On Wed, 01 May 2024 01:31:23 +0900,
Philippe Mathieu-Daudé wrote:
>
> The documentation says:
>
> SUBV Rm, Rn Rn - Rm -> Rn, underflow -> T
>
> The overflow / underflow can be calculated as:
>
> T = ((Rn ^ Rm) & (Result ^ Rn)) >> 31
>
> However we were using the incorrect:
>
> T = ((Rn ^ Rm) & (Result ^ Rm)) >> 31
>
> Fix by using the Rn register instead of Rm.
>
> Add tests provided by Paul Cercueil.
>
> Cc: qemu-sta...@nongnu.org
> Fixes: ad8d25a11f ("target-sh4: implement addv and subv using TCG")
> Reported-by: Paul Cercueil <p...@crapouillou.net>
> Suggested-by: Paul Cercueil <p...@crapouillou.net>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2318
> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
> ---
> target/sh4/translate.c | 2 +-
> tests/tcg/sh4/test-subv.c | 30 ++++++++++++++++++++++++++++++
> tests/tcg/sh4/Makefile.target | 3 +++
> 3 files changed, 34 insertions(+), 1 deletion(-)
> create mode 100644 tests/tcg/sh4/test-subv.c
>
> diff --git a/target/sh4/translate.c b/target/sh4/translate.c
> index 4a1dd0d1f4..3e013b7c7c 100644
> --- a/target/sh4/translate.c
> +++ b/target/sh4/translate.c
> @@ -933,7 +933,7 @@ static void _decode_opc(DisasContext * ctx)
> t0 = tcg_temp_new();
> tcg_gen_sub_i32(t0, REG(B11_8), REG(B7_4));
> t1 = tcg_temp_new();
> - tcg_gen_xor_i32(t1, t0, REG(B7_4));
> + tcg_gen_xor_i32(t1, t0, REG(B11_8));
> t2 = tcg_temp_new();
> tcg_gen_xor_i32(t2, REG(B11_8), REG(B7_4));
> tcg_gen_and_i32(t1, t1, t2);
> diff --git a/tests/tcg/sh4/test-subv.c b/tests/tcg/sh4/test-subv.c
> new file mode 100644
> index 0000000000..0dd8fcdaac
> --- /dev/null
> +++ b/tests/tcg/sh4/test-subv.c
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +
> +#include <limits.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +static void subv(const int a, const int b, const int res, const int carry)
> +{
> + int o = a, c;
> +
> + asm volatile("subv %2,%0\n"
> + "movt %1\n"
> + : "+r"(o), "=r"(c) : "r"(b) :);
> +
> + if (c != carry || o != res) {
> + printf("SUBV %d, %d = %d/%d [T = %d/%d]\n", a, b, o, res, c, carry);
> + abort();
> + }
> +}
> +
> +int main(void)
> +{
> + subv(INT_MIN, 1, INT_MAX, 1);
> + subv(INT_MAX, -1, INT_MIN, 1);
> + subv(INT_MAX, 1, INT_MAX - 1, 0);
> + subv(0, 1, -1, 0);
> + subv(-1, -1, 0, 0);
> +
> + return 0;
> +}
> diff --git a/tests/tcg/sh4/Makefile.target b/tests/tcg/sh4/Makefile.target
> index 521b8b0a76..7852fa62d8 100644
> --- a/tests/tcg/sh4/Makefile.target
> +++ b/tests/tcg/sh4/Makefile.target
> @@ -20,3 +20,6 @@ TESTS += test-macw
>
> test-addv: CFLAGS += -O -g
> TESTS += test-addv
> +
> +test-subv: CFLAGS += -O -g
> +TESTS += test-subv
> --
> 2.41.0
>
Reviewed-by: Yoshinori Sato <ys...@users.sourceforge.jp>
--
Yosinori Sato
