From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>,
"René Scharfe" <l.s.r@web.de>, "Jinoh Kang" <luke1337@theori.io>,
"Phillip Wood" <phillip.wood@talktalk.net>,
"Glen Choo" <chooglen@google.com>,
"Paul Tan" <pyokagan@gmail.com>,
"Han-Wen Nienhuys" <hanwen@google.com>,
"Karthik Nayak" <karthik.188@gmail.com>,
"Jeff Smith" <whydoubt@gmail.com>,
"Taylor Blau" <me@ttaylorr.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: [RFC PATCH 14/15] config.mak.dev: add a DEVOPTS=analyzer mode to use GCC's -fanalyzer
Date: Fri, 3 Jun 2022 20:37:51 +0200 [thread overview]
Message-ID: <RFC-patch-14.15-9cf550688d4-20220603T183608Z-avarab@gmail.com> (raw)
In-Reply-To: <RFC-cover-00.15-00000000000-20220603T183608Z-avarab@gmail.com>
Add an option to compile with GCC's -fanalyzer, which as noted in [1]
and [2] has become much more useful in the recently released GCC v12
series.
Here we're quieting a few outstanding -fanalyzer issues that require
us to use -Wno-error=* on an entire file:
* range-diff.c, because it involves loop variables and would be
painfully verbose to instrument with the ASSERT_FOR_FANALYZER() macro
introduced in the subsequent commit.
* http-fetch.c and fsmonitor-settings.c, because those aren't issues
where we're referencing NULL, and therefore we can't quiet it with an
assert().
For non-GCC compilers I considered wrapping the DEVOPTS logic in:
ifneq ($(filter gcc10,$(COMPILER_FEATURES)),)
endif
Which would make it OK to specify DEVOPTS=analyzer under other
compilers, or on older GCC. But then we'd silently ignore the option
on those. Let's instead trust the compiler to error out if it doesn't
support -fanalyzer.
There are various limitations and bugs in the analyzer engine, e.g. I
filed [3] for a false positive in builtin/merge-file.c before GCC v12
was released, which was subsequently fixed in GCC 12 trunk in [4], but
many other issues remain.
1. https://developers.redhat.com/articles/2022/04/12/state-static-analysis-gcc-12-compiler
2. https://gcc.gnu.org/gcc-12/changes.html
3. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105264
4. https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=a358e4b60815b41e27f3508014ceb592f86b9b45
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
Makefile | 14 ++++++++++++
config.mak.dev | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 75 insertions(+)
diff --git a/Makefile b/Makefile
index 18ca6744a50..129d55f5992 100644
--- a/Makefile
+++ b/Makefile
@@ -507,6 +507,20 @@ include shared.mak
# no-pedantic:
#
# Disable -pedantic compilation.
+#
+# analyzer:
+#
+# Compile with GCC's -fanalyzer, this analysis is much more
+# expensive than other GCC warnings.
+#
+# The set of analysis flags is curated based on known issues
+# and compiler version. Known issues are made into non-fatal
+# warnings (even "no-error" isn't set).
+#
+# no-suppress-analyzer:
+#
+# When using "analyzer" disable the suppression of known
+# -fanalyzer issues.
GIT-VERSION-FILE: FORCE
@$(SHELL_PATH) ./GIT-VERSION-GEN
diff --git a/config.mak.dev b/config.mak.dev
index c3104f400b2..d6f5be92297 100644
--- a/config.mak.dev
+++ b/config.mak.dev
@@ -72,3 +72,64 @@ DEVELOPER_CFLAGS += -Wno-error=dangling-pointer
endif
GIT_TEST_PERL_FATAL_WARNINGS = YesPlease
+
+# GCC's -fanalyzer mode
+ifeq ($(filter analyzer,$(DEVOPTS)),analyzer)
+
+ifeq ($(filter gcc1,$(COMPILER_FEATURES)),)
+$(error you must be using a new-ish version of GCC for DEVOPTS=analyzer, your \
+$(CC) is not GCC at all!)
+endif
+
+DEVELOPER_CFLAGS += -fanalyzer
+
+## -fanalyzer exists exists as of gcc10, but versions older than gcc12
+## have a lot of false positives.
+ifeq ($(filter gcc12,$(COMPILER_FEATURES)),)
+DEVELOPER_CFLAGS += -Wno-analyzer-double-free
+DEVELOPER_CFLAGS += -Wno-analyzer-free-of-non-heap
+endif
+
+## Helper templates to whitelist existing issues
+define fn_disable_analyzer_tmpl
+$(1).sp $(1).s $(1).o: EXTRA_CPPFLAGS += $(2)
+
+endef
+
+define fn_disable_analyzer
+$(foreach f,$(2),$(call fn_disable_analyzer_tmpl,$(f),$(1)))
+endef
+
+## -Wno-error=analyzer-null-dereference
+$(eval $(call fn_disable_analyzer, \
+ -Wno-error=analyzer-null-dereference, \
+ range-diff \
+))
+## -Wno-error=analyzer-malloc-leak
+$(eval $(call fn_disable_analyzer, \
+ -Wno-error=analyzer-malloc-leak, \
+ fsmonitor-settings \
+))
+## per-GCC version annotations
+### -Wno-error=analyzer-use-of-uninitialized-value: gcc >= 12
+ifneq ($(filter gcc12,$(COMPILER_FEATURES)),)
+$(eval $(call fn_disable_analyzer, \
+ -Wno-error=analyzer-use-of-uninitialized-value, \
+ http-fetch \
+))
+else # gcc < 12
+### -Wno-error=analyzer-null-dereference: gcc == 11
+ifneq ($(filter gcc11,$(COMPILER_FEATURES)),)
+$(eval $(call fn_disable_analyzer, \
+ -Wno-error=analyzer-null-dereference, \
+ merge \
+ xdiff/xemit \
+ reftable/reader \
+))
+else
+$(error Your GCC version is too old for -fanalyze, or you are using \
+gcc10 which has it, but has too many false positives!)
+endif
+endif # gcc < 12
+
+endif
--
2.36.1.1124.g577fa9c2ebd
next prev parent reply other threads:[~2022-06-03 18:41 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-03 18:37 [RFC PATCH 00/15] Fix GCC -fanalyzer warnings & add -fanalyzer DEVOPTS mode Ævar Arnfjörð Bjarmason
2022-06-03 18:37 ` [RFC PATCH 01/15] remote.c: don't dereference NULL in freeing loop Ævar Arnfjörð Bjarmason
2022-06-03 21:07 ` René Scharfe
2022-06-03 21:28 ` Junio C Hamano
2022-06-03 22:32 ` Glen Choo
2022-06-04 12:51 ` Phillip Wood
2022-06-04 16:20 ` Ævar Arnfjörð Bjarmason
2022-06-03 18:37 ` [RFC PATCH 02/15] pull.c: don't feed NULL to strcmp() on get_rebase_fork_point() path Ævar Arnfjörð Bjarmason
2022-06-03 21:27 ` René Scharfe
2022-06-03 18:37 ` [RFC PATCH 03/15] reftable: don't memset() a NULL from failed malloc() Ævar Arnfjörð Bjarmason
2022-06-03 22:22 ` René Scharfe
2022-06-04 0:54 ` Ævar Arnfjörð Bjarmason
2022-06-04 12:24 ` René Scharfe
2022-06-04 16:23 ` Ævar Arnfjörð Bjarmason
2022-06-04 20:31 ` René Scharfe
2022-06-06 16:53 ` Junio C Hamano
2022-06-06 17:38 ` Ævar Arnfjörð Bjarmason
2022-06-06 17:44 ` Junio C Hamano
2022-06-06 17:46 ` Ævar Arnfjörð Bjarmason
2022-06-03 18:37 ` [RFC PATCH 04/15] diff-lib.c: don't dereference NULL in oneway_diff() Ævar Arnfjörð Bjarmason
2022-06-03 22:48 ` René Scharfe
2022-06-03 18:37 ` [RFC PATCH 05/15] refs/packed-backend.c: add a BUG() if iter is NULL Ævar Arnfjörð Bjarmason
2022-06-03 23:14 ` René Scharfe
2022-06-03 18:37 ` [RFC PATCH 06/15] ref-filter.c: BUG() out on show_ref() with NULL refname Ævar Arnfjörð Bjarmason
2022-06-04 18:07 ` René Scharfe
2022-06-03 18:37 ` [RFC PATCH 07/15] strbuf.c: placate -fanalyzer in strbuf_grow() Ævar Arnfjörð Bjarmason
2022-06-04 12:24 ` René Scharfe
2022-06-04 12:46 ` Phillip Wood
2022-06-04 16:21 ` Ævar Arnfjörð Bjarmason
2022-06-04 20:37 ` René Scharfe
2022-06-05 10:20 ` Phillip Wood
2022-06-03 18:37 ` [RFC PATCH 08/15] strbuf.c: use st_add3(), not unsigned_add_overflows() Ævar Arnfjörð Bjarmason
2022-06-04 21:27 ` René Scharfe
2022-06-03 18:37 ` [RFC PATCH 09/15] add-patch: assert parse_diff() expectations with BUG() Ævar Arnfjörð Bjarmason
2022-06-04 13:04 ` Phillip Wood
2022-06-03 18:37 ` [RFC PATCH 10/15] reftable: don't have reader_get_block() confuse -fanalyzer Ævar Arnfjörð Bjarmason
2022-06-03 18:37 ` [RFC PATCH 11/15] blame.c: clarify the state of "final_commit" for -fanalyzer Ævar Arnfjörð Bjarmason
2022-06-03 18:37 ` [RFC PATCH 12/15] pack.h: wrap write_*file*() functions Ævar Arnfjörð Bjarmason
2022-06-03 18:37 ` [RFC PATCH 13/15] pack-write API: pass down "verify" not arbitrary flags Ævar Arnfjörð Bjarmason
2022-06-03 18:37 ` Ævar Arnfjörð Bjarmason [this message]
2022-06-03 18:37 ` [RFC PATCH 15/15] config.mak.dev: add and use ASSERT_FOR_FANALYZER() macro Ævar Arnfjörð Bjarmason
2022-06-04 13:12 ` Phillip Wood
2022-06-07 15:50 ` [PATCH 0/3] remote API: fix -fanalyzer-spotted freeing issue Ævar Arnfjörð Bjarmason
2022-06-07 15:50 ` [PATCH 1/3] remote.c: remove braces from one-statement "for"-loops Ævar Arnfjörð Bjarmason
2022-06-07 15:50 ` [PATCH 2/3] remote.c: don't dereference NULL in freeing loop Ævar Arnfjörð Bjarmason
2022-06-07 17:23 ` Junio C Hamano
2022-06-07 15:50 ` [PATCH 3/3] remote API: don't buggily FREE_AND_NULL(), free() instead Ævar Arnfjörð Bjarmason
2022-06-07 17:02 ` Glen Choo
2022-06-07 18:09 ` Junio C Hamano
2022-06-07 17:29 ` Junio C Hamano
2022-06-07 17:32 ` [PATCH 0/3] remote API: fix -fanalyzer-spotted freeing issue Junio C Hamano
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