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From: Taylor Simpson <tsimpson@quicinc.com>
To: Richard Henderson <richard.henderson@linaro.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: "ale@rev.ng" <ale@rev.ng>, Brian Cain <bcain@quicinc.com>,
	"philmd@redhat.com" <philmd@redhat.com>
Subject: RE: [PATCH v2 01/21] Hexagon (target/hexagon) TCG generation cleanup
Date: Fri, 2 Apr 2021 19:42:17 +0000	[thread overview]
Message-ID: <BYAPR02MB48860C83CC91FDFC9D9DC06DDE7A9@BYAPR02MB4886.namprd02.prod.outlook.com> (raw)
In-Reply-To: <0cbf66d0-e306-972a-ca39-aadae2e9dc27@linaro.org>


> -----Original Message-----
> From: Richard Henderson <richard.henderson@linaro.org>
> Sent: Friday, April 2, 2021 12:47 PM
> To: Taylor Simpson <tsimpson@quicinc.com>; qemu-devel@nongnu.org
> Cc: philmd@redhat.com; ale@rev.ng; Brian Cain <bcain@quicinc.com>
> Subject: Re: [PATCH v2 01/21] Hexagon (target/hexagon) TCG generation
> cleanup
>
> On 3/31/21 8:53 PM, Taylor Simpson wrote:
> > Simplify TCG generation of hex_reg_written
> >
> > Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> > Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
> > ---
> >   target/hexagon/genptr.c | 14 +++++++++-----
> >   1 file changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/target/hexagon/genptr.c b/target/hexagon/genptr.c
> > index 7481f4c..87f5d92 100644
> > --- a/target/hexagon/genptr.c
> > +++ b/target/hexagon/genptr.c
> > @@ -35,7 +35,6 @@ static inline TCGv gen_read_preg(TCGv pred, uint8_t
> num)
> >
> >   static inline void gen_log_predicated_reg_write(int rnum, TCGv val, int
> slot)
> >   {
> > -    TCGv one = tcg_const_tl(1);
> >       TCGv zero = tcg_const_tl(0);
> >       TCGv slot_mask = tcg_temp_new();
> >
> > @@ -43,12 +42,17 @@ static inline void gen_log_predicated_reg_write(int
> rnum, TCGv val, int slot)
> >       tcg_gen_movcond_tl(TCG_COND_EQ, hex_new_value[rnum],
> slot_mask, zero,
> >                              val, hex_new_value[rnum]);
> >   #if HEX_DEBUG
> > -    /* Do this so HELPER(debug_commit_end) will know */
> > -    tcg_gen_movcond_tl(TCG_COND_EQ, hex_reg_written[rnum],
> slot_mask, zero,
> > -                       one, hex_reg_written[rnum]);
> > +    /*
> > +     * Do this so HELPER(debug_commit_end) will know
> > +     *
> > +     * Note that slot_mask indicates the value is not written
> > +     * (i.e., slot was cancelled), so we create a true/false value before
> > +     * or'ing with hex_reg_written[rnum].
> > +     */
> > +    tcg_gen_setcond_tl(TCG_COND_EQ, slot_mask, slot_mask, zero);
> > +    tcg_gen_or_tl(hex_reg_written[rnum], hex_reg_written[rnum],
> slot_mask);
> >   #endif
>
> Having looked forward at patch 5, it appears this could be further improved
> by examining ctx->regs_written.

It's not obvious how.  This is for a predicated instruction (e.g., if (p0) r2 = add(r1, r0)), so the checks need to be made at runtime.  There can be more than one predicated instruction in a packet that writes to the same register as long as only one of the predicates is true at runtime.

Am I missing something?


Thanks,
Taylor


  reply	other threads:[~2021-04-02 19:43 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01  3:53 [PATCH v2 00/21] Hexagon (target/hexagon) update Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 01/21] Hexagon (target/hexagon) TCG generation cleanup Taylor Simpson
2021-04-02 17:25   ` Richard Henderson
2021-04-02 17:46   ` Richard Henderson
2021-04-02 19:42     ` Taylor Simpson [this message]
2021-04-02 20:00       ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 02/21] Hexagon (target/hexagon) remove unnecessary inline directives Taylor Simpson
2021-04-02 17:26   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 03/21] Hexagon (target/hexagon) use env_archcpu and env_cpu Taylor Simpson
2021-04-02 17:27   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 04/21] Hexagon (target/hexagon) properly generate TB end for DISAS_NORETURN Taylor Simpson
2021-04-02 17:34   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 05/21] Hexagon (target/hexagon) decide if pred has been written at TCG gen time Taylor Simpson
2021-04-02 17:44   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 06/21] Hexagon (target/hexagon) change variables from int to bool when appropriate Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 07/21] Hexagon (target/hexagon) remove unused carry_from_add64 function Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 08/21] Hexagon (target/hexagon) change type of softfloat_roundingmodes Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 09/21] Hexagon (target/hexagon) use softfloat default NaN and tininess Taylor Simpson
2021-04-02 17:48   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 10/21] Hexagon (target/hexagon) replace float32_mul_pow2 with float32_scalbn Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 11/21] Hexagon (target/hexagon) use softfloat for float-to-int conversions Taylor Simpson
2021-04-06 20:09   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 12/21] Hexagon (target/hexagon) add F2_sfrecipa instruction Taylor Simpson
2021-04-06 20:30   ` Richard Henderson
2021-04-06 20:46   ` Richard Henderson
2021-04-06 21:55     ` Taylor Simpson
2021-04-06 22:13       ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 13/21] Hexagon (target/hexagon) add F2_sfinvsqrta Taylor Simpson
2021-04-06 20:47   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 14/21] Hexagon (target/hexagon) add A5_ACS (vacsh) Taylor Simpson
2021-04-06 20:51   ` Richard Henderson
2021-04-06 21:31     ` Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 15/21] Hexagon (target/hexagon) add A6_vminub_RdP Taylor Simpson
2021-04-06 20:57   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 16/21] Hexagon (target/hexagon) add A4_addp_c/A4_subp_c Taylor Simpson
2021-04-06 21:11   ` Richard Henderson
2021-04-06 21:58     ` Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 17/21] Hexagon (target/hexagon) circular addressing Taylor Simpson
2021-04-06 22:11   ` Richard Henderson
2021-04-07  3:11     ` Taylor Simpson
2021-04-07 16:27       ` Taylor Simpson
2021-04-01  3:53 ` [PATCH v2 18/21] Hexagon (target/hexagon) bit reverse (brev) addressing Taylor Simpson
2021-04-06 22:35   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 19/21] Hexagon (target/hexagon) load and unpack bytes instructions Taylor Simpson
2021-04-06 22:46   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 20/21] Hexagon (target/hexagon) load into shifted register instructions Taylor Simpson
2021-04-06 22:50   ` Richard Henderson
2021-04-01  3:53 ` [PATCH v2 21/21] Hexagon (target/hexagon) CABAC decode bin Taylor Simpson
2021-04-06 22:54   ` Richard Henderson

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