From 8830e46777407a7d5cd3de353394ffc46f2c785c Mon Sep 17 00:00:00 2001
From: Andrew Pinski <apinski@marvell.com>
Date: Tue, 2 May 2023 20:21:12 -0700
Subject: [PATCH] PHIOPT: Improve replace_phi_edge_with_variable's
 dce_ssa_names slightly

When I added the dce_ssa_names argument, I didn't realize bitmap was a
pointer so I used the default argument value as auto_bitmap(). But
instead we could just use nullptr and check if it was a nullptr
before calling simple_dce_from_worklist.

OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	* tree-ssa-phiopt.cc (replace_phi_edge_with_variable): Change
	the default argument value for dce_ssa_names to nullptr.
	Check to make sure dce_ssa_names is a non-nullptr before
	calling simple_dce_from_worklist.
---
 gcc/tree-ssa-phiopt.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 51f33e1e81aa..154a5abf86bb 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -89,7 +89,7 @@ single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1)
 static void
 replace_phi_edge_with_variable (basic_block cond_block,
 				edge e, gphi *phi, tree new_tree,
-				bitmap dce_ssa_names = auto_bitmap())
+				bitmap dce_ssa_names = nullptr)
 {
   basic_block bb = gimple_bb (phi);
   gimple_stmt_iterator gsi;
@@ -164,7 +164,8 @@ replace_phi_edge_with_variable (basic_block cond_block,
 	gimple_cond_make_true (cond);
     }
 
-  simple_dce_from_worklist (dce_ssa_names);
+  if (dce_ssa_names)
+    simple_dce_from_worklist (dce_ssa_names);
 
   statistics_counter_event (cfun, "Replace PHI with variable", 1);
 
-- 
GitLab