[Qemu-devel] How does TCG gen host code for a TB?

[Valerón JC]

I want to trace a bug in tcg, which for me, at some point, generate infinite loop TB chains, that's unexpected. and I've found the final TB(head, since they're chaining) which run in an infinite loop, and I know a very weird trick to 'disable' this bug, so I would like to track the tcg-ops for the TB, hope that I can figure what's wrong.

 

but when I read the tcg_gen_code(), I'm confused...

 

how does tcg_gen_code() generate codes for one TB? if I read the code correctly, gen_intermediate_code() will not flush the tcg_ctx->gen_opc_buf[], codes for previous TB are mixed together... and tcg_gen_code() will start gen from index 0 of gen_opc_buf, how does it generate codes for the TB just created?

 

even though there's label for a TB-start(I'm not familiar with this label stuff yet), but the fact that the gen_opc_buf not flush every time a new TB is generated seems weird to me, won't the new tcg-ops mixed with the ones of previous TB? Isn’t the newly generated host-code dedicate to one TB?

 

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