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Date: Thu, 27 Jan 2022 16:47:19 -0500
From: Brendan Higgins <brendanhiggins@...gle.com>
To: David Gow <davidgow@...gle.com>
Cc: Daniel Latypov <dlatypov@...gle.com>, linux-kernel@...r.kernel.org,
kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org,
skhan@...uxfoundation.org
Subject: Re: [PATCH 3/3] kunit: factor out str constants from binary assertion structs
On Wed, Jan 26, 2022 at 10:39 PM David Gow <davidgow@...gle.com> wrote:
>
> On Wed, Jan 26, 2022 at 5:00 AM Daniel Latypov <dlatypov@...gle.com> wrote:
> >
> > 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 and a suggestion
> > from Linus to move data from the structs into static const's where
> > possible [1].
> >
> > This builds upon [2] which did so for the base struct kunit_assert type.
> > That only reduced sizeof(struct kunit_binary_assert) from 88 to 64.
> >
> > Given these are by far the most commonly used asserts, this patch
> > factors out the textual representations of the operands and comparator
> > into another static const, saving 16 more bytes.
> >
> > In detail, KUNIT_EXPECT_EQ(test, 2 + 2, 5) yields the following struct
> > (struct kunit_binary_assert) {
> > .assert = <struct kunit_assert>,
> > .operation = "==",
> > .left_text = "2 + 2",
> > .left_value = 4,
> > .right_text = "5",
> > .right_value = 5,
> > }
> > After this change
> > static const struct kunit_binary_assert_text __text = {
> > .operation = "==",
> > .left_text = "2 + 2",
> > .right_text = "5",
> > };
> > (struct kunit_binary_assert) {
> > .assert = <struct kunit_assert>,
> > .text = &__text,
> > .left_value = 4,
> > .right_value = 5,
> > }
> >
> > This also DRYs the code a bit more since these str fields were repeated
> > for the string and pointer versions of kunit_binary_assert.
> >
> > Note: we could name the kunit_binary_assert_text fields left/right
> > instead of left_text/right_text. But that would require changing the
> > macros a bit since they have args called "left" and "right" which would
> > be substituted in `.left = #left` as `.2 + 2 = \"2 + 2\"`.
> >
> > [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/
> >
> > Signed-off-by: Daniel Latypov <dlatypov@...gle.com>
> > ---
>
> This definitely _feels_ like it's adding a bit more complexity than
> would be ideal by splitting this out into a separate function, but I
> do agree that it's worth it.
Agreed.
> I think left_text / right_text are good enough names, too: I wouldn't
> bother trying to make them .left/.right.
Yeah, I don't think it matters too much either.
> Reviewed-by: David Gow <davidgow@...gle.com>
>
> Cheers,
> -- David
>
> > include/kunit/assert.h | 49 +++++++++++++++++++-----------------------
> > include/kunit/test.h | 20 +++++++++++------
> > lib/kunit/assert.c | 38 ++++++++++++++++----------------
> > 3 files changed, 54 insertions(+), 53 deletions(-)
> >
> > diff --git a/include/kunit/assert.h b/include/kunit/assert.h
> > index 649bfac9f406..4b52e12c2ae8 100644
> > --- a/include/kunit/assert.h
> > +++ b/include/kunit/assert.h
> > @@ -150,14 +150,25 @@ void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
> > .value = val \
> > }
> >
> > +/**
> > + * struct kunit_binary_assert_text - holds strings for &struct
> > + * kunit_binary_assert and friends to try and make the structs smaller.
> > + * @operation: A string representation of the comparison operator (e.g. "==").
> > + * @left_text: A string representation of the left expression (e.g. "2+2").
> > + * @right_text: A string representation of the right expression (e.g. "2+2").
> > + */
> > +struct kunit_binary_assert_text {
> > + const char *operation;
> > + const char *left_text;
> > + const char *right_text;
> > +};
> > +
> > /**
> > * struct kunit_binary_assert - An expectation/assertion that compares two
> > * non-pointer values (for example, KUNIT_EXPECT_EQ(test, 1 + 1, 2)).
> > * @assert: The parent of this type.
> > - * @operation: A string representation of the comparison operator (e.g. "==").
> > - * @left_text: A string representation of the expression in the left slot.
> > + * @text: Holds the textual representations of the operands and op (e.g. "==").
> > * @left_value: The actual evaluated value of the expression in the left slot.
> > - * @right_text: A string representation of the expression in the right slot.
> > * @right_value: The actual evaluated value of the expression in the right slot.
> > *
> > * Represents an expectation/assertion that compares two non-pointer values. For
> > @@ -166,10 +177,8 @@ void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
> > */
> > struct kunit_binary_assert {
> > struct kunit_assert assert;
> > - const char *operation;
> > - const char *left_text;
> > + const struct kunit_binary_assert_text *text;
> > long long left_value;
> > - const char *right_text;
> > long long right_value;
> > };
> >
> > @@ -182,10 +191,8 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
> > * kunit_binary_assert, kunit_binary_ptr_assert, etc.
> > *
> > * @format_func: a function which formats the assert to a string.
> > - * @op_str: A string representation of the comparison operator (e.g. "==").
> > - * @left_str: A string representation of the expression in the left slot.
> > + * @text_: Pointer to a kunit_binary_assert_text.
> > * @left_val: The actual evaluated value of the expression in the left slot.
> > - * @right_str: A string representation of the expression in the right slot.
> > * @right_val: The actual evaluated value of the expression in the right slot.
> > *
> > * Initializes a binary assert like kunit_binary_assert,
> > @@ -194,16 +201,12 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
> > * This is ultimately used by binary assertion macros like KUNIT_EXPECT_EQ, etc.
> > */
> > #define KUNIT_INIT_BINARY_ASSERT_STRUCT(format_func, \
> > - op_str, \
> > - left_str, \
> > + text_, \
> > left_val, \
> > - right_str, \
> > right_val) { \
> > .assert = { .format = format_func }, \
> > - .operation = op_str, \
> > - .left_text = left_str, \
> > + .text = text_, \
> > .left_value = left_val, \
> > - .right_text = right_str, \
> > .right_value = right_val \
> > }
> >
> > @@ -211,10 +214,8 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
> > * struct kunit_binary_ptr_assert - An expectation/assertion that compares two
> > * pointer values (for example, KUNIT_EXPECT_PTR_EQ(test, foo, bar)).
> > * @assert: The parent of this type.
> > - * @operation: A string representation of the comparison operator (e.g. "==").
> > - * @left_text: A string representation of the expression in the left slot.
> > + * @text: Holds the textual representations of the operands and op (e.g. "==").
> > * @left_value: The actual evaluated value of the expression in the left slot.
> > - * @right_text: A string representation of the expression in the right slot.
> > * @right_value: The actual evaluated value of the expression in the right slot.
> > *
> > * Represents an expectation/assertion that compares two pointer values. For
> > @@ -223,10 +224,8 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
> > */
> > struct kunit_binary_ptr_assert {
> > struct kunit_assert assert;
> > - const char *operation;
> > - const char *left_text;
> > + const struct kunit_binary_assert_text *text;
> > const void *left_value;
> > - const char *right_text;
> > const void *right_value;
> > };
> >
> > @@ -238,10 +237,8 @@ void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
> > * struct kunit_binary_str_assert - An expectation/assertion that compares two
> > * string values (for example, KUNIT_EXPECT_STREQ(test, foo, "bar")).
> > * @assert: The parent of this type.
> > - * @operation: A string representation of the comparison operator (e.g. "==").
> > - * @left_text: A string representation of the expression in the left slot.
> > + * @text: Holds the textual representations of the operands and comparator.
> > * @left_value: The actual evaluated value of the expression in the left slot.
> > - * @right_text: A string representation of the expression in the right slot.
> > * @right_value: The actual evaluated value of the expression in the right slot.
> > *
> > * Represents an expectation/assertion that compares two string values. For
> > @@ -250,10 +247,8 @@ void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
> > */
> > struct kunit_binary_str_assert {
> > struct kunit_assert assert;
> > - const char *operation;
> > - const char *left_text;
> > + const struct kunit_binary_assert_text *text;
> > const char *left_value;
> > - const char *right_text;
> > const char *right_value;
> > };
> >
> > diff --git a/include/kunit/test.h b/include/kunit/test.h
> > index a93dfb8ff393..088ff394ae94 100644
> > --- a/include/kunit/test.h
> > +++ b/include/kunit/test.h
> > @@ -874,16 +874,19 @@ void kunit_do_failed_assertion(struct kunit *test,
> > do { \
> > typeof(left) __left = (left); \
> > typeof(right) __right = (right); \
> > + static const struct kunit_binary_assert_text __text = { \
> > + .operation = #op, \
> > + .left_text = #left, \
> > + .right_text = #right, \
> > + }; \
> > \
> > KUNIT_ASSERTION(test, \
> > assert_type, \
> > __left op __right, \
> > assert_class, \
> > KUNIT_INIT_BINARY_ASSERT_STRUCT(format_func, \
> > - #op, \
> > - #left, \
> > + &__text, \
> > __left, \
> > - #right, \
> > __right), \
> > fmt, \
> > ##__VA_ARGS__); \
> > @@ -928,17 +931,20 @@ do { \
> > ...) \
> > do { \
> > const char *__left = (left); \
> > - const char *__right = (right); \
> > + const char *__right = (right); \
> > + static const struct kunit_binary_assert_text __text = { \
> > + .operation = #op, \
> > + .left_text = #left, \
> > + .right_text = #right, \
> > + }; \
> > \
> > KUNIT_ASSERTION(test, \
> > assert_type, \
> > strcmp(__left, __right) op 0, \
> > kunit_binary_str_assert, \
> > KUNIT_INIT_BINARY_ASSERT_STRUCT(kunit_binary_str_assert_format,\
> > - #op, \
> > - #left, \
> > + &__text, \
> > __left, \
> > - #right, \
> > __right), \
> > fmt, \
> > ##__VA_ARGS__); \
> > diff --git a/lib/kunit/assert.c b/lib/kunit/assert.c
> > index c9c7ee0dfafa..d00d6d181ee8 100644
> > --- a/lib/kunit/assert.c
> > +++ b/lib/kunit/assert.c
> > @@ -122,18 +122,18 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
> >
> > string_stream_add(stream,
> > KUNIT_SUBTEST_INDENT "Expected %s %s %s, but\n",
> > - binary_assert->left_text,
> > - binary_assert->operation,
> > - binary_assert->right_text);
> > - if (!is_literal(stream->test, binary_assert->left_text,
> > + binary_assert->text->left_text,
> > + binary_assert->text->operation,
> > + binary_assert->text->right_text);
> > + if (!is_literal(stream->test, binary_assert->text->left_text,
> > binary_assert->left_value, stream->gfp))
> > string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld\n",
> > - binary_assert->left_text,
> > + binary_assert->text->left_text,
> > binary_assert->left_value);
> > - if (!is_literal(stream->test, binary_assert->right_text,
> > + if (!is_literal(stream->test, binary_assert->text->right_text,
> > binary_assert->right_value, stream->gfp))
> > string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld",
> > - binary_assert->right_text,
> > + binary_assert->text->right_text,
> > binary_assert->right_value);
> > kunit_assert_print_msg(message, stream);
> > }
> > @@ -150,14 +150,14 @@ void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
> >
> > string_stream_add(stream,
> > KUNIT_SUBTEST_INDENT "Expected %s %s %s, but\n",
> > - binary_assert->left_text,
> > - binary_assert->operation,
> > - binary_assert->right_text);
> > + binary_assert->text->left_text,
> > + binary_assert->text->operation,
> > + binary_assert->text->right_text);
> > string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %px\n",
> > - binary_assert->left_text,
> > + binary_assert->text->left_text,
> > binary_assert->left_value);
> > string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %px",
> > - binary_assert->right_text,
> > + binary_assert->text->right_text,
> > binary_assert->right_value);
> > kunit_assert_print_msg(message, stream);
> > }
> > @@ -190,16 +190,16 @@ void kunit_binary_str_assert_format(const struct kunit_assert *assert,
> >
> > string_stream_add(stream,
> > KUNIT_SUBTEST_INDENT "Expected %s %s %s, but\n",
> > - binary_assert->left_text,
> > - binary_assert->operation,
> > - binary_assert->right_text);
> > - if (!is_str_literal(binary_assert->left_text, binary_assert->left_value))
> > + binary_assert->text->left_text,
> > + binary_assert->text->operation,
> > + binary_assert->text->right_text);
> > + if (!is_str_literal(binary_assert->text->left_text, binary_assert->left_value))
> > string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == \"%s\"\n",
> > - binary_assert->left_text,
> > + binary_assert->text->left_text,
> > binary_assert->left_value);
> > - if (!is_str_literal(binary_assert->right_text, binary_assert->right_value))
> > + if (!is_str_literal(binary_assert->text->right_text, binary_assert->right_value))
> > string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == \"%s\"",
> > - binary_assert->right_text,
> > + binary_assert->text->right_text,
> > binary_assert->right_value);
> > kunit_assert_print_msg(message, stream);
> > }
> > --
> > 2.35.0.rc2.247.g8bbb082509-goog
> >
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