Re: [x86_64 PATCH] PR target/106450: Tweak timode_remove_non_convertible_regs.

["H.J. Lu" <hjl.tools@gmail.com>]

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.