> On Thu, 11 Jul 2019, Jan Hubicka wrote:
>
> > Hi,
> > this patch makes nonoverlapping_component_refs_since_match_p to accept
> > paths with non-trivial MEM_REFs and TMRs assuming that they have same
> > semantics.
>
> Hmm. We'll never get any TARGET_MEM_REFs wrapped with
> handled-components so I wonder if it makes sense to handle it in
> nonoverlapping_component_refs_since_match_p at all.
OK, that makes my life easier. Here is updated patch.
Index: tree-ssa-alias.c
===================================================================
--- tree-ssa-alias.c (revision 273322)
+++ tree-ssa-alias.c (working copy)
@@ -1265,20 +1265,6 @@ nonoverlapping_component_refs_since_matc
component_refs1.safe_push (ref1);
ref1 = TREE_OPERAND (ref1, 0);
}
- if (TREE_CODE (ref1) == MEM_REF && ref1 != match1)
- {
- if (!integer_zerop (TREE_OPERAND (ref1, 1)))
- {
- ++alias_stats.nonoverlapping_component_refs_since_match_p_may_alias;
- return -1;
- }
- }
- /* TODO: Handle TARGET_MEM_REF later. */
- if (TREE_CODE (ref1) == TARGET_MEM_REF && ref1 != match1)
- {
- ++alias_stats.nonoverlapping_component_refs_since_match_p_may_alias;
- return -1;
- }
/* Create the stack of handled components for REF2. */
while (handled_component_p (ref2) && ref2 != match2)
@@ -1290,20 +1276,31 @@ nonoverlapping_component_refs_since_matc
component_refs2.safe_push (ref2);
ref2 = TREE_OPERAND (ref2, 0);
}
- if (TREE_CODE (ref2) == MEM_REF && ref2 != match2)
- {
- if (!integer_zerop (TREE_OPERAND (ref2, 1)))
- {
- ++alias_stats.nonoverlapping_component_refs_since_match_p_may_alias;
- return -1;
- }
- }
- if (TREE_CODE (ref2) == TARGET_MEM_REF && ref2 != match2)
+
+ bool mem_ref1 = TREE_CODE (ref1) == MEM_REF && ref1 != match1;
+ bool mem_ref2 = TREE_CODE (ref2) == MEM_REF && ref2 != match2;
+
+ /* If only one of access paths starts with MEM_REF check that offset is 0
+ so the addresses stays the same after stripping it.
+ TODO: In this case we may walk the other access path until we get same
+ offset.
+
+ If both starts with MEM_REF, offset has to be same. */
+ if ((mem_ref1 && !mem_ref2 && !integer_zerop (TREE_OPERAND (ref1, 1)))
+ || (mem_ref2 && !mem_ref1 && !integer_zerop (TREE_OPERAND (ref2, 1)))
+ || (mem_ref1 && mem_ref2
+ && !tree_int_cst_equal (TREE_OPERAND (ref1, 1),
+ TREE_OPERAND (ref2, 1))))
{
++alias_stats.nonoverlapping_component_refs_since_match_p_may_alias;
return -1;
}
+ /* TARGET_MEM_REF are never wrapped in handled components, so we do not need
+ to handle them here at all. */
+ gcc_checking_assert (TREE_CODE (ref1) != TARGET_MEM_REF
+ && TREE_CODE (ref2) != TARGET_MEM_REF);
+
/* Pop the stacks in parallel and examine the COMPONENT_REFs of the same
rank. This is sufficient because we start from the same DECL and you
cannot reference several fields at a time with COMPONENT_REFs (unlike
