Subject: [nathanw_sa] Incorrect handling of _UC_USER in alpha SETC() macro?
To: None <email@example.com>
From: Jason R Thorpe <firstname.lastname@example.org>
Date: 01/05/2003 17:56:27
The SETC() macro (used in _setcontext_u() in libpthread) looks like
this on alpha:
#define SETC(reg) ; \
ldl t0, (UC_FLAGS)(reg) ; \
ldiq t1, 1 ; \
sll t1, _UC_USER_BIT, t1 ; \
and t0, t1, t0 ; \
beq t0, 1f ; \
t0 = uc->uc_flags;
t1 = (1 << _UC_USER_BIT);
t0 = t0 & t1;
The "beq" insn on Alpha branches if the source operand is 0. So, if I
am reading this right, it branches to the non-_UC_USER case if _UC_USER
is set, and falls through to the _UC_USER case for non-_UC_USER contexts.
I.e. the handling is exactly backwards.
Now, I have caught a cold, and am a little out of it today, so I could
appreciate a sanity check to make sure I'm not just being delusional.
-- Jason R. Thorpe <email@example.com>