tree-optimization/105012 - fix ICE from local DSE of if-conversion

The following guards dse_classify_store with the same condition as
the DSE pass does - availability of a virtual definition.  For
the PR we run into the fortran frontend generating a clobber for
a FUNCTION_DECL lhs which is ignored by the operand scanner and has
no virtual operands assigned.  Apart from fixing the frontend the
following fixes the ICE by adjusting if-conversion.

2022-03-22  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105012
	* tree-if-conv.cc (ifcvt_local_dce): Only call
	dse_classify_store when we have a VDEF.

diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index 375628e..7495ed6 100644 (file)
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -3145,7 +3145,7 @@ ifcvt_local_dce (class loop *loop)
       gimple_stmt_iterator gsiprev = gsi;
       gsi_prev (&gsiprev);
       stmt = gsi_stmt (gsi);
-      if (gimple_store_p (stmt))
+      if (gimple_store_p (stmt) && gimple_vdef (stmt))
        {
          tree lhs = gimple_get_lhs (stmt);
          ao_ref write;