Hi!
__builtin_unreachable and __ubsan_handle_builtin_unreachable don't
use vops, they are marked const/leaf/noreturn/nothrow/cold.
But __builtin_trap uses vops, isn't const, just leaf/noreturn/nothrow/cold.
This is I believe so that when users explicitly use __builtin_trap in their
sources they get stores visible at the trap side.
-fsanitize=unreachable -fsanitize-undefined-trap-on-error used to transform
__builtin_unreachable to __builtin_trap even in the past, but the sanopt pass
has TODO_update_ssa, so it worked fine.
Now that gimple_build_builtin_unreachable can build a __builtin_trap call
right away, we can run into problems that whenever we need it we would need
to either manually or through TODO_update* ensure the vops being updated.
Though, as it is originally __builtin_unreachable which is just implemented
as trap, I think for this case it is fine to avoid vops. For this the
patch introduces IFN_TRAP, which has ECF_* flags like __builtin_unreachable
and is expanded as __builtin_trap.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2022-07-27 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/106099
* internal-fn.def (TRAP): New internal fn.
* internal-fn.h (expand_TRAP): Declare.
* internal-fn.cc (expand_TRAP): Define.
* gimple.cc (gimple_build_builtin_unreachable): For BUILT_IN_TRAP,
use internal fn rather than builtin.
* gcc.dg/ubsan/pr106099.c: New test.
--- gcc/internal-fn.def.jj 2022-07-26 10:32:23.886269144 +0200
+++ gcc/internal-fn.def 2022-07-26 11:40:41.799927048 +0200
@@ -456,6 +456,10 @@ DEF_INTERNAL_FN (SHUFFLEVECTOR, ECF_CONS
/* <=> optimization. */
DEF_INTERNAL_FN (SPACESHIP, ECF_CONST | ECF_LEAF | ECF_NOTHROW, NULL)
+/* __builtin_trap created from/for __builtin_unreachable. */
+DEF_INTERNAL_FN (TRAP, ECF_CONST | ECF_LEAF | ECF_NORETURN
+ | ECF_NOTHROW | ECF_COLD, NULL)
+
#undef DEF_INTERNAL_INT_FN
#undef DEF_INTERNAL_FLT_FN
#undef DEF_INTERNAL_FLT_FLOATN_FN
--- gcc/internal-fn.h.jj 2022-06-16 10:56:28.945385251 +0200
+++ gcc/internal-fn.h 2022-07-26 11:45:50.483837472 +0200
@@ -242,6 +242,7 @@ extern void expand_internal_call (intern
extern void expand_PHI (internal_fn, gcall *);
extern void expand_SHUFFLEVECTOR (internal_fn, gcall *);
extern void expand_SPACESHIP (internal_fn, gcall *);
+extern void expand_TRAP (internal_fn, gcall *);
extern bool vectorized_internal_fn_supported_p (internal_fn, tree);
--- gcc/internal-fn.cc.jj 2022-07-26 10:32:23.885269157 +0200
+++ gcc/internal-fn.cc 2022-07-26 11:42:02.611856420 +0200
@@ -4494,3 +4494,9 @@ expand_SPACESHIP (internal_fn, gcall *st
if (!rtx_equal_p (target, ops[0].value))
emit_move_insn (target, ops[0].value);
}
+
+void
+expand_TRAP (internal_fn, gcall *)
+{
+ expand_builtin_trap ();
+}
--- gcc/gimple.cc.jj 2022-06-27 11:18:02.680058429 +0200
+++ gcc/gimple.cc 2022-07-26 11:57:17.049760135 +0200
@@ -430,7 +430,16 @@ gimple_build_builtin_unreachable (locati
{
tree data = NULL_TREE;
tree fn = sanitize_unreachable_fn (&data, loc);
- gcall *g = gimple_build_call (fn, data != NULL_TREE, data);
+ gcall *g;
+ if (DECL_FUNCTION_CODE (fn) != BUILT_IN_TRAP)
+ g = gimple_build_call (fn, data != NULL_TREE, data);
+ else
+ {
+ /* Instead of __builtin_trap use .TRAP, so that it doesn't
+ need vops. */
+ gcc_checking_assert (data == NULL_TREE);
+ g = gimple_build_call_internal (IFN_TRAP, 0);
+ }
gimple_set_location (g, loc);
return g;
}
--- gcc/testsuite/gcc.dg/ubsan/pr106099.c.jj 2022-07-26 12:22:26.248156163
+0200
+++ gcc/testsuite/gcc.dg/ubsan/pr106099.c 2022-07-26 11:34:25.660909186
+0200
@@ -0,0 +1,10 @@
+/* PR tree-optimization/106099 */
+/* { dg-do compile } */
+/* { dg-options "-O -fsanitize=unreachable -fsanitize-undefined-trap-on-error
-fno-tree-ccp -fno-tree-dominator-opts" } */
+
+void
+foo (void)
+{
+ for (unsigned i = 0; i == 0; i++)
+ ;
+}
Jakub
