From: Robin Dapp <rd...@ventanamicro.com>
When predicating a load we implicitly assume that the else value is
zero. This matters in case the loaded value is padded (like e.g.
a Bool) and we must ensure that the padding bytes are zero on targets
that don't implicitly zero inactive elements.
A former version of this patch still had this handling in ifcvt but
the latest version defers it to the vectorizer.
gcc/ChangeLog:
* tree-if-conv.cc (predicate_load_or_store): Add zero else
operand and comment.
---
gcc/tree-if-conv.cc | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index eb981642bae..83b77fd6663 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -2555,10 +2555,17 @@ predicate_load_or_store (gimple_stmt_iterator *gsi,
gassign *stmt, tree mask)
ref);
if (TREE_CODE (lhs) == SSA_NAME)
{
- new_stmt
- = gimple_build_call_internal (IFN_MASK_LOAD, 3, addr,
- ptr, mask);
- gimple_call_set_lhs (new_stmt, lhs);
+ /* Get a zero else value. This might not be what a target actually uses
+ but we cannot be sure about which vector mode the vectorizer will
+ choose. Therefore, leave the decision whether we need to force the
+ inactive elements to zero to the vectorizer. */
+ tree els = vect_get_mask_load_else (MASK_LOAD_ELSE_ZERO,
+ TREE_TYPE (lhs));
+
+ new_stmt = gimple_build_call_internal (IFN_MASK_LOAD, 4, addr,
+ ptr, mask, els);
+
+ gimple_set_lhs (new_stmt, lhs);
gimple_set_vuse (new_stmt, gimple_vuse (stmt));
}
else
@@ -2876,7 +2883,6 @@ predicate_statements (loop_p loop)
new_stmt = predicate_load_or_store (&gsi, stmt, mask);
else
new_stmt = predicate_rhs_code (stmt, mask, cond, &ssa_names);
-
gsi_replace (&gsi, new_stmt, true);
}
else if (((lhs = gimple_assign_lhs (stmt)), true)
--
2.47.0
