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//===-- compute_size_class_config.cpp -------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <vector>
struct Alloc {
size_t size, count;
};
size_t measureWastage(const std::vector<Alloc> &allocs,
const std::vector<size_t> &classes, size_t pageSize,
size_t headerSize) {
size_t totalWastage = 0;
for (auto &a : allocs) {
size_t sizePlusHeader = a.size + headerSize;
size_t wastage = -1ull;
for (auto c : classes)
if (c >= sizePlusHeader && c - sizePlusHeader < wastage)
wastage = c - sizePlusHeader;
if (wastage == -1ull)
continue;
if (wastage > 2 * pageSize)
wastage = 2 * pageSize;
totalWastage += wastage * a.count;
}
return totalWastage;
}
void readAllocs(std::vector<Alloc> &allocs, const char *path) {
FILE *f = fopen(path, "r");
if (!f) {
fprintf(stderr, "compute_size_class_config: could not open %s: %s\n", path,
strerror(errno));
exit(1);
}
const char header[] = "<malloc version=\"scudo-1\">\n";
char buf[sizeof(header) - 1];
if (fread(buf, 1, sizeof(header) - 1, f) != sizeof(header) - 1 ||
memcmp(buf, header, sizeof(header) - 1) != 0) {
fprintf(stderr, "compute_size_class_config: invalid input format\n");
exit(1);
}
Alloc a;
while (fscanf(f, "<alloc size=\"%zu\" count=\"%zu\"/>\n", &a.size,
&a.count) == 2)
allocs.push_back(a);
fclose(f);
}
size_t log2Floor(size_t x) { return sizeof(long) * 8 - 1 - __builtin_clzl(x); }
void usage() {
fprintf(stderr,
"usage: compute_size_class_config [-p pageSize] [-c largestClass] "
"[-h headerSize] [-n numClasses] [-b numBits] profile...\n");
exit(1);
}
int main(int argc, char **argv) {
size_t pageSize = 4096;
size_t largestClass = 65552;
size_t headerSize = 16;
size_t numClasses = 32;
size_t numBits = 5;
std::vector<Alloc> allocs;
for (size_t i = 1; i != argc;) {
auto matchArg = [&](size_t &arg, const char *name) {
if (strcmp(argv[i], name) == 0) {
if (i + 1 != argc) {
arg = atoi(argv[i + 1]);
i += 2;
} else {
usage();
}
return true;
}
return false;
};
if (matchArg(pageSize, "-p") || matchArg(largestClass, "-c") ||
matchArg(headerSize, "-h") || matchArg(numClasses, "-n") ||
matchArg(numBits, "-b"))
continue;
readAllocs(allocs, argv[i]);
++i;
}
if (allocs.empty())
usage();
std::vector<size_t> classes;
classes.push_back(largestClass);
for (size_t i = 1; i != numClasses; ++i) {
size_t minWastage = -1ull;
size_t minWastageClass;
for (size_t newClass = 16; newClass != largestClass; newClass += 16) {
// Skip classes with more than numBits bits, ignoring leading or trailing
// zero bits.
if (__builtin_ctzl(newClass - headerSize) +
__builtin_clzl(newClass - headerSize) <
sizeof(long) * 8 - numBits)
continue;
classes.push_back(newClass);
size_t newWastage = measureWastage(allocs, classes, pageSize, headerSize);
classes.pop_back();
if (newWastage < minWastage) {
minWastage = newWastage;
minWastageClass = newClass;
}
}
classes.push_back(minWastageClass);
}
std::sort(classes.begin(), classes.end());
size_t minSizeLog = log2Floor(headerSize);
size_t midSizeIndex = 0;
while (classes[midSizeIndex + 1] - classes[midSizeIndex] == (1 << minSizeLog))
midSizeIndex++;
size_t midSizeLog = log2Floor(classes[midSizeIndex] - headerSize);
size_t maxSizeLog = log2Floor(classes.back() - headerSize - 1) + 1;
printf(R"(// wastage = %zu
struct MySizeClassConfig {
static const uptr NumBits = %zu;
static const uptr MinSizeLog = %zu;
static const uptr MidSizeLog = %zu;
static const uptr MaxSizeLog = %zu;
static const u16 MaxNumCachedHint = 14;
static const uptr MaxBytesCachedLog = 14;
static constexpr u32 Classes[] = {)",
measureWastage(allocs, classes, pageSize, headerSize), numBits,
minSizeLog, midSizeLog, maxSizeLog);
for (size_t i = 0; i != classes.size(); ++i) {
if ((i % 8) == 0)
printf("\n ");
else
printf(" ");
printf("0x%05zx,", classes[i]);
}
printf(R"(
};
static const uptr SizeDelta = %zu;
};
)",
headerSize);
}
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