Massive SemA/BC refactoring to support better type systems. Read on for more.
The previous compiler had a simple pipeline, best outlined as:
(1) Parsing and name binding -> AST
(2) Storage allocation -> AST
(3) Semantic Analysis (SemA) -> AST
(4) Bytecode Compilation (BC) -> Code
This pipeline, unfortunately, had two problems. First, name binding cannot be performed in one pass if we wish to have multi-file support in the form of modules. Name binding must be two-pass.
Second, because SemA was only capable of annotating AST nodes with a single type, most coercion work had to be duplicated in the BC phase, as coercion was not explicit in the SemA output. This made introducing new type rules extremely difficult, and all but precluded concepts like operator overloading (or overloading at all).
This patch rewrites most of Keima's backend. Of interest are the following changes:
(1) CompileContext has been refactored around future multi-file support.
(2) Parsing no longer performs any name binding.
(3) The grammar for type-and-name has been changed from:
(Label | Identifier)? Identifier
to:
Type? Identifier
where:
Type ::= OldType | NewType
OldType ::= Label
NewType ::= Identifier (. NewType)*
Although we do not implement the full production for Type yet, this
distinction is important. A type identifier is now affixed to the AST
as an Expression (right now, always a NameProxy), so it can fully
participate in name binding.
(4) Immediately after parsing, the AST goes through a NamePopulation phase.
This phase creates Scope objects for every scope which declares a name,
and if those names are declaring types or functions, a Symbol is created
and entered into the scope. Symbols entirely replace the old BoundName
classes.
(5) After NamePopulation comes NameBinding. This phase performs three steps:
(a) Links Scope objects together, to form a tree.
(b) Binds any free name to an existing name in the scope chain.
(c) Creates and registers any Symbols for names which have not yet been
added to the scope (for example, local variables).
In accordance, all "allocation" and "binding" concepts have been removed
from Scopes, which are now lightweight container classes.
(6) SemA now generates bytecode for each statement in the AST. Expression
compilation is performed via a separate mechanism called HIR (High-level
Intermediate Representation). To analyze an expression, SemA will walk
the AST, and produce a HIR object for each node. HIR is typed, and SemA
may insert coercion nodes, or even expand an AST node into multiple HIR
nodes. The result of evaluating an expression in SemA is therefore the
the root of a HIR tree, which SemA then sends to the HIRTranslator, which
performs bytecode generation.
As before, SemA still performs full semantic analysis. However, not it
also produces each function's bytecode.
This split allows us to decompose potentially complex semantics into
a more fine-grained, AST-like structure, which can have very simple
code-generation logic. For example, (1.0 + 5) might look like:
HAdd(HFloat(1.0), HConvert(HInteger(5), <Float>))
As part of this decomposition, many opcodes have been removed. Rather than
using typed jumps, we now expand jumps into longer tests. For example:
jge.f <label>
becomes:
ge.f
cvt.f2b
jt <label>
This simplifies the pipeline, and JITs should be able to melt the added
work away.
HIR is not used at a statement level, and HIR does not have any concept
of control-flow.
(7) The old BytecodeCompiler has been removed, as its work is now split
between SemA and HIRTranslator.
In addition, some minor refactorings have taken place:
(1) Opcodes.tbl no longer hardcodes numbers (aaah).
(2) Type has been split into smaller, typed structs.
(3) BytecodeEmitter no longer relies on Pools or RootScopes.
(4) SemA is now responsible for variable/storage allocation.
(5) Native table are now global, rather than per-module. As such, native
declarations now result in a Native object (which still requires a
CALLNATIVE opcode), which is an index into the global table. Natives
must be bound globally. This is in preparation for module support.
(6) Publics are no longer tracked, but rather registered via a global
callback upon module load. This callback can be set by embedders. This
is in preparation for multi-file support.
(7) The BytecodeEmitter now performs Symbol allocations itself, and it
also generates Code objects itself, which removes a good deal of
complexity.
Finally, a test harness has been added. This harness is a python script which finds *.test files, recursively, in the tests folder. For each file it runs the corresponding .sp. The contents of the .test file must match stdout+stderr.
1 /* vim: set ts=4 sw=4 tw=99 et:
3 * Copyright (C) 2012 David Anderson
5 * This file is part of JITCraft.
7 * JITCraft is free software: you can redistribute it and/or modify it under
8 * the terms of the GNU General Public License as published by the Free
9 * Software Foundation, either version 3 of the License, or (at your option)
12 * Foobar is distributed in the hope that it will be useful, but WITHOUT ANY
13 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License along with
17 * JITCraft. If not, see http://www.gnu.org/licenses/.
21 #include "StringPool.h"
22 #include "TypeManager.h"
23 #include "GlobalRoots.h"
24 #include "AllocatorPolicies.h"
26 #include "NativeTable.h"
27 #include "Spaces-inl.h"
32 Zone *ke::SingleThreadedZone;
34 void * const NullAddress::Sentinel = NULL;
37 : stack_(thisFromCtor()),
38 heap_(thisFromCtor()),
44 hasPendingException_(false),
60 if (!stack_.initialize())
62 if (!heap_.initialize())
65 symbols_ = new StringPool(this);
66 if (!symbols_ || !symbols_->initialize())
69 globalRoots_ = new GlobalRoots(this);
70 if (!globalRoots_ || !globalRoots_->initialize())
73 nativeTable_ = new NativeTable(this);
74 if (!nativeTable_ || !nativeTable_->initialize())
77 maps_[MapKind_Meta] = heap_.metaMap();
78 if ((maps_[MapKind_Type] = allocateMap(MapKind_Type, sizeof(Map))) == NULL)
80 if ((maps_[MapKind_FunctionType] = allocateMap(MapKind_FunctionType, sizeof(Map))) == NULL)
82 if ((maps_[MapKind_StructType] = allocateMap(MapKind_StructType, sizeof(Map))) == NULL)
84 if ((maps_[MapKind_FixedArray] = allocateMap(MapKind_FixedArray, sizeof(Map))) == NULL)
86 if ((maps_[MapKind_ByteArray] = allocateMap(MapKind_ByteArray, sizeof(Map))) == NULL)
88 if ((maps_[MapKind_Code] = allocateMap(MapKind_Code, sizeof(Map))) == NULL)
90 if ((maps_[MapKind_Reference] = allocateMap(MapKind_Reference, sizeof(Map))) == NULL)
92 if ((maps_[MapKind_MetaArray] = allocateMap(MapKind_MetaArray, sizeof(Map))) == NULL)
94 if ((maps_[MapKind_MetaStruct] = allocateMap(MapKind_MetaStruct, sizeof(Map))) == NULL)
96 if ((maps_[MapKind_MetaEnvironment] = allocateMap(MapKind_MetaEnvironment, sizeof(Map))) == NULL)
98 if ((maps_[MapKind_Module] = allocateMap(MapKind_Module, sizeof(Map))) == NULL)
100 if ((maps_[MapKind_Function] = allocateMap(MapKind_Function, sizeof(Map))) == NULL)
102 if ((maps_[MapKind_String] = allocateMap(MapKind_String, sizeof(Map))) == NULL)
104 if ((maps_[MapKind_Native] = allocateMap(MapKind_Native, sizeof(Map))) == NULL)
106 if ((maps_[MapKind_Descriptor] = allocateMap(MapKind_Descriptor, sizeof(Map))) == NULL)
108 if ((maps_[MapKind_Box] = allocateMap(MapKind_Box, sizeof(Map))) == NULL)
110 if ((maps_[MapKind_FreeRegion] = allocateMap(MapKind_FreeRegion, sizeof(Map))) == NULL)
112 if ((maps_[MapKind_EnvironmentSlotDescriptorArray] =
113 allocateMap(MapKind_EnvironmentSlotDescriptorArray, sizeof(Map))) == NULL)
118 types_ = new TypeManager(this);
119 if (!types_ || !types_->initialize())
122 // Create the cached array maps for generic arrays. This is for the API
123 // version of Invoke(), which needs to make arrays very quickly from C++.
125 // Generic "cell" array (contents do not matter, just non-gc things).
126 Local<Type> type(this, types_->getPrimitive(PrimitiveType_Int32));
130 type = types_->newExternalArray(type);
136 externalGenericArrayMap_ = ArrayMap::Attach(this, type);
137 if (!externalGenericArrayMap_)
141 type = types_->getPrimitive(PrimitiveType_Char);
145 type = types_->newExternalArray(type);
151 externalCharArrayMap_ = ArrayMap::Attach(this, type);
152 if (!externalCharArrayMap_)
161 Zone::allocateMap(MapKind kind, size_t bytes, MapKind parent)
163 assert(maps_[parent]);
164 Map *map = heap_.allocateMap(kind, bytes);
167 map->init(maps_[parent]);
172 Zone::accept(VirtualObjectVisitor *visitor)
174 for (unsigned i = 0; i < MapKinds_Total; i++)
175 visitor->visit(maps_[i].address());
176 visitor->visit(externalCharArrayMap_.address());
177 visitor->visit(externalGenericArrayMap_.address());
178 types()->accept(visitor);
180 Local<Object> *local = lastLocalRoot_;
182 visitor->visit(local->address());
183 local = local->prev();
186 globalRoots_->accept(visitor);
187 rootScopes_.accept(visitor);
188 nativeTable_->accept(visitor);
190 stack_.accept(visitor);
194 Zone::makeSymbol(const char *str, size_t length)
196 return symbols_->add(str, length);
200 Zone::makeSymbol(const char *str)
202 return makeSymbol(str, strlen(str));
206 Zone::hasPendingException()
208 return hasPendingException_;
212 Zone::reportOutOfMemory()
218 Zone::reportError(Message message, ...)
221 va_start(ap, message);
222 reportErrorVA(message, ap);
226 #if defined(_MSC_VER)
227 # define VA_COPY(to, from) to = from
229 # define VA_COPY(to, from) va_copy(to, from)
233 BuildErrorMessage(const char *format, va_list ap)
238 // We over-allocate and zero terminate ahead of time, since LIBCRT's
239 // version of vsnprintf is screwy.
241 char *buffer = (char *)calloc(size + 1, 1);
246 int r = vsnprintf(buffer, size, format, use);
248 if (r > -1 && size_t(r) < size)
251 #if defined(_MSC_VER)
256 size = size_t(r) + 1;
262 if ((buffer = (char *)calloc(size + 1, 1)) == NULL)
270 Zone::reportErrorVA(Message message, va_list ap)
272 char *report = BuildErrorMessage(Messages[message].format, ap);
279 // Reporters can re-enter. When we start having actual exception
280 // objects that can be caught and inspected, this code will have to
281 // save and restore the exception state.
282 reporter_->onUncaughtException(report);
285 hasPendingException_ = true;
291 Zone::beginCompilationErrors(const char *file)
294 reporter_->beginCompilationErrors(file);
298 Zone::reportCompilationError(Message message, unsigned line, unsigned col, va_list ap)
300 char *report = BuildErrorMessage(Messages[message].format, ap);
307 // Reporters can re-enter. When we start having actual exception
308 // objects that can be caught and inspected, this code will have to
309 // save and restore the exception state.
310 reporter_->reportCompilationError(report, line, col);
317 Zone::endCompilationErrors()
320 reporter_->endCompilationErrors();
324 Zone::installErrorReporter(Ke::IMessageReporter *reporter)
326 reporter_ = reporter;
330 ZoneAllocatorPolicy::reportOutOfMemory()
332 ZONE()->reportOutOfMemory();
336 ZoneAllocatorPolicy::reportAllocationOverflow()
338 ZONE()->reportAllocationOverflow();
342 Zone::reportAllocationOverflow()
344 reportError(Message_AllocationOverflow);
348 Zone::clearPendingException()
350 hasPendingException_ = false;
354 Zone::setPublicFunctionListener(Ke::IPublicFunctionListener *listener)
356 publicFunctionListener_ = listener;
359 AutoRooted::AutoRooted(Zone *zone)
361 prev_(*zone->lastSpecialRoot())
363 *zone->lastSpecialRoot() = this;
366 AutoRooted::~AutoRooted()
368 *zone_->lastSpecialRoot() = prev_;