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[0/3] kunit: further reduce stack usage of asserts

Message ID 20220125210011.3817742-1-dlatypov@google.com (mailing list archive)
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Series kunit: further reduce stack usage of asserts | expand

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Daniel Latypov Jan. 25, 2022, 9 p.m. UTC 
If the compiler doesn't optimize them away, each kunit assertion (use of
KUNIT_EXPECT_EQ, etc.) can use 88 bytes of stack space in the worst and
most common case. This has led to compiler warnings for certain configs
+ arches [1].

This series builds upon [2] which cut down kunit_assert from 48 => 24
bytes, but only reduced kunit_binary_assert (the most common one) from
88 => 48.

Now we have kunit_assert = 8 and kunit_binary_assert = 32.
The cost is we need to pass around another parameter to some functions
(struct va_format *), and we introduce a new type
(sturct kunit_binary_assert_text) for holding the textual representation
of the KUNIT_EXPECT_EQ arguments.

Note: it's possible to get kunit_assert = 0 and kunit_binary_assert =
24 by removing the `format` function pointer field from kunit_assert.
I think it's an improvement, but others might think that readability
suffers from doing so, so I'm leaving that off from this series.

Meta: this series applies on top of 5.17-rc1 + [2] and [3].
That should be available at in Shuah's kunit branch [4], but my version
of git is constantly segfaulting, so I can't try and rebase to verify.

[1] https://groups.google.com/g/kunit-dev/c/i3fZXgvBrfA/m/VULQg1z6BAAJ
[2] https://lore.kernel.org/linux-kselftest/20220113165931.451305-6-dlatypov@google.com/
[3] https://lore.kernel.org/linux-kselftest/20220118223506.1701553-1-dlatypov@google.com/
[4] https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git/?h=kunit 

Daniel Latypov (3):
  kunit: remove va_format from kunit_assert
  kunit: consolidate KUNIT_INIT_BINARY_ASSERT_STRUCT macros
  kunit: factor out str constants from binary assertion structs

 include/kunit/assert.h | 152 ++++++++++++-----------------------------
 include/kunit/test.h   |  32 +++++----
 lib/kunit/assert.c     |  65 ++++++++++--------
 lib/kunit/test.c       |  12 ++--
 4 files changed, 104 insertions(+), 157 deletions(-)