When clang was changed to -fcommon, perl's P_hash_{seed,state} variables

moved into BSS in the .o, with padding rules following the types -- they
are both char[].  Since P_hash_seed is (system-dependent) not a multiple of 8,
P_hash_state gets layed out misaligned, which sucks because the hash functions
demand 64-bit alignment for both variables.  There is the possibility of using
misalignment macros, but this is not cheap.  Could also use kernel-trap fault
repair, but the performance would really suck for something so crucial.
The correct fix would be for upstream to declare these types as uint64[],
we have requested that in https://github.com/Perl/perl5/issues/18555
In the meantime, carry a diff to roundup P_hash_seed to 64-bit alignment so that
P_hash_state will land aligned.
ok afresh1

diff --git a/gnu/usr.bin/perl/hv_func.h b/gnu/usr.bin/perl/hv_func.h
index a519839..151aead 100644 (file)
--- a/gnu/usr.bin/perl/hv_func.h
+++ b/gnu/usr.bin/perl/hv_func.h
@@ -83,7 +83,8 @@
 
 #define _PERL_HASH_FUNC         "SBOX32_WITH_" __PERL_HASH_FUNC
 
-#define _PERL_HASH_SEED_BYTES   ( __PERL_HASH_SEED_BYTES + (int)( 3 * sizeof(U32) ) )
+#define _PERL_HASH_SEED_roundup(x, y)   ((((x)+((y)-1))/(y))*(y))
+#define _PERL_HASH_SEED_BYTES   ( _PERL_HASH_SEED_roundup(__PERL_HASH_SEED_BYTES + (int)( 3 * sizeof(U32)), sizeof(U64) ) )
 
 #define _PERL_HASH_STATE_BYTES  \
     ( __PERL_HASH_STATE_BYTES + ( ( 1 + ( 256 * SBOX32_MAX_LEN ) ) * sizeof(U32) ) )