24ebc5404b
Previously, if the analyzer saw a call to a non-pure and non-const
built-in function that it didn't have explicit knowledge of the behavior
of, it would fall back to assuming that the builtin could have arbitrary
behavior, similar to a function defined outside of the current TU.
However, this only worked for BUILTIN_NORMAL functions that matched
gimple_builtin_call_types_compatible_p; for BUILT_IN_FRONTEND and
BUILT_IN_MD, and for mismatched types the analyzer would erroneously
assume that the builtin had no side-effects, leading e.g. to
PR analyzer/107565, where the analyzer falsely reported that x
was still uninitialized after this target-specific builtin:
_1 = __builtin_ia32_rdrand64_step (&x);
This patch generalizes the handling to cover all classes of builtin,
fixing the above false positive.
Unfortunately this patch regresses gcc.dg/analyzer/pr99716-1.c due to
the:
fprintf (fp, "hello");
being optimized to:
__builtin_fwrite ("hello", 1, (ssizetype)5, fp_6);
and the latter has gimple_builtin_call_types_compatible_p return false,
whereas the original call had it return true. I'm assuming that this is
an optimization bug, and have filed it as PR middle-end/108988. The
effect on the analyzer is that it fails to recognize the call to
__builtin_fwrite and instead assumes arbitraty side-effects (including
that it could call fclose on fp, hence the report about the leak goes
away).
I tried various more involved fixes with new heuristics for handling
built-ins that aren't explicitly covered by the analyzer, but those
fixes tended to introduce many more regressions, so I'm going with this
simpler fix.
gcc/analyzer/ChangeLog:
PR analyzer/107565
* region-model.cc (region_model::on_call_pre): Flatten logic by
returning early. Consolidate logic for detecting const and pure
functions. When considering whether an unhandled built-in
function has side-effects, consider all kinds of builtin, rather
than just BUILT_IN_NORMAL, and don't require
gimple_builtin_call_types_compatible_p.
gcc/testsuite/ChangeLog:
PR analyzer/107565
* gcc.dg/analyzer/builtins-pr107565.c: New test.
* gcc.dg/analyzer/pr99716-1.c (test_2): Mark the leak as xfailing.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
|
||
|---|---|---|
| c++tools | ||
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| gotools | ||
| include | ||
| INSTALL | ||
| intl | ||
| libada | ||
| libatomic | ||
| libbacktrace | ||
| libcc1 | ||
| libcody | ||
| libcpp | ||
| libdecnumber | ||
| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgm2 | ||
| libgo | ||
| libgomp | ||
| libiberty | ||
| libitm | ||
| libobjc | ||
| libphobos | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| libvtv | ||
| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| ABOUT-NLS | ||
| ar-lib | ||
| ChangeLog | ||
| ChangeLog.jit | ||
| ChangeLog.tree-ssa | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING.LIB | ||
| COPYING.RUNTIME | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| depcomp | ||
| install-sh | ||
| libtool-ldflags | ||
| libtool.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| lt~obsolete.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| multilib.am | ||
| README | ||
| symlink-tree | ||
| test-driver | ||
| ylwrap | ||
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.