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Re: [Qemu-devel] [PATCH] tcg: Use bitmaps for free temporaries
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH] tcg: Use bitmaps for free temporaries |
Date: |
Sat, 07 Dec 2013 06:47:51 +1300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 |
Ping.
r~
On 11/19/2013 07:57 PM, Richard Henderson wrote:
> Ping?
>
> r~
>
> On 09/20/2013 05:58 AM, Richard Henderson wrote:
>> We previously allocated 32-bits per temp for the next_free_temp entry.
>> We now allocate 4 bits per temp across the 4 bitmaps.
>>
>> Using a linked list meant that if a translator is tweeked, resulting in
>> temps being freed in a different order, that would have follow-on effects
>> throughout the TB. Always allocating the lowest free temp means that
>> follow-on effects are minimized, which can make it easier to diff output
>> when debugging the translators.
>>
>> Signed-off-by: Richard Henderson <address@hidden>
>> ---
>> tcg/tcg.c | 32 +++++++++++++++-----------------
>> tcg/tcg.h | 11 ++++++-----
>> 2 files changed, 21 insertions(+), 22 deletions(-)
>>
>> diff --git a/tcg/tcg.c b/tcg/tcg.c
>> index fd7fb6b..41ed8b0 100644
>> --- a/tcg/tcg.c
>> +++ b/tcg/tcg.c
>> @@ -316,11 +316,12 @@ void tcg_set_frame(TCGContext *s, int reg, intptr_t
>> start, intptr_t size)
>>
>> void tcg_func_start(TCGContext *s)
>> {
>> - int i;
>> tcg_pool_reset(s);
>> s->nb_temps = s->nb_globals;
>> - for(i = 0; i < (TCG_TYPE_COUNT * 2); i++)
>> - s->first_free_temp[i] = -1;
>> +
>> + /* No temps have been previously allocated for size or locality. */
>> + memset(s->free_temps, 0, sizeof(s->free_temps));
>> +
>> s->labels = tcg_malloc(sizeof(TCGLabel) * TCG_MAX_LABELS);
>> s->nb_labels = 0;
>> s->current_frame_offset = s->frame_start;
>> @@ -468,16 +469,15 @@ static inline int tcg_temp_new_internal(TCGType type,
>> int temp_local)
>> TCGTemp *ts;
>> int idx, k;
>>
>> - k = type;
>> - if (temp_local)
>> - k += TCG_TYPE_COUNT;
>> - idx = s->first_free_temp[k];
>> - if (idx != -1) {
>> - /* There is already an available temp with the
>> - right type */
>> + k = type + (temp_local ? TCG_TYPE_COUNT : 0);
>> + idx = find_first_bit(s->free_temps[k].l, TCG_MAX_TEMPS);
>> + if (idx < TCG_MAX_TEMPS) {
>> + /* There is already an available temp with the right type. */
>> + clear_bit(idx, s->free_temps[k].l);
>> +
>> ts = &s->temps[idx];
>> - s->first_free_temp[k] = ts->next_free_temp;
>> ts->temp_allocated = 1;
>> + assert(ts->base_type == type);
>> assert(ts->temp_local == temp_local);
>> } else {
>> idx = s->nb_temps;
>> @@ -533,7 +533,7 @@ TCGv_i64 tcg_temp_new_internal_i64(int temp_local)
>> return MAKE_TCGV_I64(idx);
>> }
>>
>> -static inline void tcg_temp_free_internal(int idx)
>> +static void tcg_temp_free_internal(int idx)
>> {
>> TCGContext *s = &tcg_ctx;
>> TCGTemp *ts;
>> @@ -550,11 +550,9 @@ static inline void tcg_temp_free_internal(int idx)
>> ts = &s->temps[idx];
>> assert(ts->temp_allocated != 0);
>> ts->temp_allocated = 0;
>> - k = ts->base_type;
>> - if (ts->temp_local)
>> - k += TCG_TYPE_COUNT;
>> - ts->next_free_temp = s->first_free_temp[k];
>> - s->first_free_temp[k] = idx;
>> +
>> + k = ts->type + (ts->temp_local ? TCG_TYPE_COUNT : 0);
>> + set_bit(idx, s->free_temps[k].l);
>> }
>>
>> void tcg_temp_free_i32(TCGv_i32 arg)
>> diff --git a/tcg/tcg.h b/tcg/tcg.h
>> index 902c751..c45e41b 100644
>> --- a/tcg/tcg.h
>> +++ b/tcg/tcg.h
>> @@ -26,7 +26,7 @@
>> #define TCG_H
>>
>> #include "qemu-common.h"
>> -
>> +#include "qemu/bitops.h"
>> #include "tcg-target.h"
>>
>> /* Default target word size to pointer size. */
>> @@ -400,8 +400,6 @@ typedef struct TCGTemp {
>> basic blocks. Otherwise, it is not
>> preserved across basic blocks. */
>> unsigned int temp_allocated:1; /* never used for code gen */
>> - /* index of next free temp of same base type, -1 if end */
>> - int next_free_temp;
>> const char *name;
>> } TCGTemp;
>>
>> @@ -412,6 +410,10 @@ typedef struct TCGHelperInfo {
>>
>> typedef struct TCGContext TCGContext;
>>
>> +typedef struct TCGTempSet {
>> + unsigned long l[BITS_TO_LONGS(TCG_MAX_TEMPS)];
>> +} TCGTempSet;
>> +
>> struct TCGContext {
>> uint8_t *pool_cur, *pool_end;
>> TCGPool *pool_first, *pool_current, *pool_first_large;
>> @@ -419,8 +421,6 @@ struct TCGContext {
>> int nb_labels;
>> int nb_globals;
>> int nb_temps;
>> - /* index of free temps, -1 if none */
>> - int first_free_temp[TCG_TYPE_COUNT * 2];
>>
>> /* goto_tb support */
>> uint8_t *code_buf;
>> @@ -446,6 +446,7 @@ struct TCGContext {
>>
>> uint8_t *code_ptr;
>> TCGTemp temps[TCG_MAX_TEMPS]; /* globals first, temps after */
>> + TCGTempSet free_temps[TCG_TYPE_COUNT * 2];
>>
>> TCGHelperInfo *helpers;
>> int nb_helpers;
>>
>
- Re: [Qemu-devel] [PATCH] tcg: Use bitmaps for free temporaries,
Richard Henderson <=