On 6/1/21 5:00 PM, Richard Henderson wrote:
> This removes all of the problems with unaligned accesses
> to the bytecode stream.
>
> With an 8-bit opcode at the bottom, we have 24 bits remaining,
> which are generally split into 6 4-bit slots. This fits well
> with the maximum length opcodes, e.g. INDEX_op_add2_i32, which
> have 6 register operands.
>
> We have, in previous patches, rearranged things such that there
> are no operations with a label which have more than one other
> operand. Which leaves us with a 20-bit field in which to encode
> a label, giving us a maximum TB size of 512k -- easily large.
>
> Change the INDEX_op_tci_movi_{i32,i64} opcodes to tci_mov[il].
> The former puts the immediate in the upper 20 bits of the insn,
> like we do for the label displacement. The later uses a label
> to reference an entry in the constant pool. Thus, in the worst
> case we still have a single memory reference for any constant,
> but now the constants are out-of-line of the bytecode and can
> be shared between different moves saving space.
>
> Change INDEX_op_call to use a label to reference a pair of
> pointers in the constant pool. This removes the only slightly
> dodgy link with the layout of struct TCGHelperInfo.
>
> The re-encode cannot be done in pieces.
>
> Tested-by: Philippe Mathieu-Daudé <[email protected]>
> Signed-off-by: Richard Henderson <[email protected]>
> ---
> include/tcg/tcg-opc.h | 4 +-
> tcg/tci/tcg-target.h | 3 +-
> tcg/tci.c | 541 +++++++++++++++------------------------
> tcg/tci/tcg-target.c.inc | 379 ++++++++++++---------------
> tcg/tci/README | 20 +-
> 5 files changed, 384 insertions(+), 563 deletions(-)
[ ... ]
> + case 0:
> + /* tcg_out_nop_fill uses zeros */
> + if (insn == 0) {
> + info->fprintf_func(info->stream, "align");
"nop"?
Otherwise,
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
> + break;
> + }
> + /* fall through */
> +
> default:
> info->fprintf_func(info->stream, "illegal opcode %d", op);
> break;
> }
