From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:37587) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hIqPM-0000s7-Qn for qemu-devel@nongnu.org; Tue, 23 Apr 2019 04:04:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hIqPL-0002yO-BQ for qemu-devel@nongnu.org; Tue, 23 Apr 2019 04:04:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47356) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hIqPL-0002yB-3A for qemu-devel@nongnu.org; Tue, 23 Apr 2019 04:04:03 -0400 References: <20190420073442.7488-1-richard.henderson@linaro.org> <20190420073442.7488-3-richard.henderson@linaro.org> From: David Hildenbrand Message-ID: <834f5c7b-c6b5-87b8-2154-3a3875726343@redhat.com> Date: Tue, 23 Apr 2019 10:03:59 +0200 MIME-Version: 1.0 In-Reply-To: <20190420073442.7488-3-richard.henderson@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 02/38] tcg: Assert fixed_reg is read-only List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson , qemu-devel@nongnu.org On 20.04.19 09:34, Richard Henderson wrote: > The only fixed_reg is cpu_env, and it should not be modified > during any TB. Therefore code that tries to special-case moves > into a fixed_reg is dead. Remove it. > > Signed-off-by: Richard Henderson > --- > tcg/tcg.c | 85 +++++++++++++++++++++++++------------------------------ > 1 file changed, 38 insertions(+), 47 deletions(-) > > diff --git a/tcg/tcg.c b/tcg/tcg.c > index ade6050982..4f77a957b0 100644 > --- a/tcg/tcg.c > +++ b/tcg/tcg.c > @@ -3279,11 +3279,8 @@ static void tcg_reg_alloc_do_movi(TCGContext *s, TCGTemp *ots, > tcg_target_ulong val, TCGLifeData arg_life, > TCGRegSet preferred_regs) > { > - if (ots->fixed_reg) { > - /* For fixed registers, we do not do any constant propagation. */ > - tcg_out_movi(s, ots->type, ots->reg, val); > - return; > - } > + /* ENV should not be modified. */ > + tcg_debug_assert(!ots->fixed_reg); > > /* The movi is not explicitly generated here. */ > if (ots->val_type == TEMP_VAL_REG) { > @@ -3319,6 +3316,9 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOp *op) > ots = arg_temp(op->args[0]); > ts = arg_temp(op->args[1]); > > + /* ENV should not be modified. */ > + tcg_debug_assert(!ots->fixed_reg); > + > /* Note that otype != itype for no-op truncation. */ > otype = ots->type; > itype = ts->type; > @@ -3343,7 +3343,7 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOp *op) > } > > tcg_debug_assert(ts->val_type == TEMP_VAL_REG); > - if (IS_DEAD_ARG(0) && !ots->fixed_reg) { > + if (IS_DEAD_ARG(0)) { > /* mov to a non-saved dead register makes no sense (even with > liveness analysis disabled). */ > tcg_debug_assert(NEED_SYNC_ARG(0)); > @@ -3356,7 +3356,7 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOp *op) > } > temp_dead(s, ots); > } else { > - if (IS_DEAD_ARG(1) && !ts->fixed_reg && !ots->fixed_reg) { > + if (IS_DEAD_ARG(1) && !ts->fixed_reg) { > /* the mov can be suppressed */ > if (ots->val_type == TEMP_VAL_REG) { > s->reg_to_temp[ots->reg] = NULL; > @@ -3509,6 +3509,10 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op) > arg = op->args[i]; > arg_ct = &def->args_ct[i]; > ts = arg_temp(arg); > + > + /* ENV should not be modified. */ > + tcg_debug_assert(!ts->fixed_reg); > + > if ((arg_ct->ct & TCG_CT_ALIAS) > && !const_args[arg_ct->alias_index]) { > reg = new_args[arg_ct->alias_index]; > @@ -3517,29 +3521,19 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op) > i_allocated_regs | o_allocated_regs, > op->output_pref[k], ts->indirect_base); > } else { > - /* if fixed register, we try to use it */ > - reg = ts->reg; > - if (ts->fixed_reg && > - tcg_regset_test_reg(arg_ct->u.regs, reg)) { > - goto oarg_end; > - } > reg = tcg_reg_alloc(s, arg_ct->u.regs, o_allocated_regs, > op->output_pref[k], ts->indirect_base); > } > tcg_regset_set_reg(o_allocated_regs, reg); > - /* if a fixed register is used, then a move will be done afterwards */ > - if (!ts->fixed_reg) { > - if (ts->val_type == TEMP_VAL_REG) { > - s->reg_to_temp[ts->reg] = NULL; > - } > - ts->val_type = TEMP_VAL_REG; > - ts->reg = reg; > - /* temp value is modified, so the value kept in memory is > - potentially not the same */ > - ts->mem_coherent = 0; > - s->reg_to_temp[reg] = ts; > + if (ts->val_type == TEMP_VAL_REG) { > + s->reg_to_temp[ts->reg] = NULL; > } > - oarg_end: > + ts->val_type = TEMP_VAL_REG; > + ts->reg = reg; > + /* temp value is modified, so the value kept in memory is > + potentially not the same */ > + ts->mem_coherent = 0; > + s->reg_to_temp[reg] = ts; > new_args[i] = reg; > } > } > @@ -3555,10 +3549,10 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op) > /* move the outputs in the correct register if needed */ > for(i = 0; i < nb_oargs; i++) { > ts = arg_temp(op->args[i]); > - reg = new_args[i]; > - if (ts->fixed_reg && ts->reg != reg) { > - tcg_out_mov(s, ts->type, ts->reg, reg); > - } > + > + /* ENV should not be modified. */ > + tcg_debug_assert(!ts->fixed_reg); > + > if (NEED_SYNC_ARG(i)) { > temp_sync(s, ts, o_allocated_regs, 0, IS_DEAD_ARG(i)); > } else if (IS_DEAD_ARG(i)) { > @@ -3679,26 +3673,23 @@ static void tcg_reg_alloc_call(TCGContext *s, TCGOp *op) > for(i = 0; i < nb_oargs; i++) { > arg = op->args[i]; > ts = arg_temp(arg); > + > + /* ENV should not be modified. */ > + tcg_debug_assert(!ts->fixed_reg); > + > reg = tcg_target_call_oarg_regs[i]; > tcg_debug_assert(s->reg_to_temp[reg] == NULL); > - > - if (ts->fixed_reg) { > - if (ts->reg != reg) { > - tcg_out_mov(s, ts->type, ts->reg, reg); > - } > - } else { > - if (ts->val_type == TEMP_VAL_REG) { > - s->reg_to_temp[ts->reg] = NULL; > - } > - ts->val_type = TEMP_VAL_REG; > - ts->reg = reg; > - ts->mem_coherent = 0; > - s->reg_to_temp[reg] = ts; > - if (NEED_SYNC_ARG(i)) { > - temp_sync(s, ts, allocated_regs, 0, IS_DEAD_ARG(i)); > - } else if (IS_DEAD_ARG(i)) { > - temp_dead(s, ts); > - } > + if (ts->val_type == TEMP_VAL_REG) { > + s->reg_to_temp[ts->reg] = NULL; > + } > + ts->val_type = TEMP_VAL_REG; > + ts->reg = reg; > + ts->mem_coherent = 0; > + s->reg_to_temp[reg] = ts; > + if (NEED_SYNC_ARG(i)) { > + temp_sync(s, ts, allocated_regs, 0, IS_DEAD_ARG(i)); > + } else if (IS_DEAD_ARG(i)) { > + temp_dead(s, ts); > } > } > } > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb