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

[Richard Henderson <richard.henderson@linaro.org>]

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~