/*
 * builtin-diff.c
 *
 * Builtin diff command: Analyze two perf.data input files, look up and read
 * DSOs and symbol information, sort them and produce a diff.
 */
#include "builtin.h"

#include "util/debug.h"
#include "util/event.h"
#include "util/hist.h"
#include "util/evsel.h"
#include "util/evlist.h"
#include "util/session.h"
#include "util/tool.h"
#include "util/sort.h"
#include "util/symbol.h"
#include "util/util.h"
#include "util/data.h"

#include <stdlib.h>
#include <math.h>

/* Diff command specific HPP columns. */
enum {
        PERF_HPP_DIFF__BASELINE,
        PERF_HPP_DIFF__PERIOD,
        PERF_HPP_DIFF__PERIOD_BASELINE,
        PERF_HPP_DIFF__DELTA,
        PERF_HPP_DIFF__RATIO,
        PERF_HPP_DIFF__WEIGHTED_DIFF,
        PERF_HPP_DIFF__FORMULA,

        PERF_HPP_DIFF__MAX_INDEX
};

struct diff_hpp_fmt {
        struct perf_hpp_fmt      fmt;
        int                      idx;
        char                    *header;
        int                      header_width;
};

struct data__file {
        struct perf_session     *session;
        struct perf_data_file   file;
        int                      idx;
        struct hists            *hists;
        struct diff_hpp_fmt      fmt[PERF_HPP_DIFF__MAX_INDEX];
};

static struct data__file *data__files;
static int data__files_cnt;

#define data__for_each_file_start(i, d, s)      \
        for (i = s, d = &data__files[s];        \
             i < data__files_cnt;               \
             i++, d = &data__files[i])

#define data__for_each_file(i, d) data__for_each_file_start(i, d, 0)
#define data__for_each_file_new(i, d) data__for_each_file_start(i, d, 1)

static bool force;
static bool show_period;
static bool show_formula;
static bool show_baseline_only;
static unsigned int sort_compute;

static s64 compute_wdiff_w1;
static s64 compute_wdiff_w2;

enum {
        COMPUTE_DELTA,
        COMPUTE_RATIO,
        COMPUTE_WEIGHTED_DIFF,
        COMPUTE_MAX,
};

const char *compute_names[COMPUTE_MAX] = {
        [COMPUTE_DELTA] = "delta",
        [COMPUTE_RATIO] = "ratio",
        [COMPUTE_WEIGHTED_DIFF] = "wdiff",
};

static int compute;

static int compute_2_hpp[COMPUTE_MAX] = {
        [COMPUTE_DELTA]         = PERF_HPP_DIFF__DELTA,
        [COMPUTE_RATIO]         = PERF_HPP_DIFF__RATIO,
        [COMPUTE_WEIGHTED_DIFF] = PERF_HPP_DIFF__WEIGHTED_DIFF,
};

#define MAX_COL_WIDTH 70

static struct header_column {
        const char *name;
        int width;
} columns[PERF_HPP_DIFF__MAX_INDEX] = {
        [PERF_HPP_DIFF__BASELINE] = {
                .name  = "Baseline",
        },
        [PERF_HPP_DIFF__PERIOD] = {
                .name  = "Period",
                .width = 14,
        },
        [PERF_HPP_DIFF__PERIOD_BASELINE] = {
                .name  = "Base period",
                .width = 14,
        },
        [PERF_HPP_DIFF__DELTA] = {
                .name  = "Delta",
                .width = 7,
        },
        [PERF_HPP_DIFF__RATIO] = {
                .name  = "Ratio",
                .width = 14,
        },
        [PERF_HPP_DIFF__WEIGHTED_DIFF] = {
                .name  = "Weighted diff",
                .width = 14,
        },
        [PERF_HPP_DIFF__FORMULA] = {
                .name  = "Formula",
                .width = MAX_COL_WIDTH,
        }
};

static int setup_compute_opt_wdiff(char *opt)
{
        char *w1_str = opt;
        char *w2_str;

        int ret = -EINVAL;

        if (!opt)
                goto out;

        w2_str = strchr(opt, ',');
        if (!w2_str)
                goto out;

        *w2_str++ = 0x0;
        if (!*w2_str)
                goto out;

        compute_wdiff_w1 = strtol(w1_str, NULL, 10);
        compute_wdiff_w2 = strtol(w2_str, NULL, 10);

        if (!compute_wdiff_w1 || !compute_wdiff_w2)
                goto out;

        pr_debug("compute wdiff w1(%" PRId64 ") w2(%" PRId64 ")\n",
                  compute_wdiff_w1, compute_wdiff_w2);

        ret = 0;

 out:
        if (ret)
                pr_err("Failed: wrong weight data, use 'wdiff:w1,w2'\n");

        return ret;
}

static int setup_compute_opt(char *opt)
{
        if (compute == COMPUTE_WEIGHTED_DIFF)
                return setup_compute_opt_wdiff(opt);

        if (opt) {
                pr_err("Failed: extra option specified '%s'", opt);
                return -EINVAL;
        }

        return 0;
}

static int setup_compute(const struct option *opt, const char *str,
                         int unset __maybe_unused)
{
        int *cp = (int *) opt->value;
        char *cstr = (char *) str;
        char buf[50];
        unsigned i;
        char *option;

        if (!str) {
                *cp = COMPUTE_DELTA;
                return 0;
        }

        option = strchr(str, ':');
        if (option) {
                unsigned len = option++ - str;

                /*
                 * The str data are not writeable, so we need
                 * to use another buffer.
                 */

                /* No option value is longer. */
                if (len >= sizeof(buf))
                        return -EINVAL;

                strncpy(buf, str, len);
                buf[len] = 0x0;
                cstr = buf;
        }

        for (i = 0; i < COMPUTE_MAX; i++)
                if (!strcmp(cstr, compute_names[i])) {
                        *cp = i;
                        return setup_compute_opt(option);
                }

        pr_err("Failed: '%s' is not computation method "
               "(use 'delta','ratio' or 'wdiff')\n", str);
        return -EINVAL;
}

static double period_percent(struct hist_entry *he, u64 period)
{
        u64 total = hists__total_period(he->hists);

        return (period * 100.0) / total;
}

static double compute_delta(struct hist_entry *he, struct hist_entry *pair)
{
        double old_percent = period_percent(he, he->stat.period);
        double new_percent = period_percent(pair, pair->stat.period);

        pair->diff.period_ratio_delta = new_percent - old_percent;
        pair->diff.computed = true;
        return pair->diff.period_ratio_delta;
}

static double compute_ratio(struct hist_entry *he, struct hist_entry *pair)
{
        double old_period = he->stat.period ?: 1;
        double new_period = pair->stat.period;

        pair->diff.computed = true;
        pair->diff.period_ratio = new_period / old_period;
        return pair->diff.period_ratio;
}

static s64 compute_wdiff(struct hist_entry *he, struct hist_entry *pair)
{
        u64 old_period = he->stat.period;
        u64 new_period = pair->stat.period;

        pair->diff.computed = true;
        pair->diff.wdiff = new_period * compute_wdiff_w2 -
                           old_period * compute_wdiff_w1;

        return pair->diff.wdiff;
}

static int formula_delta(struct hist_entry *he, struct hist_entry *pair,
                         char *buf, size_t size)
{
        u64 he_total = he->hists->stats.total_period;
        u64 pair_total = pair->hists->stats.total_period;

        if (symbol_conf.filter_relative) {
                he_total = he->hists->stats.total_non_filtered_period;
                pair_total = pair->hists->stats.total_non_filtered_period;
        }
        return scnprintf(buf, size,
                         "(%" PRIu64 " * 100 / %" PRIu64 ") - "
                         "(%" PRIu64 " * 100 / %" PRIu64 ")",
                         pair->stat.period, pair_total,
                         he->stat.period, he_total);
}

static int formula_ratio(struct hist_entry *he, struct hist_entry *pair,
                         char *buf, size_t size)
{
        double old_period = he->stat.period;
        double new_period = pair->stat.period;

        return scnprintf(buf, size, "%.0F / %.0F", new_period, old_period);
}

static int formula_wdiff(struct hist_entry *he, struct hist_entry *pair,
                         char *buf, size_t size)
{
        u64 old_period = he->stat.period;
        u64 new_period = pair->stat.period;

        return scnprintf(buf, size,
                  "(%" PRIu64 " * " "%" PRId64 ") - (%" PRIu64 " * " "%" PRId64 ")",
                  new_period, compute_wdiff_w2, old_period, compute_wdiff_w1);
}

static int formula_fprintf(struct hist_entry *he, struct hist_entry *pair,
                           char *buf, size_t size)
{
        switch (compute) {
        case COMPUTE_DELTA:
                return formula_delta(he, pair, buf, size);
        case COMPUTE_RATIO:
                return formula_ratio(he, pair, buf, size);
        case COMPUTE_WEIGHTED_DIFF:
                return formula_wdiff(he, pair, buf, size);
        default:
                BUG_ON(1);
        }

        return -1;
}

static int diff__process_sample_event(struct perf_tool *tool __maybe_unused,
                                      union perf_event *event,
                                      struct perf_sample *sample,
                                      struct perf_evsel *evsel,
                                      struct machine *machine)
{
        struct addr_location al;
        struct hists *hists = evsel__hists(evsel);
        int ret = -1;

        if (machine__resolve(machine, &al, sample) < 0) {
                pr_warning("problem processing %d event, skipping it.\n",
                           event->header.type);
                return -1;
        }

        if (!hists__add_entry(hists, &al, NULL, NULL, NULL, sample, true)) {
                pr_warning("problem incrementing symbol period, skipping event\n");
                goto out_put;
        }

        /*
         * The total_period is updated here before going to the output
         * tree since normally only the baseline hists will call
         * hists__output_resort() and precompute needs the total
         * period in order to sort entries by percentage delta.
         */
        hists->stats.total_period += sample->period;
        if (!al.filtered)
                hists->stats.total_non_filtered_period += sample->period;
        ret = 0;
out_put:
        addr_location__put(&al);
        return ret;
}

static struct perf_tool tool = {
        .sample = diff__process_sample_event,
        .mmap   = perf_event__process_mmap,
        .mmap2  = perf_event__process_mmap2,
        .comm   = perf_event__process_comm,
        .exit   = perf_event__process_exit,
        .fork   = perf_event__process_fork,
        .lost   = perf_event__process_lost,
        .ordered_events = true,
        .ordering_requires_timestamps = true,
};

static struct perf_evsel *evsel_match(struct perf_evsel *evsel,
                                      struct perf_evlist *evlist)
{
        struct perf_evsel *e;

        evlist__for_each_entry(evlist, e) {
                if (perf_evsel__match2(evsel, e))
                        return e;
        }

        return NULL;
}

static void perf_evlist__collapse_resort(struct perf_evlist *evlist)
{
        struct perf_evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                struct hists *hists = evsel__hists(evsel);

                hists__collapse_resort(hists, NULL);
        }
}

static struct data__file *fmt_to_data_file(struct perf_hpp_fmt *fmt)
{
        struct diff_hpp_fmt *dfmt = container_of(fmt, struct diff_hpp_fmt, fmt);
        void *ptr = dfmt - dfmt->idx;
        struct data__file *d = container_of(ptr, struct data__file, fmt);

        return d;
}

static struct hist_entry*
get_pair_data(struct hist_entry *he, struct data__file *d)
{
        if (hist_entry__has_pairs(he)) {
                struct hist_entry *pair;

                list_for_each_entry(pair, &he->pairs.head, pairs.node)
                        if (pair->hists == d->hists)
                                return pair;
        }

        return NULL;
}

static struct hist_entry*
get_pair_fmt(struct hist_entry *he, struct diff_hpp_fmt *dfmt)
{
        struct data__file *d = fmt_to_data_file(&dfmt->fmt);

        return get_pair_data(he, d);
}

static void hists__baseline_only(struct hists *hists)
{
        struct rb_root *root;
        struct rb_node *next;

        if (hists__has(hists, need_collapse))
                root = &hists->entries_collapsed;
        else
                root = hists->entries_in;

        next = rb_first(root);
        while (next != NULL) {
                struct hist_entry *he = rb_entry(next, struct hist_entry, rb_node_in);

                next = rb_next(&he->rb_node_in);
                if (!hist_entry__next_pair(he)) {
                        rb_erase(&he->rb_node_in, root);
                        hist_entry__delete(he);
                }
        }
}

static void hists__precompute(struct hists *hists)
{
        struct rb_root *root;
        struct rb_node *next;

        if (hists__has(hists, need_collapse))
                root = &hists->entries_collapsed;
        else
                root = hists->entries_in;

        next = rb_first(root);
        while (next != NULL) {
                struct hist_entry *he, *pair;
                struct data__file *d;
                int i;

                he   = rb_entry(next, struct hist_entry, rb_node_in);
                next = rb_next(&he->rb_node_in);

                data__for_each_file_new(i, d) {
                        pair = get_pair_data(he, d);
                        if (!pair)
                                continue;

                        switch (compute) {
                        case COMPUTE_DELTA:
                                compute_delta(he, pair);
                                break;
                        case COMPUTE_RATIO:
                                compute_ratio(he, pair);
                                break;
                        case COMPUTE_WEIGHTED_DIFF:
                                compute_wdiff(he, pair);
                                break;
                        default:
                                BUG_ON(1);
                        }
                }
        }
}

static int64_t cmp_doubles(double l, double r)
{
        if (l > r)
                return -1;
        else if (l < r)
                return 1;
        else
                return 0;
}

static int64_t
__hist_entry__cmp_compute(struct hist_entry *left, struct hist_entry *right,
                        int c)
{
        switch (c) {
        case COMPUTE_DELTA:
        {
                double l = left->diff.period_ratio_delta;
                double r = right->diff.period_ratio_delta;

                return cmp_doubles(l, r);
        }
        case COMPUTE_RATIO:
        {
                double l = left->diff.period_ratio;
                double r = right->diff.period_ratio;

                return cmp_doubles(l, r);
        }
        case COMPUTE_WEIGHTED_DIFF:
        {
                s64 l = left->diff.wdiff;
                s64 r = right->diff.wdiff;

                return r - l;
        }
        default:
                BUG_ON(1);
        }

        return 0;
}

static int64_t
hist_entry__cmp_compute(struct hist_entry *left, struct hist_entry *right,
                        int c, int sort_idx)
{
        bool pairs_left  = hist_entry__has_pairs(left);
        bool pairs_right = hist_entry__has_pairs(right);
        struct hist_entry *p_right, *p_left;

        if (!pairs_left && !pairs_right)
                return 0;

        if (!pairs_left || !pairs_right)
                return pairs_left ? -1 : 1;

        p_left  = get_pair_data(left,  &data__files[sort_idx]);
        p_right = get_pair_data(right, &data__files[sort_idx]);

        if (!p_left && !p_right)
                return 0;

        if (!p_left || !p_right)
                return p_left ? -1 : 1;

        /*
         * We have 2 entries of same kind, let's
         * make the data comparison.
         */
        return __hist_entry__cmp_compute(p_left, p_right, c);
}

static int64_t
hist_entry__cmp_compute_idx(struct hist_entry *left, struct hist_entry *right,
                            int c, int sort_idx)
{
        struct hist_entry *p_right, *p_left;

        p_left  = get_pair_data(left,  &data__files[sort_idx]);
        p_right = get_pair_data(right, &data__files[sort_idx]);

        if (!p_left && !p_right)
                return 0;

        if (!p_left || !p_right)
                return p_left ? -1 : 1;

        if (c != COMPUTE_DELTA) {
                /*
                 * The delta can be computed without the baseline, but
                 * others are not.  Put those entries which have no
                 * values below.
                 */
                if (left->dummy && right->dummy)
                        return 0;

                if (left->dummy || right->dummy)
                        return left->dummy ? 1 : -1;
        }

        return __hist_entry__cmp_compute(p_left, p_right, c);
}

static int64_t
hist_entry__cmp_nop(struct perf_hpp_fmt *fmt __maybe_unused,
                    struct hist_entry *left __maybe_unused,
                    struct hist_entry *right __maybe_unused)
{
        return 0;
}

static int64_t
hist_entry__cmp_baseline(struct perf_hpp_fmt *fmt __maybe_unused,
                         struct hist_entry *left, struct hist_entry *right)
{
        if (left->stat.period == right->stat.period)
                return 0;
        return left->stat.period > right->stat.period ? 1 : -1;
}

static int64_t
hist_entry__cmp_delta(struct perf_hpp_fmt *fmt,
                      struct hist_entry *left, struct hist_entry *right)
{
        struct data__file *d = fmt_to_data_file(fmt);

        return hist_entry__cmp_compute(right, left, COMPUTE_DELTA, d->idx);
}

static int64_t
hist_entry__cmp_ratio(struct perf_hpp_fmt *fmt,
                      struct hist_entry *left, struct hist_entry *right)
{
        struct data__file *d = fmt_to_data_file(fmt);

        return hist_entry__cmp_compute(right, left, COMPUTE_RATIO, d->idx);
}

static int64_t
hist_entry__cmp_wdiff(struct perf_hpp_fmt *fmt,
                      struct hist_entry *left, struct hist_entry *right)
{
        struct data__file *d = fmt_to_data_file(fmt);

        return hist_entry__cmp_compute(right, left, COMPUTE_WEIGHTED_DIFF, d->idx);
}

static int64_t
hist_entry__cmp_delta_idx(struct perf_hpp_fmt *fmt __maybe_unused,
                          struct hist_entry *left, struct hist_entry *right)
{
        return hist_entry__cmp_compute_idx(right, left, COMPUTE_DELTA,
                                           sort_compute);
}

static int64_t
hist_entry__cmp_ratio_idx(struct perf_hpp_fmt *fmt __maybe_unused,
                          struct hist_entry *left, struct hist_entry *right)
{
        return hist_entry__cmp_compute_idx(right, left, COMPUTE_RATIO,
                                           sort_compute);
}

static int64_t
hist_entry__cmp_wdiff_idx(struct perf_hpp_fmt *fmt __maybe_unused,
                          struct hist_entry *left, struct hist_entry *right)
{
        return hist_entry__cmp_compute_idx(right, left, COMPUTE_WEIGHTED_DIFF,
                                           sort_compute);
}

static void hists__process(struct hists *hists)
{
        if (show_baseline_only)
                hists__baseline_only(hists);

        hists__precompute(hists);
        hists__output_resort(hists, NULL);

        hists__fprintf(hists, true, 0, 0, 0, stdout,
                       symbol_conf.use_callchain);
}

static void data__fprintf(void)
{
        struct data__file *d;
        int i;

        fprintf(stdout, "# Data files:\n");

        data__for_each_file(i, d)
                fprintf(stdout, "#  [%d] %s %s\n",
                        d->idx, d->file.path,
                        !d->idx ? "(Baseline)" : "");

        fprintf(stdout, "#\n");
}

static void data_process(void)
{
        struct perf_evlist *evlist_base = data__files[0].session->evlist;
        struct perf_evsel *evsel_base;
        bool first = true;

        evlist__for_each_entry(evlist_base, evsel_base) {
                struct hists *hists_base = evsel__hists(evsel_base);
                struct data__file *d;
                int i;

                data__for_each_file_new(i, d) {
                        struct perf_evlist *evlist = d->session->evlist;
                        struct perf_evsel *evsel;
                        struct hists *hists;

                        evsel = evsel_match(evsel_base, evlist);
                        if (!evsel)
                                continue;

                        hists = evsel__hists(evsel);
                        d->hists = hists;

                        hists__match(hists_base, hists);

                        if (!show_baseline_only)
                                hists__link(hists_base, hists);
                }

                fprintf(stdout, "%s# Event '%s'\n#\n", first ? "" : "\n",
                        perf_evsel__name(evsel_base));

                first = false;

                if (verbose || data__files_cnt > 2)
                        data__fprintf();

                /* Don't sort callchain for perf diff */
                perf_evsel__reset_sample_bit(evsel_base, CALLCHAIN);

                hists__process(hists_base);
        }
}

static void data__free(struct data__file *d)
{
        int col;

        for (col = 0; col < PERF_HPP_DIFF__MAX_INDEX; col++) {
                struct diff_hpp_fmt *fmt = &d->fmt[col];

                zfree(&fmt->header);
        }
}

static int __cmd_diff(void)
{
        struct data__file *d;
        int ret = -EINVAL, i;

        data__for_each_file(i, d) {
                d->session = perf_session__new(&d->file, false, &tool);
                if (!d->session) {
                        pr_err("Failed to open %s\n", d->file.path);
                        ret = -1;
                        goto out_delete;
                }

                ret = perf_session__process_events(d->session);
                if (ret) {
                        pr_err("Failed to process %s\n", d->file.path);
                        goto out_delete;
                }

                perf_evlist__collapse_resort(d->session->evlist);
        }

        data_process();

 out_delete:
        data__for_each_file(i, d) {
                perf_session__delete(d->session);
                data__free(d);
        }

        free(data__files);
        return ret;
}

static const char * const diff_usage[] = {
        "perf diff [<options>] [old_file] [new_file]",
        NULL,
};

static const struct option options[] = {
        OPT_INCR('v', "verbose", &verbose,
                    "be more verbose (show symbol address, etc)"),
        OPT_BOOLEAN('b', "baseline-only", &show_baseline_only,
                    "Show only items with match in baseline"),
        OPT_CALLBACK('c', "compute", &compute,
                     "delta,ratio,wdiff:w1,w2 (default delta)",
                     "Entries differential computation selection",
                     setup_compute),
        OPT_BOOLEAN('p', "period", &show_period,
                    "Show period values."),
        OPT_BOOLEAN('F', "formula", &show_formula,
                    "Show formula."),
        OPT_BOOLEAN('D', "dump-raw-trace", &dump_trace,
                    "dump raw trace in ASCII"),
        OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
        OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
                   "file", "kallsyms pathname"),
        OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
                    "load module symbols - WARNING: use only with -k and LIVE kernel"),
        OPT_STRING('d', "dsos", &symbol_conf.dso_list_str, "dso[,dso...]",
                   "only consider symbols in these dsos"),
        OPT_STRING('C', "comms", &symbol_conf.comm_list_str, "comm[,comm...]",
                   "only consider symbols in these comms"),
        OPT_STRING('S', "symbols", &symbol_conf.sym_list_str, "symbol[,symbol...]",
                   "only consider these symbols"),
        OPT_STRING('s', "sort", &sort_order, "key[,key2...]",
                   "sort by key(s): pid, comm, dso, symbol, parent, cpu, srcline, ..."
                   " Please refer the man page for the complete list."),
        OPT_STRING_NOEMPTY('t', "field-separator", &symbol_conf.field_sep, "separator",
                   "separator for columns, no spaces will be added between "
                   "columns '.' is reserved."),
        OPT_CALLBACK(0, "symfs", NULL, "directory",
                     "Look for files with symbols relative to this directory",
                     symbol__config_symfs),
        OPT_UINTEGER('o', "order", &sort_compute, "Specify compute sorting."),
        OPT_CALLBACK(0, "percentage", NULL, "relative|absolute",
                     "How to display percentage of filtered entries", parse_filter_percentage),
        OPT_END()
};

static double baseline_percent(struct hist_entry *he)
{
        u64 total = hists__total_period(he->hists);

        return 100.0 * he->stat.period / total;
}

static int hpp__color_baseline(struct perf_hpp_fmt *fmt,
                               struct perf_hpp *hpp, struct hist_entry *he)
{
        struct diff_hpp_fmt *dfmt =
                container_of(fmt, struct diff_hpp_fmt, fmt);
        double percent = baseline_percent(he);
        char pfmt[20] = " ";

        if (!he->dummy) {
                scnprintf(pfmt, 20, "%%%d.2f%%%%", dfmt->header_width - 1);
                return percent_color_snprintf(hpp->buf, hpp->size,
                                              pfmt, percent);
        } else
                return scnprintf(hpp->buf, hpp->size, "%*s",
                                 dfmt->header_width, pfmt);
}

static int hpp__entry_baseline(struct hist_entry *he, char *buf, size_t size)
{
        double percent = baseline_percent(he);
        const char *fmt = symbol_conf.field_sep ? "%.2f" : "%6.2f%%";
        int ret = 0;

        if (!he->dummy)
                ret = scnprintf(buf, size, fmt, percent);

        return ret;
}

static int __hpp__color_compare(struct perf_hpp_fmt *fmt,
                                struct perf_hpp *hpp, struct hist_entry *he,
                                int comparison_method)
{
        struct diff_hpp_fmt *dfmt =
                container_of(fmt, struct diff_hpp_fmt, fmt);
        struct hist_entry *pair = get_pair_fmt(he, dfmt);
        double diff;
        s64 wdiff;
        char pfmt[20] = " ";

        if (!pair)
                goto no_print;

        switch (comparison_method) {
        case COMPUTE_DELTA:
                if (pair->diff.computed)
                        diff = pair->diff.period_ratio_delta;
                else
                        diff = compute_delta(he, pair);

                scnprintf(pfmt, 20, "%%%+d.2f%%%%", dfmt->header_width - 1);
                return percent_color_snprintf(hpp->buf, hpp->size,
                                        pfmt, diff);
        case COMPUTE_RATIO:
                if (he->dummy)
                        goto dummy_print;
                if (pair->diff.computed)
                        diff = pair->diff.period_ratio;
                else
                        diff = compute_ratio(he, pair);

                scnprintf(pfmt, 20, "%%%d.6f", dfmt->header_width);
                return value_color_snprintf(hpp->buf, hpp->size,
                                        pfmt, diff);
        case COMPUTE_WEIGHTED_DIFF:
                if (he->dummy)
                        goto dummy_print;
                if (pair->diff.computed)
                        wdiff = pair->diff.wdiff;
                else
                        wdiff = compute_wdiff(he, pair);

                scnprintf(pfmt, 20, "%%14ld", dfmt->header_width);
                return color_snprintf(hpp->buf, hpp->size,
                                get_percent_color(wdiff),
                                pfmt, wdiff);
        default:
                BUG_ON(1);
        }
dummy_print:
        return scnprintf(hpp->buf, hpp->size, "%*s",
                        dfmt->header_width, "N/A");
no_print:
        return scnprintf(hpp->buf, hpp->size, "%*s",
                        dfmt->header_width, pfmt);
}

static int hpp__color_delta(struct perf_hpp_fmt *fmt,
                        struct perf_hpp *hpp, struct hist_entry *he)
{
        return __hpp__color_compare(fmt, hpp, he, COMPUTE_DELTA);
}

static int hpp__color_ratio(struct perf_hpp_fmt *fmt,
                        struct perf_hpp *hpp, struct hist_entry *he)
{
        return __hpp__color_compare(fmt, hpp, he, COMPUTE_RATIO);
}

static int hpp__color_wdiff(struct perf_hpp_fmt *fmt,
                        struct perf_hpp *hpp, struct hist_entry *he)
{
        return __hpp__color_compare(fmt, hpp, he, COMPUTE_WEIGHTED_DIFF);
}

static void
hpp__entry_unpair(struct hist_entry *he, int idx, char *buf, size_t size)
{
        switch (idx) {
        case PERF_HPP_DIFF__PERIOD_BASELINE:
                scnprintf(buf, size, "%" PRIu64, he->stat.period);
                break;

        default:
                break;
        }
}

static void
hpp__entry_pair(struct hist_entry *he, struct hist_entry *pair,
                int idx, char *buf, size_t size)
{
        double diff;
        double ratio;
        s64 wdiff;

        switch (idx) {
        case PERF_HPP_DIFF__DELTA:
                if (pair->diff.computed)
                        diff = pair->diff.period_ratio_delta;
                else
                        diff = compute_delta(he, pair);

                scnprintf(buf, size, "%+4.2F%%", diff);
                break;

        case PERF_HPP_DIFF__RATIO:
                /* No point for ratio number if we are dummy.. */
                if (he->dummy) {
                        scnprintf(buf, size, "N/A");
                        break;
                }

                if (pair->diff.computed)
                        ratio = pair->diff.period_ratio;
                else
                        ratio = compute_ratio(he, pair);

                if (ratio > 0.0)
                        scnprintf(buf, size, "%14.6F", ratio);
                break;

        case PERF_HPP_DIFF__WEIGHTED_DIFF:
                /* No point for wdiff number if we are dummy.. */
                if (he->dummy) {
                        scnprintf(buf, size, "N/A");
                        break;
                }

                if (pair->diff.computed)
                        wdiff = pair->diff.wdiff;
                else
                        wdiff = compute_wdiff(he, pair);

                if (wdiff != 0)
                        scnprintf(buf, size, "%14ld", wdiff);
                break;

        case PERF_HPP_DIFF__FORMULA:
                formula_fprintf(he, pair, buf, size);
                break;

        case PERF_HPP_DIFF__PERIOD:
                scnprintf(buf, size, "%" PRIu64, pair->stat.period);
                break;

        default:
                BUG_ON(1);
        };
}

static void
__hpp__entry_global(struct hist_entry *he, struct diff_hpp_fmt *dfmt,
                    char *buf, size_t size)
{
        struct hist_entry *pair = get_pair_fmt(he, dfmt);
        int idx = dfmt->idx;

        /* baseline is special */
        if (idx == PERF_HPP_DIFF__BASELINE)
                hpp__entry_baseline(he, buf, size);
        else {
                if (pair)
                        hpp__entry_pair(he, pair, idx, buf, size);
                else
                        hpp__entry_unpair(he, idx, buf, size);
        }
}

static int hpp__entry_global(struct perf_hpp_fmt *_fmt, struct perf_hpp *hpp,
                             struct hist_entry *he)
{
        struct diff_hpp_fmt *dfmt =
                container_of(_fmt, struct diff_hpp_fmt, fmt);
        char buf[MAX_COL_WIDTH] = " ";

        __hpp__entry_global(he, dfmt, buf, MAX_COL_WIDTH);

        if (symbol_conf.field_sep)
                return scnprintf(hpp->buf, hpp->size, "%s", buf);
        else
                return scnprintf(hpp->buf, hpp->size, "%*s",
                                 dfmt->header_width, buf);
}

static int hpp__header(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
                       struct hists *hists __maybe_unused,
                       int line __maybe_unused,
                       int *span __maybe_unused)
{
        struct diff_hpp_fmt *dfmt =
                container_of(fmt, struct diff_hpp_fmt, fmt);

        BUG_ON(!dfmt->header);
        return scnprintf(hpp->buf, hpp->size, dfmt->header);
}

static int hpp__width(struct perf_hpp_fmt *fmt,
                      struct perf_hpp *hpp __maybe_unused,
                      struct hists *hists __maybe_unused)
{
        struct diff_hpp_fmt *dfmt =
                container_of(fmt, struct diff_hpp_fmt, fmt);

        BUG_ON(dfmt->header_width <= 0);
        return dfmt->header_width;
}

static void init_header(struct data__file *d, struct diff_hpp_fmt *dfmt)
{
#define MAX_HEADER_NAME 100
        char buf_indent[MAX_HEADER_NAME];
        char buf[MAX_HEADER_NAME];
        const char *header = NULL;
        int width = 0;

        BUG_ON(dfmt->idx >= PERF_HPP_DIFF__MAX_INDEX);
        header = columns[dfmt->idx].name;
        width  = columns[dfmt->idx].width;

        /* Only our defined HPP fmts should appear here. */
        BUG_ON(!header);

        if (data__files_cnt > 2)
                scnprintf(buf, MAX_HEADER_NAME, "%s/%d", header, d->idx);

#define NAME (data__files_cnt > 2 ? buf : header)
        dfmt->header_width = width;
        width = (int) strlen(NAME);
        if (dfmt->header_width < width)
                dfmt->header_width = width;

        scnprintf(buf_indent, MAX_HEADER_NAME, "%*s",
                  dfmt->header_width, NAME);

        dfmt->header = strdup(buf_indent);
#undef MAX_HEADER_NAME
#undef NAME
}

static void data__hpp_register(struct data__file *d, int idx)
{
        struct diff_hpp_fmt *dfmt = &d->fmt[idx];
        struct perf_hpp_fmt *fmt = &dfmt->fmt;

        dfmt->idx = idx;

        fmt->header = hpp__header;
        fmt->width  = hpp__width;
        fmt->entry  = hpp__entry_global;
        fmt->cmp    = hist_entry__cmp_nop;
        fmt->collapse = hist_entry__cmp_nop;

        /* TODO more colors */
        switch (idx) {
        case PERF_HPP_DIFF__BASELINE:
                fmt->color = hpp__color_baseline;
                fmt->sort  = hist_entry__cmp_baseline;
                break;
        case PERF_HPP_DIFF__DELTA:
                fmt->color = hpp__color_delta;
                fmt->sort  = hist_entry__cmp_delta;
                break;
        case PERF_HPP_DIFF__RATIO:
                fmt->color = hpp__color_ratio;
                fmt->sort  = hist_entry__cmp_ratio;
                break;
        case PERF_HPP_DIFF__WEIGHTED_DIFF:
                fmt->color = hpp__color_wdiff;
                fmt->sort  = hist_entry__cmp_wdiff;
                break;
        default:
                fmt->sort  = hist_entry__cmp_nop;
                break;
        }

        init_header(d, dfmt);
        perf_hpp__column_register(fmt);
        perf_hpp__register_sort_field(fmt);
}

static int ui_init(void)
{
        struct data__file *d;
        struct perf_hpp_fmt *fmt;
        int i;

        data__for_each_file(i, d) {

                /*
                 * Baseline or compute realted columns:
                 *
                 *   PERF_HPP_DIFF__BASELINE
                 *   PERF_HPP_DIFF__DELTA
                 *   PERF_HPP_DIFF__RATIO
                 *   PERF_HPP_DIFF__WEIGHTED_DIFF
                 */
                data__hpp_register(d, i ? compute_2_hpp[compute] :
                                          PERF_HPP_DIFF__BASELINE);

                /*
                 * And the rest:
                 *
                 * PERF_HPP_DIFF__FORMULA
                 * PERF_HPP_DIFF__PERIOD
                 * PERF_HPP_DIFF__PERIOD_BASELINE
                 */
                if (show_formula && i)
                        data__hpp_register(d, PERF_HPP_DIFF__FORMULA);

                if (show_period)
                        data__hpp_register(d, i ? PERF_HPP_DIFF__PERIOD :
                                                  PERF_HPP_DIFF__PERIOD_BASELINE);
        }

        if (!sort_compute)
                return 0;

        /*
         * Prepend an fmt to sort on columns at 'sort_compute' first.
         * This fmt is added only to the sort list but not to the
         * output fields list.
         *
         * Note that this column (data) can be compared twice - one
         * for this 'sort_compute' fmt and another for the normal
         * diff_hpp_fmt.  But it shouldn't a problem as most entries
         * will be sorted out by first try or baseline and comparing
         * is not a costly operation.
         */
        fmt = zalloc(sizeof(*fmt));
        if (fmt == NULL) {
                pr_err("Memory allocation failed\n");
                return -1;
        }

        fmt->cmp      = hist_entry__cmp_nop;
        fmt->collapse = hist_entry__cmp_nop;

        switch (compute) {
        case COMPUTE_DELTA:
                fmt->sort = hist_entry__cmp_delta_idx;
                break;
        case COMPUTE_RATIO:
                fmt->sort = hist_entry__cmp_ratio_idx;
                break;
        case COMPUTE_WEIGHTED_DIFF:
                fmt->sort = hist_entry__cmp_wdiff_idx;
                break;
        default:
                BUG_ON(1);
        }

        perf_hpp__register_sort_field(fmt);
        return 0;
}

static int data_init(int argc, const char **argv)
{
        struct data__file *d;
        static const char *defaults[] = {
                "perf.data.old",
                "perf.data",
        };
        bool use_default = true;
        int i;

        data__files_cnt = 2;

        if (argc) {
                if (argc == 1)
                        defaults[1] = argv[0];
                else {
                        data__files_cnt = argc;
                        use_default = false;
                }
        } else if (perf_guest) {
                defaults[0] = "perf.data.host";
                defaults[1] = "perf.data.guest";
        }

        if (sort_compute >= (unsigned int) data__files_cnt) {
                pr_err("Order option out of limit.\n");
                return -EINVAL;
        }

        data__files = zalloc(sizeof(*data__files) * data__files_cnt);
        if (!data__files)
                return -ENOMEM;

        data__for_each_file(i, d) {
                struct perf_data_file *file = &d->file;

                file->path  = use_default ? defaults[i] : argv[i];
                file->mode  = PERF_DATA_MODE_READ,
                file->force = force,

                d->idx  = i;
        }

        return 0;
}

int cmd_diff(int argc, const char **argv, const char *prefix __maybe_unused)
{
        int ret = hists__init();

        if (ret < 0)
                return ret;

        argc = parse_options(argc, argv, options, diff_usage, 0);

        if (symbol__init(NULL) < 0)
                return -1;

        if (data_init(argc, argv) < 0)
                return -1;

        if (ui_init() < 0)
                return -1;

        sort__mode = SORT_MODE__DIFF;

        if (setup_sorting(NULL) < 0)
                usage_with_options(diff_usage, options);

        setup_pager();

        sort__setup_elide(NULL);

        return __cmd_diff();
}