Re: [PATCH 0/2] tcg: Fix branch/label link during plugin expansion

[Richard Henderson]

On 9/10/24 14:23, Richard Henderson wrote:
> With tcg_last_op(), we always get the last op of the stream.
> With TCGContext.emit_before_op, the most recently emitted op
> is no longer the last op.
>
> Instead, pass the op being emitted back from the allocator so
> that we can link it to the label without needing to look it up.

Oh, I meant to point out from whence this comes.
The plugin uses a conditional

 ld_i32 tmp18,env,$0xffffffffffffdb10
 mul_i32 tmp18,tmp18,$0x18
 ext_i32_i64 tmp17,tmp18
 add_i64 tmp17,tmp17,$0x575410edadc8
 ld_i64 tmp21,tmp17,$0x0
 brcond_i64 tmp21,$0x0,ltu,$L1
 ld_i32 tmp18,env,$0xffffffffffffdb10
 call plugin(0x79a2abfde66a),$0x1,$0,tmp18,$0x0
 set_label $L1

Note that the branch is X < 0 (unsigned), which is always false, and thus the branch is 
optimized away.


r~