From: Richard Biener <rguenther@suse.de>
Date: Tue, 4 Jul 2023 07:51:05 +0000 (+0200)
Subject: tree-optimization/110436 - bogus live/relevant for unused pattern
X-Git-Tag: basepoints/gcc-15~7851
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=729aa4fa48d627c4344764676edad3b65d40a003;p=thirdparty%2Fgcc.git

tree-optimization/110436 - bogus live/relevant for unused pattern

When we compute liveness and relevantness we have to make sure to
handle live but not relevant stmts in a way we can later vectorize
them.  When the stmt uses only operands that do not need vectorization
we can just leave such stmts in place - but not in the case they
are recognized as patterns.  Since we don't have a way to cancel
pattern recognition we have to force mark such stmts as relevant.

	PR tree-optimization/110436
	* tree-vect-stmts.cc (vect_mark_relevant): Expand dumping,
	force live but not relevant pattern stmts relevant.

	* gcc.dg/pr110436.c: New testcase.
---

diff --git a/gcc/testsuite/gcc.dg/pr110436.c b/gcc/testsuite/gcc.dg/pr110436.c
new file mode 100644
index 000000000000..8e63ca04cbed
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr110436.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+#include "pr83089.c"
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index a0c39268bf0b..c3e6f2d34ed3 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -261,11 +261,26 @@ vect_mark_relevant (vec<stmt_vec_info> *worklist, stmt_vec_info stmt_info,
 	dump_printf_loc (MSG_NOTE, vect_location,
 			 "last stmt in pattern. don't mark"
 			 " relevant/live.\n");
+
       stmt_vec_info old_stmt_info = stmt_info;
       stmt_info = STMT_VINFO_RELATED_STMT (stmt_info);
       gcc_assert (STMT_VINFO_RELATED_STMT (stmt_info) == old_stmt_info);
       save_relevant = STMT_VINFO_RELEVANT (stmt_info);
       save_live_p = STMT_VINFO_LIVE_P (stmt_info);
+
+      if (live_p && relevant == vect_unused_in_scope)
+	{
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_NOTE, vect_location,
+			     "vec_stmt_relevant_p: forcing live patern stmt "
+			     "relevant.\n");
+	  relevant = vect_used_only_live;
+	}
+
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_NOTE, vect_location,
+			 "mark relevant %d, live %d: %G", relevant, live_p,
+			 stmt_info->stmt);
     }
 
   STMT_VINFO_LIVE_P (stmt_info) |= live_p;