[Bug target/95076] Failure to tail-call on function call of different return type

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95076

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Failure to optimize out     |Failure to tail-call on
                   |stack alignment on function |function call of different
                   |call of different type on   |return type
                   |x86                         |
                 CC|                            |hjl.tools at gmail dot com
             Target|                            |x86_64-*-* i?86-*-*

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC doesn't tail-call because the return types are not compatible.  With a call
it cannot optimize the stack adjustment because of the ABI.

Note I'm not sure whether the ABI allows %rax to contain "garbage" in the
upper half for a function returning in %eax.  So what LLVM does may be wrong.