Loop invariant code corrupting xstormy16 insn

[Nick Clifton]

Hi Zdenek,


>>>     (parallel [
>>>               (set (pc)
>>>                    (if_then_else (lt:SI (reg:SI 45)    <---
>>>                                         (reg:SI 26))
>>>                                  (label_ref:HI 129)
>>>                                  (pc)))
>>>               (clobber (reg:SI 45))                    <-- must be the same
>>>               (clobber (scratch:BI))
>>>               ])

> actually, I probably misunderstood what you meant.  The problem is that
> invariant motion rewrites just part of the considered insn, changing
> reg:45 to another register in if_then_else, but leaving it the same in
> the clobber?

Correct.  I originally had a patch like this

Index: gcc/loop-invariant.c
===================================================================
--- gcc/loop-invariant.c	(revision 125308)
+++ gcc/loop-invariant.c	(working copy)
@@ -1212,7 +1212,14 @@ move_invariant_reg (struct loop *loop, u
    if (inv->def)
      {
        for (use = inv->def->uses; use; use = use->next)
-	*use->pos = reg;
+	{
+	  rtx orig = *use->pos;
+
+	  /* Use replace_rtx() in case there are other references to
+	     ORIG inside the insn which are not recorded in the USE
+	     list.  eg references inside CLOBBERs.  */
+	  replace_rtx (use->insn, orig, reg);
+	}
      }

    return true;

which I thought would solve the problem, but I found that it introduced 
regressions into the gcc testsuite for an x86_64-linux-gnulibc 
toolchain, so I abandoned it.  (I did not investigate why it caused 
regressions, I just assumed that my approach was wrong).

Cheers
   Nick