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* [gcc r13-1076] ubsan: -Wreturn-type and ubsan trap-on-error
@ 2022-06-13 21:55 Jason Merrill
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From: Jason Merrill @ 2022-06-13 21:55 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:2c11662391bafd74c9d19bf7626b7bcef41c1323
commit r13-1076-g2c11662391bafd74c9d19bf7626b7bcef41c1323
Author: Jason Merrill <jason@redhat.com>
Date: Fri Jun 10 15:26:36 2022 -0400
ubsan: -Wreturn-type and ubsan trap-on-error
I noticed that -fsanitize=undefined -fsanitize-undefined-trap-on-error was
omitting the usual -Wreturn-type warning for control flowing off the end of
a function. This was because the warning code was looking for calls either
to __builtin_unreachable or the UBSan function, but these flags produce a
call to __builtin_trap instead.
gcc/c-family/ChangeLog:
* c-ubsan.cc (ubsan_instrument_return): Use BUILTINS_LOCATION.
gcc/ChangeLog:
* tree-cfg.cc (pass_warn_function_return::execute): Also check
BUILT_IN_TRAP.
gcc/testsuite/ChangeLog:
* g++.dg/ubsan/return-8.C: New test.
Diff:
---
gcc/c-family/c-ubsan.cc | 4 +++-
gcc/testsuite/g++.dg/ubsan/return-8.C | 9 +++++++++
gcc/tree-cfg.cc | 5 +++--
3 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/gcc/c-family/c-ubsan.cc b/gcc/c-family/c-ubsan.cc
index 48f948745f8..a2cd8fb3262 100644
--- a/gcc/c-family/c-ubsan.cc
+++ b/gcc/c-family/c-ubsan.cc
@@ -308,7 +308,9 @@ tree
ubsan_instrument_return (location_t loc)
{
if (flag_sanitize_undefined_trap_on_error)
- return build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
+ return build_call_expr_loc
+ /* pass_warn_function_return checks for BUILTINS_LOCATION. */
+ (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/testsuite/g++.dg/ubsan/return-8.C b/gcc/testsuite/g++.dg/ubsan/return-8.C
new file mode 100644
index 00000000000..354c96098d2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ubsan/return-8.C
@@ -0,0 +1,9 @@
+// { dg-additional-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" }
+
+bool b;
+
+int f() {
+ if (b) return 42;
+} // { dg-warning "-Wreturn-type" }
+
+int main() { f(); }
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index 9e5d84a9805..c67c278dad0 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -9543,7 +9543,7 @@ pass_warn_function_return::execute (function *fun)
}
/* The C++ FE turns fallthrough from the end of non-void function
into __builtin_unreachable () call with BUILTINS_LOCATION.
- Recognize those too. */
+ Recognize those as well as calls from ubsan_instrument_return. */
basic_block bb;
if (!warning_suppressed_p (fun->decl, OPT_Wreturn_type))
FOR_EACH_BB_FN (bb, fun)
@@ -9555,7 +9555,8 @@ pass_warn_function_return::execute (function *fun)
if (last
&& ((LOCATION_LOCUS (gimple_location (last))
== BUILTINS_LOCATION
- && gimple_call_builtin_p (last, BUILT_IN_UNREACHABLE))
+ && (gimple_call_builtin_p (last, BUILT_IN_UNREACHABLE)
+ || gimple_call_builtin_p (last, BUILT_IN_TRAP)))
|| gimple_call_builtin_p (last, ubsan_missing_ret)))
{
gimple_stmt_iterator gsi = gsi_for_stmt (last);
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