tree 4ec713f43436ea47beb20fb2df10140edeb9050d
parent f69a8299c1d95548e1539227fb7b8f5581aeb29b
author Jeff Law <jlaw@ventanamicro.com> 1668649679 -0700
committer Jeff Law <jlaw@ventanamicro.com> 1668649679 -0700

Fix multiple recent sh3/sh3eb regressions

So my tester started showing even more regressions on the sh3/sh4 runs
recently (beyond the one recently reported in BZ triggered by some DCE
related changes).  Bisection kept showing inconsistent results.  I was
starting to think memory management error, but valgrind didn't flag anything.

After a bit of head-banging I was able to track it down to predicate
tests called from the SH specific combiner passes.  And once I started
getting inside the actual code for the predicate function it became
pretty obvious.  The predicate routines are supposed to return a bool,
fine and they dutifully set the low bit in %eax properly.

The *caller* was looking at the full register.  Uh-oh.  Naturally we
became dependent on what happened to be in the upper 31 bits of a register.
That's why the bug would come and go so willy-nilly.  This was ultimately
chased down to an incorrect prototype in sh_treg_combine.cc for predicate
functions defined via define_predicate.

Removing the bogus prototypes and instead including the generated
tm-preds.h fixes this problem.  I also checked the other ports for
similar problems (specifically looking for a extern int.*_operand, then
for each of the hits looking to see if the predicate was defined via
define_predicate).  No other ports had similar braindamage.

This fixes the most recent regressions in my tester for sh3/sh3eb
and I strongly suspect sh4.  It does not fix 107704, but I think
Richi and I both agree that's a visitation order issue and we were
just getting lucky before.

gcc/

	* config/sh/sh_treg_combine.cc: Include tm-preds.h.
	(t_reg_operand): Remove bogus prototype.
	(negt_reg_operand): Likewise.