x32 is a 64-bit process with 32-bit software pointer and kernel may
place x32 shadow stack above 4GB. We need to save and restore 64-bit
shadow stack register for x32. builtin jmp buf size is 5 pointers. We
have space to save 64-bit shadow stack pointers: 32-bit SP, 32-bit FP,
32-bit IP, 64-bit SSP for x32.
PR target/84066
* gcc/config/i386/i386.md: Replace Pmode with word_mode in
builtin_setjmp_setup and builtin_longjmp to support x32.
* gcc/testsuite/gcc.target/i386/cet-sjlj-6a.c: New test.
* gcc/testsuite/gcc.target/i386/cet-sjlj-6b.c: Likewise.
From-SVN: r257326
