tailcall which might warrant a separate mention:

    struct big{ long _[10]; };
    void takePtr(void *);
    void takeBigAndPassItsAddress(struct big X){ takePtr(&X); }

This should ideally compile to just `lea 8(%rsp), %rdi; jmp takePtr;`.

The compiler might be tempted here to use the taking of an address of a local
here
as a reason not to tail call, and clang misses this optimization too, probably
for this reason,
but tailcalling here is fine as the particular local here isn't
allocated by the function but rather the callee during the call.

Icc does do this optimization: https://godbolt.org/z/a6coTzPjz

      parent reply	other threads:[~2024-05-26 20:41 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-93487-4@http.gcc.gnu.org/bugzilla/>
2020-04-20  6:07 ` pskocik at gmail dot com
2021-08-22  0:16 ` pinskia at gcc dot gnu.org
2024-05-26 20:41 ` pskocik at gmail dot com [this message]

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