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Re: [Qemu-devel] [PATCH] ppc: Convert op_440_dlmzb to TCG
From: |
Laurent Desnogues |
Subject: |
Re: [Qemu-devel] [PATCH] ppc: Convert op_440_dlmzb to TCG |
Date: |
Sun, 30 Nov 2008 18:40:27 +0100 |
On Sun, Nov 30, 2008 at 6:25 PM, Andreas Färber <address@hidden> wrote:
>
> Am 30.11.2008 um 17:31 schrieb Aurélien Jarno:
>>
>> 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.
Going for a helper might be better for larger sequences of TCG ops;
Fabrice mentions a threshold of about 20 ops. And your replacement
is certainly larger than 20 ops :-) Plus given it uses brcond, it would
prevent TCG liveness analysis from doing its job in the basic block
containing that instruction.
Laurent
> 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
>>
>>
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