Checkasm: assembly testing and benchmarking tool

It provides the following features:
 * verify correctness by comparing output to the C version.
 * detect failure to save and restore clobbered callee-saved registers.
 * detect 32-bit parameters being used as if they were 64-bit in x86-64
   (the upper halves are not guaranteed to be zero - but in practice
   they very often are, which makes those bugs hard to spot otherwise).
 * easy benchmarking.

Compile by running 'make checkasm'.
Execute by running 'tests/checkasm/checkasm'.

Optional arguments are '--bench' to run benchmarks for all functions,
'--bench=<pattern>' to run benchmarks for all functions that starts with
<pattern>, and '<integer>' to seed the PRNG for reproducible results.

Contains unit tests for most h264pred functions to get started, more tests
can be added afterwards using those as a reference.

Loosely based on code from x264. Currently only supports x86 and x86-64,
but additional architectures shouldn't be too much of an obstacle to add.

Note that functions with floating point parameters or floating point
return values are not supported. Some compiler-specific features or
preprocessor hacks would likely be required to add support for that.

Signed-off-by: Janne Grunau <janne-libav@jannau.net>

1 files changed, 484 insertions, 0 deletions

diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
new file mode 100644
index 0000000000..59383b8931
--- /dev/null
+++ b/tests/checkasm/checkasm.c
@@ -0,0 +1,484 @@
+/*
+ * Assembly testing and benchmarking tool
+ * Copyright (c) 2015 Henrik Gramner
+ * Copyright (c) 2008 Loren Merritt
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with Libav; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "checkasm.h"
+#include "libavutil/common.h"
+#include "libavutil/cpu.h"
+#include "libavutil/random_seed.h"
+
+#if ARCH_X86
+#include "libavutil/x86/cpu.h"
+#endif
+
+#if HAVE_SETCONSOLETEXTATTRIBUTE
+#include <windows.h>
+#define COLOR_RED    FOREGROUND_RED
+#define COLOR_GREEN  FOREGROUND_GREEN
+#define COLOR_YELLOW (FOREGROUND_RED|FOREGROUND_GREEN)
+#else
+#define COLOR_RED    1
+#define COLOR_GREEN  2
+#define COLOR_YELLOW 3
+#endif
+
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#if !HAVE_ISATTY
+#define isatty(fd) 1
+#endif
+
+/* List of tests to invoke */
+static void (* const tests[])(void) = {
+#if CONFIG_H264PRED
+    checkasm_check_h264pred,
+#endif
+    NULL
+};
+
+/* List of cpu flags to check */
+static const struct {
+    const char *name;
+    const char *suffix;
+    int flag;
+} cpus[] = {
+#if ARCH_X86
+    { "MMX",      "mmx",      AV_CPU_FLAG_MMX|AV_CPU_FLAG_CMOV },
+    { "MMXEXT",   "mmxext",   AV_CPU_FLAG_MMXEXT },
+    { "3DNOW",    "3dnow",    AV_CPU_FLAG_3DNOW },
+    { "3DNOWEXT", "3dnowext", AV_CPU_FLAG_3DNOWEXT },
+    { "SSE",      "sse",      AV_CPU_FLAG_SSE },
+    { "SSE2",     "sse2",     AV_CPU_FLAG_SSE2|AV_CPU_FLAG_SSE2SLOW },
+    { "SSE3",     "sse3",     AV_CPU_FLAG_SSE3|AV_CPU_FLAG_SSE3SLOW },
+    { "SSSE3",    "ssse3",    AV_CPU_FLAG_SSSE3|AV_CPU_FLAG_ATOM },
+    { "SSE4.1",   "sse4",     AV_CPU_FLAG_SSE4 },
+    { "SSE4.2",   "sse42",    AV_CPU_FLAG_SSE42 },
+    { "AVX",      "avx",      AV_CPU_FLAG_AVX },
+    { "XOP",      "xop",      AV_CPU_FLAG_XOP },
+    { "FMA3",     "fma3",     AV_CPU_FLAG_FMA3 },
+    { "FMA4",     "fma4",     AV_CPU_FLAG_FMA4 },
+    { "AVX2",     "avx2",     AV_CPU_FLAG_AVX2 },
+#endif
+    { NULL }
+};
+
+typedef struct CheckasmFuncVersion {
+    struct CheckasmFuncVersion *next;
+    intptr_t (*func)();
+    int ok;
+    int cpu;
+    int iterations;
+    uint64_t cycles;
+} CheckasmFuncVersion;
+
+/* Binary search tree node */
+typedef struct CheckasmFunc {
+    struct CheckasmFunc *child[2];
+    CheckasmFuncVersion versions;
+    char name[1];
+} CheckasmFunc;
+
+/* Internal state */
+static struct {
+    CheckasmFunc *funcs;
+    CheckasmFunc *current_func;
+    CheckasmFuncVersion *current_func_ver;
+    const char *bench_pattern;
+    int bench_pattern_len;
+    int num_checked;
+    int num_failed;
+    int nop_time;
+    int cpu_flag;
+    const char *cpu_flag_name;
+} state;
+
+/* PRNG state */
+AVLFG checkasm_lfg;
+
+/* Print colored text to stderr if the terminal supports it */
+static void color_printf(int color, const char *fmt, ...)
+{
+    static int use_color = -1;
+    va_list arg;
+
+#if HAVE_SETCONSOLETEXTATTRIBUTE
+    static HANDLE con;
+    static WORD org_attributes;
+
+    if (use_color < 0) {
+        CONSOLE_SCREEN_BUFFER_INFO con_info;
+        con = GetStdHandle(STD_ERROR_HANDLE);
+        if (con && con != INVALID_HANDLE_VALUE && GetConsoleScreenBufferInfo(con, &con_info)) {
+            org_attributes = con_info.wAttributes;
+            use_color = 1;
+        } else
+            use_color = 0;
+    }
+    if (use_color)
+        SetConsoleTextAttribute(con, (org_attributes & 0xfff0) | (color & 0x0f));
+#else
+    if (use_color < 0) {
+        const char *term = getenv("TERM");
+        use_color = term && strcmp(term, "dumb") && isatty(2);
+    }
+    if (use_color)
+        fprintf(stderr, "\x1b[%d;3%dm", (color & 0x08) >> 3, color & 0x07);
+#endif
+
+    va_start(arg, fmt);
+    vfprintf(stderr, fmt, arg);
+    va_end(arg);
+
+    if (use_color) {
+#if HAVE_SETCONSOLETEXTATTRIBUTE
+        SetConsoleTextAttribute(con, org_attributes);
+#else
+        fprintf(stderr, "\x1b[0m");
+#endif
+    }
+}
+
+/* Deallocate a tree */
+static void destroy_func_tree(CheckasmFunc *f)
+{
+    if (f) {
+        CheckasmFuncVersion *v = f->versions.next;
+        while (v) {
+            CheckasmFuncVersion *next = v->next;
+            free(v);
+            v = next;
+        }
+
+        destroy_func_tree(f->child[0]);
+        destroy_func_tree(f->child[1]);
+        free(f);
+    }
+}
+
+/* Allocate a zero-initialized block, clean up and exit on failure */
+static void *checkasm_malloc(size_t size)
+{
+    void *ptr = calloc(1, size);
+    if (!ptr) {
+        fprintf(stderr, "checkasm: malloc failed\n");
+        destroy_func_tree(state.funcs);
+        exit(1);
+    }
+    return ptr;
+}
+
+/* Get the suffix of the specified cpu flag */
+static const char *cpu_suffix(int cpu)
+{
+    int i = FF_ARRAY_ELEMS(cpus);
+
+    while (--i >= 0)
+        if (cpu & cpus[i].flag)
+            return cpus[i].suffix;
+
+    return "c";
+}
+
+#ifdef AV_READ_TIME
+static int cmp_nop(const void *a, const void *b)
+{
+    return *(const uint16_t*)a - *(const uint16_t*)b;
+}
+
+/* Measure the overhead of the timing code (in decicycles) */
+static int measure_nop_time(void)
+{
+    uint16_t nops[10000];
+    int i, nop_sum = 0;
+
+    for (i = 0; i < 10000; i++) {
+        uint64_t t = AV_READ_TIME();
+        nops[i] = AV_READ_TIME() - t;
+    }
+
+    qsort(nops, 10000, sizeof(uint16_t), cmp_nop);
+    for (i = 2500; i < 7500; i++)
+        nop_sum += nops[i];
+
+    return nop_sum / 500;
+}
+
+/* Print benchmark results */
+static void print_benchs(CheckasmFunc *f)
+{
+    if (f) {
+        print_benchs(f->child[0]);
+
+        /* Only print functions with at least one assembly version */
+        if (f->versions.cpu || f->versions.next) {
+            CheckasmFuncVersion *v = &f->versions;
+            do {
+                if (v->iterations) {
+                    int decicycles = (10*v->cycles/v->iterations - state.nop_time) / 4;
+                    printf("%s_%s: %d.%d\n", f->name, cpu_suffix(v->cpu), decicycles/10, decicycles%10);
+                }
+            } while ((v = v->next));
+        }
+
+        print_benchs(f->child[1]);
+    }
+}
+#endif
+
+/* ASCIIbetical sort except preserving natural order for numbers */
+static int cmp_func_names(const char *a, const char *b)
+{
+    int ascii_diff, digit_diff;
+
+    for (; !(ascii_diff = *a - *b) && *a; a++, b++);
+    for (; av_isdigit(*a) && av_isdigit(*b); a++, b++);
+
+    return (digit_diff = av_isdigit(*a) - av_isdigit(*b)) ? digit_diff : ascii_diff;
+}
+
+/* Get a node with the specified name, creating it if it doesn't exist */
+static CheckasmFunc *get_func(const char *name, int length)
+{
+    CheckasmFunc *f, **f_ptr = &state.funcs;
+
+    /* Search the tree for a matching node */
+    while ((f = *f_ptr)) {
+        int cmp = cmp_func_names(name, f->name);
+        if (!cmp)
+            return f;
+
+        f_ptr = &f->child[(cmp > 0)];
+    }
+
+    /* Allocate and insert a new node into the tree */
+    f = *f_ptr = checkasm_malloc(sizeof(CheckasmFunc) + length);
+    memcpy(f->name, name, length+1);
+
+    return f;
+}
+
+/* Perform tests and benchmarks for the specified cpu flag if supported by the host */
+static void check_cpu_flag(const char *name, int flag)
+{
+    int old_cpu_flag = state.cpu_flag;
+
+    flag |= old_cpu_flag;
+    av_set_cpu_flags_mask(flag);
+    state.cpu_flag = av_get_cpu_flags();
+
+    if (!flag || state.cpu_flag != old_cpu_flag) {
+        int i;
+
+        state.cpu_flag_name = name;
+        for (i = 0; tests[i]; i++)
+            tests[i]();
+    }
+}
+
+/* Print the name of the current CPU flag, but only do it once */
+static void print_cpu_name(void)
+{
+    if (state.cpu_flag_name) {
+        color_printf(COLOR_YELLOW, "%s:\n", state.cpu_flag_name);
+        state.cpu_flag_name = NULL;
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    int i, seed, ret = 0;
+
+    if (!tests[0] || !cpus[0].flag) {
+        fprintf(stderr, "checkasm: no tests to perform\n");
+        return 1;
+    }
+
+    if (argc > 1 && !strncmp(argv[1], "--bench", 7)) {
+#ifndef AV_READ_TIME
+        fprintf(stderr, "checkasm: --bench is not supported on your system\n");
+        return 1;
+#endif
+        if (argv[1][7] == '=') {
+            state.bench_pattern = argv[1] + 8;
+            state.bench_pattern_len = strlen(state.bench_pattern);
+        } else
+            state.bench_pattern = "";
+
+        argc--;
+        argv++;
+    }
+
+    seed = (argc > 1) ? atoi(argv[1]) : av_get_random_seed();
+    fprintf(stderr, "checkasm: using random seed %u\n", seed);
+    av_lfg_init(&checkasm_lfg, seed);
+
+    check_cpu_flag(NULL, 0);
+    for (i = 0; cpus[i].flag; i++)
+        check_cpu_flag(cpus[i].name, cpus[i].flag);
+
+    if (state.num_failed) {
+        fprintf(stderr, "checkasm: %d of %d tests have failed\n", state.num_failed, state.num_checked);
+        ret = 1;
+    } else {
+        fprintf(stderr, "checkasm: all %d tests passed\n", state.num_checked);
+#ifdef AV_READ_TIME
+        if (state.bench_pattern) {
+            state.nop_time = measure_nop_time();
+            printf("nop: %d.%d\n", state.nop_time/10, state.nop_time%10);
+            print_benchs(state.funcs);
+        }
+#endif
+    }
+
+    destroy_func_tree(state.funcs);
+    return ret;
+}
+
+/* Decide whether or not the specified function needs to be tested and
+ * allocate/initialize data structures if needed. Returns a pointer to a
+ * reference function if the function should be tested, otherwise NULL */
+intptr_t (*checkasm_check_func(intptr_t (*func)(), const char *name, ...))()
+{
+    char name_buf[256];
+    intptr_t (*ref)() = func;
+    CheckasmFuncVersion *v;
+    int name_length;
+    va_list arg;
+
+    va_start(arg, name);
+    name_length = vsnprintf(name_buf, sizeof(name_buf), name, arg);
+    va_end(arg);
+
+    if (!func || name_length <= 0 || name_length >= sizeof(name_buf))
+        return NULL;
+
+    state.current_func = get_func(name_buf, name_length);
+    v = &state.current_func->versions;
+
+    if (v->func) {
+        CheckasmFuncVersion *prev;
+        do {
+            /* Only test functions that haven't already been tested */
+            if (v->func == func)
+                return NULL;
+
+            if (v->ok)
+                ref = v->func;
+
+            prev = v;
+        } while ((v = v->next));
+
+        v = prev->next = checkasm_malloc(sizeof(CheckasmFuncVersion));
+    }
+
+    v->func = func;
+    v->ok = 1;
+    v->cpu = state.cpu_flag;
+    state.current_func_ver = v;
+
+    if (state.cpu_flag)
+        state.num_checked++;
+
+    return ref;
+}
+
+/* Decide whether or not the current function needs to be benchmarked */
+int checkasm_bench_func(void)
+{
+    return !state.num_failed && state.bench_pattern &&
+           !strncmp(state.current_func->name, state.bench_pattern, state.bench_pattern_len);
+}
+
+/* Indicate that the current test has failed */
+void checkasm_fail_func(const char *msg, ...)
+{
+    if (state.current_func_ver->cpu && state.current_func_ver->ok) {
+        va_list arg;
+
+        print_cpu_name();
+        fprintf(stderr, "   %s_%s (", state.current_func->name, cpu_suffix(state.current_func_ver->cpu));
+        va_start(arg, msg);
+        vfprintf(stderr, msg, arg);
+        va_end(arg);
+        fprintf(stderr, ")\n");
+
+        state.current_func_ver->ok = 0;
+        state.num_failed++;
+    }
+}
+
+/* Update benchmark results of the current function */
+void checkasm_update_bench(int iterations, uint64_t cycles)
+{
+    state.current_func_ver->iterations += iterations;
+    state.current_func_ver->cycles += cycles;
+}
+
+/* Print the outcome of all tests performed since the last time this function was called */
+void checkasm_report(const char *name, ...)
+{
+    static int prev_checked, prev_failed, max_length;
+
+    if (state.num_checked > prev_checked) {
+        print_cpu_name();
+
+        if (*name) {
+            int pad_length = max_length;
+            va_list arg;
+
+            fprintf(stderr, " - ");
+            va_start(arg, name);
+            pad_length -= vfprintf(stderr, name, arg);
+            va_end(arg);
+            fprintf(stderr, "%*c", FFMAX(pad_length, 0) + 2, '[');
+        } else
+            fprintf(stderr, " - %-*s [", max_length, state.current_func->name);
+
+        if (state.num_failed == prev_failed)
+            color_printf(COLOR_GREEN, "OK");
+        else
+            color_printf(COLOR_RED, "FAILED");
+        fprintf(stderr, "]\n");
+
+        prev_checked = state.num_checked;
+        prev_failed  = state.num_failed;
+    } else if (!state.cpu_flag) {
+        int length;
+
+        /* Calculate the amount of padding required to make the output vertically aligned */
+        if (*name) {
+            va_list arg;
+            va_start(arg, name);
+            length = vsnprintf(NULL, 0, name, arg);
+            va_end(arg);
+        } else
+            length = strlen(state.current_func->name);
+
+        if (length > max_length)
+            max_length = length;
+    }
+}