ubsan: Add -fsanitize-trap= support

On Thu, Jun 16, 2022 at 09:32:02PM +0100, Jonathan Wakely wrote:
> It looks like clang has addressed this deficiency now:
>
> https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html#usage

Thanks, that is roughly what I'd implement anyway and apparently they have
it already since 2015, we've added the -fsanitize-undefined-trap-on-error
support back in 2014 and didn't change it since then.

As a small divergence from clang, I chose -fsanitize-undefined-trap-on-error
to be a (deprecated) alias for -fsanitize-trap aka -fsanitize-trap=all
rather thn -fsanitize-trap=undefined which seems to be what clang does,
because for a deprecated option it is IMHO more important backwards
compatibility with what gcc did over the past 8 years rather than clang
compatibility.
Some sanitizers (e.g. asan, lsan, tsan) don't support traps,
-fsanitize-trap=address etc. will be rejected (if enabled at the end of
command line), -fno-sanitize-trap= can be specified even for them.
This is similar behavior to -fsanitize-recover=.
One complication is vptr sanitization, which can't easily trap,
as the whole slow path of the checking is inside of libubsan.
Previously, -fsanitize=vptr -fsanitize-undefined-trap-on-error
silently ignored vptr sanitization.
This patch similarly to what clang does will accept
-fsanitize-trap=all or -fsanitize-trap=undefined which enable
the vptr bit as trapping and again that causes silent disabling
of vptr sanitization, while -fsanitize-trap=vptr is rejected
(already during option processing).

2022-06-18  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* common.opt (flag_sanitize_trap): New variable.
	(fsanitize-trap=, fsanitize-trap): New options.
	(fsanitize-undefined-trap-on-error): Change into deprecated alias
	for -fsanitize-trap=all.
	* opts.h (struct sanitizer_opts_s): Add can_trap member.
	* opts.cc (finish_options): Complain about unsupported
	-fsanitize-trap= options.
	(sanitizer_opts): Add can_trap values to all entries.
	(get_closest_sanitizer_option): Ignore -fsanitize-trap=
	options which have can_trap false.
	(parse_sanitizer_options): Add support for -fsanitize-trap=.
	For -fsanitize-trap=all, enable
	SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT.  Disallow
	-fsanitize-trap=vptr here.
	(common_handle_option): Handle OPT_fsanitize_trap_ and
	OPT_fsanitize_trap.
	* sanopt.cc (maybe_optimize_ubsan_null_ifn): Check
	flag_sanitize_trap & SANITIZE_{NULL,ALIGNMENT} instead of
	flag_sanitize_undefined_trap_on_error.
	* gcc.cc (sanitize_spec_function): Use
	flag_sanitize & ~flag_sanitize_trap instead of flag_sanitize
	and drop use of flag_sanitize_undefined_trap_on_error in
	"undefined" handling.
	* ubsan.cc (ubsan_instrument_unreachable): Use
	flag_sanitize_trap & SANITIZE_??? instead of
	flag_sanitize_undefined_trap_on_error.
	(ubsan_expand_bounds_ifn, ubsan_expand_null_ifn,
	ubsan_expand_objsize_ifn, ubsan_expand_ptr_ifn,
	ubsan_build_overflow_builtin, instrument_bool_enum_load,
	ubsan_instrument_float_cast, instrument_nonnull_arg,
	instrument_nonnull_return, instrument_builtin): Likewise.
	* doc/invoke.texi (-fsanitize-trap=, -fsanitize-trap): Document.
	(-fsanitize-undefined-trap-on-error): Document as deprecated
	alias of -fsanitize-trap.
gcc/c-family/
	* c-ubsan.cc (ubsan_instrument_division, ubsan_instrument_shift):
	Use flag_sanitize_trap & SANITIZE_??? instead of
	flag_sanitize_undefined_trap_on_error.  If 2 sanitizers are involved
	and flag_sanitize_trap differs for them, emit __builtin_trap only
	for the comparison where trap is requested.
	(ubsan_instrument_vla, ubsan_instrument_return): Use
	lag_sanitize_trap & SANITIZE_??? instead of
	flag_sanitize_undefined_trap_on_error.
gcc/cp/
	* cp-ubsan.cc (cp_ubsan_instrument_vptr_p): Use
	flag_sanitize_trap & SANITIZE_VPTR instead of
	flag_sanitize_undefined_trap_on_error.
gcc/testsuite/
	* c-c++-common/ubsan/nonnull-4.c: Use -fsanitize-trap=all
	instead of -fsanitize-undefined-trap-on-error.
	* c-c++-common/ubsan/div-by-zero-4.c: Use
	-fsanitize-trap=signed-integer-overflow instead of
	-fsanitize-undefined-trap-on-error.
	* c-c++-common/ubsan/overflow-add-4.c: Use -fsanitize-trap=undefined
	instead of -fsanitize-undefined-trap-on-error.
	* c-c++-common/ubsan/pr56956.c: Likewise.
	* c-c++-common/ubsan/pr68142.c: Likewise.
	* c-c++-common/ubsan/pr80932.c: Use
	-fno-sanitize-trap=all -fsanitize-trap=shift,undefined
	instead of -fsanitize-undefined-trap-on-error.
	* c-c++-common/ubsan/align-8.c: Use -fsanitize-trap=alignment
	instead of -fsanitize-undefined-trap-on-error.

16 files changed, 226 insertions, 109 deletions

diff --git a/gcc/c-family/c-ubsan.cc b/gcc/c-family/c-ubsan.cc
index a2cd8fb..360ba82 100644
--- a/gcc/c-family/c-ubsan.cc
+++ b/gcc/c-family/c-ubsan.cc
@@ -83,8 +83,9 @@ ubsan_instrument_division (location_t loc, tree op0, tree op1)
 	  x = NULL_TREE;
 	  flag = SANITIZE_SI_OVERFLOW;
 	}
-      else if (flag_sanitize_undefined_trap_on_error
-	       || (((flag_sanitize_recover & SANITIZE_DIVIDE) == 0)
+      else if ((((flag_sanitize_trap & SANITIZE_DIVIDE) == 0)
+		== ((flag_sanitize_trap & SANITIZE_SI_OVERFLOW) == 0))
+	       && (((flag_sanitize_recover & SANITIZE_DIVIDE) == 0)
 		   == ((flag_sanitize_recover & SANITIZE_SI_OVERFLOW) == 0)))
 	{
 	  t = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, t, x);
@@ -105,7 +106,7 @@ ubsan_instrument_division (location_t loc, tree op0, tree op1)
      make sure it gets evaluated before the condition.  */
   t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), unshare_expr (op0), t);
   t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), unshare_expr (op1), t);
-  if (flag_sanitize_undefined_trap_on_error)
+  if ((flag_sanitize_trap & flag) && x == NULL_TREE)
     tt = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -113,25 +114,41 @@ ubsan_instrument_division (location_t loc, tree op0, tree op1)
 				     ubsan_type_descriptor (type), NULL_TREE,
 				     NULL_TREE);
       data = build_fold_addr_expr_loc (loc, data);
-      enum built_in_function bcode
-	= (flag_sanitize_recover & flag)
-	  ? BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW
-	  : BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW_ABORT;
-      tt = builtin_decl_explicit (bcode);
-      op0 = unshare_expr (op0);
-      op1 = unshare_expr (op1);
-      tt = build_call_expr_loc (loc, tt, 3, data, ubsan_encode_value (op0),
-				ubsan_encode_value (op1));
-      if (x)
+      if (flag_sanitize_trap & flag)
+	tt = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP),
+				  0);
+      else
 	{
-	  bcode = (flag_sanitize_recover & SANITIZE_SI_OVERFLOW)
-		  ? BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW
-		  : BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW_ABORT;
-	  tree xt = builtin_decl_explicit (bcode);
+	  enum built_in_function bcode
+	    = (flag_sanitize_recover & flag)
+	      ? BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW
+	      : BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW_ABORT;
+	  tt = builtin_decl_explicit (bcode);
 	  op0 = unshare_expr (op0);
 	  op1 = unshare_expr (op1);
-	  xt = build_call_expr_loc (loc, xt, 3, data, ubsan_encode_value (op0),
+	  tt = build_call_expr_loc (loc, tt, 3, data, ubsan_encode_value (op0),
 				    ubsan_encode_value (op1));
+	}
+      if (x)
+	{
+	  tree xt;
+	  if (flag_sanitize_trap & SANITIZE_SI_OVERFLOW)
+	    xt = build_call_expr_loc (loc,
+				      builtin_decl_explicit (BUILT_IN_TRAP),
+				      0);
+	  else
+	    {
+	      enum built_in_function bcode
+		= (flag_sanitize_recover & SANITIZE_SI_OVERFLOW)
+		   ? BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW
+		   : BUILT_IN_UBSAN_HANDLE_DIVREM_OVERFLOW_ABORT;
+	      xt = builtin_decl_explicit (bcode);
+	      op0 = unshare_expr (op0);
+	      op1 = unshare_expr (op1);
+	      xt = build_call_expr_loc (loc, xt, 3, data,
+					ubsan_encode_value (op0),
+					ubsan_encode_value (op1));
+	    }
 	  x = fold_build3 (COND_EXPR, void_type_node, x, xt, void_node);
 	}
     }
@@ -225,8 +242,9 @@ ubsan_instrument_shift (location_t loc, enum tree_code code,
 	}
       else
 	{
-	  if (flag_sanitize_undefined_trap_on_error
-	      || ((!(flag_sanitize_recover & SANITIZE_SHIFT_EXPONENT))
+	  if (((!(flag_sanitize_trap & SANITIZE_SHIFT_EXPONENT))
+	       == (!(flag_sanitize_trap & SANITIZE_SHIFT_BASE)))
+	      && ((!(flag_sanitize_recover & SANITIZE_SHIFT_EXPONENT))
 		  == (!(flag_sanitize_recover & SANITIZE_SHIFT_BASE))))
 	    t = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, t, tt);
 	  else
@@ -234,7 +252,7 @@ ubsan_instrument_shift (location_t loc, enum tree_code code,
 	}
     }
 
-  if (flag_sanitize_undefined_trap_on_error)
+  if ((flag_sanitize_trap & recover_kind) && else_t == void_node)
     tt = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -244,26 +262,40 @@ ubsan_instrument_shift (location_t loc, enum tree_code code,
 				     NULL_TREE);
       data = build_fold_addr_expr_loc (loc, data);
 
-      enum built_in_function bcode
-	= (flag_sanitize_recover & recover_kind)
-	  ? BUILT_IN_UBSAN_HANDLE_SHIFT_OUT_OF_BOUNDS
-	  : BUILT_IN_UBSAN_HANDLE_SHIFT_OUT_OF_BOUNDS_ABORT;
-      tt = builtin_decl_explicit (bcode);
-      op0 = unshare_expr (op0);
-      op1 = unshare_expr (op1);
-      tt = build_call_expr_loc (loc, tt, 3, data, ubsan_encode_value (op0),
-				ubsan_encode_value (op1));
+      if (flag_sanitize_trap & recover_kind)
+	tt = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
+      else
+	{
+	  enum built_in_function bcode
+	    = (flag_sanitize_recover & recover_kind)
+	      ? BUILT_IN_UBSAN_HANDLE_SHIFT_OUT_OF_BOUNDS
+	      : BUILT_IN_UBSAN_HANDLE_SHIFT_OUT_OF_BOUNDS_ABORT;
+	  tt = builtin_decl_explicit (bcode);
+	  op0 = unshare_expr (op0);
+	  op1 = unshare_expr (op1);
+	  tt = build_call_expr_loc (loc, tt, 3, data, ubsan_encode_value (op0),
+				    ubsan_encode_value (op1));
+	}
       if (else_t != void_node)
 	{
-	  bcode = (flag_sanitize_recover & SANITIZE_SHIFT_BASE)
+	  tree else_tt;
+	  if (flag_sanitize_trap & SANITIZE_SHIFT_BASE)
+	    else_tt
+	      = build_call_expr_loc (loc,
+				     builtin_decl_explicit (BUILT_IN_TRAP), 0);
+	  else
+	    {
+	      enum built_in_function bcode
+		= (flag_sanitize_recover & SANITIZE_SHIFT_BASE)
 		  ? BUILT_IN_UBSAN_HANDLE_SHIFT_OUT_OF_BOUNDS
 		  : BUILT_IN_UBSAN_HANDLE_SHIFT_OUT_OF_BOUNDS_ABORT;
-	  tree else_tt = builtin_decl_explicit (bcode);
-	  op0 = unshare_expr (op0);
-	  op1 = unshare_expr (op1);
-	  else_tt = build_call_expr_loc (loc, else_tt, 3, data,
-					 ubsan_encode_value (op0),
-					 ubsan_encode_value (op1));
+	      else_tt = builtin_decl_explicit (bcode);
+	      op0 = unshare_expr (op0);
+	      op1 = unshare_expr (op1);
+	      else_tt = build_call_expr_loc (loc, else_tt, 3, data,
+					     ubsan_encode_value (op0),
+					     ubsan_encode_value (op1));
+	    }
 	  else_t = fold_build3 (COND_EXPR, void_type_node, else_t,
 				else_tt, void_node);
 	}
@@ -282,7 +314,7 @@ ubsan_instrument_vla (location_t loc, tree size)
   tree t, tt;
 
   t = fold_build2 (LE_EXPR, boolean_type_node, size, build_int_cst (type, 0));
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & SANITIZE_VLA)
     tt = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -307,10 +339,10 @@ ubsan_instrument_vla (location_t loc, tree size)
 tree
 ubsan_instrument_return (location_t loc)
 {
-  if (flag_sanitize_undefined_trap_on_error)
-    return build_call_expr_loc
-      /* pass_warn_function_return checks for BUILTINS_LOCATION.  */
-      (BUILTINS_LOCATION, builtin_decl_explicit (BUILT_IN_TRAP), 0);
+  if (flag_sanitize_trap & SANITIZE_RETURN)
+    /* pass_warn_function_return checks for BUILTINS_LOCATION.  */
+    return build_call_expr_loc (BUILTINS_LOCATION,
+				builtin_decl_explicit (BUILT_IN_TRAP), 0);
 
   tree data = ubsan_create_data ("__ubsan_missing_return_data", 1, &loc,
 				 NULL_TREE, NULL_TREE);
diff --git a/gcc/common.opt b/gcc/common.opt
index 8e961f1..32917aa 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -223,6 +223,10 @@ unsigned int flag_sanitize
 Variable
 unsigned int flag_sanitize_recover = (SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT | SANITIZE_KERNEL_ADDRESS | SANITIZE_KERNEL_HWADDRESS) & ~(SANITIZE_UNREACHABLE | SANITIZE_RETURN)
 
+; What sanitizers should use __builtin_trap () instead of runtime diagnostics
+Variable
+unsigned int flag_sanitize_trap
+
 ; Flag whether a prefix has been added to dump_base_name
 Variable
 bool dump_base_name_prefixed = false
@@ -1105,12 +1109,19 @@ fsanitize-recover
 Common
 This switch is deprecated; use -fsanitize-recover= instead.
 
+fsanitize-trap=
+Common Driver Joined
+Use traps instead of diagnostics of undefined behavior sanitizers.
+
+fsanitize-trap
+Common Driver
+
 fsanitize-address-use-after-scope
 Common Driver Var(flag_sanitize_address_use_after_scope) Init(0)
 
 fsanitize-undefined-trap-on-error
-Common Driver Var(flag_sanitize_undefined_trap_on_error) Init(0)
-Use trap instead of a library function for undefined behavior sanitization.
+Common Driver Alias(fsanitize-trap)
+This switch is deprecated; use -fsanitize-trap= instead.
 
 fasynchronous-unwind-tables
 Common Var(flag_asynchronous_unwind_tables) Optimization
diff --git a/gcc/cp/cp-ubsan.cc b/gcc/cp/cp-ubsan.cc
index 2532521..edad2bd 100644
--- a/gcc/cp/cp-ubsan.cc
+++ b/gcc/cp/cp-ubsan.cc
@@ -32,7 +32,7 @@ along with GCC; see the file COPYING3.  If not see
 static bool
 cp_ubsan_instrument_vptr_p (tree type)
 {
-  if (!flag_rtti || flag_sanitize_undefined_trap_on_error)
+  if (!flag_rtti || (flag_sanitize_trap & SANITIZE_VPTR))
     return false;
 
   if (!sanitize_flags_p (SANITIZE_VPTR))
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 60b7b5a..50f5787 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -609,6 +609,7 @@ Objective-C and Objective-C++ Dialects}.
 -fprofile-exclude-files=@var{regex} @gol
 -fprofile-reproducible=@r{[}multithreaded@r{|}parallel-runs@r{|}serial@r{]} @gol
 -fsanitize=@var{style}  -fsanitize-recover  -fsanitize-recover=@var{style} @gol
+-fsanitize-trap   -fsanitize-trap=@var{style}  @gol
 -fasan-shadow-offset=@var{number}  -fsanitize-sections=@var{s1},@var{s2},... @gol
 -fsanitize-undefined-trap-on-error  -fbounds-check @gol
 -fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{|}check@r{]} @gol
@@ -16116,13 +16117,37 @@ undefined,float-cast-overflow,float-divide-by-zero,bounds-strict
 Enable sanitization of local variables to detect use-after-scope bugs.
 The option sets @option{-fstack-reuse} to @samp{none}.
 
+@item -fsanitize-trap@r{[}=@var{opts}@r{]}
+@opindex fsanitize-trap
+@opindex fno-sanitize-trap
+The @option{-fsanitize-trap=} option instructs the compiler to
+report for sanitizers mentioned in comma-separated list of @var{opts}
+undefined behavior using @code{__builtin_trap} rather than a @code{libubsan}
+library routine.  If this option is enabled for certain sanitizer,
+it takes precedence over the @option{-fsanitizer-recover=} for that
+sanitizer, @code{__builtin_trap} will be emitted and be fatal regardless
+of whether recovery is enabled or disabled using @option{-fsanitize-recover=}.
+
+The advantage of this is that the @code{libubsan} library is not needed
+and is not linked in, so this is usable even in freestanding environments.
+
+Currently this feature works with @option{-fsanitize=undefined} (and its suboptions
+except for @option{-fsanitize=vptr}), @option{-fsanitize=float-cast-overflow},
+@option{-fsanitize=float-divide-by-zero} and
+@option{-fsanitize=bounds-strict}.  @code{-fsanitize-trap=all} can be also
+specified, which enables it for @code{undefined} suboptions,
+@option{-fsanitize=float-cast-overflow},
+@option{-fsanitize=float-divide-by-zero} and
+@option{-fsanitize=bounds-strict}.
+If @code{-fsanitize-trap=undefined} or @code{-fsanitize-trap=all} is used
+and @code{-fsanitize=vptr} is enabled on the command line, the
+instrumentation is silently ignored as the instrumentation always needs
+@code{libubsan} support, @option{-fsanitize-trap=vptr} is not allowed.
+
 @item -fsanitize-undefined-trap-on-error
 @opindex fsanitize-undefined-trap-on-error
-The @option{-fsanitize-undefined-trap-on-error} option instructs the compiler to
-report undefined behavior using @code{__builtin_trap} rather than
-a @code{libubsan} library routine.  The advantage of this is that the
-@code{libubsan} library is not needed and is not linked in, so this
-is usable even in freestanding environments.
+The @option{-fsanitize-undefined-trap-on-error} option is deprecated
+equivalent of @option{-fsanitize-trap=all}.
 
 @item -fsanitize-coverage=trace-pc
 @opindex fsanitize-coverage=trace-pc
diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index 563f535..5cbb385 100644
--- a/gcc/gcc.cc
+++ b/gcc/gcc.cc
@@ -10313,8 +10313,9 @@ sanitize_spec_function (int argc, const char **argv)
     return (flag_sanitize & SANITIZE_THREAD) ? "" : NULL;
   if (strcmp (argv[0], "undefined") == 0)
     return ((flag_sanitize
-	     & (SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT))
-	    && !flag_sanitize_undefined_trap_on_error) ? "" : NULL;
+	     & ~flag_sanitize_trap
+	     & (SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT)))
+	   ? "" : NULL;
   if (strcmp (argv[0], "leak") == 0)
     return ((flag_sanitize
 	     & (SANITIZE_ADDRESS | SANITIZE_LEAK | SANITIZE_THREAD))
diff --git a/gcc/opts.cc b/gcc/opts.cc
index 55859f5..959d48d 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -1232,6 +1232,18 @@ finish_options (struct gcc_options *opts, struct gcc_options *opts_set,
       error_at (loc, "%<-fsanitize-recover=%s%> is not supported",
 		sanitizer_opts[i].name);
 
+  /* Check -fsanitize-trap option.  */
+  for (int i = 0; sanitizer_opts[i].name != NULL; ++i)
+    if ((opts->x_flag_sanitize_trap & sanitizer_opts[i].flag)
+	&& !sanitizer_opts[i].can_trap
+	/* Allow -fsanitize-trap=all or -fsanitize-trap=undefined
+	   to set flag_sanitize_trap & SANITIZE_VPTR bit which will
+	   effectively disable -fsanitize=vptr, just disallow
+	   explicit -fsanitize-trap=vptr.  */
+	&& sanitizer_opts[i].flag != SANITIZE_VPTR)
+      error_at (loc, "%<-fsanitize-trap=%s%> is not supported",
+		sanitizer_opts[i].name);
+
   /* When instrumenting the pointers, we don't want to remove
      the null pointer checks.  */
   if (opts->x_flag_sanitize & (SANITIZE_NULL | SANITIZE_NONNULL_ATTRIBUTE
@@ -2020,48 +2032,50 @@ enable_fdo_optimizations (struct gcc_options *opts,
 /* -f{,no-}sanitize{,-recover}= suboptions.  */
 const struct sanitizer_opts_s sanitizer_opts[] =
 {
-#define SANITIZER_OPT(name, flags, recover) \
-    { #name, flags, sizeof #name - 1, recover }
-  SANITIZER_OPT (address, (SANITIZE_ADDRESS | SANITIZE_USER_ADDRESS), true),
+#define SANITIZER_OPT(name, flags, recover, trap) \
+    { #name, flags, sizeof #name - 1, recover, trap }
+  SANITIZER_OPT (address, (SANITIZE_ADDRESS | SANITIZE_USER_ADDRESS), true,
+		 false),
   SANITIZER_OPT (hwaddress, (SANITIZE_HWADDRESS | SANITIZE_USER_HWADDRESS),
-		 true),
+		 true, false),
   SANITIZER_OPT (kernel-address, (SANITIZE_ADDRESS | SANITIZE_KERNEL_ADDRESS),
-		 true),
+		 true, false),
   SANITIZER_OPT (kernel-hwaddress,
 		 (SANITIZE_HWADDRESS | SANITIZE_KERNEL_HWADDRESS),
+		 true, false),
+  SANITIZER_OPT (pointer-compare, SANITIZE_POINTER_COMPARE, true, false),
+  SANITIZER_OPT (pointer-subtract, SANITIZE_POINTER_SUBTRACT, true, false),
+  SANITIZER_OPT (thread, SANITIZE_THREAD, false, false),
+  SANITIZER_OPT (leak, SANITIZE_LEAK, false, false),
+  SANITIZER_OPT (shift, SANITIZE_SHIFT, true, true),
+  SANITIZER_OPT (shift-base, SANITIZE_SHIFT_BASE, true, true),
+  SANITIZER_OPT (shift-exponent, SANITIZE_SHIFT_EXPONENT, true, true),
+  SANITIZER_OPT (integer-divide-by-zero, SANITIZE_DIVIDE, true, true),
+  SANITIZER_OPT (undefined, SANITIZE_UNDEFINED, true, true),
+  SANITIZER_OPT (unreachable, SANITIZE_UNREACHABLE, false, true),
+  SANITIZER_OPT (vla-bound, SANITIZE_VLA, true, true),
+  SANITIZER_OPT (return, SANITIZE_RETURN, false, true),
+  SANITIZER_OPT (null, SANITIZE_NULL, true, true),
+  SANITIZER_OPT (signed-integer-overflow, SANITIZE_SI_OVERFLOW, true, true),
+  SANITIZER_OPT (bool, SANITIZE_BOOL, true, true),
+  SANITIZER_OPT (enum, SANITIZE_ENUM, true, true),
+  SANITIZER_OPT (float-divide-by-zero, SANITIZE_FLOAT_DIVIDE, true, true),
+  SANITIZER_OPT (float-cast-overflow, SANITIZE_FLOAT_CAST, true, true),
+  SANITIZER_OPT (bounds, SANITIZE_BOUNDS, true, true),
+  SANITIZER_OPT (bounds-strict, SANITIZE_BOUNDS | SANITIZE_BOUNDS_STRICT, true,
 		 true),
-  SANITIZER_OPT (pointer-compare, SANITIZE_POINTER_COMPARE, true),
-  SANITIZER_OPT (pointer-subtract, SANITIZE_POINTER_SUBTRACT, true),
-  SANITIZER_OPT (thread, SANITIZE_THREAD, false),
-  SANITIZER_OPT (leak, SANITIZE_LEAK, false),
-  SANITIZER_OPT (shift, SANITIZE_SHIFT, true),
-  SANITIZER_OPT (shift-base, SANITIZE_SHIFT_BASE, true),
-  SANITIZER_OPT (shift-exponent, SANITIZE_SHIFT_EXPONENT, true),
-  SANITIZER_OPT (integer-divide-by-zero, SANITIZE_DIVIDE, true),
-  SANITIZER_OPT (undefined, SANITIZE_UNDEFINED, true),
-  SANITIZER_OPT (unreachable, SANITIZE_UNREACHABLE, false),
-  SANITIZER_OPT (vla-bound, SANITIZE_VLA, true),
-  SANITIZER_OPT (return, SANITIZE_RETURN, false),
-  SANITIZER_OPT (null, SANITIZE_NULL, true),
-  SANITIZER_OPT (signed-integer-overflow, SANITIZE_SI_OVERFLOW, true),
-  SANITIZER_OPT (bool, SANITIZE_BOOL, true),
-  SANITIZER_OPT (enum, SANITIZE_ENUM, true),
-  SANITIZER_OPT (float-divide-by-zero, SANITIZE_FLOAT_DIVIDE, true),
-  SANITIZER_OPT (float-cast-overflow, SANITIZE_FLOAT_CAST, true),
-  SANITIZER_OPT (bounds, SANITIZE_BOUNDS, true),
-  SANITIZER_OPT (bounds-strict, SANITIZE_BOUNDS | SANITIZE_BOUNDS_STRICT, true),
-  SANITIZER_OPT (alignment, SANITIZE_ALIGNMENT, true),
-  SANITIZER_OPT (nonnull-attribute, SANITIZE_NONNULL_ATTRIBUTE, true),
+  SANITIZER_OPT (alignment, SANITIZE_ALIGNMENT, true, true),
+  SANITIZER_OPT (nonnull-attribute, SANITIZE_NONNULL_ATTRIBUTE, true, true),
   SANITIZER_OPT (returns-nonnull-attribute, SANITIZE_RETURNS_NONNULL_ATTRIBUTE,
-		 true),
-  SANITIZER_OPT (object-size, SANITIZE_OBJECT_SIZE, true),
-  SANITIZER_OPT (vptr, SANITIZE_VPTR, true),
-  SANITIZER_OPT (pointer-overflow, SANITIZE_POINTER_OVERFLOW, true),
-  SANITIZER_OPT (builtin, SANITIZE_BUILTIN, true),
-  SANITIZER_OPT (shadow-call-stack, SANITIZE_SHADOW_CALL_STACK, false),
-  SANITIZER_OPT (all, ~0U, true),
+		 true, true),
+  SANITIZER_OPT (object-size, SANITIZE_OBJECT_SIZE, true, true),
+  SANITIZER_OPT (vptr, SANITIZE_VPTR, true, false),
+  SANITIZER_OPT (pointer-overflow, SANITIZE_POINTER_OVERFLOW, true, true),
+  SANITIZER_OPT (builtin, SANITIZE_BUILTIN, true, true),
+  SANITIZER_OPT (shadow-call-stack, SANITIZE_SHADOW_CALL_STACK, false, false),
+  SANITIZER_OPT (all, ~0U, true, true),
 #undef SANITIZER_OPT
-  { NULL, 0U, 0UL, false }
+  { NULL, 0U, 0UL, false, false }
 };
 
 /* -fzero-call-used-regs= suboptions.  */
@@ -2114,7 +2128,7 @@ struct edit_distance_traits<const string_fragment &>
 /* Given ARG, an unrecognized sanitizer option, return the best
    matching sanitizer option, or NULL if there isn't one.
    OPTS is array of candidate sanitizer options.
-   CODE is OPT_fsanitize_ or OPT_fsanitize_recover_.
+   CODE is OPT_fsanitize_, OPT_fsanitize_recover_ or OPT_fsanitize_trap_.
    VALUE is non-zero for the regular form of the option, zero
    for the "no-" form (e.g. "-fno-sanitize-recover=").  */
 
@@ -2139,6 +2153,13 @@ get_closest_sanitizer_option (const string_fragment &arg,
 	  && value)
 	continue;
 
+      /* For -fsanitize-trap= (and not -fno-sanitize-trap=),
+	 don't offer the non-trapping options.  */
+      if (code == OPT_fsanitize_trap_
+	  && !opts[i].can_trap
+	  && value)
+	continue;
+
       bm.consider (opts[i].name);
     }
   return bm.get_best_meaningful_candidate ();
@@ -2183,10 +2204,13 @@ parse_sanitizer_options (const char *p, location_t loc, int scode,
 		    if (complain)
 		      error_at (loc, "%<-fsanitize=all%> option is not valid");
 		  }
-		else
+		else if (code == OPT_fsanitize_recover_)
 		  flags |= ~(SANITIZE_THREAD | SANITIZE_LEAK
 			     | SANITIZE_UNREACHABLE | SANITIZE_RETURN
 			     | SANITIZE_SHADOW_CALL_STACK);
+		else /* if (code == OPT_fsanitize_trap_) */
+		  flags |= (SANITIZE_UNDEFINED
+			    | SANITIZE_UNDEFINED_NONDEFAULT);
 	      }
 	    else if (value)
 	      {
@@ -2197,6 +2221,10 @@ parse_sanitizer_options (const char *p, location_t loc, int scode,
 		    && sanitizer_opts[i].flag == SANITIZE_UNDEFINED)
 		  flags |= (SANITIZE_UNDEFINED
 			    & ~(SANITIZE_UNREACHABLE | SANITIZE_RETURN));
+		else if (code == OPT_fsanitize_trap_
+			 && sanitizer_opts[i].flag == SANITIZE_VPTR)
+		  error_at (loc, "%<-fsanitize-trap=%s%> is not supported",
+			    sanitizer_opts[i].name);
 		else
 		  flags |= sanitizer_opts[i].flag;
 	      }
@@ -2215,6 +2243,8 @@ parse_sanitizer_options (const char *p, location_t loc, int scode,
 	  const char *suffix;
 	  if (code == OPT_fsanitize_recover_)
 	    suffix = "-recover";
+	  else if (code == OPT_fsanitize_trap_)
+	    suffix = "-trap";
 	  else
 	    suffix = "";
 
@@ -2647,6 +2677,12 @@ common_handle_option (struct gcc_options *opts,
 				   opts->x_flag_sanitize_recover, value, true);
       break;
 
+    case OPT_fsanitize_trap_:
+      opts->x_flag_sanitize_trap
+	= parse_sanitizer_options (arg, loc, code,
+				   opts->x_flag_sanitize_trap, value, true);
+      break;
+
     case OPT_fasan_shadow_offset_:
       /* Deferred.  */
       break;
@@ -2665,6 +2701,15 @@ common_handle_option (struct gcc_options *opts,
 	  &= ~(SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT);
       break;
 
+    case OPT_fsanitize_trap:
+      if (value)
+	opts->x_flag_sanitize_trap
+	  |= (SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT);
+      else
+	opts->x_flag_sanitize_trap
+	  &= ~(SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT);
+      break;
+
     case OPT_O:
     case OPT_Os:
     case OPT_Ofast:
diff --git a/gcc/opts.h b/gcc/opts.h
index a43ce66..73a96f3 100644
--- a/gcc/opts.h
+++ b/gcc/opts.h
@@ -473,6 +473,7 @@ extern const struct sanitizer_opts_s
   unsigned int flag;
   size_t len;
   bool can_recover;
+  bool can_trap;
 } sanitizer_opts[];
 
 extern const struct zero_call_used_regs_opts_s
diff --git a/gcc/sanopt.cc b/gcc/sanopt.cc
index 125e0c9..c318763 100644
--- a/gcc/sanopt.cc
+++ b/gcc/sanopt.cc
@@ -392,11 +392,11 @@ maybe_optimize_ubsan_null_ifn (class sanopt_ctx *ctx, gimple *stmt)
      stmts have same location.  */
   else if (integer_zerop (align))
     remove = (flag_sanitize_recover & SANITIZE_NULL) == 0
-	      || flag_sanitize_undefined_trap_on_error
+	      || (flag_sanitize_trap & SANITIZE_NULL) != 0
 	      || gimple_location (g) == gimple_location (stmt);
   else if (tree_int_cst_le (cur_align, align))
     remove = (flag_sanitize_recover & SANITIZE_ALIGNMENT) == 0
-	      || flag_sanitize_undefined_trap_on_error
+	      || (flag_sanitize_trap & SANITIZE_ALIGNMENT) != 0
 	      || gimple_location (g) == gimple_location (stmt);
 
   if (!remove && gimple_bb (g) == gimple_bb (stmt)
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-8.c b/gcc/testsuite/c-c++-common/ubsan/align-8.c
index 5fe0e0f..53b2b6c 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-8.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-8.c
@@ -1,6 +1,6 @@
 /* Limit this to known non-strict alignment targets.  */
 /* { dg-do run { target { i?86-*-linux* x86_64-*-linux* } } } */
-/* { dg-options "-O -fsanitize=alignment -fsanitize-undefined-trap-on-error -Wno-address-of-packed-member -fdump-tree-sanopt-details" } */
+/* { dg-options "-O -fsanitize=alignment -fsanitize-trap=alignment -Wno-address-of-packed-member -fdump-tree-sanopt-details" } */
 /* { dg-skip-if "" { *-*-* } { "-flto -fno-fat-lto-objects" } } */
 /* { dg-shouldfail "ubsan" } */
 
diff --git a/gcc/testsuite/c-c++-common/ubsan/div-by-zero-4.c b/gcc/testsuite/c-c++-common/ubsan/div-by-zero-4.c
index ef431c9..e2cc9fe 100644
--- a/gcc/testsuite/c-c++-common/ubsan/div-by-zero-4.c
+++ b/gcc/testsuite/c-c++-common/ubsan/div-by-zero-4.c
@@ -1,5 +1,5 @@
 /* { dg-do run } */
-/* { dg-options "-fsanitize=signed-integer-overflow -fsanitize-undefined-trap-on-error -Wno-overflow" } */
+/* { dg-options "-fsanitize=signed-integer-overflow -fsanitize-trap=signed-integer-overflow -Wno-overflow" } */
 
 #define INT_MIN (-__INT_MAX__ - 1)
 
diff --git a/gcc/testsuite/c-c++-common/ubsan/nonnull-4.c b/gcc/testsuite/c-c++-common/ubsan/nonnull-4.c
index b49c72e..65b6dfb 100644
--- a/gcc/testsuite/c-c++-common/ubsan/nonnull-4.c
+++ b/gcc/testsuite/c-c++-common/ubsan/nonnull-4.c
@@ -1,6 +1,6 @@
 /* { dg-do run } */
 /* { dg-shouldfail "ubsan" } */
-/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
+/* { dg-options "-fsanitize=undefined -fsanitize-trap=all" } */
 
 int q, r;
 void *a, *b, *c = (void *) &q, *d, *e, *f = (void *) &q, *g, *h;
diff --git a/gcc/testsuite/c-c++-common/ubsan/overflow-add-4.c b/gcc/testsuite/c-c++-common/ubsan/overflow-add-4.c
index 3f6f6bd..ac9df4d 100644
--- a/gcc/testsuite/c-c++-common/ubsan/overflow-add-4.c
+++ b/gcc/testsuite/c-c++-common/ubsan/overflow-add-4.c
@@ -1,5 +1,5 @@
 /* { dg-do run } */
-/* { dg-options "-fsanitize=signed-integer-overflow -Wno-unused-variable -fsanitize-undefined-trap-on-error" } */
+/* { dg-options "-fsanitize=signed-integer-overflow -Wno-unused-variable -fsanitize-trap=undefined" } */
 /* { dg-shouldfail "ubsan" } */
 
 #define INT_MAX __INT_MAX__
diff --git a/gcc/testsuite/c-c++-common/ubsan/pr56956.c b/gcc/testsuite/c-c++-common/ubsan/pr56956.c
index 996e1dd..a3280c2 100644
--- a/gcc/testsuite/c-c++-common/ubsan/pr56956.c
+++ b/gcc/testsuite/c-c++-common/ubsan/pr56956.c
@@ -1,5 +1,5 @@
 /* { dg-do run } */
-/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
+/* { dg-options "-fsanitize=undefined -fsanitize-trap=undefined" } */
 
 unsigned int __attribute__((noinline,noclone))
 foo (unsigned int x)
diff --git a/gcc/testsuite/c-c++-common/ubsan/pr68142.c b/gcc/testsuite/c-c++-common/ubsan/pr68142.c
index 9498f08..13b7ef6 100644
--- a/gcc/testsuite/c-c++-common/ubsan/pr68142.c
+++ b/gcc/testsuite/c-c++-common/ubsan/pr68142.c
@@ -1,5 +1,5 @@
 /* { dg-do run } */
-/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
+/* { dg-options "-fsanitize=undefined -fsanitize-trap=undefined" } */
 
 int __attribute__((noinline,noclone))
 h(int a)
diff --git a/gcc/testsuite/c-c++-common/ubsan/pr80932.c b/gcc/testsuite/c-c++-common/ubsan/pr80932.c
index 92903f7..3ee56c8 100644
--- a/gcc/testsuite/c-c++-common/ubsan/pr80932.c
+++ b/gcc/testsuite/c-c++-common/ubsan/pr80932.c
@@ -1,6 +1,6 @@
 /* PR sanitizer/80932 */
 /* { dg-do run } */
-/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
+/* { dg-options "-fsanitize=undefined -fno-sanitize-trap=all -fsanitize-trap=shift,undefined" } */
 
 int x = 1;
 
diff --git a/gcc/ubsan.cc b/gcc/ubsan.cc
index 6c05814..3aa25b5 100644
--- a/gcc/ubsan.cc
+++ b/gcc/ubsan.cc
@@ -647,7 +647,7 @@ ubsan_instrument_unreachable (gimple_stmt_iterator *gsi)
   gimple *g;
   location_t loc = gimple_location (gsi_stmt (*gsi));
 
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & SANITIZE_UNREACHABLE)
     g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -719,7 +719,7 @@ ubsan_expand_bounds_ifn (gimple_stmt_iterator *gsi)
 
   /* Generate __ubsan_handle_out_of_bounds call.  */
   *gsi = gsi_after_labels (then_bb);
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & SANITIZE_BOUNDS)
     g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -827,7 +827,8 @@ ubsan_expand_null_ifn (gimple_stmt_iterator *gsip)
     set_immediate_dominator (CDI_DOMINATORS, then_bb, cond_bb);
 
   /* Put the ubsan builtin call into the newly created BB.  */
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & ((check_align ? SANITIZE_ALIGNMENT + 0 : 0)
+			    | (check_null ? SANITIZE_NULL + 0 : 0)))
     g = gimple_build_call (builtin_decl_implicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -997,7 +998,7 @@ ubsan_expand_objsize_ifn (gimple_stmt_iterator *gsi)
 	}
 
       /* Generate __ubsan_handle_type_mismatch call.  */
-      if (flag_sanitize_undefined_trap_on_error)
+      if (flag_sanitize_trap & SANITIZE_OBJECT_SIZE)
 	g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
       else
 	{
@@ -1143,7 +1144,7 @@ ubsan_expand_ptr_ifn (gimple_stmt_iterator *gsip)
     }
 
   /* Put the ubsan builtin call into the newly created BB.  */
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & SANITIZE_POINTER_OVERFLOW)
     g = gimple_build_call (builtin_decl_implicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -1518,7 +1519,7 @@ tree
 ubsan_build_overflow_builtin (tree_code code, location_t loc, tree lhstype,
 			      tree op0, tree op1, tree *datap)
 {
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & SANITIZE_SI_OVERFLOW)
     return build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
 
   tree data;
@@ -1741,7 +1742,8 @@ instrument_bool_enum_load (gimple_stmt_iterator *gsi)
     }
 
   gsi2 = gsi_after_labels (then_bb);
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & (TREE_CODE (type) == BOOLEAN_TYPE
+			    ? SANITIZE_BOOL : SANITIZE_ENUM))
     g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -1904,7 +1906,7 @@ ubsan_instrument_float_cast (location_t loc, tree type, tree expr)
   if (integer_zerop (t))
     return NULL_TREE;
 
-  if (flag_sanitize_undefined_trap_on_error)
+  if (flag_sanitize_trap & SANITIZE_FLOAT_CAST)
     fn = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
   else
     {
@@ -1974,7 +1976,7 @@ instrument_nonnull_arg (gimple_stmt_iterator *gsi)
 	  gsi_insert_after (gsi, g, GSI_NEW_STMT);
 
 	  *gsi = gsi_after_labels (then_bb);
-	  if (flag_sanitize_undefined_trap_on_error)
+	  if (flag_sanitize_trap & SANITIZE_NONNULL_ATTRIBUTE)
 	    g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
 	  else
 	    {
@@ -2030,7 +2032,7 @@ instrument_nonnull_return (gimple_stmt_iterator *gsi)
       gsi_insert_after (gsi, g, GSI_NEW_STMT);
 
       *gsi = gsi_after_labels (then_bb);
-      if (flag_sanitize_undefined_trap_on_error)
+      if (flag_sanitize_trap & SANITIZE_RETURNS_NONNULL_ATTRIBUTE)
 	g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
       else
 	{
@@ -2279,7 +2281,7 @@ instrument_builtin (gimple_stmt_iterator *gsi)
 	  gsi_insert_after (gsi, g, GSI_NEW_STMT);
 
 	  *gsi = gsi_after_labels (then_bb);
-	  if (flag_sanitize_undefined_trap_on_error)
+	  if (flag_sanitize_trap & SANITIZE_BUILTIN)
 	    g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
 	  else
 	    {