tree-optimization/116079 - store motion and clobbers

When we move a store out of an inner loop and remove a clobber in
the process, analysis of the inner loop can run into the clobber
via the meta-data and crash when accessing its basic-block.  The
following avoids this by clearing the VDEF which is how it identifies
already processed stores.

	PR tree-optimization/116079
	* tree-ssa-loop-im.cc (hoist_memory_references): Clear
	VDEF of elided clobbers.

	* gcc.dg/torture/pr116079.c: New testcase.

2 files changed, 22 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/torture/pr116079.c b/gcc/testsuite/gcc.dg/torture/pr116079.c
new file mode 100644
index 0000000..e912096
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr116079.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+
+char g_132;
+int g_701, g_1189, func_24___trans_tmp_15, func_24_l_2691;
+long func_24___trans_tmp_9;
+int *func_24_l_2684;
+void func_24() {
+  for (; g_1189;) {
+    g_132 = 0;
+    for (; g_132 < 6; ++g_132) {
+      func_24___trans_tmp_9 = *func_24_l_2684 = func_24_l_2691;
+      g_701 = 4;
+      for (; g_701; g_701 -= 1) {
+        int l_2748[4];
+        int si2 = l_2748[3];
+        func_24___trans_tmp_15 = si2;
+      }
+    }
+  }
+}
diff --git a/gcc/tree-ssa-loop-im.cc b/gcc/tree-ssa-loop-im.cc
index c53efbb..ccc56dc 100644
--- a/gcc/tree-ssa-loop-im.cc
+++ b/gcc/tree-ssa-loop-im.cc
@@ -2880,6 +2880,7 @@ hoist_memory_references (class loop *loop, bitmap mem_refs,
 	  gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
 	  unlink_stmt_vdef (stmt);
 	  release_defs (stmt);
+	  gimple_set_vdef (stmt, NULL_TREE);
 	  gsi_remove (&gsi, true);
 	}
 
@@ -3062,6 +3063,7 @@ hoist_memory_references (class loop *loop, bitmap mem_refs,
       gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
       unlink_stmt_vdef (stmt);
       release_defs (stmt);
+      gimple_set_vdef (stmt, NULL_TREE);
       gsi_remove (&gsi, true);
     }