From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38551) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dLQFB-0000c5-QG for qemu-devel@nongnu.org; Thu, 15 Jun 2017 04:35:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dLQF8-0007Tw-IG for qemu-devel@nongnu.org; Thu, 15 Jun 2017 04:35:09 -0400 Received: from mail-lf0-x22c.google.com ([2a00:1450:4010:c07::22c]:34494) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1dLQF8-0007TK-BW for qemu-devel@nongnu.org; Thu, 15 Jun 2017 04:35:06 -0400 Received: by mail-lf0-x22c.google.com with SMTP id v20so4335679lfa.1 for ; Thu, 15 Jun 2017 01:35:06 -0700 (PDT) References: <20170614194821.8754-1-rth@twiddle.net> <20170614194821.8754-2-rth@twiddle.net> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <20170614194821.8754-2-rth@twiddle.net> Date: Thu, 15 Jun 2017 09:35:39 +0100 Message-ID: <87wp8dmyw4.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH v2 1/5] tcg: Refactor helper_lookup_tb_ptr List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: qemu-devel@nongnu.org, cota@braap.org, pbonzini@redhat.com Richard Henderson writes: > We can call tb_htable_lookup even when the tb_jmp_cache > is completely empty. Therefore, un-nest most of the code > dependent on tb != NULL from the read from the cache. > > Signed-off-by: Richard Henderson Reviewed-by: Alex Bennée > --- > tcg-runtime.c | 34 ++++++++++++++++++---------------- > 1 file changed, 18 insertions(+), 16 deletions(-) > > diff --git a/tcg-runtime.c b/tcg-runtime.c > index 7fa90ce..a35c725 100644 > --- a/tcg-runtime.c > +++ b/tcg-runtime.c > @@ -147,30 +147,32 @@ uint64_t HELPER(ctpop_i64)(uint64_t arg) > void *HELPER(lookup_tb_ptr)(CPUArchState *env, target_ulong addr) > { > CPUState *cpu = ENV_GET_CPU(env); > + void *ret = tcg_ctx.code_gen_epilogue; > TranslationBlock *tb; > target_ulong cs_base, pc; > - uint32_t flags; > - > - tb = atomic_rcu_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(addr)]); > - if (likely(tb)) { > - cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); > - if (likely(tb->pc == addr && tb->cs_base == cs_base && > - tb->flags == flags)) { > - goto found; > - } > + uint32_t flags, addr_hash; > + > + addr_hash = tb_jmp_cache_hash_func(addr); > + tb = atomic_rcu_read(&cpu->tb_jmp_cache[addr_hash]); > + cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); > + > + if (unlikely(!(tb > + && tb->pc == addr > + && tb->cs_base == cs_base > + && tb->flags == flags))) { > tb = tb_htable_lookup(cpu, addr, cs_base, flags); > - if (likely(tb)) { > - atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(addr)], tb); > - goto found; > + if (!tb) { > + return ret; > } > + atomic_set(&cpu->tb_jmp_cache[addr_hash], tb); > } > - return tcg_ctx.code_gen_epilogue; > - found: > + > + ret = tb->tc_ptr; > qemu_log_mask_and_addr(CPU_LOG_EXEC, addr, > "Chain %p [%d: " TARGET_FMT_lx "] %s\n", > - tb->tc_ptr, cpu->cpu_index, addr, > + ret, cpu->cpu_index, addr, > lookup_symbol(addr)); > - return tb->tc_ptr; > + return ret; > } > > void HELPER(exit_atomic)(CPUArchState *env) -- Alex Bennée