On 10/2/22 02:20, BitFriends wrote:
I now came up with this code:
TCGv_i64 res = 0;
TCGv_i64 addr = (TCGv_i64)(env->regs[R_EDI]);
tcg_gen_qemu_ld_i64(res, addr, 0, MO_LEUQ);
env->regs[R_EAX] = (target_ulong)res;
However this crashes afterwards in test_bit. Maybe this is caused by an invalid access?
Anything wrong about the code? This still gives some warnings, like TCGv_i32 expected (and
when you use TCGv_i32, it says TCGv_i64 expected) plus some casting warnings.
It is as if you did not read the second paragraph of my response at all.
tcg_gen_qemu_ld_i64 is for generating code, not performing a direct action.
Can you see how your code differs from *all* of the code around it?
r~
Am Sa., 1. Okt. 2022 um 22:23 Uhr schrieb Richard Henderson <richard.hender...@linaro.org
<mailto:richard.hender...@linaro.org>>:
On 10/1/22 13:10, BitFriends wrote:
> Hello,
>
> I am trying to create a custom instruction that accesses guest memory
specified by an
> address in a register. I specifically want to read from that address. So
I tried to do
> that using "tcg_gen_qemu_ld_i64(&res, env->regs[R_EDI], 0, MO_LEUQ);",
but that
doesn't
> save any result in res.
This statement should have given you compilation errors, so I don't know
what you mean by
"doesn't save any result". There's clearly a disconnect between what you
describe and
what you actually attempted.
Anyway, by the name you can see that function "gen"erates a "tcg"
operation, which is
then
later compiled by the jit, the output of which is later executed to produce
a result.
Which is, in general, what you want for implementing a custom instruction.
r~
