aarch64: Guard VF-based costing with !m_costing_for_scalar

g:4b47acfe2b626d1276e229a0cf165e934813df6c caused a segfault
in aarch64_vector_costs::analyze_loop_vinfo when costing scalar
code, since we'd end up dividing by a zero VF.

Much of the structure of the aarch64 costing code dates from
a stage 4 patch, when we had to work within the bounds of what
the target-independent code did.  Some of it could do with a
rework now that we're not so constrained.

This patch is therefore an emergency fix rather than the best
long-term solution.  I'll revisit when I have more time to think
about it.

gcc/
	* config/aarch64/aarch64.cc (aarch64_vector_costs::add_stmt_cost):
	Guard VF-based costing with !m_costing_for_scalar.

diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 27c315fc35e8cc4aaa21f459aa15020adab12d47..10b8ed5d3874a2d866a84d7139732b8629b1db36 100644 (file)
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -17932,7 +17932,7 @@ aarch64_vector_costs::add_stmt_cost (int count, vect_cost_for_stmt kind,
 
   /* Do one-time initialization based on the vinfo.  */
   loop_vec_info loop_vinfo = dyn_cast<loop_vec_info> (m_vinfo);
-  if (!m_analyzed_vinfo)
+  if (!m_analyzed_vinfo && !m_costing_for_scalar)
     {
       if (loop_vinfo)
        analyze_loop_vinfo (loop_vinfo);