[RV64_DYNAREC] Fix the issue where source register values get overwritten.

[zengdage]

In the implementations of addsd/subsd/mulsd/divsd when BOX64_DYNAREC_FASTNAN is enabled, the source register values are being overwritten. This violates the x86-64 instruction specification, which prohibits modification of source registers. The resulting loss of source register data triggers subsequent runtime errors.

I referenced the LA64 and ARM64 implementations and used temporary floating-point registers to store intermediate values.

SNAN-to-QNAN conversion handling may also need to be added here. I will address this in a separate follow-up patch.

[zengdage]

Tests as follow:

cimpile command: gcc -msse2 -O2 -o test test.c

#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>
#include <string.h>

typedef union {
    uint64_t u64[2];
    double   d64[2];
    __attribute__((aligned(16))) char align[16];
} xmm128_t;

static void print_xmm(const char* name, const xmm128_t* v) {
    printf("%s = [hi:0x%016"PRIx64", lo:0x%016"PRIx64"]\n", name, v->u64[1], v->u64[0]);
}

void test_mulsd(int *pass)
{
    printf("\n=== Test 1: MULSD xmm0, xmm1 ===\n");

    xmm128_t dst = {{ 0x4000000000000000ULL,
                      0x1234567890ABCDEFULL }};
    xmm128_t src = {{ 0x4008000000000000ULL,
                      0xDEADBEEFCAFEBABEULL }};
    xmm128_t dst_out, src_out;

    print_xmm("dst before", &dst);
    print_xmm("src before", &src);

    __asm__ __volatile__ (
        "movaps %[dst], %%xmm0\n\t"
        "movaps %[src], %%xmm1\n\t"
        "mulsd  %%xmm1, %%xmm0\n\t"
        "movaps %%xmm0, %[dst_out]\n\t"
        "movaps %%xmm1, %[src_out]\n\t"
        : [dst_out] "=m" (dst_out), [src_out] "=m" (src_out)
        : [dst] "m" (dst), [src] "m" (src)
        : "xmm0", "xmm1"
    );

    print_xmm("dst after ", &dst_out);
    print_xmm("src after ", &src_out);

    if (src_out.u64[0] != 0x4008000000000000ULL) {
        printf("FAIL: src lo = 0x%016"PRIx64", expected 0x4008000000000000 (3.0)\n", src_out.u64[0]);
        *pass = 0;
    }
    if (src_out.u64[1] != 0xDEADBEEFCAFEBABEULL) {
        printf("FAIL: src hi = 0x%016"PRIx64", expected 0xDEADBEEFCAFEBABE\n", src_out.u64[1]);
        *pass = 0;
    }
}


void test_addsd(int *pass)
{
    printf("\n=== Test 1: ADDSD xmm0, xmm1 ===\n");

    xmm128_t dst = {{ 0x4000000000000000ULL,
                      0x1234567890ABCDEFULL }};
    xmm128_t src = {{ 0x4008000000000000ULL,
                      0xDEADBEEFCAFEBABEULL }};
    xmm128_t dst_out, src_out;

    print_xmm("dst before", &dst);
    print_xmm("src before", &src);

    __asm__ __volatile__ (
        "movaps %[dst], %%xmm0\n\t"
        "movaps %[src], %%xmm1\n\t"
        "addsd  %%xmm1, %%xmm0\n\t"
        "movaps %%xmm0, %[dst_out]\n\t"
        "movaps %%xmm1, %[src_out]\n\t"
        : [dst_out] "=m" (dst_out), [src_out] "=m" (src_out)
        : [dst] "m" (dst), [src] "m" (src)
        : "xmm0", "xmm1"
    );

    print_xmm("dst after ", &dst_out);
    print_xmm("src after ", &src_out);

    if (src_out.u64[0] != 0x4008000000000000ULL) {
        printf("FAIL: src lo = 0x%016"PRIx64", expected 0x4008000000000000 (3.0)\n", src_out.u64[0]);
        *pass = 0;
    }
    if (src_out.u64[1] != 0xDEADBEEFCAFEBABEULL) {
        printf("FAIL: src hi = 0x%016"PRIx64", expected 0xDEADBEEFCAFEBABE\n", src_out.u64[1]);
        *pass = 0;
    }
}

void test_subsd(int *pass)
{
    printf("\n=== Test 1: SUBSD xmm0, xmm1 ===\n");

    xmm128_t dst = {{ 0x4000000000000000ULL,
                      0x1234567890ABCDEFULL }};
    xmm128_t src = {{ 0x4008000000000000ULL,
                      0xDEADBEEFCAFEBABEULL }};
    xmm128_t dst_out, src_out;

    print_xmm("dst before", &dst);
    print_xmm("src before", &src);

    __asm__ __volatile__ (
        "movaps %[dst], %%xmm0\n\t"
        "movaps %[src], %%xmm1\n\t"
        "subsd  %%xmm1, %%xmm0\n\t"
        "movaps %%xmm0, %[dst_out]\n\t"
        "movaps %%xmm1, %[src_out]\n\t"
        : [dst_out] "=m" (dst_out), [src_out] "=m" (src_out)
        : [dst] "m" (dst), [src] "m" (src)
        : "xmm0", "xmm1"
    );

    print_xmm("dst after ", &dst_out);
    print_xmm("src after ", &src_out);

    if (src_out.u64[0] != 0x4008000000000000ULL) {
        printf("FAIL: src lo = 0x%016"PRIx64", expected 0x4008000000000000 (3.0)\n", src_out.u64[0]);
        *pass = 0;
    }
    if (src_out.u64[1] != 0xDEADBEEFCAFEBABEULL) {
        printf("FAIL: src hi = 0x%016"PRIx64", expected 0xDEADBEEFCAFEBABE\n", src_out.u64[1]);
        *pass = 0;
    }
}

void test_divsd(int *pass)
{
    printf("\n=== Test 1: DIVSD xmm0, xmm1 ===\n");

    xmm128_t dst = {{ 0x4000000000000000ULL,
                      0x1234567890ABCDEFULL }};
    xmm128_t src = {{ 0x4008000000000000ULL,
                      0xDEADBEEFCAFEBABEULL }};
    xmm128_t dst_out, src_out;

    print_xmm("dst before", &dst);
    print_xmm("src before", &src);

    __asm__ __volatile__ (
        "movaps %[dst], %%xmm0\n\t"
        "movaps %[src], %%xmm1\n\t"
        "divsd  %%xmm1, %%xmm0\n\t"
        "movaps %%xmm0, %[dst_out]\n\t"
        "movaps %%xmm1, %[src_out]\n\t"
        : [dst_out] "=m" (dst_out), [src_out] "=m" (src_out)
        : [dst] "m" (dst), [src] "m" (src)
        : "xmm0", "xmm1"
    );

    print_xmm("dst after ", &dst_out);
    print_xmm("src after ", &src_out);

    if (src_out.u64[0] != 0x4008000000000000ULL) {
        printf("FAIL: src lo = 0x%016"PRIx64", expected 0x4008000000000000 (3.0)\n", src_out.u64[0]);
        *pass = 0;
    }
    if (src_out.u64[1] != 0xDEADBEEFCAFEBABEULL) {
        printf("FAIL: src hi = 0x%016"PRIx64", expected 0xDEADBEEFCAFEBABE\n", src_out.u64[1]);
        *pass = 0;
    }
}

int main() {
    int pass = 1;

    test_addsd(&pass);
    test_subsd(&pass);
    test_mulsd(&pass);
    test_divsd(&pass);

    printf("\n%s\n", pass ? "ALL PASSED" : "SOME TESTS FAILED");
    return pass ? 0 : 1;
}

[ksco]

LGTM