This improves on top of r14-478-gd256dc28f0eadd. Instead of checking if
the two middle bbs are empty, we can check if the new phi entry is depends
on either branch instead. Since we move the statements in
match_simplify_replacement, this does not make a difference. This will
make a difference when we support multiple stmts though. As we might not remove
the middles bb even though we could. I don't have a testcase for that
but a LLM based review of allowing more than one stmt to be phiopt marked
as a possibility of wrong code/ICE (neither is true due to the way the code
is structed as there would be no uses of those statements left behind as we
would have replaced the phi entry for that case).
This helps the next patch which is the `allowing more than one stmt to be
phiopt`.
gcc/ChangeLog:
* tree-ssa-phiopt.cc (replace_phi_edge_with_variable): Handle non-empty
middle bbs for diamond case.
(match_simplify_replacement): Mark phi args to be maybe dce'd also.
Signed-off-by: Andrea Pinski <[email protected]>
---
gcc/tree-ssa-phiopt.cc | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index a8c3a94a3f9..53256d1f787 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -145,9 +145,15 @@ replace_phi_edge_with_variable (basic_block cond_block,
{
basic_block bb1 = EDGE_SUCC (cond_block, 0)->dest;
basic_block bb2 = EDGE_SUCC (cond_block, 1)->dest;
+ // If the new phi entry does not refer to either of
+ // the middle bb, then either middle bbs can be deleted
+ // as long as the middle bbs only reach the phi bb and only
+ // reachable from the conditional bb.
if (single_pred_p (bb1) && single_pred_p (bb2)
&& single_succ_p (bb1) && single_succ_p (bb2)
- && empty_block_p (bb1) && empty_block_p (bb2))
+ && (TREE_CODE (new_tree) != SSA_NAME
+ || (gimple_bb (SSA_NAME_DEF_STMT (new_tree)) != bb1
+ && gimple_bb (SSA_NAME_DEF_STMT (new_tree)) != bb2)))
deleteboth = true;
}
else
@@ -1250,6 +1256,12 @@ match_simplify_replacement (basic_block cond_bb,
basic_block middle_bb,
&& !SSA_NAME_IS_DEFAULT_DEF (gimple_cond_rhs (stmt)))
bitmap_set_bit (exprs_maybe_dce,
SSA_NAME_VERSION (gimple_cond_rhs (stmt)));
+ if (TREE_CODE (arg_true) == SSA_NAME
+ && !SSA_NAME_IS_DEFAULT_DEF (arg_true))
+ bitmap_set_bit (exprs_maybe_dce, SSA_NAME_VERSION (arg_true));
+ if (TREE_CODE (arg_false) == SSA_NAME
+ && !SSA_NAME_IS_DEFAULT_DEF (arg_false))
+ bitmap_set_bit (exprs_maybe_dce, SSA_NAME_VERSION (arg_false));
gsi = gsi_last_bb (cond_bb);
/* Insert the sequence generated from gimple_simplify_phiopt. */
--
2.43.0
