https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111401
Robin Dapp <rdapp at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rdapp at gcc dot gnu.org
--- Comment #2 from Robin Dapp <rdapp at gcc dot gnu.org> ---
I played around with this a bit. Emitting a COND_LEN in if-convert is easy:
_ifc__35 = .COND_ADD (_23, init_20, _8, init_20);
However, during reduction handling we rely on the reduction being a gimple
assign and binary operation, though so I needed to fix some places and indices
as well as the proper mask.
What complicates things a bit is that we assume that "init_20" (i.e. the
reduction def) occurs once when we have it twice in the COND_ADD. I just
special cased that for now. Is this the proper thing to do?
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 23c6e8259e7..e99add3cf16 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -3672,7 +3672,7 @@ vect_analyze_loop (class loop *loop, vec_info_shared
*shared)
static bool
fold_left_reduction_fn (code_helper code, internal_fn *reduc_fn)
{
- if (code == PLUS_EXPR)
+ if (code == PLUS_EXPR || code == IFN_COND_ADD)
{
*reduc_fn = IFN_FOLD_LEFT_PLUS;
return true;
@@ -4106,8 +4106,11 @@ vect_is_simple_reduction (loop_vec_info loop_info,
stmt_vec_info phi_info,
return NULL;
}
- nphi_def_loop_uses++;
- phi_use_stmt = use_stmt;
+ if (use_stmt != phi_use_stmt)
+ {
+ nphi_def_loop_uses++;
+ phi_use_stmt = use_stmt;
+ }
@@ -7440,6 +7457,9 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
if (i == STMT_VINFO_REDUC_IDX (stmt_info))
continue;
+ if (op.ops[i] == op.ops[STMT_VINFO_REDUC_IDX (stmt_info)])
+ continue;
+
Apart from that I think what's mainly missing is making the added code nicer.
Going to attach a tentative patch later.
