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Re: Loop invariant code corrupting xstormy16 insn
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