Re: [PATCH] target/arm: gdbstub: Guard M-profile code with CONFIG_TCG

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 4/7/23 17:44, Peter Maydell wrote:
> On Tue, 4 Jul 2023 at 16:21, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>>
>> On 28/6/23 18:48, Fabiano Rosas wrote:
>>> This code is only relevant when TCG is present in the build. Building
>>> with --disable-tcg --enable-xen on an x86 host we get:
>>>
>>> $ ../configure --target-list=x86_64-softmmu,aarch64-softmmu --disable-tcg --enable-xen
>>> $ make -j$(nproc)
>>> ...
>>> libqemu-aarch64-softmmu.fa.p/target_arm_gdbstub.c.o: in function `m_sysreg_ptr':
>>>    ../target/arm/gdbstub.c:358: undefined reference to `arm_v7m_get_sp_ptr'
>>>    ../target/arm/gdbstub.c:361: undefined reference to `arm_v7m_get_sp_ptr'
>>>
>>> libqemu-aarch64-softmmu.fa.p/target_arm_gdbstub.c.o: in function `arm_gdb_get_m_systemreg':
>>> ../target/arm/gdbstub.c:405: undefined reference to `arm_v7m_mrs_control'
>>>
>>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>>> ---
>>> This is a respin of:
>>> https://lore.kernel.org/r/20230313151058.19645-5-farosas@suse.de
>>> ---
>>>    target/arm/gdbstub.c | 4 ++++
>>>    1 file changed, 4 insertions(+)
>>>
>>> diff --git a/target/arm/gdbstub.c b/target/arm/gdbstub.c
>>> index 03b17c814f..f421c5d041 100644
>>> --- a/target/arm/gdbstub.c
>>> +++ b/target/arm/gdbstub.c
>>> @@ -324,6 +324,7 @@ static int arm_gen_dynamic_sysreg_xml(CPUState *cs, int base_reg)
>>>        return cpu->dyn_sysreg_xml.num;
>>>    }
>>>
>>> +#ifdef CONFIG_TCG
>>
>> OK.
>>
>>>    typedef enum {
>>>        M_SYSREG_MSP,
>>>        M_SYSREG_PSP,
>>> @@ -481,6 +482,7 @@ static int arm_gen_dynamic_m_secextreg_xml(CPUState *cs, int orig_base_reg)
>>>        return cpu->dyn_m_secextreg_xml.num;
>>>    }
>>>    #endif
>>> +#endif /* CONFIG_TCG */
>>>
>>>    const char *arm_gdb_get_dynamic_xml(CPUState *cs, const char *xmlname)
>>>    {
>>> @@ -561,6 +563,7 @@ void arm_cpu_register_gdb_regs_for_features(ARMCPU *cpu)
>>>                                 arm_gen_dynamic_sysreg_xml(cs, cs->gdb_num_regs),
>>>                                 "system-registers.xml", 0);
>>>
>>> +#ifdef CONFIG_TCG
>>
>> IIUC tcg_enabled(), this guard shouldn't be necessary; if CONFIG_TCG
>> is not defined, tcg_enabled() evaluates to 0, and the compiler should
>> elide the whole block.
> 
> IME it's a bit optimistic to assume that the compiler will always
> do that, especially with no optimisation enabled.

OK I see, thanks.