Fix potential out of bounds scope allocation

[SuperFola]

Description

It is possible for ArkScript to create too many variables (more than 8192 at once), which results in a segfault. This aims to fix this bug, but I am aware that it will likely hinder performance.

Checklist

• [ ] I have read the Contributor guide
• [ ] My code follows the style guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have updated the documentation if needed
• [ ] I have added tests that prove my fix/feature is working
• [ ] New and existing tests pass locally with my changes

[github-actions[bot]]

Static analysis report

Lizard report

Listing only functions with cyclomatic complexity >= 15 or NLOC >= 100 or parameters >= 6.

Report about files you didn't modify in this PR

Filename	Start line:end line	Function name	Parameters	NLOC	CCN
src/arkreactor/VM/VM.cpp	450:1903	Ark::VM::safeRun	3	1217	249
src/arkreactor/Compiler/Macros/Processor.cpp	239:617	Ark::internal::MacroProcessor::evaluate	3	355	125
src/arkreactor/Compiler/BytecodeReader.cpp	274:557	Ark::BytecodeReader::display	4	241	95
src/arkreactor/Exceptions.cpp	87:297	Ark::Diagnostics::makeContext	9	152	61
src/arkreactor/Compiler/Lowerer/ASTLowerer.cpp	539:710	Ark::internal::ASTLowerer::handleCalls	4	130	42
src/arkscript/JsonCompiler.cpp	27:260	JsonCompiler::_compile	1	200	36
include/Ark/Compiler/AST/Parser.hpp	107:196	Ark::internal::ARK_APIParser::string	0	87	32
src/arkreactor/Compiler/NameResolution/NameResolutionPass.cpp	162:273	Ark::internal::NameResolutionPass::visitKeyword	3	93	32
src/arkscript/main.cpp	23:352	main	2	284	31
src/arkreactor/Compiler/AST/Node.cpp	189:287	Ark::internal::Node::repr	0	84	28
src/arkreactor/Compiler/Lowerer/ASTLowerer.cpp	138:241	Ark::internal::ASTLowerer::compileExpression	4	85	27
src/arkreactor/Compiler/Macros/Processor.cpp	102:185	Ark::internal::MacroProcessor::processNode	3	61	27
src/arkreactor/Compiler/AST/Node.cpp	289:362	Ark::internal::Node::debugPrint	1	64	24
src/arkreactor/TypeChecker.cpp	110:194	Ark::types::generateError	5	72	24
src/arkreactor/Compiler/NameResolution/NameResolutionPass.cpp	54:160	Ark::internal::NameResolutionPass::visit	2	87	23
src/arkreactor/Compiler/AST/Parser.cpp	292:427	Ark::internal::Parser::import_	0	109	23
src/arkreactor/Compiler/Lowerer/ASTLowerer.cpp	267:326	Ark::internal::ASTLowerer::compileListInstruction	3	49	22
src/arkreactor/VM/VM.cpp	2022:2131	Ark::VM::backtrace	3	94	22
include/utf8.hpp	138:184	utf8::isValid	1	44	21
src/arkreactor/Compiler/AST/Optimizer.cpp	33:83	Ark::internal::Optimizer::countAndPruneDeadCode	1	42	20
src/arkscript/REPL/Utils.cpp	52:184	Ark::internal::getColorPerKeyword	0	110	19
src/arkreactor/TypeChecker.cpp	28:108	Ark::types::displayContract	4	70	19
src/arkreactor/Compiler/NameResolution/StaticScope.cpp	68:109	Ark::internal::NamespaceScope::get	2	32	18
src/arkreactor/VM/Value.cpp	72:132	Ark::Value::toString	1	48	18
src/arkreactor/Compiler/Macros/Executors/Function.cpp	16:88	Ark::internal::FunctionExecutor::applyMacro	2	55	17
include/Ark/Compiler/AST/Predicates.hpp	132:156	Ark::internal::IsSymbol::operator ( )	1	24	16
src/arkscript/Formatter.cpp	168:224	Formatter::format	3	53	16
src/arkreactor/Compiler/Macros/Processor.cpp	699:738	Ark::internal::MacroProcessor::isConstEval	1	35	16
src/arkscript/Formatter.cpp	274:315	Formatter::formatFunction	2	35	15
src/arkreactor/Compiler/Lowerer/ASTLowerer.cpp	78:94	Ark::internal::ASTLowerer::nodeProducesOutput	1	13	15
src/arkreactor/Compiler/IntermediateRepresentation/IROptimizer.cpp	12:198	Ark::internal::IROptimizer::IROptimizer	1	163	4
src/arkreactor/Exceptions.cpp	299:310	Ark::Diagnostics::helper	9	11	2

---

CppCheck report

Filename	Line	Type	Description
include/Ark/VM/VM.inl	250	style	Variable 'maybe_value_ptr' can be declared as pointer to const

Report files about files you didn't modify in this PR

Filename	Line	Type	Description
include/Ark/VM/Value/Procedure.hpp	43	style	Class 'Procedure' has a constructor with 1 argument that is not explicit.
include/Ark/VM/Value/Procedure.hpp	51	style	Class 'Procedure' has a constructor with 1 argument that is not explicit.
include/Ark/Logger.hpp	77	performance	Function parameter 'data' should be passed by const reference.
src/arkreactor/Builtins/IO.cpp	81	style	Parameter 'n' can be declared as reference to const
src/arkreactor/Builtins/IO.cpp	105	style	Parameter 'n' can be declared as reference to const
src/arkreactor/Compiler/BytecodeReader.cpp	440	style	struct member 'Arg::kind' is never used.
src/arkreactor/Compiler/Lowerer/ASTLowerer.cpp	243	style	Parameter 'x' can be declared as reference to const
src/arkreactor/Compiler/Lowerer/ASTLowerer.cpp	493	style	Parameter 'x' can be declared as reference to const
src/arkreactor/Compiler/NameResolution/NameResolutionPass.cpp	142	style	Consider using std::find_if algorithm instead of a raw loop.
src/arkreactor/VM/State.cpp	187	style	Consider using std::any_of, std::all_of, std::none_of algorithm instead of a raw loop.
src/arkreactor/VM/Value/Procedure.cpp	15	performance	Variable 'm_procedure' is assigned in constructor body. Consider performing initialization in initialization list.

[coveralls]

coverage: 86.694% (-0.02%) from 86.717% when pulling 36aea3591f46c37e4e4b501d203ccc54d39178bd on fix/scope-bad-alloc into 66d9c291c0532985a9f57fa1d0e2e00fec792b3d on dev.

[github-actions[bot]]

Fuzzing report

/usr/local/bin/afl-whatsup status check tool for afl-fuzz by Michal Zalewski

Summary stats

    Fuzzers alive : 0
   Dead or remote : 1 (included in stats)
   Total run time : 5 minutes, 0 seconds
      Total execs : 41 thousands
 Cumulative speed : 137 execs/sec
    Pending items : 147 faves, 1131 total
 Coverage reached : 12.92%
    Crashes saved : 0
      Hangs saved : 0

Cycles without finds : 0 Time without finds : 0

[+] Captured 47650 tuples (map size 215762, highest value 255, total values 387050435) in '/dev/null'. [+] A coverage of 47650 edges were achieved out of 215808 existing (22.08%) with 1141 input files.

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #559 will degrade performances by 3.71%

_{Comparing fix/scope-bad-alloc (36aea35) with dev (66d9c29)}

Summary

❌ 4 regressions
✅ 13 untouched benchmarks

:warning: Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	ackermann	309.9 ms	321.8 ms	-3.71%
❌	binary_trees	4.7 s	4.8 s	-3.17%
❌	create_closure	4.5 ms	4.6 ms	-1.11%
❌	fibonacci	27.8 ms	28.4 ms	-2.13%

[SuperFola]

Adding the check inside VM::store is deemed too expensive; perhaps changing the backing storage data structure might help?

It still needs to be contiguous though, so maybe we should allocate a few kernel pages via mmap, and mark them used as we go, like an arena allocator would do?

[SuperFola]

Reproduction:

(let foo (fun (a b c d e f g h i j k l m n o p q) {
  (foo a b c d e f g h i j k l m n o p q)
  1 }))
(foo 1 2 3 4 5 6 7 9 1 2 3 4 5 6 7 8 9)

Fixing this bug heavily impacts performance, more than I'm willing to accept.