https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84945
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
Last reconfirmed|2018-03-19 00:00:00 |
CC| |hjl.tools at gmail dot com,
| |jakub at gcc dot gnu.org,
| |kyukhin at gcc dot gnu.org,
| |uros at gcc dot gnu.org
Version|unknown |8.0
Summary|UBSAN: |[8 Regression] UBSAN:
|gcc/config/i386/i386.c:3331 |gcc/config/i386/i386.c:3331
|2:22: runtime error: shift |2:22: runtime error: shift
|exponent 32 is too large |exponent 32 is too large
|for 32-bit type 'int' |for 32-bit type 'int'
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Ugh, this is an important issue.
In GCC 7 we had F_MAX 31, so all of the runtime feature tests are fine.
We have:
struct __processor_model
{
unsigned int __cpu_vendor;
unsigned int __cpu_type;
unsigned int __cpu_subtype;
unsigned int __cpu_features[1];
} __cpu_model;
and that is an exported variable from libgcc, thankfully only as @GCC_4.8
symbol and thus new programs shouldn't link against that.
No matter what, at least for targets that don't use symbol versioning and
prevent using that symbol, I think we need to rename __cpu_model to something
else (__cpu_model2), add at least one another 32-bit __cpu_features bitfield
and for features >= 32 use the second field instead of the first one.
