From b14768544fd715a3f1742c10fc36ae81c703cbc1 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Llu=C3=ADs=20Vilanova?= Date: Fri, 14 Jul 2017 12:14:07 +0300 Subject: [PATCH] target/arm: [tcg] Port to tb_start MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Incrementally paves the way towards using the generic instruction translation loop. Signed-off-by: Lluís Vilanova Reviewed-by: Richard Henderson Reviewed-by: Alex Benneé Message-Id: <150002364681.22386.1701754996184325808.stgit@frigg.lan> [rth: Adjust for tb_start interface change.] Signed-off-by: Richard Henderson --- target/arm/translate.c | 82 +++++++++++++++++++++++++++----------------------- 1 file changed, 44 insertions(+), 38 deletions(-) diff --git a/target/arm/translate.c b/target/arm/translate.c index a95c183cee..3138a23e0c 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -11893,6 +11893,49 @@ static int arm_tr_init_disas_context(DisasContextBase *dcbase, return max_insns; } +static void arm_tr_tb_start(DisasContextBase *dcbase, CPUState *cpu) +{ + DisasContext *dc = container_of(dcbase, DisasContext, base); + + /* A note on handling of the condexec (IT) bits: + * + * We want to avoid the overhead of having to write the updated condexec + * bits back to the CPUARMState for every instruction in an IT block. So: + * (1) if the condexec bits are not already zero then we write + * zero back into the CPUARMState now. This avoids complications trying + * to do it at the end of the block. (For example if we don't do this + * it's hard to identify whether we can safely skip writing condexec + * at the end of the TB, which we definitely want to do for the case + * where a TB doesn't do anything with the IT state at all.) + * (2) if we are going to leave the TB then we call gen_set_condexec() + * which will write the correct value into CPUARMState if zero is wrong. + * This is done both for leaving the TB at the end, and for leaving + * it because of an exception we know will happen, which is done in + * gen_exception_insn(). The latter is necessary because we need to + * leave the TB with the PC/IT state just prior to execution of the + * instruction which caused the exception. + * (3) if we leave the TB unexpectedly (eg a data abort on a load) + * then the CPUARMState will be wrong and we need to reset it. + * This is handled in the same way as restoration of the + * PC in these situations; we save the value of the condexec bits + * for each PC via tcg_gen_insn_start(), and restore_state_to_opc() + * then uses this to restore them after an exception. + * + * Note that there are no instructions which can read the condexec + * bits, and none which can write non-static values to them, so + * we don't need to care about whether CPUARMState is correct in the + * middle of a TB. + */ + + /* Reset the conditional execution bits immediately. This avoids + complications trying to do it at the end of the block. */ + if (dc->condexec_mask || dc->condexec_cond) { + TCGv_i32 tmp = tcg_temp_new_i32(); + tcg_gen_movi_i32(tmp, 0); + store_cpu_field(tmp, condexec_bits); + } +} + /* generate intermediate code for basic block 'tb'. */ void gen_intermediate_code(CPUState *cs, TranslationBlock *tb) { @@ -11932,45 +11975,8 @@ void gen_intermediate_code(CPUState *cs, TranslationBlock *tb) gen_tb_start(tb); tcg_clear_temp_count(); + arm_tr_tb_start(&dc->base, cs); - /* A note on handling of the condexec (IT) bits: - * - * We want to avoid the overhead of having to write the updated condexec - * bits back to the CPUARMState for every instruction in an IT block. So: - * (1) if the condexec bits are not already zero then we write - * zero back into the CPUARMState now. This avoids complications trying - * to do it at the end of the block. (For example if we don't do this - * it's hard to identify whether we can safely skip writing condexec - * at the end of the TB, which we definitely want to do for the case - * where a TB doesn't do anything with the IT state at all.) - * (2) if we are going to leave the TB then we call gen_set_condexec() - * which will write the correct value into CPUARMState if zero is wrong. - * This is done both for leaving the TB at the end, and for leaving - * it because of an exception we know will happen, which is done in - * gen_exception_insn(). The latter is necessary because we need to - * leave the TB with the PC/IT state just prior to execution of the - * instruction which caused the exception. - * (3) if we leave the TB unexpectedly (eg a data abort on a load) - * then the CPUARMState will be wrong and we need to reset it. - * This is handled in the same way as restoration of the - * PC in these situations; we save the value of the condexec bits - * for each PC via tcg_gen_insn_start(), and restore_state_to_opc() - * then uses this to restore them after an exception. - * - * Note that there are no instructions which can read the condexec - * bits, and none which can write non-static values to them, so - * we don't need to care about whether CPUARMState is correct in the - * middle of a TB. - */ - - /* Reset the conditional execution bits immediately. This avoids - complications trying to do it at the end of the block. */ - if (dc->condexec_mask || dc->condexec_cond) - { - TCGv_i32 tmp = tcg_temp_new_i32(); - tcg_gen_movi_i32(tmp, 0); - store_cpu_field(tmp, condexec_bits); - } do { dc->base.num_insns++; dc->insn_start_idx = tcg_op_buf_count(); -- 2.11.4.GIT