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Upstream-Status: Inappropriate [Backport]
From 21e7558c6e06c35620e80478f4e6b5ccd1c78aa9 Mon Sep 17 00:00:00 2001
From: jason <jason@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Tue, 29 Mar 2011 14:24:42 +0000
Subject: [PATCH 025/200] c-family/
* c.opt (fconstexpr-depth): New option.
cp/
* semantics.c (push_cx_call_context): Return bool.
(cxx_eval_call_expression): Handle excess depth.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch@171666 138bc75d-0d04-0410-961f-82ee72b054a4
index fe746e2..4c4727f 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -719,6 +719,10 @@ fconstant-string-class=
ObjC ObjC++ Joined MissingArgError(no class name specified with %qs)
-fconst-string-class=<name> Use class <name> for constant strings
+fconstexpr-depth=
+C++ ObjC++ Joined RejectNegative UInteger Var(max_constexpr_depth) Init(512)
+-fconstexpr-depth=<number> Specify maximum constexpr recursion depth
+
fdeduce-init-list
C++ ObjC++ Var(flag_deduce_init_list) Init(1)
-fno-deduce-init-list disable deduction of std::initializer_list for a template type parameter from a brace-enclosed initializer-list
index 5fe1414..3213483 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -5922,17 +5922,21 @@ cxx_bind_parameters_in_call (const constexpr_call *old_call, tree t,
/* Variables and functions to manage constexpr call expansion context.
These do not need to be marked for PCH or GC. */
+/* FIXME remember and print actual constant arguments. */
static VEC(tree,heap) *call_stack = NULL;
static int call_stack_tick;
static int last_cx_error_tick;
-static void
+static bool
push_cx_call_context (tree call)
{
++call_stack_tick;
if (!EXPR_HAS_LOCATION (call))
SET_EXPR_LOCATION (call, input_location);
VEC_safe_push (tree, heap, call_stack, call);
+ if (VEC_length (tree, call_stack) > (unsigned) max_constexpr_depth)
+ return false;
+ return true;
}
static void
@@ -5967,6 +5971,9 @@ cxx_eval_call_expression (const constexpr_call *old_call, tree t,
tree result;
constexpr_call new_call = { NULL, NULL, NULL, 0 };
constexpr_call **slot;
+ constexpr_call *entry;
+ bool depth_ok;
+
if (TREE_CODE (fun) != FUNCTION_DECL)
{
/* Might be a constexpr function pointer. */
@@ -6029,7 +6036,7 @@ cxx_eval_call_expression (const constexpr_call *old_call, tree t,
if (*non_constant_p)
return t;
- push_cx_call_context (t);
+ depth_ok = push_cx_call_context (t);
new_call.hash
= iterative_hash_template_arg (new_call.bindings,
@@ -6039,37 +6046,43 @@ cxx_eval_call_expression (const constexpr_call *old_call, tree t,
maybe_initialize_constexpr_call_table ();
slot = (constexpr_call **)
htab_find_slot (constexpr_call_table, &new_call, INSERT);
- if (*slot != NULL)
- {
- /* Calls which are in progress have their result set to NULL
- so that we can detect circular dependencies. */
- if ((*slot)->result == NULL)
- {
- if (!allow_non_constant)
- error ("call has circular dependency");
- (*slot)->result = result = error_mark_node;
- }
- else
- {
- result = (*slot)->result;
- if (result == error_mark_node && !allow_non_constant)
- /* Re-evaluate to get the error. */
- cxx_eval_constant_expression (&new_call, new_call.fundef->body,
- allow_non_constant, addr,
- non_constant_p);
- }
- }
- else
+ entry = *slot;
+ if (entry == NULL)
{
/* We need to keep a pointer to the entry, not just the slot, as the
slot can move in the call to cxx_eval_builtin_function_call. */
- constexpr_call *entry = ggc_alloc_constexpr_call ();
+ *slot = entry = ggc_alloc_constexpr_call ();
*entry = new_call;
- *slot = entry;
- result
- = cxx_eval_constant_expression (&new_call, new_call.fundef->body,
- allow_non_constant, addr,
- non_constant_p);
+ }
+ /* Calls which are in progress have their result set to NULL
+ so that we can detect circular dependencies. */
+ else if (entry->result == NULL)
+ {
+ if (!allow_non_constant)
+ error ("call has circular dependency");
+ *non_constant_p = true;
+ entry->result = result = error_mark_node;
+ }
+
+ if (!depth_ok)
+ {
+ if (!allow_non_constant)
+ error ("constexpr evaluation depth exceeds maximum of %d (use "
+ "-fconstexpr-depth= to increase the maximum)",
+ max_constexpr_depth);
+ *non_constant_p = true;
+ entry->result = result = error_mark_node;
+ }
+ else
+ {
+ result = entry->result;
+ if (!result || (result == error_mark_node && !allow_non_constant))
+ result = (cxx_eval_constant_expression
+ (&new_call, new_call.fundef->body,
+ allow_non_constant, addr,
+ non_constant_p));
+ if (result == error_mark_node)
+ *non_constant_p = true;
if (*non_constant_p)
entry->result = result = error_mark_node;
else
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 5478f79..4bcf83a 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -181,7 +181,7 @@ in the following sections.
@item C++ Language Options
@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@gccoptlist{-fabi-version=@var{n} -fno-access-control -fcheck-new @gol
--fconserve-space -ffriend-injection @gol
+-fconserve-space -fconstexpr-depth=@var{n} -ffriend-injection @gol
-fno-elide-constructors @gol
-fno-enforce-eh-specs @gol
-ffor-scope -fno-for-scope -fno-gnu-keywords @gol
@@ -1881,6 +1881,13 @@ two definitions were merged.
This option is no longer useful on most targets, now that support has
been added for putting variables into BSS without making them common.
+@item -fconstexpr-depth=@var{n}
+@opindex fconstexpr-depth
+Set the maximum nested evaluation depth for C++0x constexpr functions
+to @var{n}. A limit is needed to detect endless recursion during
+constant expression evaluation. The minimum specified by the standard
+is 512.
+
@item -fno-deduce-init-list
@opindex fno-deduce-init-list
Disable deduction of a template type parameter as
new file mode 100644
index 0000000..2f9b488
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C
@@ -0,0 +1,5 @@
+// Test that we catch excessive recursion.
+// { dg-options "-std=c++0x -fconstexpr-depth=5" }
+// { dg-prune-output "in constexpr expansion" }
+constexpr int f (int i) { return f (i-1); }
+constexpr int i = f(42); // { dg-error "constexpr evaluation depth" }
--
1.7.0.4
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