Re: [PATCH] memory: Use QEMU_ALWAYS_INLINE to silence compile-time warning

[Richard Henderson]

On 2/5/20 10:01 AM, Richard Henderson wrote:
> On 2/5/20 8:17 AM, Zenghui Yu wrote:
>> Our robot reported the following compile-time warning while compiling
>> Qemu with -fno-inline cflags:
> 
> Why are you doing this?
> 
>>
>> In function 'load_memop',
>>     inlined from 'load_helper' at /qemu/accel/tcg/cputlb.c:1578:20,
>>     inlined from 'full_ldub_mmu' at /qemu/accel/tcg/cputlb.c:1624:12:
>> /qemu/accel/tcg/cputlb.c:1502:9: error: call to 'qemu_build_not_reached' 
>> declared with attribute error: code path is reachable
>>          qemu_build_not_reached();
>>          ^~~~~~~~~~~~~~~~~~~~~~~~
>>     [...]
> 
> Of course, the assert is compiled out when optimization is off, which is the
> only time we expect inlining to be off.
> 
> The patch isn't wrong, exactly, but I question whether we want to support
> completely arbitrary combinations of compile flags.

To follow up: if you *really* need to support -fno-inline, then perhaps the
correct patch is to change

- #ifdef __OPTIMIZE__
+ #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__)
  extern void QEMU_NORETURN QEMU_ERROR("code path is reachable")
      qemu_build_not_reached(void);
  #else
  #define qemu_build_not_reached()  g_assert_not_reached()
  #endif

within include/qemu/compiler.h.


r~