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From: "marxin at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/108695] [13 Regression] Wrong code since
 r13-5215-gb1f30bf42d8d47 for dd_rescue package
Date: Wed, 08 Feb 2023 11:16:42 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108695

--- Comment #6 from Martin Li=C5=A1ka <marxin at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
> I am 99% sure there is aliasing violations in this code too:
> #if _MSC_VER
> #define GETU32(p) SWAP(*((u32 *)(p)))
> #define PUTU32(ct, st)                                                  \
>         {                                                               \
>                 *((u32 *)(ct)) =3D SWAP((st));                           =
 \
>         }

Yes, I'm also suspecting this code and I can verify that using optimize("O0=
")
for rijndaelEncrypt fixes the issue.

The thing below is cast from 'const u8 *' and I thought it's valid to case
to 'u32 *' and then access it. Can you explain to me how exactly the violat=
ion
happens?

> #else   /* _MSC_VER */
> # if __BYTE_ORDER =3D=3D __BIG_ENDIAN
> #define GETU32(p) *((u32*)(p))
> #define PUTU32(ct, st) *((u32*)(ct)) =3D (st)
> #else   /* BIG_ENDIAN */
> #if 0 //def HAVE_LINUX_SWAB_H
> #define GETU32(p) __swab32(*((u32*)(p)))
> #define PUTU32(ct, st) *((u32*)(ct)) =3D __swab32((st))
> #else   /* __GNUC__ */
> #include <netinet/in.h>
> #define GETU32(p) ntohl(*((u32*)(p)))
> #define PUTU32(ct, st) *((u32*)(ct)) =3D htonl((st))
> #endif  /* __GNUC__ */
> #endif  /* BIG_ENDIAN */
> #endif  /*_MSC_VER */
>=20

This part below is guarded with '#if 0'..

> #if 0
> #define GETU32(pt) (((u32)(pt)[0] << 24) ^ ((u32)(pt)[1] << 16) ^
> ((u32)(pt)[2] << 8) ^ ((u32)(pt)[3]))
> #define PUTU32(ct, st)                                                  \
>         {                                                               \
>                 (ct)[0] =3D (u8)((st) >> 24);                            =
 \
>                 (ct)[1] =3D (u8)((st) >> 16);                            =
 \
>                 (ct)[2] =3D (u8)((st) >> 8);                             =
 \
>                 (ct)[3] =3D (u8)(st);                                    =
 \
>         }
> #endif
>=20
> A few other places too ...=