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Maintain LC SSA when doing SVE vectorization

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The final loop IV use after the loop has that not in LC SSA
(and inserts not simplified _2 = _3 - 0 stmts).  In particular
since it splits the exit edge when there's a virtual PHI in the
destination it breaks virtual LC SSA form (but likely also
non-virtual).

The following properly inserts LC PHIs instead.

2022-07-04  Richard Biener  <rguenther@suse.de>

	* tree-vect-loop-manip.cc (vect_set_loop_condition_normal):
	Maintain LC SSA.
This commit is contained in:
Richard Biener 2022-07-04 14:58:41 +02:00
parent 510ac273a7
commit 7f4028ae9b
1 changed files with 16 additions and 3 deletions
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19
gcc/tree-vect-loop-manip.cc
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@ -920,9 +920,22 @@ vect_set_loop_condition_normal (class loop *loop, tree niters, tree step,
if (final_iv)
{
gassign *assign = gimple_build_assign (final_iv, MINUS_EXPR,
indx_after_incr, init);
gsi_insert_on_edge_immediate (single_exit (loop), assign);
gassign *assign;
edge exit = single_exit (loop);
gcc_assert (single_pred_p (exit->dest));
tree phi_dest
= integer_zerop (init) ? final_iv : copy_ssa_name (indx_after_incr);
/* Make sure to maintain LC SSA form here and elide the subtraction
if the value is zero. */
gphi *phi = create_phi_node (phi_dest, exit->dest);
add_phi_arg (phi, indx_after_incr, exit, UNKNOWN_LOCATION);
if (!integer_zerop (init))
{
assign = gimple_build_assign (final_iv, MINUS_EXPR,
phi_dest, init);
gimple_stmt_iterator gsi = gsi_after_labels (exit->dest);
gsi_insert_before (&gsi, assign, GSI_SAME_STMT);
}
}
return cond_stmt;