[Issue 859] Improve compiler inlining

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=859


bearophile_hugs at eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs at eml.cc


--- Comment #6 from bearophile_hugs at eml.cc 2010-07-08 05:10:27 PDT ---
An improved version of the test program, that allows to compare dmd and ldc on
this inlining problem:


version (Tango) {
    import tango.stdc.stdio: printf;
    import tango.stdc.stdlib: atof;
} else {
    import std.c.stdio: printf;
    import std.c.stdlib: atof;
}

struct Vec3 {
    float x, y, z;
}

float dot(Vec3 A, Vec3 B) {
    return A.x * B.x + A.y * B.y + A.z * B.z;
}

struct Timer {
    long starttime;

    static long getTime() {
        asm {
            naked;
            rdtsc;
            ret;
        }
    }

    void start() {
        starttime = getTime();
    }

    void stop() {
        long endTime = getTime();
        printf("time: %lld\n", endTime - starttime);
    }
}

void main() {
    int n = 30_000;
    Vec3 a = Vec3(atof("1.0"), atof("2.0"), atof("3.0"));
    Vec3 b = Vec3(atof("4.0"), atof("5.0"), atof("6.0"));
    Timer t;
    float sum;

    printf("    Auto inlined ");
    sum = 0.0;
    t.start();
    for (int i; i < n; i++) {
        a.x++;
        a.y++;
        a.z++;
        sum += dot(a, b);
    }
    t.stop();
    printf("sum: %f\n", sum);

    printf("Manually inlined ");
    sum = 0.0;
    t.start();;
    for (int i; i < n; i++) {
        a.x++;
        a.y++;
        a.z++;
        sum += a.x * b.x + a.y * b.y + a.z * b.z;
    }
    t.stop();
    printf("sum: %f\n", sum);
}

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