From: Richard Biener <rguenther@suse.de>
Date: Tue, 5 Jul 2022 09:38:52 +0000 (+0200)
Subject: tree-optimization/106186 - propagate out virtual LC PHI nodes properly
X-Git-Tag: basepoints/gcc-14~5704
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c3d2600cfb476e576fd27f3f29f49e968e86774d;p=thirdparty%2Fgcc.git

tree-optimization/106186 - propagate out virtual LC PHI nodes properly

The code to remove LC PHI nodes in clean_up_loop_closed_phi does not handle
virtual operands because may_propagate_copy generally returns false
for them.  The following copies the merge_blocks variant for
dealing with them.

This fixes a missed jump threading in gcc.dg/auto-init-uninit-4.c
which manifests in bogus uninit diagnostics.

	PR tree-optimization/106186
	* tree-ssa-propagate.cc (clean_up_loop_closed_phi):
	Properly handle virtual PHI nodes.
---

diff --git a/gcc/tree-ssa-propagate.cc b/gcc/tree-ssa-propagate.cc
index 163b24f0e69..9dc4bfd85bf 100644
--- a/gcc/tree-ssa-propagate.cc
+++ b/gcc/tree-ssa-propagate.cc
@@ -1272,7 +1272,21 @@ clean_up_loop_closed_phi (function *fun)
 	      rhs = gimple_phi_arg_def (phi, 0);
 	      lhs = gimple_phi_result (phi);
 
-	      if (rhs && may_propagate_copy (lhs, rhs))
+	      if (virtual_operand_p (rhs))
+		{
+		  imm_use_iterator iter;
+		  use_operand_p use_p;
+		  gimple *stmt;
+
+		  FOR_EACH_IMM_USE_STMT (stmt, iter, lhs)
+		    FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
+		      SET_USE (use_p, rhs);
+
+		  if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
+		    SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
+		  remove_phi_node (&gsi, true);
+		}
+	      else if (may_propagate_copy (lhs, rhs))
 		{
 		  /* Dump details.  */
 		  if (dump_file && (dump_flags & TDF_DETAILS))