luau/CLI/Reduce.cpp
2022-08-11 13:42:54 -07:00

512 lines
14 KiB
C++

// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#include "Luau/Ast.h"
#include "Luau/Common.h"
#include "Luau/Parser.h"
#include "Luau/Transpiler.h"
#include "FileUtils.h"
#include <algorithm>
#include <stdio.h>
#include <string>
#include <string_view>
#include <queue>
#define VERBOSE 0 // 1 - print out commandline invocations. 2 - print out stdout
#ifdef _WIN32
const auto popen = &_popen;
const auto pclose = &_pclose;
#endif
using namespace Luau;
enum class TestResult
{
BugFound, // We encountered the bug we are trying to isolate
NoBug, // We did not encounter the bug we are trying to isolate
};
struct Enqueuer : public AstVisitor
{
std::queue<AstStatBlock*>* queue;
explicit Enqueuer(std::queue<AstStatBlock*>* queue)
: queue(queue)
{
LUAU_ASSERT(queue);
}
bool visit(AstStatBlock* block) override
{
queue->push(block);
return false;
}
};
struct Reducer
{
Allocator allocator;
AstNameTable nameTable{allocator};
ParseOptions parseOptions;
ParseResult parseResult;
AstStatBlock* root;
std::string tempScriptName;
std::string appName;
std::vector<std::string> appArgs;
std::string_view searchText;
Reducer()
{
parseOptions.captureComments = true;
}
std::string readLine(FILE* f)
{
std::string line = "";
char buffer[256];
while (fgets(buffer, sizeof(buffer), f))
{
auto len = strlen(buffer);
line += std::string(buffer, len);
if (buffer[len - 1] == '\n')
break;
}
return line;
}
void writeTempScript(bool minify = false)
{
std::string source = transpileWithTypes(*root);
if (minify)
{
size_t pos = 0;
do
{
pos = source.find("\n\n", pos);
if (pos == std::string::npos)
break;
source.erase(pos, 1);
} while (true);
}
FILE* f = fopen(tempScriptName.c_str(), "w");
if (!f)
{
printf("Unable to open temp script to %s\n", tempScriptName.c_str());
exit(2);
}
for (const HotComment& comment : parseResult.hotcomments)
fprintf(f, "--!%s\n", comment.content.c_str());
auto written = fwrite(source.data(), 1, source.size(), f);
if (written != source.size())
{
printf("??? %zu %zu\n", written, source.size());
printf("Unable to write to temp script %s\n", tempScriptName.c_str());
exit(3);
}
fclose(f);
}
int step = 0;
std::string escape(const std::string& s)
{
std::string result;
result.reserve(s.size() + 20); // guess
result += '"';
for (char c : s)
{
if (c == '"')
result += '\\';
result += c;
}
result += '"';
return result;
}
TestResult run()
{
writeTempScript();
std::string command = appName + " " + escape(tempScriptName);
for (const auto& arg : appArgs)
command += " " + escape(arg);
#if VERBOSE >= 1
printf("running %s\n", command.c_str());
#endif
TestResult result = TestResult::NoBug;
++step;
printf("Step %4d...\n", step);
FILE* p = popen(command.c_str(), "r");
while (!feof(p))
{
std::string s = readLine(p);
#if VERBOSE >= 2
printf("%s", s.c_str());
#endif
if (std::string::npos != s.find(searchText))
{
result = TestResult::BugFound;
break;
}
}
pclose(p);
return result;
}
std::vector<AstStat*> getNestedStats(AstStat* stat)
{
std::vector<AstStat*> result;
auto append = [&](AstStatBlock* block) {
if (block)
result.insert(result.end(), block->body.data, block->body.data + block->body.size);
};
if (auto block = stat->as<AstStatBlock>())
append(block);
else if (auto ifs = stat->as<AstStatIf>())
{
append(ifs->thenbody);
if (ifs->elsebody)
{
if (AstStatBlock* elseBlock = ifs->elsebody->as<AstStatBlock>())
append(elseBlock);
else if (AstStatIf* elseIf = ifs->elsebody->as<AstStatIf>())
{
auto innerStats = getNestedStats(elseIf);
result.insert(end(result), begin(innerStats), end(innerStats));
}
else
{
printf("AstStatIf's else clause can have more statement types than I thought\n");
LUAU_ASSERT(0);
}
}
}
else if (auto w = stat->as<AstStatWhile>())
append(w->body);
else if (auto r = stat->as<AstStatRepeat>())
append(r->body);
else if (auto f = stat->as<AstStatFor>())
append(f->body);
else if (auto f = stat->as<AstStatForIn>())
append(f->body);
else if (auto f = stat->as<AstStatFunction>())
append(f->func->body);
else if (auto f = stat->as<AstStatLocalFunction>())
append(f->func->body);
return result;
}
// Move new body data into allocator-managed storage so that it's safe to keep around longterm.
AstStat** reallocateStatements(const std::vector<AstStat*>& statements)
{
AstStat** newData = static_cast<AstStat**>(allocator.allocate(sizeof(AstStat*) * statements.size()));
std::copy(statements.data(), statements.data() + statements.size(), newData);
return newData;
}
// Semiopen interval
using Span = std::pair<size_t, size_t>;
// Generates 'chunks' semiopen spans of equal-ish size to span the indeces running from 0 to 'size'
// Also inverses.
std::vector<std::pair<Span, Span>> generateSpans(size_t size, size_t chunks)
{
if (size <= 1)
return {};
LUAU_ASSERT(chunks > 0);
size_t chunkLength = std::max<size_t>(1, size / chunks);
std::vector<std::pair<Span, Span>> result;
auto append = [&result](Span a, Span b) {
if (a.first == a.second && b.first == b.second)
return;
else
result.emplace_back(a, b);
};
size_t i = 0;
while (i < size)
{
size_t end = std::min(i + chunkLength, size);
append(Span{0, i}, Span{end, size});
i = end;
}
i = 0;
while (i < size)
{
size_t end = std::min(i + chunkLength, size);
append(Span{i, end}, Span{size, size});
i = end;
}
return result;
}
// Returns the statements of block within span1 and span2
// Also has the hokey restriction that span1 must come before span2
std::vector<AstStat*> prunedSpan(AstStatBlock* block, Span span1, Span span2)
{
std::vector<AstStat*> result;
for (size_t i = span1.first; i < span1.second; ++i)
result.push_back(block->body.data[i]);
for (size_t i = span2.first; i < span2.second; ++i)
result.push_back(block->body.data[i]);
return result;
}
// returns true if anything was culled plus the chunk count
std::pair<bool, size_t> deleteChildStatements(AstStatBlock* block, size_t chunkCount)
{
if (block->body.size == 0)
return {false, chunkCount};
do
{
auto permutations = generateSpans(block->body.size, chunkCount);
for (const auto& [span1, span2] : permutations)
{
auto tempStatements = prunedSpan(block, span1, span2);
AstArray<AstStat*> backupBody{tempStatements.data(), tempStatements.size()};
std::swap(block->body, backupBody);
TestResult result = run();
if (result == TestResult::BugFound)
{
// The bug still reproduces without the statements we've culled. Commit.
block->body.data = reallocateStatements(tempStatements);
return {true, std::max<size_t>(2, chunkCount - 1)};
}
else
{
// The statements we've culled are critical for the reproduction of the bug.
// TODO try promoting its contents into this scope
std::swap(block->body, backupBody);
}
}
chunkCount *= 2;
} while (chunkCount <= block->body.size);
return {false, block->body.size};
}
bool deleteChildStatements(AstStatBlock* b)
{
bool result = false;
size_t chunkCount = 2;
while (true)
{
auto [workDone, newChunkCount] = deleteChildStatements(b, chunkCount);
if (workDone)
{
result = true;
chunkCount = newChunkCount;
continue;
}
else
break;
}
return result;
}
bool tryPromotingChildStatements(AstStatBlock* b, size_t index)
{
std::vector<AstStat*> tempStats(b->body.data, b->body.data + b->body.size);
AstStat* removed = tempStats.at(index);
tempStats.erase(begin(tempStats) + index);
std::vector<AstStat*> nestedStats = getNestedStats(removed);
tempStats.insert(begin(tempStats) + index, begin(nestedStats), end(nestedStats));
AstArray<AstStat*> tempArray{tempStats.data(), tempStats.size()};
std::swap(b->body, tempArray);
TestResult result = run();
if (result == TestResult::BugFound)
{
b->body.data = reallocateStatements(tempStats);
return true;
}
else
{
std::swap(b->body, tempArray);
return false;
}
}
// We live with some weirdness because I'm kind of lazy: If a statement's
// contents are promoted, we try promoting those prometed statements right
// away. I don't think it matters: If we can delete a statement and still
// exhibit the bug, we should do so. The order isn't so important.
bool tryPromotingChildStatements(AstStatBlock* b)
{
size_t i = 0;
while (i < b->body.size)
{
bool promoted = tryPromotingChildStatements(b, i);
if (!promoted)
++i;
}
return false;
}
void walk(AstStatBlock* block)
{
std::queue<AstStatBlock*> queue;
Enqueuer enqueuer{&queue};
queue.push(block);
while (!queue.empty())
{
AstStatBlock* b = queue.front();
queue.pop();
bool result = false;
do
{
result = deleteChildStatements(b);
/* Try other reductions here before we walk into child statements
* Other reductions to try someday:
*
* Promoting a statement's children to the enclosing block.
* Deleting type annotations
* Deleting parts of type annotations
* Replacing subexpressions with ({} :: any)
* Inlining type aliases
* Inlining constants
* Inlining functions
*/
result |= tryPromotingChildStatements(b);
} while (result);
for (AstStat* stat : b->body)
stat->visit(&enqueuer);
}
}
void run(const std::string scriptName, const std::string appName, const std::vector<std::string>& appArgs, std::string_view source,
std::string_view searchText)
{
tempScriptName = scriptName;
if (tempScriptName.substr(tempScriptName.size() - 4) == ".lua")
{
tempScriptName.erase(tempScriptName.size() - 4);
tempScriptName += "-reduced.lua";
}
else
{
this->tempScriptName = scriptName + "-reduced";
}
#if 0
// Handy debugging trick: VS Code will update its view of the file in realtime as it is edited.
std::string wheee = "code " + tempScriptName;
system(wheee.c_str());
#endif
printf("Temp script: %s\n", tempScriptName.c_str());
this->appName = appName;
this->appArgs = appArgs;
this->searchText = searchText;
parseResult = Parser::parse(source.data(), source.size(), nameTable, allocator, parseOptions);
if (!parseResult.errors.empty())
{
printf("Parse errors\n");
exit(1);
}
root = parseResult.root;
const TestResult initialResult = run();
if (initialResult == TestResult::NoBug)
{
printf("Could not find failure string in the unmodified script! Check your commandline arguments\n");
exit(2);
}
walk(root);
writeTempScript(/* minify */ true);
printf("Done! Check %s\n", tempScriptName.c_str());
}
};
[[noreturn]] void help(const std::vector<std::string_view>& args)
{
printf("Syntax: %s script application \"search text\" [arguments]\n", args[0].data());
exit(1);
}
int main(int argc, char** argv)
{
const std::vector<std::string_view> args(argv, argv + argc);
if (args.size() < 4)
help(args);
for (int i = 1; i < args.size(); ++i)
{
if (args[i] == "--help")
help(args);
}
const std::string scriptName = argv[1];
const std::string appName = argv[2];
const std::string searchText = argv[3];
const std::vector<std::string> appArgs(begin(args) + 4, end(args));
std::optional<std::string> source = readFile(scriptName);
if (!source)
{
printf("Could not read source %s\n", argv[1]);
exit(1);
}
Reducer reducer;
reducer.run(scriptName, appName, appArgs, *source, searchText);
}