From: Richard Biener <rguenther@suse.de>
Date: Tue, 22 Jul 2025 11:02:03 +0000 (+0200)
Subject: tree-optimization/121202 - fix vector stmt placement
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4d0c17354e42d57d3f94a7b66ab59299b076ee68;p=thirdparty%2Fgcc.git

tree-optimization/121202 - fix vector stmt placement

When we have a vector shift with a scalar the shift operand can be
external - in that case we should not use the shift operand def
as hint where to place the vector shift instruction.  The ICE
in the PR is because stmt dominance queries only work inside of
the vector region.  But we should also never place stmts outside
of it.

	PR tree-optimization/121202
	* tree-vect-slp.cc (vect_schedule_slp_node): Do not take
	an out-of-region stmt as "last".

	* gcc.dg/pr121202.c: New testcase.

(cherry picked from commit bdfb5cc5aa6959a6959fc0cf98da08db89c81032)
---

diff --git a/gcc/testsuite/gcc.dg/pr121202.c b/gcc/testsuite/gcc.dg/pr121202.c
new file mode 100644
index 00000000000..30ecf4a5e01
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr121202.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fno-tree-copy-prop" } */
+
+int a, b, c;
+int e(int f, int g) { return f >> g; }
+int h(int f) { return a > 1 ? 0 : f << a; }
+int main() {
+  while (c--)
+    b = e(h(1), a);
+  return 0;
+}
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index f5286e6b819..b2af2682e58 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -11258,7 +11258,11 @@ vect_schedule_slp_node (vec_info *vinfo,
 		  && !SSA_NAME_IS_DEFAULT_DEF (def))
 		{
 		  gimple *stmt = SSA_NAME_DEF_STMT (def);
-		  if (!last_stmt)
+		  if (gimple_uid (stmt) == -1u)
+		    /* If the stmt is not inside the region do not
+		       use it as possible insertion point.  */
+		    ;
+		  else if (!last_stmt)
 		    last_stmt = stmt;
 		  else if (vect_stmt_dominates_stmt_p (last_stmt, stmt))
 		    last_stmt = stmt;