[gcc(refs/users/aoliva/heads/testme)] hardcfr: mark expected-throw functions

[Alexandre Oliva <aoliva@gcc.gnu.org>]

https://gcc.gnu.org/g:20c7519c2eef3f4ea541f0c2d0d8b98e13b21bf8

commit 20c7519c2eef3f4ea541f0c2d0d8b98e13b21bf8
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Wed Oct 19 20:36:22 2022 -0300

    hardcfr: mark expected-throw functions

Diff:
---
 gcc/calls.cc                                        |  3 +++
 gcc/common.opt                                      | 12 +++---------
 gcc/cp/decl.cc                                      |  3 ++-
 gcc/cp/except.cc                                    |  8 +++++---
 gcc/doc/invoke.texi                                 | 12 ++++++++----
 gcc/flag-types.h                                    |  4 ++--
 gcc/gimple-harden-control-flow.cc                   |  9 +++++++--
 gcc/gimple.cc                                       |  5 +++++
 gcc/gimple.h                                        | 21 +++++++++++++++++++++
 .../c-c++-common/torture/harden-cfr-abrt-always.c   | 11 +++++++++++
 .../c-c++-common/torture/harden-cfr-abrt-never.c    | 11 +++++++++++
 .../torture/harden-cfr-abrt-not-always.c            | 11 +++++++++++
 .../c-c++-common/torture/harden-cfr-abrt-nothrow.c  | 11 +++++++++++
 .../c-c++-common/torture/harden-cfr-abrt.c          | 10 +++++++++-
 .../c-c++-common/torture/harden-cfr-always.c        | 13 +++++++++++++
 .../torture/harden-cfr-bret-not-always.c            | 14 ++++++++++++++
 .../c-c++-common/torture/harden-cfr-never.c         | 13 +++++++++++++
 .../c-c++-common/torture/harden-cfr-not-always.c    | 13 +++++++++++++
 .../c-c++-common/torture/harden-cfr-nothrow.c       | 13 +++++++++++++
 gcc/testsuite/c-c++-common/torture/harden-cfr.c     | 17 ++++++++++-------
 gcc/testsuite/g++.dg/harden-cfr-throw-always-O0.C   |  2 ++
 .../g++.dg/harden-cfr-throw-returning-O0.C          |  2 ++
 .../g++.dg/harden-cfr-throw-returning-enabled-O0.C  | 11 +++++++++++
 .../g++.dg/torture/harden-cfr-throw-always.C        |  7 -------
 .../g++.dg/torture/harden-cfr-throw-never.C         | 12 ++++++++++++
 .../g++.dg/torture/harden-cfr-throw-nocleanup.C     |  2 +-
 .../g++.dg/torture/harden-cfr-throw-not-always.C    | 12 ++++++++++++
 .../g++.dg/torture/harden-cfr-throw-nothrow.C       | 11 +++++++++++
 .../g++.dg/torture/harden-cfr-throw-returning.C     |  2 +-
 gcc/testsuite/g++.dg/torture/harden-cfr-throw.C     |  8 ++++++++
 gcc/tree-core.h                                     |  3 +++
 gcc/tree.cc                                         |  9 +++++++--
 32 files changed, 255 insertions(+), 40 deletions(-)

diff --git a/gcc/calls.cc b/gcc/calls.cc
index 6dd6f73e978..0c50d83b0ba 100644
--- a/gcc/calls.cc
+++ b/gcc/calls.cc
@@ -845,6 +845,9 @@ flags_from_decl_or_type (const_tree exp)
 	    flags |= ECF_TM_PURE;
 	}
 
+      if (lookup_attribute ("expected_throw", DECL_ATTRIBUTES (exp)))
+	flags |= ECF_THROW;
+
       flags = special_function_p (exp, flags);
     }
   else if (TYPE_P (exp))
diff --git a/gcc/common.opt b/gcc/common.opt
index 2f37d2fcbd3..e57646ce125 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1808,7 +1808,7 @@ Check CFR execution paths also when exiting a function through an exception.
 
 fhardcfr-check-noreturn-calls=
 Common Joined RejectNegative Enum(hardcfr_check_noreturn_calls) Var(flag_harden_control_flow_redundancy_check_noreturn) Init(HCFRNR_UNSPECIFIED) Optimization
--fhardcfr-check-noreturn-calls=[always|nothrow|never]	Check CFR execution paths also before calling noreturn functions.
+-fhardcfr-check-noreturn-calls=[always|not-always|nothrow|never]	Check CFR execution paths also before calling noreturn functions.
 
 Enum
 Name(hardcfr_check_noreturn_calls) Type(enum hardcfr_noret) UnknownError(unknown hardcfr noreturn checking level %qs)
@@ -1819,14 +1819,8 @@ Enum(hardcfr_check_noreturn_calls) String(never) Value(HCFRNR_NEVER)
 EnumValue
 Enum(hardcfr_check_noreturn_calls) String(nothrow) Value(HCFRNR_NOTHROW)
 
-; ??? There could be yet another option here, that checked before
-; noreturn calls, except for those known to always throw, if we had
-; means to distinguish noreturn functions known to always throw, such
-; as those used to (re)raise exceptions, from those that merely might
-; throw.  "not always" stands for "not always-throwing", but it also
-; contrasts with "always" below.
-; EnumValue
-; Enum(hardcfr_check_noreturn_calls) String(not-always) Value(HCFRNR_NOT_ALWAYS)
+EnumValue
+Enum(hardcfr_check_noreturn_calls) String(not-always) Value(HCFRNR_NOT_ALWAYS)
 
 EnumValue
 Enum(hardcfr_check_noreturn_calls) String(always) Value(HCFRNR_ALWAYS)
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 85b892cddf0..5d8f88d8419 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -5144,7 +5144,8 @@ push_cp_library_fn (enum tree_code operator_code, tree type,
 tree
 push_throw_library_fn (tree name, tree type)
 {
-  tree fn = push_library_fn (name, type, NULL_TREE, ECF_NORETURN | ECF_COLD);
+  tree fn = push_library_fn (name, type, NULL_TREE,
+			     ECF_NORETURN | ECF_THROW | ECF_COLD);
   return fn;
 }
 \f
diff --git a/gcc/cp/except.cc b/gcc/cp/except.cc
index 2677a9b7678..0131fbcf305 100644
--- a/gcc/cp/except.cc
+++ b/gcc/cp/except.cc
@@ -652,12 +652,13 @@ build_throw (location_t loc, tree exp)
 	  tree args[3] = {ptr_type_node, ptr_type_node, cleanup_type};
 
 	  throw_fn = declare_library_fn_1 ("__cxa_throw",
-					   ECF_NORETURN | ECF_COLD,
+					   ECF_NORETURN | ECF_THROW | ECF_COLD,
 					   void_type_node, 3, args);
 	  if (flag_tm && throw_fn != error_mark_node)
 	    {
 	      tree itm_fn = declare_library_fn_1 ("_ITM_cxa_throw",
-						  ECF_NORETURN | ECF_COLD,
+						  ECF_NORETURN | ECF_THROW
+						  | ECF_COLD,
 						  void_type_node, 3, args);
 	      if (itm_fn != error_mark_node)
 		{
@@ -788,7 +789,8 @@ build_throw (location_t loc, tree exp)
       if (!rethrow_fn)
 	{
 	  rethrow_fn = declare_library_fn_1 ("__cxa_rethrow",
-					     ECF_NORETURN | ECF_COLD,
+					     ECF_NORETURN | ECF_THROW
+					     | ECF_COLD,
 					     void_type_node, 0, NULL);
 	  if (flag_tm && rethrow_fn != error_mark_node)
 	    apply_tm_attr (rethrow_fn, get_identifier ("transaction_pure"));
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 1ea9525c78d..24ff8e36721 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -16687,13 +16687,15 @@ are enabled (see @option{-foptimize-sibling-calls}), but it can be
 enabled (or disabled, using its negated form) explicitly, regardless of
 the optimizations.
 
-@item -fhardcfr-check-noreturn-calls=@r{[}always@r{|}nothrow@r{|}never@r{]}
+@item -fhardcfr-check-noreturn-calls=@r{[}always@r{|}not-always@r{|}nothrow@r{|}never@r{]}
 @opindex fhardcfr-check-noreturn-calls
 When @option{-fharden-control-flow-redundancy} is active, check the
 recorded execution path against the control flow graph before
 @code{noreturn} calls, either all of them (@option{always}), those that
-may not return control to the caller through an exception either
-(@option{nothrow}), or none of them (@option{never}, the default).
+aren't expected to return control to the caller through an exception
+(@option{not-always}, the default), those that may not return control to
+the caller through an exception either (@option{nothrow}), or none of
+them (@option{never}).
 
 Checking before a @code{noreturn} function that may return control to
 the caller through an exception may cause checking to be performed more
@@ -16713,7 +16715,9 @@ attributes, which may affect the placement of checks before calls, as
 well as the addition of implicit cleanup handlers for them.  This
 unpredictability, and the fact that raising and reraising exceptions
 frequently amounts to implicitly calling @code{noreturn} functions, have
-made @option{never} the default setting for this option.
+made @option{not-always} the default setting for this option: it
+excludes from the @code{noreturn} treatment only internal functions used
+to (re)raise exceptions, that are not affected by these optimizations.
 
 @item -fstack-protector
 @opindex fstack-protector
diff --git a/gcc/flag-types.h b/gcc/flag-types.h
index 3fae7548cab..d6d3b0e7800 100644
--- a/gcc/flag-types.h
+++ b/gcc/flag-types.h
@@ -162,9 +162,9 @@ enum hardcfr_noret
 {
   HCFRNR_NEVER,
   HCFRNR_NOTHROW,
-  HCFRNR_NOT_ALWAYS, /* Reserved for future use.  */
+  HCFRNR_NOT_ALWAYS,
+  HCFRNR_UNSPECIFIED,
   HCFRNR_ALWAYS,
-  HCFRNR_UNSPECIFIED = -1
 };
 
 /* The live patching level.  */
diff --git a/gcc/gimple-harden-control-flow.cc b/gcc/gimple-harden-control-flow.cc
index fe322f021ee..1ea47615cd4 100644
--- a/gcc/gimple-harden-control-flow.cc
+++ b/gcc/gimple-harden-control-flow.cc
@@ -1066,9 +1066,14 @@ public:
    unwinders could be detected here and handled differently from other
    noreturn functions.  */
 static bool
-always_throwing_noreturn_call_p (gimple *)
+always_throwing_noreturn_call_p (gimple *stmt)
 {
-  return false;
+  if (!is_a <gcall *> (stmt))
+    return is_a <gresx *> (stmt);
+
+  gcall *call = as_a <gcall *> (stmt);
+  return (gimple_call_noreturn_p (call)
+	  && gimple_call_expected_throw_p (call));
 }
 
 /* Control flow redundancy hardening: record the execution path, and
diff --git a/gcc/gimple.cc b/gcc/gimple.cc
index 6c23dd77609..d96fd3a40e2 100644
--- a/gcc/gimple.cc
+++ b/gcc/gimple.cc
@@ -399,6 +399,9 @@ gimple_build_call_from_tree (tree t, tree fnptrtype)
     gimple_call_set_from_thunk (call, CALL_FROM_THUNK_P (t));
   gimple_call_set_va_arg_pack (call, CALL_EXPR_VA_ARG_PACK (t));
   gimple_call_set_nothrow (call, TREE_NOTHROW (t));
+  if (fndecl)
+    gimple_call_set_expected_throw (call,
+				    flags_from_decl_or_type (fndecl) & ECF_THROW);
   gimple_call_set_by_descriptor (call, CALL_EXPR_BY_DESCRIPTOR (t));
   copy_warning (call, t);
 
@@ -1544,6 +1547,8 @@ gimple_call_flags (const gimple *stmt)
 
   if (stmt->subcode & GF_CALL_NOTHROW)
     flags |= ECF_NOTHROW;
+  if (stmt->subcode & GF_CALL_EXPECTED_THROW)
+    flags |= ECF_THROW;
 
   if (stmt->subcode & GF_CALL_BY_DESCRIPTOR)
     flags |= ECF_BY_DESCRIPTOR;
diff --git a/gcc/gimple.h b/gcc/gimple.h
index adbeb063186..86b683b4831 100644
--- a/gcc/gimple.h
+++ b/gcc/gimple.h
@@ -150,6 +150,7 @@ enum gf_mask {
     GF_CALL_BY_DESCRIPTOR	= 1 << 10,
     GF_CALL_NOCF_CHECK		= 1 << 11,
     GF_CALL_FROM_NEW_OR_DELETE	= 1 << 12,
+    GF_CALL_EXPECTED_THROW	= 1 << 13,
     GF_OMP_PARALLEL_COMBINED	= 1 << 0,
     GF_OMP_TASK_TASKLOOP	= 1 << 0,
     GF_OMP_TASK_TASKWAIT	= 1 << 1,
@@ -3575,6 +3576,26 @@ gimple_call_nothrow_p (gcall *s)
   return (gimple_call_flags (s) & ECF_NOTHROW) != 0;
 }
 
+/* If NOTHROW_P is true, GIMPLE_CALL S is a call that is known to not throw
+   even if the called function can throw in other cases.  */
+
+static inline void
+gimple_call_set_expected_throw (gcall *s, bool expected_throw_p)
+{
+  if (expected_throw_p)
+    s->subcode |= GF_CALL_EXPECTED_THROW;
+  else
+    s->subcode &= ~GF_CALL_EXPECTED_THROW;
+}
+
+/* Return true if S is a nothrow call.  */
+
+static inline bool
+gimple_call_expected_throw_p (gcall *s)
+{
+  return (gimple_call_flags (s) & ECF_THROW) != 0;
+}
+
 /* If FOR_VAR is true, GIMPLE_CALL S is a call to builtin_alloca that
    is known to be emitted for VLA objects.  Those are wrapped by
    stack_save/stack_restore calls and hence can't lead to unbounded
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-always.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-always.c
new file mode 100644
index 00000000000..26c0f270716
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-always.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=always -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check the noreturn handling of a builtin call with always.  */
+
+#include "harden-cfr-abrt.c"
+
+/* Out-of-line checking, before both builtin_abort and return in f.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 2 "hardcfr" } } */
+/* Inline checking before builtin_abort in g.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-never.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-never.c
new file mode 100644
index 00000000000..a9eca9893bb
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-never.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=never -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check the noreturn handling of a builtin call with never.  */
+
+#include "harden-cfr-abrt.c"
+
+/* No out-of-line checking.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 0 "hardcfr" } } */
+/* Inline checking only before return in f.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-not-always.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-not-always.c
new file mode 100644
index 00000000000..a91cc1726dc
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-not-always.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=not-always -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check the noreturn handling of a builtin call with not-always.  */
+
+#include "harden-cfr-abrt.c"
+
+/* Out-of-line checking, before both builtin_abort and return in f.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 2 "hardcfr" } } */
+/* Inline checking before builtin_abort in g.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-nothrow.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-nothrow.c
new file mode 100644
index 00000000000..24363bdfe57
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt-nothrow.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=nothrow -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check the noreturn handling of a builtin call with =nothrow.  */
+
+#include "harden-cfr-abrt.c"
+
+/* Out-of-line checking, before both builtin_abort and return in f.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 2 "hardcfr" } } */
+/* Inline checking before builtin_abort in g.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt.c
index 4aada93ad94..1ed727317f1 100644
--- a/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt.c
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-abrt.c
@@ -1,11 +1,19 @@
 /* { dg-do compile } */
 /* { dg-options "-fharden-control-flow-redundancy -fdump-tree-hardcfr -ffat-lto-objects" } */
 
+/* Check the noreturn handling of a builtin call.  */
+
 int f(int i) {
   if (!i)
     __builtin_abort ();
   return i;
 }
 
-/* No checking before the noreturn abort, so single inline check.  */
+int g() {
+  __builtin_abort ();
+}
+
+/* Out-of-line checking, before both builtin_abort and return in f.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 2 "hardcfr" } } */
+/* Inline checking before builtin_return in g.  */
 /* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-always.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-always.c
new file mode 100644
index 00000000000..6e0767aad69
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-always.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=always -fdump-tree-hardcfr --param hardcfr-max-blocks=9 --param hardcfr-max-inline-blocks=5 -ffat-lto-objects -w" } */
+
+/* Check the instrumentation and the parameters with checking before
+   all noreturn calls.  */
+
+#include "harden-cfr.c"
+
+/* Inlined checking thus trap for f.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
+/* Out-of-line checking for g (param), and before both noreturn calls in main.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 3 "hardcfr" } } */
+/* No checking for h (too many blocks).  */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-bret-not-always.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-bret-not-always.c
new file mode 100644
index 00000000000..a454f2b36fc
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-bret-not-always.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=not-always -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check that, even enabling checks before not-always-throwing noreturn calls
+   (leaving returning calls enabled), we get checks before __builtin_return
+   without duplication (__builtin_return is both noreturn and a returning
+   call).  */
+
+#include "harden-cfr-bret.c"
+
+/* Out-of-line checking, before both builtin_return and return in f.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 2 "hardcfr" } } */
+/* Inline checking before builtin_return in g.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-never.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-never.c
new file mode 100644
index 00000000000..7fe0bb4a663
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-never.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=never -fdump-tree-hardcfr --param hardcfr-max-blocks=9 --param hardcfr-max-inline-blocks=5 -ffat-lto-objects -w" } */
+
+/* Check the instrumentation and the parameters without checking before
+   noreturn calls.  */
+
+#include "harden-cfr.c"
+
+/* Inlined checking thus trap for f.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
+/* Out-of-line checking for g (param).  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 1 "hardcfr" } } */
+/* No checking for h (too many blocks) or main (no edges to exit block).  */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-not-always.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-not-always.c
new file mode 100644
index 00000000000..b9eda188201
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-not-always.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=not-always -fdump-tree-hardcfr --param hardcfr-max-blocks=9 --param hardcfr-max-inline-blocks=5 -ffat-lto-objects -w" } */
+
+/* Check the instrumentation and the parameters with checking before
+   all noreturn calls that aren't expected to throw.  */
+
+#include "harden-cfr.c"
+
+/* Inlined checking thus trap for f.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
+/* Out-of-line checking for g (param), and before both noreturn calls in main.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 3 "hardcfr" } } */
+/* No checking for h (too many blocks).  */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr-nothrow.c b/gcc/testsuite/c-c++-common/torture/harden-cfr-nothrow.c
new file mode 100644
index 00000000000..da54fc0b57a
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr-nothrow.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=nothrow -fdump-tree-hardcfr --param hardcfr-max-blocks=9 --param hardcfr-max-inline-blocks=5 -ffat-lto-objects -w" } */
+
+/* Check the instrumentation and the parameters without checking before
+   nothrow noreturn calls.  */
+
+#include "harden-cfr.c"
+
+/* Inlined checking thus trap for f.  */
+/* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
+/* Out-of-line checking for g (param), and before both noreturn calls in main.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 3 "hardcfr" } } */
+/* No checking for h (too many blocks).  */
diff --git a/gcc/testsuite/c-c++-common/torture/harden-cfr.c b/gcc/testsuite/c-c++-common/torture/harden-cfr.c
index 2f5946c0387..73824c66f50 100644
--- a/gcc/testsuite/c-c++-common/torture/harden-cfr.c
+++ b/gcc/testsuite/c-c++-common/torture/harden-cfr.c
@@ -1,6 +1,8 @@
 /* { dg-do run } */
 /* { dg-options "-fharden-control-flow-redundancy -fdump-tree-hardcfr --param hardcfr-max-blocks=9 --param hardcfr-max-inline-blocks=5 -ffat-lto-objects" } */
 
+/* Check the instrumentation and the parameters.  */
+
 int
 f (int i, int j)
 {
@@ -64,18 +66,19 @@ h (unsigned i, int j) /* { dg-warning "has more than 9 blocks, the requested max
 }
 
 int
-main ()
+main (int argc, char *argv[])
 {
-  if (f (1, 2) != 2 || f (3, 2) != 6
-      || g (2, 5) != 25 || h (4, 3) != 33)
+  if (f (1, 2) != 2 || g (2, 5) != 25 || h (4, 3) != 33
+      || argc < 0)
     __builtin_abort ();
   /* Call exit, instead of returning, to avoid an edge to the exit block and
-     thus implicitly disable hardening of main.  */
+     thus implicitly disable hardening of main, when checking before noreturn
+     calls is disabled.  */
   __builtin_exit (0);
 }
 
 /* Inlined checking thus trap for f.  */
 /* { dg-final { scan-tree-dump-times "__builtin_trap" 1 "hardcfr" } } */
-/* Out-of-line checking for g.  */
-/* { dg-final { scan-tree-dump-times "__hardcfr_check" 1 "hardcfr" } } */
-/* No checking for h (too many blocks) or main (no edges to exit block).  */
+/* Out-of-line checking for g (param), and before both noreturn calls in main.  */
+/* { dg-final { scan-tree-dump-times "__hardcfr_check" 3 "hardcfr" } } */
+/* No checking for h (too many blocks).  */
diff --git a/gcc/testsuite/g++.dg/harden-cfr-throw-always-O0.C b/gcc/testsuite/g++.dg/harden-cfr-throw-always-O0.C
index 17ea79f7cfb..e3c109b89c5 100644
--- a/gcc/testsuite/g++.dg/harden-cfr-throw-always-O0.C
+++ b/gcc/testsuite/g++.dg/harden-cfr-throw-always-O0.C
@@ -5,6 +5,8 @@
    maybe-throwing functions, and also checking before noreturn
    calls.  h2 and h2b get an extra resx without ehcleanup.  */
 
+#define NO_OPTIMIZE
+
 #include "torture/harden-cfr-throw.C"
 
 /* { dg-final { scan-tree-dump-times "hardcfr_check" 16 "hardcfr" } } */
diff --git a/gcc/testsuite/g++.dg/harden-cfr-throw-returning-O0.C b/gcc/testsuite/g++.dg/harden-cfr-throw-returning-O0.C
index f0338ccc361..207bdb7471a 100644
--- a/gcc/testsuite/g++.dg/harden-cfr-throw-returning-O0.C
+++ b/gcc/testsuite/g++.dg/harden-cfr-throw-returning-O0.C
@@ -4,6 +4,8 @@
 /* -fhardcfr-check-returning-calls gets implicitly disabled because,
    -at O0, -foptimize-sibling-calls has no effect.  */
 
+#define NO_OPTIMIZE
+
 #include "torture/harden-cfr-throw.C"
 
 /* { dg-final { scan-tree-dump-times "hardcfr_check" 12 "hardcfr" } } */
diff --git a/gcc/testsuite/g++.dg/harden-cfr-throw-returning-enabled-O0.C b/gcc/testsuite/g++.dg/harden-cfr-throw-returning-enabled-O0.C
new file mode 100644
index 00000000000..b2df689c932
--- /dev/null
+++ b/gcc/testsuite/g++.dg/harden-cfr-throw-returning-enabled-O0.C
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-returning-calls -fdump-tree-hardcfr -O0" } */
+
+/* Explicitly enable -fhardcfr-check-returning-calls -at O0.  */
+
+#include "torture/harden-cfr-throw.C"
+
+/* Same expectations as those in torture/harden-cfr-throw-returning.C.  */
+
+/* { dg-final { scan-tree-dump-times "hardcfr_check" 10 "hardcfr" } } */
+/* { dg-final { scan-tree-dump-times "builtin_trap" 2 "hardcfr" } } */
diff --git a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-always.C b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-always.C
index 0286f6e6d3f..4d303e769ef 100644
--- a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-always.C
+++ b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-always.C
@@ -5,13 +5,6 @@
    maybe-throwing functions, and also checking before noreturn
    calls.  */
 
-#if ! __OPTIMIZE__
-/* Without optimization, functions with cleanups end up with an extra
-   resx that is not optimized out, so arrange to optimize them.  */
-void __attribute__ ((__optimize__ (1))) h2(void);
-void __attribute__ ((__optimize__ (1))) h2b(void);
-#endif
-
 #include "harden-cfr-throw.C"
 
 /* { dg-final { scan-tree-dump-times "hardcfr_check" 14 "hardcfr" } } */
diff --git a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-never.C b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-never.C
new file mode 100644
index 00000000000..81c1b1abae6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-never.C
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fno-hardcfr-check-returning-calls -fhardcfr-check-noreturn-calls=never -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check that we insert cleanups for checking around the bodies of
+   maybe-throwing functions, without checking before noreturn
+   calls.  */
+
+#include "harden-cfr-throw.C"
+
+/* { dg-final { scan-tree-dump-times "hardcfr_check" 12 "hardcfr" } } */
+/* { dg-final { scan-tree-dump-times "builtin_trap" 1 "hardcfr" } } */
+/* { dg-final { scan-tree-dump-times "Bypassing" 0 "hardcfr" } } */
diff --git a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-nocleanup.C b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-nocleanup.C
index 885b0b236af..9f359363d17 100644
--- a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-nocleanup.C
+++ b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-nocleanup.C
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-fharden-control-flow-redundancy -fno-hardcfr-check-exceptions  -fno-hardcfr-check-returning-calls -fdump-tree-hardcfr -ffat-lto-objects" } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=never -fno-hardcfr-check-exceptions  -fno-hardcfr-check-returning-calls -fdump-tree-hardcfr -ffat-lto-objects" } */
 
 /* Check that we do not insert cleanups for checking around the bodies
    of maybe-throwing functions.  h4 doesn't get any checks, because we
diff --git a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-not-always.C b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-not-always.C
new file mode 100644
index 00000000000..9723d92bfec
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-not-always.C
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fno-hardcfr-check-returning-calls -fhardcfr-check-noreturn-calls=not-always -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check that we insert cleanups for checking around the bodies of
+   maybe-throwing functions, and also checking before noreturn
+   calls.  */
+
+#include "harden-cfr-throw.C"
+
+/* { dg-final { scan-tree-dump-times "hardcfr_check" 12 "hardcfr" } } */
+/* { dg-final { scan-tree-dump-times "builtin_trap" 1 "hardcfr" } } */
+/* { dg-final { scan-tree-dump-times "Bypassing" 0 "hardcfr" } } */
diff --git a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-nothrow.C b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-nothrow.C
new file mode 100644
index 00000000000..e1c2e8d73bb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-nothrow.C
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fharden-control-flow-redundancy -fno-hardcfr-check-returning-calls -fhardcfr-check-noreturn-calls=nothrow -fdump-tree-hardcfr -ffat-lto-objects" } */
+
+/* Check that we insert cleanups for checking around the bodies of
+   maybe-throwing functions, without checking before noreturn
+   calls.  */
+
+#include "harden-cfr-throw.C"
+
+/* { dg-final { scan-tree-dump-times "hardcfr_check" 12 "hardcfr" } } */
+/* { dg-final { scan-tree-dump-times "builtin_trap" 1 "hardcfr" } } */
diff --git a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-returning.C b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-returning.C
index 32def637255..37e4551d096 100644
--- a/gcc/testsuite/g++.dg/torture/harden-cfr-throw-returning.C
+++ b/gcc/testsuite/g++.dg/torture/harden-cfr-throw-returning.C
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-fharden-control-flow-redundancy -foptimize-sibling-calls -fdump-tree-hardcfr -ffat-lto-objects" } */
+/* { dg-options "-fharden-control-flow-redundancy -fhardcfr-check-noreturn-calls=never -foptimize-sibling-calls -fdump-tree-hardcfr -ffat-lto-objects" } */
 
 /* Check that we insert cleanups for checking around the bodies of
    maybe-throwing functions.  These results depend on checking before
diff --git a/gcc/testsuite/g++.dg/torture/harden-cfr-throw.C b/gcc/testsuite/g++.dg/torture/harden-cfr-throw.C
index 992fbdad381..8e46b900cd2 100644
--- a/gcc/testsuite/g++.dg/torture/harden-cfr-throw.C
+++ b/gcc/testsuite/g++.dg/torture/harden-cfr-throw.C
@@ -1,6 +1,13 @@
 /* { dg-do compile } */
 /* { dg-options "-fharden-control-flow-redundancy -fno-hardcfr-check-returning-calls -fdump-tree-hardcfr -ffat-lto-objects" } */
 
+#if ! __OPTIMIZE__ && ! defined NO_OPTIMIZE
+/* Without optimization, functions with cleanups end up with an extra
+   resx that is not optimized out, so arrange to optimize them.  */
+void __attribute__ ((__optimize__ (1))) h2(void);
+void __attribute__ ((__optimize__ (1))) h2b(void);
+#endif
+
 /* Check that we insert cleanups for checking around the bodies of
    maybe-throwing functions.  */
 
@@ -63,3 +70,4 @@ void h4(void) {
 
 /* { dg-final { scan-tree-dump-times "hardcfr_check" 12 "hardcfr" } } */
 /* { dg-final { scan-tree-dump-times "builtin_trap" 1 "hardcfr" } } */
+/* { dg-final { scan-tree-dump-times "Bypassing" 0 "hardcfr" } } */
diff --git a/gcc/tree-core.h b/gcc/tree-core.h
index 80b886cc3e4..91e7c1af8ac 100644
--- a/gcc/tree-core.h
+++ b/gcc/tree-core.h
@@ -96,6 +96,9 @@ struct die_struct;
 /* Nonzero if this is a cold function.  */
 #define ECF_COLD		  (1 << 15)
 
+/* Nonzero if this is a function expected to end with an exception.  */
+#define ECF_THROW		  (1 << 16)
+
 /* Call argument flags.  */
 
 /* Nonzero if the argument is not used by the function.  */
diff --git a/gcc/tree.cc b/gcc/tree.cc
index 81a6ceaf181..bfbf5729981 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -9637,6 +9637,10 @@ set_call_expr_flags (tree decl, int flags)
 		   DECL_ATTRIBUTES (decl));
   if ((flags & ECF_TM_PURE) && flag_tm)
     apply_tm_attr (decl, get_identifier ("transaction_pure"));
+  if ((flags & ECF_THROW))
+    DECL_ATTRIBUTES (decl)
+      = tree_cons (get_identifier ("expected_throw"),
+		   NULL, DECL_ATTRIBUTES (decl));
   /* Looping const or pure is implied by noreturn.
      There is currently no way to declare looping const or looping pure alone.  */
   gcc_assert (!(flags & ECF_LOOPING_CONST_OR_PURE)
@@ -9842,7 +9846,8 @@ build_common_builtin_nodes (void)
       ftype = build_function_type_list (void_type_node, NULL_TREE);
       local_define_builtin ("__builtin_cxa_end_cleanup", ftype,
 			    BUILT_IN_CXA_END_CLEANUP,
-			    "__cxa_end_cleanup", ECF_NORETURN | ECF_LEAF);
+			    "__cxa_end_cleanup",
+			    ECF_NORETURN | ECF_THROW | ECF_LEAF);
     }
 
   ftype = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
@@ -9851,7 +9856,7 @@ build_common_builtin_nodes (void)
 			((targetm_common.except_unwind_info (&global_options)
 			  == UI_SJLJ)
 			 ? "_Unwind_SjLj_Resume" : "_Unwind_Resume"),
-			ECF_NORETURN);
+			ECF_NORETURN | ECF_THROW);
 
   if (builtin_decl_explicit (BUILT_IN_RETURN_ADDRESS) == NULL_TREE)
     {