target/sh4: Fix mac.w with saturation enabled

The saturation arithmetic logic in helper_macw is not correct.
I tested and verified this behavior on a SH7091.

Reviewd-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Zack Buhman <zack@buhman.org>
Message-Id: <20240405233802.29128-3-zack@buhman.org>
[rth: Reformat helper_macw, add a test case.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
This commit is contained in:
Zack Buhman 2024-04-05 17:11:47 -10:00 committed by Richard Henderson
parent c97e8977dc
commit 7227c0cd50
4 changed files with 82 additions and 12 deletions

View file

@ -12,7 +12,7 @@ DEF_HELPER_1(discard_movcal_backup, void, env)
DEF_HELPER_2(ocbi, void, env, i32)
DEF_HELPER_3(macl, void, env, s32, s32)
DEF_HELPER_3(macw, void, env, i32, i32)
DEF_HELPER_3(macw, void, env, s32, s32)
DEF_HELPER_2(ld_fpscr, void, env, i32)

View file

@ -177,22 +177,28 @@ void helper_macl(CPUSH4State *env, int32_t arg0, int32_t arg1)
env->mac = res;
}
void helper_macw(CPUSH4State *env, uint32_t arg0, uint32_t arg1)
void helper_macw(CPUSH4State *env, int32_t arg0, int32_t arg1)
{
int64_t res;
/* Inputs are already sign-extended from 16 bits. */
int32_t mul = arg0 * arg1;
res = ((uint64_t) env->mach << 32) | env->macl;
res += (int64_t) (int16_t) arg0 *(int64_t) (int16_t) arg1;
env->mach = (res >> 32) & 0xffffffff;
env->macl = res & 0xffffffff;
if (env->sr & (1u << SR_S)) {
if (res < -0x80000000) {
/*
* In saturation arithmetic mode, the accumulator is 32-bit
* with carry. MACH is not considered during the addition
* operation nor the 32-bit saturation logic.
*/
int32_t res, macl = env->macl;
if (sadd32_overflow(macl, mul, &res)) {
res = macl < 0 ? INT32_MIN : INT32_MAX;
/* If overflow occurs, the MACH register is set to 1. */
env->mach = 1;
env->macl = 0x80000000;
} else if (res > 0x000000007fffffff) {
env->mach = 1;
env->macl = 0x7fffffff;
}
env->macl = res;
} else {
/* In non-saturation arithmetic mode, the accumulator is 64-bit */
env->mac += mul;
}
}

View file

@ -14,3 +14,6 @@ VPATH += $(SRC_PATH)/tests/tcg/sh4
test-macl: CFLAGS += -O -g
TESTS += test-macl
test-macw: CFLAGS += -O -g
TESTS += test-macw

61
tests/tcg/sh4/test-macw.c Normal file
View file

@ -0,0 +1,61 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
int64_t mac_w(int64_t mac, const int16_t *a, const int16_t *b)
{
register uint32_t macl __asm__("macl") = mac;
register uint32_t mach __asm__("mach") = mac >> 32;
asm volatile("mac.w @%0+,@%1+"
: "+r"(a), "+r"(b), "+x"(macl), "+x"(mach));
return ((uint64_t)mach << 32) | macl;
}
typedef struct {
int64_t mac;
int16_t a, b;
int64_t res[2];
} Test;
__attribute__((noinline))
void test(const Test *t, int sat)
{
int64_t res;
if (sat) {
asm volatile("sets");
} else {
asm volatile("clrs");
}
res = mac_w(t->mac, &t->a, &t->b);
if (res != t->res[sat]) {
fprintf(stderr, "%#llx + (%#x * %#x) = %#llx -- got %#llx\n",
t->mac, t->a, t->b, t->res[sat], res);
abort();
}
}
int main()
{
static const Test tests[] = {
{ 0, 2, 3, { 6, 6 } },
{ 0x123456787ffffffell, 2, -3,
{ 0x123456787ffffff8ll, 0x123456787ffffff8ll } },
{ 0xabcdef127ffffffall, 2, 3,
{ 0xabcdef1280000000ll, 0x000000017fffffffll } },
{ 0xfffffffffll, INT16_MAX, INT16_MAX,
{ 0x103fff0000ll, 0xf3fff0000ll } },
};
for (int i = 0; i < sizeof(tests) / sizeof(tests[0]); ++i) {
for (int j = 0; j < 2; ++j) {
test(&tests[i], j);
}
}
return 0;
}