From e88a856efd1d3c3ffa8e53da4831eff8da290808 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Tue, 30 Apr 2024 13:10:19 +0200 Subject: [PATCH] target/sh4: Fix SUBV opcode MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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-stable@nongnu.org Fixes: ad8d25a11f ("target-sh4: implement addv and subv using TCG") Reported-by: Paul Cercueil Suggested-by: Paul Cercueil Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2318 Reviewed-by: Richard Henderson Signed-off-by: Philippe Mathieu-Daudé Reviewed-by: Yoshinori Sato Message-Id: <20240430163125.77430-3-philmd@linaro.org> --- target/sh4/translate.c | 2 +- tests/tcg/sh4/Makefile.target | 3 +++ tests/tcg/sh4/test-subv.c | 30 ++++++++++++++++++++++++++++++ 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/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 diff --git a/tests/tcg/sh4/test-subv.c b/tests/tcg/sh4/test-subv.c new file mode 100644 index 0000000000..a3c2db96e4 --- /dev/null +++ b/tests/tcg/sh4/test-subv.c @@ -0,0 +1,30 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include +#include +#include + +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; +}