re PR tree-optimization/79740 (ICE on -Os and above in both 32-bit and 64-bit modes on x86_64-linux-gnu (internal compiler error: in VN_INFO_GET, at tree-ssa-sccvn.c:407 }))

2017-02-28  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/79740
	* tree-ssa-sccvn.c (vn_nary_op_insert_into): Allow redundant
	inserts.
	(visit_nary_op): Insert the nary into the hashtable if we
	pattern-matched sth.
	* tree-ssa-pre.c (eliminate_insert): Robustify.

	* gcc.dg/torture/pr79740.c: New testcase.

From-SVN: r245780

5 files changed, 59 insertions, 5 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b65f820..17acce5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,14 @@
 2017-02-28  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/79740
+	* tree-ssa-sccvn.c (vn_nary_op_insert_into): Allow redundant
+	inserts.
+	(visit_nary_op): Insert the nary into the hashtable if we
+	pattern-matched sth.
+	* tree-ssa-pre.c (eliminate_insert): Robustify.
+
+2017-02-28  Richard Biener  <rguenther@suse.de>
+
 	PR middle-end/79731
 	* fold-const.c (decode_field_reference): Reject out-of-bound
 	accesses.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 82933d3..a09eb28 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2017-02-28  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/79740
+	* gcc.dg/torture/pr79740.c: New testcase.
+
+2017-02-28  Richard Biener  <rguenther@suse.de>
+
 	PR middle-end/79731
 	* c-c++-common/torture/pr79731.c: New testcase.
 
diff --git a/gcc/testsuite/gcc.dg/torture/pr79740.c b/gcc/testsuite/gcc.dg/torture/pr79740.c
new file mode 100644
index 0000000..25b8de5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr79740.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+
+int a;
+short b;
+short fn1(unsigned short p1) { return p1 << a; }
+
+int main()
+{
+  short c;
+  int d = 4;
+  for (; b;)
+    {
+      c = d + 1;
+      fn1(c);
+      d = 0;
+    }
+  d++;
+  return 0;
+}
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index a1d7677..bdf48ad7 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -4099,8 +4099,12 @@ eliminate_push_avail (tree op)
 static tree
 eliminate_insert (gimple_stmt_iterator *gsi, tree val)
 {
-  gimple *stmt = gimple_seq_first_stmt (VN_INFO (val)->expr);
-  if (!is_gimple_assign (stmt)
+  /* We can insert a sequence with a single assignment only.  */
+  gimple_seq stmts = VN_INFO (val)->expr;
+  if (!gimple_seq_singleton_p (stmts))
+    return NULL_TREE;
+  gassign *stmt = dyn_cast <gassign *> (gimple_seq_first_stmt (stmts));
+  if (!stmt
       || (!CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt))
 	  && gimple_assign_rhs_code (stmt) != VIEW_CONVERT_EXPR
 	  && gimple_assign_rhs_code (stmt) != BIT_FIELD_REF
@@ -4116,8 +4120,8 @@ eliminate_insert (gimple_stmt_iterator *gsi, tree val)
   if (!leader)
     return NULL_TREE;
 
-  gimple_seq stmts = NULL;
   tree res;
+  stmts = NULL;
   if (gimple_assign_rhs_code (stmt) == BIT_FIELD_REF)
     res = gimple_build (&stmts, BIT_FIELD_REF,
 			TREE_TYPE (val), leader,
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 4f5e852..e7502de 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -2820,6 +2820,15 @@ vn_nary_op_insert_into (vn_nary_op_t vno, vn_nary_op_table_type *table,
     vno->hashcode = vn_nary_op_compute_hash (vno);
 
   slot = table->find_slot_with_hash (vno, vno->hashcode, INSERT);
+  /* While we do not want to insert things twice it's awkward to
+     avoid it in the case where visit_nary_op pattern-matches stuff
+     and ends up simplifying the replacement to itself.  We then
+     get two inserts, one from visit_nary_op and one from
+     vn_nary_build_or_lookup.
+     So allow inserts with the same value number.  */
+  if (*slot && (*slot)->result == vno->result)
+    return *slot;
+
   gcc_assert (!*slot);
 
   *slot = vno;
@@ -3544,7 +3553,11 @@ visit_nary_op (tree lhs, gassign *stmt)
 			  result = vn_nary_build_or_lookup (NOP_EXPR,
 							    type, ops);
 			  if (result)
-			    return set_ssa_val_to (lhs, result);
+			    {
+			      bool changed = set_ssa_val_to (lhs, result);
+			      vn_nary_op_insert_stmt (stmt, result);
+			      return changed;
+			    }
 			}
 		      else
 			{
@@ -3555,7 +3568,11 @@ visit_nary_op (tree lhs, gassign *stmt)
 							    TREE_TYPE (lhs),
 							    ops);
 			  if (result)
-			    return set_ssa_val_to (lhs, result);
+			    {
+			      bool changed = set_ssa_val_to (lhs, result);
+			      vn_nary_op_insert_stmt (stmt, result);
+			      return changed;
+			    }
 			}
 		    }
 		}