Well, not actually measurable but we can save get_continuation_for_phi
calls from translate_vuse_through_block if we do not end up using
the result.
Bootstrap / regtest running on x86_64-unknown-linux-gnu.
Richard.
2019-05-07 Richard Biener <rguent...@suse.de>
PR tree-optimization/90316
* tree-ssa-pre.c (translate_vuse_through_block): When
same_valid is NULL do not bother to search for a virtual
PHI continuation.
(phi_translate_1): When operands changed we cannot keep
the same value-number so do not bother to ask whether
that's possible from translate_vuse_through_block.
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c (revision 270940)
+++ gcc/tree-ssa-pre.c (working copy)
@@ -1146,7 +1146,8 @@ translate_vuse_through_block (vec<vn_ref
edge e = NULL;
bool use_oracle;
- *same_valid = true;
+ if (same_valid)
+ *same_valid = true;
if (gimple_bb (phi) != phiblock)
return vuse;
@@ -1179,7 +1180,7 @@ translate_vuse_through_block (vec<vn_ref
if (e)
{
- if (use_oracle)
+ if (use_oracle && same_valid)
{
bitmap visited = NULL;
/* Try to find a vuse that dominates this phi node by skipping
@@ -1191,13 +1192,9 @@ translate_vuse_through_block (vec<vn_ref
}
else
vuse = NULL_TREE;
- if (!vuse)
- {
- /* If we didn't find any, the value ID can't stay the same,
- but return the translated vuse. */
- *same_valid = false;
- vuse = PHI_ARG_DEF (phi, e->dest_idx);
- }
+ /* If we didn't find any, the value ID can't stay the same. */
+ if (!vuse && same_valid)
+ *same_valid = false;
/* ??? We would like to return vuse here as this is the canonical
upmost vdef that this reference is associated with. But during
insertion of the references into the hash tables we only ever
@@ -1535,7 +1532,8 @@ phi_translate_1 (bitmap_set_t dest,
? newoperands : operands,
ref->set, ref->type,
vuse, phiblock, pred,
- &same_valid);
+ changed
+ ? NULL : &same_valid);
if (newvuse == NULL_TREE)
{
newoperands.release ();
