Thursday, September 19, 2024
Richard Sandiford <richard.sandif...@arm.com> wrote:
>> For instance:
>> float __attribute__((aligned (32))) large_aligned_array[3];
>>
>> BIGGEST_ALIGNMENT could be up to 512 bits on x64.
>> This patch has been added to cover this case without needing to
>> change the FFmpeg code.
>
> What goes wrong if we don't do this? I'm not sure from the description
> whether it's a correctness fix, a performance fix, or whether it's about
> avoiding wasted space.
It is a correctness fix.
>> +#define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGNMENT) \
>> + { \
>> + unsigned HOST_WIDE_INT rounded = MAX ((SIZE), 1); \
>> + unsigned HOST_WIDE_INT alignment = MAX ((ALIGNMENT),
>> BIGGEST_ALIGNMENT); \
>> + rounded += (alignment / BITS_PER_UNIT) - 1; \
>> + rounded = (rounded / (alignment / BITS_PER_UNIT) \
>> + * (alignment / BITS_PER_UNIT)); \
>
> There's a ROUND_UP macro that could be used here.
Here is the patch after applying ROUND_UP.
Regards,
Evgeny
diff --git a/gcc/config/aarch64/aarch64-coff.h
b/gcc/config/aarch64/aarch64-coff.h
index 3c8aed806c9..1a45256ebfe 100644
--- a/gcc/config/aarch64/aarch64-coff.h
+++ b/gcc/config/aarch64/aarch64-coff.h
@@ -58,6 +58,13 @@
assemble_name ((FILE), (NAME)), \
fprintf ((FILE), "," HOST_WIDE_INT_PRINT_DEC "\n", (ROUNDED)))
+#define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGNMENT) \
+ { \
+ unsigned rounded = ROUND_UP (MAX ((SIZE), 1), \
+ MAX ((ALIGNMENT), BIGGEST_ALIGNMENT) / BITS_PER_UNIT); \
+ ASM_OUTPUT_LOCAL (FILE, NAME, SIZE, rounded); \
+ }
+
#define ASM_OUTPUT_SKIP(STREAM, NBYTES) \
fprintf (STREAM, "\t.space\t%d // skip\n", (int) (NBYTES))
