re PR bootstrap/80887 (gnat bootstrap fails at s-regpat.o: raised STORAGE_ERROR : stack overflow or erroneous memory access)

2017-06-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/80887
        c/
	* gimple-parser.c (c_parser_gimple_postfix_expression): Handle
	negated _Literals to parse _Literal (int) -1.

	* tree-ssa-sccvn.c (mprts_hook_cnt): New global.
	(vn_lookup_simplify_result): Allow only mprts_hook_cnt succesful
	simplified lookups, then reset mprts_hook.
	(vn_nary_build_or_lookup_1): Set mprts_hook_cnt to 9 before
	simplifying.
	(try_to_simplify): Likewise.

	* gcc.dg/tree-ssa/pr80887.c: New testcase.

From-SVN: r249373

6 files changed, 85 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aab38b1..99a7242 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2017-06-19  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/80887
+	* tree-ssa-sccvn.c (mprts_hook_cnt): New global.
+	(vn_lookup_simplify_result): Allow only mprts_hook_cnt succesful
+	simplified lookups, then reset mprts_hook.
+	(vn_nary_build_or_lookup_1): Set mprts_hook_cnt to 9 before
+	simplifying.
+	(try_to_simplify): Likewise.
+
 2017-06-19  Martin Liska  <mliska@suse.cz>
 
 	PR sanitizer/80879
diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 173fa92..58d59a6 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,8 @@
+2017-06-19  Richard Biener  <rguenther@suse.de>
+
+	* gimple-parser.c (c_parser_gimple_postfix_expression): Handle
+	negated _Literals to parse _Literal (int) -1.
+
 2017-06-13  Martin Liska  <mliska@suse.cz>
 
 	PR sanitize/78204
diff --git a/gcc/c/gimple-parser.c b/gcc/c/gimple-parser.c
index 4a55904..22f58f4 100644
--- a/gcc/c/gimple-parser.c
+++ b/gcc/c/gimple-parser.c
@@ -850,7 +850,7 @@ c_parser_gimple_postfix_expression (c_parser *parser)
 	    }
 	  else if (strcmp (IDENTIFIER_POINTER (id), "_Literal") == 0)
 	    {
-	      /* _Literal '(' type-name ')' number  */
+	      /* _Literal '(' type-name ')' [ '-' ] constant */
 	      c_parser_consume_token (parser);
 	      tree type = NULL_TREE;
 	      if (c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
@@ -862,15 +862,27 @@ c_parser_gimple_postfix_expression (c_parser *parser)
 		  c_parser_skip_until_found (parser, CPP_CLOSE_PAREN,
 					     "expected %<)%>");
 		}
+	      bool neg_p;
+	      if ((neg_p = c_parser_next_token_is (parser, CPP_MINUS)))
+		c_parser_consume_token (parser);
 	      tree val = c_parser_gimple_postfix_expression (parser).value;
 	      if (! type
 		  || ! val
 		  || val == error_mark_node
-		  || TREE_CODE (val) != INTEGER_CST)
+		  || ! CONSTANT_CLASS_P (val))
 		{
 		  c_parser_error (parser, "invalid _Literal");
 		  return expr;
 		}
+	      if (neg_p)
+		{
+		  val = const_unop (NEGATE_EXPR, TREE_TYPE (val), val);
+		  if (! val)
+		    {
+		      c_parser_error (parser, "invalid _Literal");
+		      return expr;
+		    }
+		}
 	      expr.value = fold_convert (type, val);
 	      return expr;
 	    }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f382a38..47e2a98 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-06-19  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/80887
+	* gcc.dg/tree-ssa/pr80887.c: New testcase.
+
 2017-06-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR ipa/81112
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr80887.c b/gcc/testsuite/gcc.dg/tree-ssa/pr80887.c
new file mode 100644
index 0000000..df7a9d9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr80887.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-options "-fgimple -O" } */
+
+int pos;
+void __GIMPLE (startwith("fre"))
+f()
+{
+  unsigned int t2;
+  unsigned int t1;
+  int a;
+  unsigned int u;
+  int _1;
+  int _2;
+  int _3;
+  unsigned int _4;
+  int _5;
+  unsigned int _6;
+
+bb_2:
+  _1 = pos;
+  _2 = _1 + 1;
+  pos = _2;
+  _3 = pos;
+  _4 = (unsigned int) _3;
+  u_9 = _4 + 4294967295u;
+  a_10 = pos;
+  _5 = a_10 + _Literal (int) -1;
+  t1_11 = (unsigned int) _5;
+  _6 = (unsigned int) a_10;
+  t2_12 = _6 + 4294967294u;
+  return;
+}
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 419da47..324cd73 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1639,6 +1639,7 @@ vn_reference_lookup_or_insert_for_pieces (tree vuse,
 }
 
 static vn_nary_op_t vn_nary_op_insert_stmt (gimple *stmt, tree result);
+static unsigned mprts_hook_cnt;
 
 /* Hook for maybe_push_res_to_seq, lookup the expression in the VN tables.  */
 
@@ -1648,8 +1649,22 @@ vn_lookup_simplify_result (code_helper rcode, tree type, tree *ops)
   if (!rcode.is_tree_code ())
     return NULL_TREE;
   vn_nary_op_t vnresult = NULL;
-  return vn_nary_op_lookup_pieces (TREE_CODE_LENGTH ((tree_code) rcode),
-				   (tree_code) rcode, type, ops, &vnresult);
+  tree res = vn_nary_op_lookup_pieces (TREE_CODE_LENGTH ((tree_code) rcode),
+				       (tree_code) rcode, type, ops, &vnresult);
+  /* We can end up endlessly recursing simplifications if the lookup above
+     presents us with a def-use chain that mirrors the original simplification.
+     See PR80887 for an example.  Limit successful lookup artificially
+     to 10 times if we are called as mprts_hook.  */
+  if (res
+      && mprts_hook
+      && --mprts_hook_cnt == 0)
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "Resetting mprts_hook after too many "
+		 "invocations.\n");
+      mprts_hook = NULL;
+    }
+  return res;
 }
 
 /* Return a value-number for RCODE OPS... either by looking up an existing
@@ -1666,6 +1681,7 @@ vn_nary_build_or_lookup_1 (code_helper rcode, tree type, tree *ops,
      So first simplify and lookup this expression to see if it
      is already available.  */
   mprts_hook = vn_lookup_simplify_result;
+  mprts_hook_cnt = 9;
   bool res = false;
   switch (TREE_CODE_LENGTH ((tree_code) rcode))
     {
@@ -3896,6 +3912,7 @@ try_to_simplify (gassign *stmt)
 
   /* First try constant folding based on our current lattice.  */
   mprts_hook = vn_lookup_simplify_result;
+  mprts_hook_cnt = 9;
   tem = gimple_fold_stmt_to_constant_1 (stmt, vn_valueize, vn_valueize);
   mprts_hook = NULL;
   if (tem