On 11/5/22 06:26, Taylor Simpson wrote:
Direct block chaining is documented here
https://qemu.readthedocs.io/en/latest/devel/tcg.html#direct-block-chaining
Recall that Hexagon allows packets with multiple jumps where only the first
one with a true predicate will actually jump. So, we can only use direct
block chaining when the packet contains a single PC-relative jump.
Not quite accurate.
Only the first two direct branches can use direct block chaining. Other exits from the
translation block could use indirect block chaining (tcg_gen_lookup_and_goto_ptr). You
just have to remember which is taken.
That said, this is certainly an improvement.
+ if (ctx->pkt->pkt_has_multi_cof) {
+ gen_write_new_pc_addr(ctx, tcg_constant_tl(dest), pred);
+ } else {
+ /* Defer this jump to the end of the TB */
+ g_assert(ctx->branch_cond == NULL);
+ ctx->has_single_direct_branch = true;
+ if (pred != NULL) {
+ ctx->branch_cond = tcg_temp_local_new();
+ tcg_gen_mov_tl(ctx->branch_cond, pred);
+ }
+ ctx->branch_dest = dest;
Perhaps re-use hex_branch_taken as branch_cond?
Anyway,
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
r~
