[PATCH] tree-optimization/105437 - BB vect with extern defs of throwing stmts

[PATCH] tree-optimization/105437 - BB vect with extern defs of throwing stmts

[Richard Biener]

We have to watch out for vectorized stmt insert locations if the
def from the last stmt alters control flow.  We constrain region
building so we know the def is outside of the current region
and thus we can insert at the region start point.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed to trunk
sofar.  If we do RC2 then I'd consider this there as well as it is
exposed by us enabling vectorization at -O2 by default in GCC 12.

Richard.

2022-05-02  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105437
	* tree-vect-slp.cc (vect_schedule_slp_node): Handle the
	case where last_stmt alters control flow.

	* g++.dg/vect/pr105437.cc: New testcase.
---
 gcc/testsuite/g++.dg/vect/pr105437.cc | 24 ++++++++++++++++++++++++
 gcc/tree-vect-slp.cc                  |  7 +++++++
 2 files changed, 31 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/vect/pr105437.cc

diff --git a/gcc/testsuite/g++.dg/vect/pr105437.cc b/gcc/testsuite/g++.dg/vect/pr105437.cc
new file mode 100644
index 00000000000..b3b440debef
--- /dev/null
+++ b/gcc/testsuite/g++.dg/vect/pr105437.cc
@@ -0,0 +1,24 @@
+// { dg-do compile }
+
+struct ControlClass
+{
+    virtual ~ControlClass();
+
+    int Width;
+    int Height;
+    unsigned IsToRepaint : 1;
+};
+
+struct SelectClass : ControlClass
+{
+    SelectClass(void);
+};
+
+int Non_Folded_Value();
+
+SelectClass::SelectClass(void)
+{
+    int factor = Non_Folded_Value();
+    Width = 32 << factor;
+    Height = 24 << factor;
+}
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 805dd7e10e2..0d400c00df1 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -7302,6 +7302,13 @@ vect_schedule_slp_node (vec_info *vinfo,
 	  gcc_assert (seen_vector_def);
 	  si = gsi_after_labels (as_a <bb_vec_info> (vinfo)->bbs[0]);
 	}
+      else if (is_ctrl_altering_stmt (last_stmt))
+	{
+	  /* We split regions to vectorize at control altering stmts
+	     with a definition so this must be an external which
+	     we can insert at the start of the region.  */
+	  si = gsi_after_labels (as_a <bb_vec_info> (vinfo)->bbs[0]);
+	}
       else if (is_a <bb_vec_info> (vinfo)
 	       && gimple_bb (last_stmt) != gimple_bb (stmt_info->stmt)
 	       && gimple_could_trap_p (stmt_info->stmt))
-- 
2.34.1