Re: [Qemu-devel] [PATCH] ide: fix enum comparison for gcc 4.7

[Mark Cave-Ayland]

On 20/09/17 22:33, John Snow wrote:

> On 09/20/2017 05:28 PM, Mark Cave-Ayland wrote:
>> On 20/09/17 20:41, John Snow wrote:
>>
>>> Apparently GCC gets bent over comparing enum values against zero.
>>> Replace the conditional with something less readable.
>>>
>>> Signed-off-by: John Snow <address@hidden>
>>> ---
>>>  hw/ide/core.c             | 2 +-
>>>  include/hw/ide/internal.h | 3 +--
>>>  2 files changed, 2 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/hw/ide/core.c b/hw/ide/core.c
>>> index a19bd90..d63eb4a 100644
>>> --- a/hw/ide/core.c
>>> +++ b/hw/ide/core.c
>>> @@ -68,7 +68,7 @@ const char *IDE_DMA_CMD_lookup[IDE_DMA__COUNT] = {
>>>  
>>>  static const char *IDE_DMA_CMD_str(enum ide_dma_cmd enval)
>>>  {
>>> -    if (enval >= IDE_DMA__BEGIN && enval < IDE_DMA__COUNT) {
>>> +    if ((unsigned)enval < IDE_DMA__COUNT) {
>>>          return IDE_DMA_CMD_lookup[enval];
>>>      }
>>>      return "DMA UNKNOWN CMD";
>>> diff --git a/include/hw/ide/internal.h b/include/hw/ide/internal.h
>>> index 180e00e..e641012 100644
>>> --- a/include/hw/ide/internal.h
>>> +++ b/include/hw/ide/internal.h
>>> @@ -333,8 +333,7 @@ struct unreported_events {
>>>  };
>>>  
>>>  enum ide_dma_cmd {
>>> -    IDE_DMA__BEGIN = 0,
>>> -    IDE_DMA_READ = IDE_DMA__BEGIN,
>>> +    IDE_DMA_READ = 0,
>>>      IDE_DMA_WRITE,
>>>      IDE_DMA_TRIM,
>>>      IDE_DMA_ATAPI,
>>>
>>
>> Really close - it fixes the error in hw/ide/core.c but then I see a
>> similar error a bit later in hw/ide/ahci.c:
>>
>> cc -I/home/build/src/qemu/git/qemu/hw/ide -Ihw/ide
>> -I/home/build/src/qemu/git/qemu/tcg
>> -I/home/build/src/qemu/git/qemu/tcg/i386
>> -I/home/build/src/qemu/git/qemu/linux-headers
>> -I/home/build/src/qemu/git/qemu/linux-headers -I.
>> -I/home/build/src/qemu/git/qemu
>> -I/home/build/src/qemu/git/qemu/accel/tcg
>> -I/home/build/src/qemu/git/qemu/include -I/usr/include/pixman-1
>> -I/home/build/src/qemu/git/qemu/dtc/libfdt -Werror -pthread
>> -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include
>> -m64 -mcx16 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
>> -Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings
>> -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv
>> -Wendif-labels -Wno-missing-include-dirs -Wempty-body -Wnested-externs
>> -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers
>> -Wold-style-declaration -Wold-style-definition -Wtype-limits
>> -fstack-protector-all -I/usr/include/p11-kit-1
>> -I/usr/include/libpng12   -I/home/build/src/qemu/git/qemu/tests -MMD -MP
>> -MT hw/ide/ahci.o -MF hw/ide/ahci.d -O2 -U_FORTIFY_SOURCE
>> -D_FORTIFY_SOURCE=2 -g   -c -o hw/ide/ahci.o hw/ide/ahci.c
>> hw/ide/ahci.c: In function ‘ahci_trigger_irq’:
>> hw/ide/ahci.c:187:5: error: comparison of unsigned expression >= 0 is
>> always true [-Werror=type-limits]
>> cc1: all warnings being treated as errors
>> make: *** [hw/ide/ahci.o] Error 1
>>
>>
>> ATB,
>>
>> Mark.
>>
> 
> Man, what's with your compiler? ...
> 
> OK, let's try:
> 
> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
> index 24c65df..32d1296 100644
> --- a/hw/ide/ahci.c
> +++ b/hw/ide/ahci.c
> @@ -184,7 +184,7 @@ static void ahci_check_irq(AHCIState *s)
>  static void ahci_trigger_irq(AHCIState *s, AHCIDevice *d,
>                               enum AHCIPortIRQ irqbit)
>  {
> -    g_assert(irqbit >= 0 && irqbit < 32);
> +    g_assert((unsigned)irqbit < 32);
>      uint32_t irq = 1U << irqbit;
>      uint32_t irqstat = d->port_regs.irq_stat | irq;
> 
> 
> I can't remember immediately if I have more spots that might cause a
> ruckus for you.

Nope, that's all folks! Combining these two together fixes the build for
me again:

Tested-by: Mark Cave-Ayland <address@hidden>


ATB,

Mark.