On Mon, Mar 26, 2012 at 10:25 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
> Hello!
>
> In a corner case of a reload, reload pass can generate partially
> reloaded address, where not all registers get allocated to a hard reg.
> When this address is checked with ix86_legitimate_address, it is
> rejected, since in strict mode, pseudos are not valid address
> registers. So, reload tries to legitimize following (partially
> invalid) address:
>
> (plus:DI (plus:DI (unspec:DI [(const_int 0 [0])] UNSPEC_TP)
> (reg:DI 97))
> (reg:DI 2 cx))
>
> via generic way by pushing all components into a register, forming
> (even more invalid) address that involves three registers (r8, r9 and
> rcx):
>
> (insn 52 78 53 5 (set (mem/j:QI (plus:DI (plus:DI (reg:DI 37 r8)
> (reg:DI 38 r9))
> (reg:DI 2 cx [orig:98 D.1709 ] [98])) [0 foo S1 A8])
> (reg:QI 1 dx [100])) /tmp/x.c:12 66 {*movqi_internal}
> (nil))
>
> BTW: x86 declares MAX_REGISTER_PER_ADDRESS to 2...
>
> Attached patch fixes this situation by (partially) reloading only
> remaining pseudo(s), leaving UNSPEC in the address RTX.
>
> 2012-03-26 Uros Bizjak <ubiz...@gmail.com>
>
> PR target/52698
> * config/i386/i386-protos.h (ix86_legitimize_reload_address):
> New prototype.
> * config/i386/i386.h (LEGITIMIZE_RELOAD_ADDRESS): New define.
> * config/i386/i386.c: Include reload.h.
> (ix86_legitimize_reload_address): New function.
>
> testsuite/ChangeLog:
>
> 2012-03-26 Uros Bizjak <ubiz...@gmail.com>
> H.J. Lu <hongjiu...@intel.com>
>
> PR target/52698
> * gcc.target/i386/pr52698.c: New test.
>
> The patch was bootstrapped and regression tested on x86_64-pc-linux-gnu
> {,-m32}.
>
> Since fixing reload issues is some kind of black magic, I'd like to
> ask Ulrich and Richard for their opinion on this approach.
>
> H.J., can you please test this fix on x32 testsuite for both address modes?
>
I am on it.
--
H.J.
