Many thanks to H.J. for pointing out a better idiom for traversing
the USEs (and also DEFs) of TImode registers in an instruction.

This revised patched has been tested on x86_64-pc-linux-gnu with
make bootstrap and make -k check, both with and without
--target_board=unix{-m32}, with no new failures.  Ok for mainline?


2022-07-30  Roger Sayle  <roger@nextmovesoftware.com>
            H.J. Lu  <hjl.tools@gmail.com>

gcc/ChangeLog
        PR target/106450
        * config/i386/i386-features.cc (timode_check_non_convertible_regs):
        Do nothing if REGNO is set in the REGS bitmap, or is a hard reg.
        (timode_remove_non_convertible_regs): Update comment.
        Call timode_check_non_convertible_reg on all TImode register
        DEFs and USEs in each instruction.

gcc/testsuite/ChangeLog
        PR target/106450
        * gcc.target/i386/pr106450.c: New test case.


Thanks (H.J. and Uros),
Roger
--

> -----Original Message-----
> From: H.J. Lu <hjl.tools@gmail.com>
> Sent: 28 July 2022 17:55
> To: Roger Sayle <roger@nextmovesoftware.com>
> Cc: GCC Patches <gcc-patches@gcc.gnu.org>
> Subject: Re: [x86_64 PATCH] PR target/106450: Tweak
> timode_remove_non_convertible_regs.
> 
> On Thu, Jul 28, 2022 at 9:43 AM Roger Sayle <roger@nextmovesoftware.com>
> wrote:
> >
> > This patch resolves PR target/106450, some more fall-out from more
> > aggressive TImode scalar-to-vector (STV) optimizations.  I continue to
> > be caught out by how far TImode STV has diverged from DImode/SImode
> > STV, and therefore requires additional (unexpected) tweaking.  Many
> > thanks to H.J. Lu for pointing out timode_remove_non_convertible_regs
> > needs to be extended to handle XOR (and other new operations).
> >
> > Unhelpfully the comment above this function states that it's the
> > TImode version of "remove_non_convertible_regs", which doesn't exist
> > anymore, so I've resurrected an explanatory comment from the git history.
> > By refactoring the checks for hard regs and already "marked" regs into
> > timode_check_non_convertible_regs itself, all its callers are
> > simplified.  This patch then uses GET_RTX_CLASS to generically handle
> > unary and binary operations, calling timode_check_non_convertible_regs
> > on each TImode register operand in the single_set's SET_SRC.
> >
> > This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> > and make -k check, both with and without --target_board=unix{-m32},
> > with no new failures.  Ok for mainline?
> >
> >
> > 2022-07-28  Roger Sayle  <roger@nextmovesoftware.com>
> >
> > gcc/ChangeLog
> >         PR target/106450
> >         * config/i386/i386-features.cc (timode_check_non_convertible_regs):
> >         Do nothing if REGNO is set in the REGS bitmap, or is a hard reg.
> >         (timode_remove_non_convertible_regs): Update comment.
> >         Call timode_check_non_convertible_regs on all register operands
> >         of supported (binary and unary) operations.
> 
> Should we use
> 
> df_ref ref;
> FOR_EACH_INSN_USE (ref, insn)
>    if (!DF_REF_REG_MEM_P (ref))
>      timode_check_non_convertible_regs (candidates, regs,
>               DF_REF_REGNO (ref));
> 
> to check each use?
> 
> > gcc/testsuite/ChangeLog
> >         PR target/106450
> >         * gcc.target/i386/pr106450.c: New test case.
> >
> >
> > Thanks in advance,
> > Roger
> > --
> --
> H.J.