diff -r 000000000000 -r 6474c204b198 tools/reorder/histogram.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/reorder/histogram.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,142 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+
+  A program that computes a call histogram from runtime call
+  information. It reads a list of address references (e.g., as
+  computed by libcygprof.so), and uses an ELF image to map the
+  addresses to functions.
+
+ */
+
+#include <fstream>
+#include <hash_map>
+#include <limits.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <fcntl.h>
+
+#include "elf_symbol_table.h"
+
+#define _GNU_SOURCE
+#include <getopt.h>
+
+const char *opt_exe;
+int opt_tick = 0;
+
+elf_symbol_table table;
+
+typedef hash_map<unsigned int, unsigned int> histogram_t;
+histogram_t histogram;
+
+static struct option long_options[] = {
+    { "exe",  required_argument, 0, 'e' },
+    { "tick", optional_argument, 0, 't' },
+    { 0,      0,                 0, 0   }
+};
+
+static void
+usage(const char *name)
+{
+    cerr << "usage: " << name << " --exe=<image> [--tick[=count]]" << endl;
+}
+
+static void
+map_addrs(int fd)
+{
+    // Read the binary addresses from stdin.
+    unsigned int buf[128];
+    ssize_t cb;
+
+    unsigned int count = 0;
+    while ((cb = read(fd, buf, sizeof buf)) > 0) {
+        if (cb % sizeof buf[0])
+            fprintf(stderr, "unaligned read\n");
+
+        unsigned int *addr = buf;
+        unsigned int *limit = buf + (cb / 4);
+
+        for (; addr < limit; ++addr) {
+            const Elf32_Sym *sym = table.lookup(*addr);
+            if (sym)
+                ++histogram[reinterpret_cast<unsigned int>(sym)];
+
+            if (opt_tick && (++count % opt_tick == 0)) {
+                cerr << ".";
+                flush(cerr);
+            }
+        }
+    }
+
+    if (opt_tick)
+        cerr << endl;
+}
+
+int
+main(int argc, char *argv[])
+{
+    int c;
+    while (1) {
+        int option_index = 0;
+        c = getopt_long(argc, argv, "e:t", long_options, &option_index);
+
+        if (c < 0)
+            break;
+
+        switch (c) {
+        case 'e':
+            opt_exe = optarg;
+            break;
+
+        case 't':
+            opt_tick = optarg ? atoi(optarg) : 1000000;
+            break;
+
+        default:
+            usage(argv[0]);
+            return 1;
+        }
+    }
+
+    if (! opt_exe) {
+        usage(argv[0]);
+        return 1;
+    }
+
+    table.init(opt_exe);
+
+    // Process addresses.
+    if (optind >= argc) {
+        map_addrs(STDIN_FILENO);
+    }
+    else {
+        do {
+            int fd = open(argv[optind], O_RDONLY);
+            if (fd < 0) {
+                perror(argv[optind]);
+                return 1;
+            }
+
+            map_addrs(fd);
+            close(fd);
+        } while (++optind < argc);
+    }
+    
+    // Emit the histogram.
+    histogram_t::const_iterator limit = histogram.end();
+    histogram_t::const_iterator i;
+    for (i = histogram.begin(); i != limit; ++i) {
+        const Elf32_Sym *sym = reinterpret_cast<const Elf32_Sym *>(i->first);
+        cout.form("%08x %6d %2d %10d ",
+                  sym->st_value,
+                  sym->st_size,
+                  sym->st_shndx,
+                  i->second);
+
+        cout << table.get_symbol_name(sym) << endl;
+    }
+
+    return 0;
+}