Re: Minor SSA cleanups

[Daniel Berlin <dan at cgsoftware dot com>]

Jeffrey A Law <law@localhost.localdomain> writes:

> We want remove_phi_alternative to have external scope so that SSA optimizers
> which remove unexecutable edges can also remove phi alternatives.  
Weird.
You seem to be doing exactly the same patches I did.

I also global scoped phi_alternative.

The other change to ssa.c I have is:

*************** mark_phi_and_copy_regs (phi_set)
*** 1959,1964 ****
--- 1995,2002 ----
        if (insn == NULL)
          continue;
        pattern = PATTERN (insn);
+       if (!pattern)
+         continue;
        /* Sometimes we get PARALLEL insns.  These aren't phi nodes or
           copies.  */
        if (GET_CODE (pattern) != SET)


Since the SSA definition array isn't kept in sync after each pass, if
you've removed a register, the insn in the ssa_defs isn't necessarily
an INSN anymore.  But it won't be NULL. It could be a deleted NOTE or
something weird.
So we crash when we attempt to GET_CODE the pattern, which is NULL.


> We're
> also going to be changing the PHI nodes to record block pointers rather
> than block indices (but that'll be a separate patch).

Why *do* we have block indices or pointers at all there?
They seem unecessary, especially given that a register can only have
one def. So to figure out what block it came from, ....


-- 
"Everywhere is walking distance if you have the time.
"-Steven Wright