Re: [PATCH dwarves 9/9] tests: Add a few clang true signature tests

On 05/03/2026 22:55, Yonghong Song wrote:
> Three tests are added.
> 
> Test 1: clang_parm_optimized.sh
>   BTF:   char * foo(struct t * a, struct t * d);
>   DWARF: char * foo(struct t * a, int b, struct t * d);
> where parameber 'b' is unused.
> 
> Test 2: clang_parm_optimized_stack.sh
>   BTF:   char * foo(struct t * a, struct t * d);
>   DWARF: char * foo(struct t * a, int b1, int b2, int b3, int b4, int b5, int b6, struct t * d);
> where parameters 'b1' to 'b6' are unused.
> 
> Test 3: clang_parm_aggregate.sh
>   BTF:   long foo(long a__f1, struct t b, int i);
>   DWARF: long foo(struct t a, struct t b, int i);
> where the 'struct t' definition is 'struct t { long f1; long f2; };', and
> a.f2 is not used in the function.
> 
> Signed-off-by: Yonghong Song <[email protected]>

tests look good but we need to ensure they are run by the ./tests script
so that they will be run in CI. also take a look at Bruce's work to
add common test functions [1], will probably simplify aspects of the tests.

Thanks!

Alan

[1] https://lore.kernel.org/dwarves/[email protected]/

> ---
>  tests/true_signatures/clang_parm_aggregate.sh | 83 ++++++++++++++++
>  tests/true_signatures/clang_parm_optimized.sh | 95 +++++++++++++++++++
>  .../clang_parm_optimized_stack.sh             | 95 +++++++++++++++++++
>  .../gcc_true_signatures.sh                    |  0
>  4 files changed, 273 insertions(+)
>  create mode 100755 tests/true_signatures/clang_parm_aggregate.sh
>  create mode 100755 tests/true_signatures/clang_parm_optimized.sh
>  create mode 100755 tests/true_signatures/clang_parm_optimized_stack.sh
>  rename tests/{ => true_signatures}/gcc_true_signatures.sh (100%)
> 
> diff --git a/tests/true_signatures/clang_parm_aggregate.sh b/tests/true_signatures/clang_parm_aggregate.sh
> new file mode 100755
> index 0000000..6d92701
> --- /dev/null
> +++ b/tests/true_signatures/clang_parm_aggregate.sh
> @@ -0,0 +1,83 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +outdir=
> +
> +fail()
> +{
> +	# Do not remove test dir; might be useful for analysis
> +	trap - EXIT
> +	if [[ -d "$outdir" ]]; then
> +		echo "Test data is in $outdir"
> +	fi
> +	exit 1
> +}
> +
> +cleanup()
> +{
> +	rm ${outdir}/*
> +	rmdir $outdir
> +}
> +
> +outdir=$(mktemp -d /tmp/clang_true.sh.XXXXXX)
> +
> +trap cleanup EXIT
> +
> +echo -n "Validation of BTF encoding of true_signatures: "
> +
> +clang_true="${outdir}/clang_true"
> +CC=$(which clang 2>/dev/null)
> +
> +if [[ -z "$CC" ]]; then
> +	echo "skip: clang not available"
> +	exit 2
> +fi
> +
> +cat > ${clang_true}.c << EOF
> +struct t { long f1; long f2; };
> +__attribute__((noinline)) static long foo(struct t a, struct t b, int i)
> +{
> +        return a.f1 + b.f1 + b.f2 + i;
> +}
> +
> +struct t p1, p2;
> +int i;
> +int main()
> +{
> +        return (int)foo(p1, p2, i);
> +}
> +EOF
> +
> +CFLAGS="$CFLAGS -g -O2"
> +${CC} ${CFLAGS} -o $clang_true ${clang_true}.c
> +if [[ $? -ne 0 ]]; then
> +	echo "Could not compile ${clang_true}.c" >& 2
> +	exit 1
> +fi
> +LLVM_OBJCOPY=objcopy pahole -J --btf_features=+true_signature $clang_true
> +if [[ $? -ne 0 ]]; then
> +	echo "Could not encode BTF for $clang_true"
> +	exit 1
> +fi
> +
> +btf_optimized=$(pfunct --all --format_path=btf $clang_true |grep "foo")
> +if [[ -z "$btf_optimized" ]]; then
> +	echo "skip: no optimizations applied."
> +	exit 2
> +fi
> +
> +btf_cmp=$btf_optimized
> +dwarf=$(pfunct --all $clang_true |grep "foo")
> +
> +test -n "$VERBOSE" && printf "\nBTF: $btf_optimized  DWARF: $dwarf \n"
> +
> +if [[ "$btf_cmp" == "$dwarf" ]]; then
> +	echo "BTF and DWARF signatures should be different and they are not: BTF: $btf_optimized ; DWARF $dwarf"
> +	exit 1
> +else
> +        echo ""
> +        echo "  BTF:   $btf_optimized"
> +        echo "  DWARF: $dwarf"
> +fi
> +echo "Ok"
> +exit 0
> diff --git a/tests/true_signatures/clang_parm_optimized.sh b/tests/true_signatures/clang_parm_optimized.sh
> new file mode 100755
> index 0000000..3022e2b
> --- /dev/null
> +++ b/tests/true_signatures/clang_parm_optimized.sh
> @@ -0,0 +1,95 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +outdir=
> +
> +fail()
> +{
> +	# Do not remove test dir; might be useful for analysis
> +	trap - EXIT
> +	if [[ -d "$outdir" ]]; then
> +		echo "Test data is in $outdir"
> +	fi
> +	exit 1
> +}
> +
> +cleanup()
> +{
> +	rm ${outdir}/*
> +	rmdir $outdir
> +}
> +
> +outdir=$(mktemp -d /tmp/clang_true.sh.XXXXXX)
> +
> +trap cleanup EXIT
> +
> +echo -n "Validation of BTF encoding of true_signatures: "
> +
> +clang_true="${outdir}/clang_true"
> +CC=$(which clang 2>/dev/null)
> +
> +if [[ -z "$CC" ]]; then
> +	echo "skip: clang not available"
> +	exit 2
> +fi
> +
> +cat > ${clang_true}.c << EOF
> +struct t { int a; };
> +__attribute__((noinline)) char *tar(struct t *a, struct t *d)
> +{
> +	if (a->a == d->a)
> +		return (char *)10;
> +	else
> +		return (char *)0;
> +}
> +
> +__attribute__((noinline)) static char * foo(struct t *a, int b, struct t *d)
> +{
> +	return tar(a, d);
> +}
> +
> +__attribute__((noinline)) char *bar(struct t *a, struct t *d)
> +{
> +	return foo(a, 1, d);
> +}
> +
> +struct t p1, p2;
> +int main()
> +{
> +	return !!bar(&p1, &p2);
> +}
> +EOF
> +
> +CFLAGS="$CFLAGS -g -O2"
> +${CC} ${CFLAGS} -o $clang_true ${clang_true}.c
> +if [[ $? -ne 0 ]]; then
> +	echo "Could not compile ${clang_true}.c" >& 2
> +	exit 1
> +fi
> +LLVM_OBJCOPY=objcopy pahole -J --btf_features=+true_signature $clang_true
> +if [[ $? -ne 0 ]]; then
> +	echo "Could not encode BTF for $clang_true"
> +	exit 1
> +fi
> +
> +btf_optimized=$(pfunct --all --format_path=btf $clang_true |grep "foo")
> +if [[ -z "$btf_optimized" ]]; then
> +	echo "skip: no optimizations applied."
> +	exit 2
> +fi
> +
> +btf_cmp=$btf_optimized
> +dwarf=$(pfunct --all $clang_true |grep "foo")
> +
> +test -n "$VERBOSE" && printf "\nBTF: $btf_optimized  DWARF: $dwarf \n"
> +
> +if [[ "$btf_cmp" == "$dwarf" ]]; then
> +	echo "BTF and DWARF signatures should be different and they are not: BTF: $btf_optimized ; DWARF $dwarf"
> +	exit 1
> +else
> +        echo ""
> +        echo "  BTF:   $btf_optimized"
> +        echo "  DWARF: $dwarf"
> +fi
> +echo "Ok"
> +exit 0
> diff --git a/tests/true_signatures/clang_parm_optimized_stack.sh b/tests/true_signatures/clang_parm_optimized_stack.sh
> new file mode 100755
> index 0000000..1abb96d
> --- /dev/null
> +++ b/tests/true_signatures/clang_parm_optimized_stack.sh
> @@ -0,0 +1,95 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +outdir=
> +
> +fail()
> +{
> +	# Do not remove test dir; might be useful for analysis
> +	trap - EXIT
> +	if [[ -d "$outdir" ]]; then
> +		echo "Test data is in $outdir"
> +	fi
> +	exit 1
> +}
> +
> +cleanup()
> +{
> +	rm ${outdir}/*
> +	rmdir $outdir
> +}
> +
> +outdir=$(mktemp -d /tmp/clang_true.sh.XXXXXX)
> +
> +trap cleanup EXIT
> +
> +echo -n "Validation of BTF encoding of true_signatures: "
> +
> +clang_true="${outdir}/clang_true"
> +CC=$(which clang 2>/dev/null)
> +
> +if [[ -z "$CC" ]]; then
> +	echo "skip: clang not available"
> +	exit 2
> +fi
> +
> +cat > ${clang_true}.c << EOF
> +struct t { int a; };
> +__attribute__((noinline)) char *tar(struct t *a, struct t *d)
> +{
> +        if (a->a == d->a)
> +                return (char *)10;
> +        else
> +                return (char *)0;
> +}
> +
> +__attribute__((noinline)) static char * foo(struct t *a, int b1, int b2, int b3, int b4, int b5, int b6, struct t *d)
> +{
> +        return tar(a, d);
> +}
> +
> +__attribute__((noinline)) char *bar(struct t *a, struct t *d)
> +{
> +        return foo(a, 1, 2, 3, 4, 5, 6, d);
> +}
> +
> +struct t p1, p2;
> +int main()
> +{
> +        return !!bar(&p1, &p2);
> +}
> +EOF
> +
> +CFLAGS="$CFLAGS -g -O2"
> +${CC} ${CFLAGS} -o $clang_true ${clang_true}.c
> +if [[ $? -ne 0 ]]; then
> +	echo "Could not compile ${clang_true}.c" >& 2
> +	exit 1
> +fi
> +LLVM_OBJCOPY=objcopy pahole -J --btf_features=+true_signature $clang_true
> +if [[ $? -ne 0 ]]; then
> +	echo "Could not encode BTF for $clang_true"
> +	exit 1
> +fi
> +
> +btf_optimized=$(pfunct --all --format_path=btf $clang_true |grep "foo")
> +if [[ -z "$btf_optimized" ]]; then
> +	echo "skip: no optimizations applied."
> +	exit 2
> +fi
> +
> +btf_cmp=$btf_optimized
> +dwarf=$(pfunct --all $clang_true |grep "foo")
> +
> +test -n "$VERBOSE" && printf "\nBTF: $btf_optimized  DWARF: $dwarf \n"
> +
> +if [[ "$btf_cmp" == "$dwarf" ]]; then
> +	echo "BTF and DWARF signatures should be different and they are not: BTF: $btf_optimized ; DWARF $dwarf"
> +	exit 1
> +else
> +        echo ""
> +        echo "  BTF:   $btf_optimized"
> +        echo "  DWARF: $dwarf"
> +fi
> +echo "Ok"
> +exit 0
> diff --git a/tests/gcc_true_signatures.sh b/tests/true_signatures/gcc_true_signatures.sh
> similarity index 100%
> rename from tests/gcc_true_signatures.sh
> rename to tests/true_signatures/gcc_true_signatures.sh