On Thu, 20 May 2021 at 10:33, Martin Liška <mli...@suse.cz> wrote:
> Hello.
>
> The patch implements one missing attribute which can be used for per-function
> disabling of coverage sanitization.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
Thanks for implementing this so quickly. One thing I just have to
double check, is if this works with always_inline (not instrumented if
inlined into no_sanitize), and inline (not inlined if inline fn is
no_sanitize_coverage). Just like the other no_sanitize* do. The test
doesn't mention them.
Thanks,
-- Marco
> Ready to be installed?
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> * asan.h (sanitize_coverage_p): New function.
> * doc/extend.texi: Document it.
> * fold-const.c (fold_range_test): Use sanitize_flags_p
> instead of flag_sanitize_coverage.
> (fold_truth_andor): Likewise.
> * sancov.c: Likewise.
> * tree-ssa-ifcombine.c (ifcombine_ifandif): Likewise.
>
> gcc/c-family/ChangeLog:
>
> * c-attribs.c (handle_no_sanitize_coverage_attribute): New.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/sancov/attribute.c: New test.
> ---
> gcc/asan.h | 10 ++++++++++
> gcc/c-family/c-attribs.c | 20 ++++++++++++++++++++
> gcc/doc/extend.texi | 6 ++++++
> gcc/fold-const.c | 4 ++--
> gcc/sancov.c | 4 ++--
> gcc/testsuite/gcc.dg/sancov/attribute.c | 15 +++++++++++++++
> gcc/tree-ssa-ifcombine.c | 4 +++-
> 7 files changed, 58 insertions(+), 5 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/sancov/attribute.c
>
> diff --git a/gcc/asan.h b/gcc/asan.h
> index f110f1db563..8c0b2baf170 100644
> --- a/gcc/asan.h
> +++ b/gcc/asan.h
> @@ -249,4 +249,14 @@ sanitize_flags_p (unsigned int flag, const_tree fn =
> current_function_decl)
> return result_flags;
> }
>
> +/* Return true when coverage sanitization should happend for FN function. */
> +
> +static inline bool
> +sanitize_coverage_p (const_tree fn = current_function_decl)
> +{
> + return (flag_sanitize_coverage
> + && lookup_attribute ("no_sanitize_coverage",
> + DECL_ATTRIBUTES (fn)) == NULL_TREE);
> +}
> +
> #endif /* TREE_ASAN */
> diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
> index ccf9e4ccf0b..671b27c3200 100644
> --- a/gcc/c-family/c-attribs.c
> +++ b/gcc/c-family/c-attribs.c
> @@ -62,6 +62,8 @@ static tree handle_no_address_safety_analysis_attribute
> (tree *, tree, tree,
> int, bool *);
> static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
> bool *);
> +static tree handle_no_sanitize_coverage_attribute (tree *, tree, tree, int,
> + bool *);
> static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
> bool *);
> static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool
> *);
> @@ -449,6 +451,8 @@ const struct attribute_spec c_common_attribute_table[] =
> handle_no_sanitize_thread_attribute, NULL },
> { "no_sanitize_undefined", 0, 0, true, false, false, false,
> handle_no_sanitize_undefined_attribute, NULL },
> + { "no_sanitize_coverage", 0, 0, true, false, false, false,
> + handle_no_sanitize_coverage_attribute, NULL },
> { "asan odr indicator", 0, 0, true, false, false, false,
> handle_asan_odr_indicator_attribute, NULL },
> { "warning", 1, 1, true, false, false, false,
> @@ -1211,6 +1215,22 @@ handle_no_sanitize_undefined_attribute (tree *node,
> tree name, tree, int,
> return NULL_TREE;
> }
>
> +/* Handle a "no_sanitize_coverage" attribute; arguments as in
> + struct attribute_spec.handler. */
> +
> +static tree
> +handle_no_sanitize_coverage_attribute (tree *node, tree name, tree, int,
> + bool *no_add_attrs)
> +{
> + if (TREE_CODE (*node) != FUNCTION_DECL)
> + {
> + warning (OPT_Wattributes, "%qE attribute ignored", name);
> + *no_add_attrs = true;
> + }
> +
> + return NULL_TREE;
> +}
> +
> /* Handle an "asan odr indicator" attribute; arguments as in
> struct attribute_spec.handler. */
>
> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> index 826804e6149..3ddeb0dee3a 100644
> --- a/gcc/doc/extend.texi
> +++ b/gcc/doc/extend.texi
> @@ -3415,6 +3415,12 @@ The @code{no_sanitize_undefined} attribute on
> functions is used
> to inform the compiler that it should not check for undefined behavior
> in the function when compiling with the @option{-fsanitize=undefined}
> option.
>
> +@item no_sanitize_coverage
> +@cindex @code{no_sanitize_coverage} function attribute
> +The @code{no_sanitize_coverage} attribute on functions is used
> +to inform the compiler that it should not do coverage-guided
> +fuzzing code instrumentation (@option{-fsanitize-coverage}).
> +
> @item no_split_stack
> @cindex @code{no_split_stack} function attribute
> @opindex fsplit-stack
> diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> index 3be9c15e6b2..d088187a057 100644
> --- a/gcc/fold-const.c
> +++ b/gcc/fold-const.c
> @@ -6016,7 +6016,7 @@ fold_range_test (location_t loc, enum tree_code code,
> tree type,
> logical_op_non_short_circuit
> = param_logical_op_non_short_circuit;
> if (logical_op_non_short_circuit
> - && !flag_sanitize_coverage
> + && !sanitize_coverage_p ()
> && lhs != 0 && rhs != 0
> && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
> && operand_equal_p (lhs, rhs, 0))
> @@ -9652,7 +9652,7 @@ fold_truth_andor (location_t loc, enum tree_code code,
> tree type,
> logical_op_non_short_circuit
> = param_logical_op_non_short_circuit;
> if (logical_op_non_short_circuit
> - && !flag_sanitize_coverage
> + && !sanitize_coverage_p ()
> && (code == TRUTH_AND_EXPR
> || code == TRUTH_ANDIF_EXPR
> || code == TRUTH_OR_EXPR
> diff --git a/gcc/sancov.c b/gcc/sancov.c
> index d656c37cae9..9cfbd425def 100644
> --- a/gcc/sancov.c
> +++ b/gcc/sancov.c
> @@ -313,9 +313,9 @@ public:
> return new pass_sancov<O0> (m_ctxt);
> }
> virtual bool
> - gate (function *)
> + gate (function *fun)
> {
> - return flag_sanitize_coverage && (!O0 || !optimize);
> + return sanitize_coverage_p (fun->decl) && (!O0 || !optimize);
> }
> virtual unsigned int
> execute (function *fun)
> diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c
> b/gcc/testsuite/gcc.dg/sancov/attribute.c
> new file mode 100644
> index 00000000000..bf6dbd4bae7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */
> +
> +void foo(void)
> +{
> +}
> +
> +void
> +__attribute__((no_sanitize_coverage))
> +bar(void)
> +{
> +}
> +
> +
> +/* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc
> \\(\\)" 1 "optimized" } } */
> diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
> index 836a12d6b80..f93e04aa4df 100644
> --- a/gcc/tree-ssa-ifcombine.c
> +++ b/gcc/tree-ssa-ifcombine.c
> @@ -40,6 +40,8 @@ along with GCC; see the file COPYING3. If not see
> #include "gimplify-me.h"
> #include "tree-cfg.h"
> #include "tree-ssa.h"
> +#include "attribs.h"
> +#include "asan.h"
>
> #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
> #define LOGICAL_OP_NON_SHORT_CIRCUIT \
> @@ -567,7 +569,7 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool
> inner_inv,
> if (param_logical_op_non_short_circuit != -1)
> logical_op_non_short_circuit
> = param_logical_op_non_short_circuit;
> - if (!logical_op_non_short_circuit || flag_sanitize_coverage)
> + if (!logical_op_non_short_circuit || sanitize_coverage_p ())
> return false;
> /* Only do this optimization if the inner bb contains only the
> conditional. */
> if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb
> (inner_cond_bb)))
> --
> 2.31.1
>
