On 3/29/23 18:09, liweiwei wrote:
@@ -51,26 +59,43 @@ static bool trans_jal(DisasContext *ctx, arg_jal *a)
static bool trans_jalr(DisasContext *ctx, arg_jalr *a)
{
TCGLabel *misaligned = NULL;
+ TCGv succ_pc = tcg_temp_new();
succ_pc can by null for !CF_PCREL...
I think this is OK since it's only used for CF_PCREL.
It allocates an unused temp. Not a bug per se, but an easily fixable mistake.
... or initialized like
} else {
succ_pc = tcg_constant_tl(ctx->pc_succ_insn);
}
If you do this, you can avoid the test/set/seti later.
if (misaligned) {
gen_set_label(misaligned);
- gen_exception_inst_addr_mis(ctx);
+ gen_exception_inst_addr_mis(ctx, target_pc);
}
This is what I expected from patch 3: cpu_pc is unchanged, with the new (incorrect)
address passed to inst_addr_mis for assigning to badaddr. Bug being fixed here, thus
should really be a separate patch.
It's OK to update cpu_pc before gen_exception_inst_addr_mis() since it will restore the
current pc by gen_set_pc_imm() after update cpu_pc into badaddr.
True, but I think it's confusing to set cpu_pc for it's mere use in copying to badaddr,
and rely on generate_exception to reset cpu_pc to the correct value.
However, after PC-relative translation is enabled, we cannot use gen_set_pc to directly
update cpu_pc in above case, since gen_set_pc() will break the pc_save, and make
gen_set_pc_imm() in gen_exception_inst_addr_mis() failed. So we introduce a temp target_pc
instead of cpu_pc to compute the destination pc and use it to do misaligned check.
Exactly.
Which is why I think it is better to simply pass gen_exception_inst_addr_mis the value to
use with badaddr in a normal temp (or constant). And do this always, not simply in the
one case where it is absolutely required to not clobber cpu_pc.
r~