[Bug target/85990] New: Wrong TARGET_THREAD_SPLIT_STACK_OFFSET

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85990

            Bug ID: 85990
           Summary: Wrong TARGET_THREAD_SPLIT_STACK_OFFSET
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
                CC: ubizjak at gmail dot com
  Target Milestone: ---
            Target: i*86-pc-linux-gnu

In glibc, sysdeps/i386/nptl/tls.h has

typedef struct
{
  void *tcb;            /* Pointer to the TCB.  Not necessarily the
                           thread descriptor used by libpthread.  */
  dtv_t *dtv;
  void *self;           /* Pointer to the thread descriptor.  */
  int multiple_threads;
  uintptr_t sysinfo;
  uintptr_t stack_guard;
  uintptr_t pointer_guard;
  int gscope_flag;
  int __glibc_reserved1;
  /* Reservation of some values for the TM ABI.  */
  void *__private_tm[4];
  /* GCC split stack support.  */
  void *__private_ss;
} tcbhead_t;

and sysdeps/x86_64/nptl/tls.h has

typedef struct
{
  void *tcb;            /* Pointer to the TCB.  Not necessarily the
                           thread descriptor used by libpthread.  */
  dtv_t *dtv;
  void *self;           /* Pointer to the thread descriptor.  */
  int multiple_threads;
  int gscope_flag;
  uintptr_t sysinfo;
  uintptr_t stack_guard;
  uintptr_t pointer_guard;
  unsigned long int vgetcpu_cache[2];
  int __glibc_reserved1;
  int __glibc_unused1;
  /* Reservation of some values for the TM ABI.  */
  void *__private_tm[4];
  /* GCC split stack support.  */
  void *__private_ss;
  long int __glibc_reserved2;
  /* Must be kept even if it is no longer used by glibc since programs,
     like AddressSanitizer, depend on the size of tcbhead_t.  */
  __128bits __glibc_unused2[8][4] __attribute__ ((aligned (32)));

  void *__padding[8];
} tcbhead_t;

The offsets of __private_tm are

i386:   36 bytes
x32:    48 bytes
x86_64: 80 bytes

gcc/config/i386/gnu-user64.h has

/* We steal the last transactional memory word.  */
#define TARGET_THREAD_SPLIT_STACK_OFFSET \
  (TARGET_64BIT ? (TARGET_X32 ? 0x40 : 0x70) : 0x30)

Should't it be

(TARGET_64BIT ? (TARGET_X32 ? 0x40 : 0x70) : 0x34)