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Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop |
Date: |
Tue, 29 Mar 2016 15:26:55 +0100 |
User-agent: |
mu4e 0.9.17; emacs 25.0.92.2 |
Sergey Fedorov <address@hidden> writes:
> On 29/03/16 16:26, Paolo Bonzini wrote:
>>
>> On 29/03/2016 15:19, Sergey Fedorov wrote:
>>> On 22/03/16 17:59, Alex Bennée wrote:
>>>> address@hidden writes:
>>>>
>>>>> From: Paolo Bonzini <address@hidden>
>>>>>
>>>>> Use a continue statement.
>>>>>
>>>>> Signed-off-by: Paolo Bonzini <address@hidden>
>>>>> [Sergey Fedorov: Fix moving to list head in case of no TB]
>>>>> Signed-off-by: Sergey Fedorov <address@hidden>
>>>>> ---
>>>>> cpu-exec.c | 50 +++++++++++++++++++++++++-------------------------
>>>>> 1 file changed, 25 insertions(+), 25 deletions(-)
>>>>>
>>>>> diff --git a/cpu-exec.c b/cpu-exec.c
>>>>> index fd92452f16f6..f90482eff778 100644
>>>>> --- a/cpu-exec.c
>>>>> +++ b/cpu-exec.c
>>>>> @@ -225,37 +225,37 @@ static TranslationBlock *tb_find_physical(CPUState
>>>>> *cpu,
>>>>> phys_pc = get_page_addr_code(env, pc);
>>>>> phys_page1 = phys_pc & TARGET_PAGE_MASK;
>>>>> h = tb_phys_hash_func(phys_pc);
>>>>> - ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h];
>>>>> - for(;;) {
>>>>> - tb = *ptb1;
>>>>> - if (!tb) {
>>>>> - return NULL;
>>>>> + for (ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h];
>>>>> + (tb = *ptb1) != NULL;
>>>>> + ptb1 = &tb->phys_hash_next) {
>>>> I'm not sure I'm keen on the assignment in the for condition clause. I
>>>> appreciate the cleansing of the if !tb return exit though. Could we be
>>>> cleaner maybe? Here is my attempt:
>>>>
>>>> static TranslationBlock *tb_find_physical(CPUState *cpu,
>>>> target_ulong pc,
>>>> target_ulong cs_base,
>>>> uint64_t flags)
>>>> {
>>>> CPUArchState *env = (CPUArchState *)cpu->env_ptr;
>>>> TranslationBlock *tb, **tb_hash_head, **ptb1;
>>>> unsigned int h;
>>>> tb_page_addr_t phys_pc, phys_page1;
>>>>
>>>> /* find translated block using physical mappings */
>>>> phys_pc = get_page_addr_code(env, pc);
>>>> phys_page1 = phys_pc & TARGET_PAGE_MASK;
>>>> h = tb_phys_hash_func(phys_pc);
>>>>
>>>> /* Start at head of the hash entry */
>>>> ptb1 = tb_hash_head = &tcg_ctx.tb_ctx.tb_phys_hash[h];
>>>> tb = *ptb1;
>>>>
>>>> while (tb) {
>>>>
>>>> if (tb->pc == pc &&
>>>> tb->page_addr[0] == phys_page1 &&
>>>> tb->cs_base == cs_base &&
>>>> tb->flags == flags) {
>>>>
>>>> if (tb->page_addr[1] == -1) {
>>>> /* done, we have a match */
>>>> break;
>>>> } else {
>>>> /* check next page if needed */
>>>> target_ulong virt_page2 = (pc & TARGET_PAGE_MASK)
>>>> + TARGET_PAGE_SIZE;
>>>> tb_page_addr_t phys_page2 = get_page_addr_code(env,
>>>> virt_page2);
>>>>
>>>> if (tb->page_addr[1] == phys_page2) {
>>>> break;
>>>> }
>>>> }
>>>> }
>>>>
>>>> ptb1 = &tb->phys_hash_next;
>>>> tb = *ptb1;
>>>> }
>>>>
>>>> if (tb) {
>>>> /* Move the TB to the head of the list */
>>>> *ptb1 = tb->phys_hash_next;
>>>> tb->phys_hash_next = *tb_hash_head;
>>>> *tb_hash_head = tb;
>>>> }
>>>> return tb;
>>>> }
>>>>
>>>> FWIW the compiled code is 9 bytes shorter on my machine.
>>> Looks like another attempt to rewrite it. I am wondering whom to
>>> attribute as an author, then? :)
>> I don't really care. :)
>
> Alex, could you give your s-o-b for your variant of code? Or would you
> like to make a patch by yourself?
Sure here:
Signed-off-by: Alex Bennée <address@hidden>
>
> Kind regards,
> Sergey
--
Alex Bennée
- [Qemu-devel] [PATCH 5/5] tcg: move tb_invalidated_flag to CPUState, (continued)
- [Qemu-devel] [PATCH 5/5] tcg: move tb_invalidated_flag to CPUState, sergey . fedorov, 2016/03/17
- [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, sergey . fedorov, 2016/03/17
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, Peter Maydell, 2016/03/17
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, Alex Bennée, 2016/03/22
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, Paolo Bonzini, 2016/03/22
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, Sergey Fedorov, 2016/03/29
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, Paolo Bonzini, 2016/03/29
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, Sergey Fedorov, 2016/03/29
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop,
Alex Bennée <=
- Re: [Qemu-devel] [PATCH 2/5] tcg: reorganize tb_find_physical loop, Sergey Fedorov, 2016/03/29
[Qemu-devel] [PATCH 1/5] tcg: code_bitmap is not used by user-mode emulation, sergey . fedorov, 2016/03/17