From: Lluís Vilanova <vilan...@ac.upc.edu>
Incrementally paves the way towards using the generic instruction translation
loop.
Signed-off-by: Lluís Vilanova <vilan...@ac.upc.edu>
Reviewed-by: Richard Henderson <r...@twiddle.net>
Reviewed-by: Alex Benneé <alex.be...@linaro.org>
Message-Id: <150002364681.22386.1701754996184325808.st...@frigg.lan>
[rth: Adjust for tb_start interface change.]
Signed-off-by: Richard Henderson <r...@twiddle.net>
---
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 4e9e3c46b3..5acdeabebb 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -11863,6 +11863,49 @@ 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)
{
@@ -11902,45 +11945,8 @@ 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();
--
2.13.3
