Re: [Qemu-devel] [PATCH] ppc: Convert op_440_dlmzb to TCG

[Andreas Färber]

Am 30.11.2008 um 17:31 schrieb Aurélien Jarno:

> On Sat, Nov 29, 2008 at 03:35:21PM +0100, Andreas Färber wrote:
> > Replace {op,do}_440_dlmzb and op_440_dlmzb_update_Rc with inline TCG
> > instructions.
> >
> > The two loops of do_440_dlmzb are unrolled.
> >
> > Signed-off-by: Andreas Faerber <address@hidden>
>
> Doing loops with TCG is a bad idea as it is very inefficient.

Did you read the code? There is no loop in TCG here, that's exactly  
what I was saying.
The labels are for conditionals only and for exiting the non-loop.

If you have a better suggestion, please say so as this is one of the  
dyngen ops that keep me from working on the conversion on my own system.

Andreas

> > ---
> > Compile-tested on Linux/amd64.
> >
> > diff --git a/target-ppc/op.c b/target-ppc/op.c
> > index 5d2cfa1..a26b1da 100644
> > --- a/target-ppc/op.c
> > +++ b/target-ppc/op.c
> > @@ -839,25 +839,6 @@ void OPPROTO op_4xx_tlbwe_hi (void)
> > }
> > #endif
> >
> > -/* SPR micro-ops */
> > -/* 440 specific */
> > -void OPPROTO op_440_dlmzb (void)
> > -{
> > -    do_440_dlmzb();
> > -    RETURN();
> > -}
> > -
> > -void OPPROTO op_440_dlmzb_update_Rc (void)
> > -{
> > -    if (T0 == 8)
> > -        T0 = 0x2;
> > -    else if (T0 < 4)
> > -        T0 = 0x4;
> > -    else
> > -        T0 = 0x8;
> > -    RETURN();
> > -}
> > -
> > #if !defined(CONFIG_USER_ONLY)
> > void OPPROTO op_store_pir (void)
> > {
> > diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
> > index 6addc74..a055ee6 100644
> > --- a/target-ppc/op_helper.c
> > +++ b/target-ppc/op_helper.c
> > @@ -1754,27 +1754,6 @@ void do_store_403_pb (int num)
> > }
> > #endif
> >
> > -/* 440 specific */
> > -void do_440_dlmzb (void)
> > -{
> > -    target_ulong mask;
> > -    int i;
> > -
> > -    i = 1;
> > -    for (mask = 0xFF000000; mask != 0; mask = mask >> 8) {
> > -        if ((T0 & mask) == 0)
> > -            goto done;
> > -        i++;
> > -    }
> > -    for (mask = 0xFF000000; mask != 0; mask = mask >> 8) {
> > -        if ((T1 & mask) == 0)
> > -            break;
> > -        i++;
> > -    }
> > - done:
> > -    T0 = i;
> > -}
> > -
> > /
> > *****************************************************************************/
> > /* SPE extension helpers */
> > /* Use a table to make this quicker */
> > diff --git a/target-ppc/op_helper.h b/target-ppc/op_helper.h
> > index 1c046d8..aaaba5c 100644
> > --- a/target-ppc/op_helper.h
> > +++ b/target-ppc/op_helper.h
> > @@ -112,9 +112,6 @@ void do_4xx_tlbwe_lo (void);
> > void do_4xx_tlbwe_hi (void);
> > #endif
> >
> > -/* PowerPC 440 specific helpers */
> > -void do_440_dlmzb (void);
> > -
> > /* PowerPC 403 specific helpers */
> > #if !defined(CONFIG_USER_ONLY)
> > void do_load_403_pb (int num);
> > diff --git a/target-ppc/translate.c b/target-ppc/translate.c
> > index 95cb482..59533ac 100644
> > --- a/target-ppc/translate.c
> > +++ b/target-ppc/translate.c
> > @@ -5872,12 +5872,49 @@ GEN_HANDLER(dlmzb, 0x1F, 0x0E, 0x02,
> > 0x00000000, PPC_440_SPEC)
> > {
> >     tcg_gen_mov_tl(cpu_T[0], cpu_gpr[rS(ctx->opcode)]);
> >     tcg_gen_mov_tl(cpu_T[1], cpu_gpr[rB(ctx->opcode)]);
> > -    gen_op_440_dlmzb();
> > +    TCGv t0 = tcg_temp_new();
> > +    int endLabel = gen_new_label();
> > +    int i = 1;
> > +    target_ulong mask;
> > +    for (mask = 0xFF000000; mask != 0; mask = mask >> 8) {
> > +        tcg_gen_andi_tl(t0, cpu_T[0], mask);
> > +        int nextLabel = gen_new_label();
> > +        tcg_gen_brcondi_tl(TCG_COND_NE, t0, 0, nextLabel);
> > +        tcg_gen_movi_tl(cpu_T[0], i++);
> > +        tcg_gen_br(endLabel);
> > +        gen_set_label(nextLabel);
> > +    }
> > +    for (mask = 0xFF000000; mask != 0; mask = mask >> 8) {
> > +        tcg_gen_andi_tl(t0, cpu_T[1], mask);
> > +        int nextLabel = gen_new_label();
> > +        tcg_gen_brcondi_tl(TCG_COND_NE, t0, 0, nextLabel);
> > +        tcg_gen_movi_tl(cpu_T[0], i++);
> > +        tcg_gen_br(endLabel);
> > +        gen_set_label(nextLabel);
> > +    }
> > +    tcg_gen_movi_tl(cpu_T[0], i);
> > +    gen_set_label(endLabel);
> > +    tcg_temp_free(t0);
> >     tcg_gen_mov_tl(cpu_gpr[rA(ctx->opcode)], cpu_T[0]);
> >     tcg_gen_andi_tl(cpu_xer, cpu_xer, ~0x7F);
> >     tcg_gen_or_tl(cpu_xer, cpu_xer, cpu_T[0]);
> >     if (Rc(ctx->opcode)) {
> > -        gen_op_440_dlmzb_update_Rc();
> > +        endLabel = gen_new_label();
> > +        int nextLabel = gen_new_label();
> > +        tcg_gen_brcondi_tl(TCG_COND_NE, cpu_T[0], 8, nextLabel);
> > +        tcg_gen_movi_tl(cpu_T[0], 0x2);
> > +        tcg_gen_br(endLabel);
> > +
> > +        gen_set_label(nextLabel);
> > +        nextLabel = gen_new_label();
> > +        tcg_gen_brcondi_tl(TCG_COND_GE, cpu_T[0], 4, nextLabel);
> > +        tcg_gen_movi_tl(cpu_T[0], 0x4);
> > +        tcg_gen_br(endLabel);
> > +
> > +        gen_set_label(nextLabel);
> > +        tcg_gen_movi_tl(cpu_T[0], 0x8);
> > +
> > +        gen_set_label(endLabel);
> >         tcg_gen_trunc_tl_i32(cpu_crf[0], cpu_T[0]);
> >         tcg_gen_andi_i32(cpu_crf[0], cpu_crf[0], 0xf);
> >     }
>
>
> >
>
>
> --
>  .''`.  Aurelien Jarno              | GPG: 1024D/F1BCDB73
> : :' :  Debian developer           | Electrical Engineer
> `. `'   address@hidden         | address@hidden
>   `-    people.debian.org/~aurel32 | www.aurel32.net