Re: [Qemu-devel] [PATCH 01/11] tci: Fix build regression

[Richard Henderson]

On 04/07/2016 01:37 PM, Stefan Weil wrote:
> I just tested a variant with tcg_debug_assert. It creates less efficient
> code when debugging is disabled. Here is the code size for x86_64:
>
> with normal tcg_debug_assert:
>
>     text       data        bss        dec        hex    filename
>     8293          0        128       8421       20e5
> bin/ndebug/x86_64-linux-gnu,tci/x86_64-softmmu/tci.o
>
> In gdb I can also see assembler code for op_size at the beginning
> of the for loop in tcg_qemu_tb_exec. This slows down the interpreter.

Please file a gcc bug.

A branch across __builtin_unreachable is supposed to fold to a simple 
compile-time assert, providing extra information to the compiler but not 
generating code.


r~