re PR ipa/88936 (-fipa-pta breaks bash (incorrect optimisation of recursive static function))

2019-04-15  Richard Biener  <rguenther@suse.de>

	PR ipa/88936
	* tree.h (auto_var_p): Declare.
	* tree.c (auto_var_p): New function, split out from ...
	(auto_var_in_fn_p): ... here.
	* tree-ssa-structalias.c (struct variable_info): Add shadow_var_uid
	member.
	(new_var_info): Initialize it.
	(set_uids_in_ptset): Also set the shadow variable uid if required.
	(ipa_pta_execute): Postprocess points-to solutions assigning
	shadow variable uids for locals that may reach their containing
	function recursively.
	* tree-ssa-ccp.c (fold_builtin_alloca_with_align): Do not
	assert but instead check whether the points-to solution is
	a singleton.

	* gcc.dg/torture/pr88936-1.c: New testcase.
	* gcc.dg/torture/pr88936-2.c: Likewise.
	* gcc.dg/torture/pr88936-3.c: Likewise.

From-SVN: r270366

1 files changed, 14 insertions, 11 deletions

diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 234d9ca..e6bcc21 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -2170,23 +2170,26 @@ fold_builtin_alloca_with_align (gimple *stmt)
   if (size > threshold)
     return NULL_TREE;
 
+  /* We have to be able to move points-to info.  We used to assert
+     that we can but IPA PTA might end up with two UIDs here
+     as it might need to handle more than one instance being
+     live at the same time.  Instead of trying to detect this case
+     (using the first UID would be OK) just give up for now.  */
+  struct ptr_info_def *pi = SSA_NAME_PTR_INFO (lhs);
+  unsigned uid = 0;
+  if (pi != NULL
+      && !pi->pt.anything
+      && !pt_solution_singleton_or_null_p (&pi->pt, &uid))
+    return NULL_TREE;
+
   /* Declare array.  */
   elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1);
   n_elem = size * 8 / BITS_PER_UNIT;
   array_type = build_array_type_nelts (elem_type, n_elem);
   var = create_tmp_var (array_type);
   SET_DECL_ALIGN (var, TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)));
-  {
-    struct ptr_info_def *pi = SSA_NAME_PTR_INFO (lhs);
-    if (pi != NULL && !pi->pt.anything)
-      {
-	bool singleton_p;
-	unsigned uid;
-	singleton_p = pt_solution_singleton_or_null_p (&pi->pt, &uid);
-	gcc_assert (singleton_p);
-	SET_DECL_PT_UID (var, uid);
-      }
-  }
+  if (uid != 0)
+    SET_DECL_PT_UID (var, uid);
 
   /* Fold alloca to the address of the array.  */
   return fold_convert (TREE_TYPE (lhs), build_fold_addr_expr (var));