From: Richard Biener <rguenther@suse.de>
To: Jeff Law <law@redhat.com>
Cc: gcc-patches@gcc.gnu.org, segher@kernel.crashing.org,
joseph@codesourcery.com, jakub@redhat.com, hp@bitrange.com,
will_schmidt@vnet.ibm.com
Subject: Re: [PATCH v5] rtl: builtins: (not just) rs6000: Add builtins for fegetround, feclearexcept and feraiseexcept [PR94193]
Date: Wed, 18 Nov 2020 08:31:28 +0100 (CET) [thread overview]
Message-ID: <nycvar.YFH.7.76.2011180830240.5418@zhemvz.fhfr.qr> (raw)
In-Reply-To: <1c09d2bc-da08-523a-709d-ec11140af3f0@redhat.com>
On Tue, 17 Nov 2020, Jeff Law wrote:
>
>
> On 11/4/20 8:10 AM, Raoni Fassina Firmino via Gcc-patches wrote:
> > On Wed, Nov 04, 2020 at 10:35:03AM +0100, Richard Biener wrote:
> >>> +/* Expand call EXP to the fegetround builtin (from C99 fenv.h), returning the
> >>> + result and setting it in TARGET. Otherwise return NULL_RTX on failure. */
> >>> +static rtx
> >>> +expand_builtin_fegetround (tree exp, rtx target, machine_mode target_mode)
> >>> +{
> >>> + if (!validate_arglist (exp, VOID_TYPE))
> >>> + return NULL_RTX;
> >>> +
> >>> + insn_code icode = direct_optab_handler (fegetround_optab, SImode);
> >>> + if (icode == CODE_FOR_nothing)
> >>> + return NULL_RTX;
> >>> +
> >>> + if (target == 0
> >>> + || GET_MODE (target) != target_mode
> >>> + || !(*insn_data[icode].operand[0].predicate) (target, target_mode))
> >>> + target = gen_reg_rtx (target_mode);
> >>> +
> >>> + rtx pat = GEN_FCN (icode) (target);
> >>> + if (!pat)
> >>> + return NULL_RTX;
> >>> + emit_insn (pat);
> >> I think you need to verify whether the expansion ended up in 'target'
> >> and otherwise emit a move since usually 'target' is just a hint.
> > I thought the "if (target == 0 ..." took care of that. The expands do
> > emit a move, if that helps.
> It looks like if we have a passed in target and it either has the wrong
> mode or it does not match the predicate, then we generaet a new target
> and use that instead.? I don't see where we'd copy from that new target
> to the original desired target.? For some expanders the caller would
> handle that, but I don't see how that's possible for this one without
> the caller digging into the generated RTL to determine that
> expand_builtin_fegetround put the result somewhere other than TARGET and
> thus a copy is needed.
>
> That may be what Richi is worried about.
I know we've added missing
if (!rtx_equal_p (target, ops[0].value))
emit_move_insn (target, ops[0].value);
to several expanders (using expand_insn rather than manual
GEN_FCN (icode) calls).
Richard.
next prev parent reply other threads:[~2020-11-18 7:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 23:12 Raoni Fassina Firmino
2020-11-04 9:35 ` Richard Biener
2020-11-04 15:10 ` Raoni Fassina Firmino
2020-11-04 21:06 ` Joseph Myers
2020-11-17 22:19 ` Jeff Law
2020-11-18 7:31 ` Richard Biener [this message]
2020-11-18 12:38 ` Segher Boessenkool
2020-11-18 21:45 ` Jeff Law
2021-01-07 14:20 ` Raoni Fassina Firmino
2020-11-17 22:23 ` Jeff Law
2021-01-07 14:20 ` Raoni Fassina Firmino
2021-01-14 17:40 ` Segher Boessenkool
2020-11-04 21:20 ` Joseph Myers
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