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Simplified LLVM grammar (combined globalDecl and globalDef) (#567)
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Added support for parsing external globals (as non-dets).
Added support for referencing other globals in initializers (first we parse the declarations and then the initializers).
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@ThomasHaas
ThomasHaas authored Nov 13, 2023
1 parent 06462cb commit 33fb46f
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Showing 2 changed files with 59 additions and 33 deletions.
10 changes: 2 additions & 8 deletions dartagnan/src/main/antlr4/LLVMIR.g4
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,6 @@ topLevelEntity:
| moduleAsm
| typeDef
| comdatDef
| globalDecl
| globalDef
| indirectSymbolDef
| funcDecl
Expand All @@ -53,14 +52,9 @@ comdatDef:
| 'nodeduplicate'
| 'samesize'
);
globalDecl:
GlobalIdent '=' externalLinkage preemption? visibility? dllStorageClass? threadLocal?
unnamedAddr? addrSpace? externallyInitialized? immutable type (
',' globalField
)* (',' metadataAttachment)* funcAttribute*;
globalDef:
GlobalIdent '=' internalLinkage? preemption? visibility? dllStorageClass? threadLocal?
unnamedAddr? addrSpace? externallyInitialized? immutable type constant (
GlobalIdent '=' (externalLinkage | internalLinkage)? preemption? visibility? dllStorageClass? threadLocal?
unnamedAddr? addrSpace? externallyInitialized? immutable type constant? (
',' globalField
)* (',' metadataAttachment)* funcAttribute*;

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82 changes: 57 additions & 25 deletions dartagnan/src/main/java/com/dat3m/dartagnan/parsers/program/visitors/VisitorLlvm.java
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Original file line number Diff line number Diff line change
Expand Up @@ -73,11 +73,15 @@ public Program buildProgram() {

@Override
public Expression visitCompilationUnit(CompilationUnitContext ctx) {
// Create the metadata mapping beforehand, so that instructions can get all attachments
// Create the metadata mapping beforehand, so that instructions can get all attachments.
// Also parse all type definitions.
for (final TopLevelEntityContext entity : ctx.topLevelEntity()) {
if (entity.metadataDef() != null) {
entity.accept(this);
}
if (entity.typeDef() != null) {
entity.accept(this);
}
}

// Declare all globals (functions and variables).
Expand All @@ -88,20 +92,21 @@ public Expression visitCompilationUnit(CompilationUnitContext ctx) {
if (entity.funcDef() != null) {
visitFuncHeader(entity.funcDef().funcHeader());
}
// FIXME: Declare global variables
if (entity.globalDef() != null) {
visitGlobalDeclaration(entity.globalDef());
}
}

// Parse global definitions after declarations.
for (final TopLevelEntityContext entity : ctx.topLevelEntity()) {
//FIXME: We need to parse the declaration of globals (similar to func headers) first
// because the initializer may refer to other globals.
if (entity.globalDecl() != null || entity.globalDef() != null || entity.typeDef() != null) {
if (entity.globalDef() != null) {
entity.accept(this);
}
}

// Parse definitions
for (final TopLevelEntityContext entity : ctx.topLevelEntity()) {
if (entity.metadataDef() == null &&
entity.globalDecl() == null &&
entity.globalDef() == null &&
entity.typeDef() == null &&
entity.funcDecl() == null) {
Expand Down Expand Up @@ -164,7 +169,7 @@ public Expression visitFuncDef(FuncDefContext ctx) {
for (final BasicBlockContext basicBlockContext : ctx.funcBody().basicBlock()) {
block = getBlock(basicBlockContext.LabelIdent());
final List<Metadata> blockHeaderMetadata;
if (basicBlockContext.instruction().size() > 0) {
if (!basicBlockContext.instruction().isEmpty()) {
blockHeaderMetadata = parseMetadataAttachment(basicBlockContext.instruction(0).metadataAttachment());
} else {
blockHeaderMetadata = parseMetadataAttachment(basicBlockContext.terminator().metadataAttachment());
Expand Down Expand Up @@ -232,31 +237,32 @@ private Block getBlock(TerminalNode node) {
return getBlock(labelName);
}

@Override
public Expression visitGlobalDecl(GlobalDeclContext ctx) {
checkSupport(false, "Declared but undefined constants are not supported", ctx);
// FIXME: See <visitGlobalDef> on how to handle this
return null;
}

@Override
public Expression visitGlobalDef(GlobalDefContext ctx) {
public void visitGlobalDeclaration(GlobalDefContext ctx) {
final String name = globalIdent(ctx.GlobalIdent());
check(!constantMap.containsKey(name), "Redefined constant in %s.", ctx);
final Type type = parseType(ctx.type());
final int size = types.getMemorySizeInBytes(type);
check(!constantMap.containsKey(name), "Redeclared constant in %s.", ctx);
final int size = types.getMemorySizeInBytes(parseType(ctx.type()));
final MemoryObject globalObject = program.getMemory().allocate(size, true);
globalObject.setCVar(name);
if (ctx.threadLocal() != null) {
globalObject.setIsThreadLocal(true);
}

//TODO: Merge GlobalDef/GlobalDecl in the LLVM grammar into one single rule with an optional "constant".
// If no constant is provided, we can generate a nondeterministic value
final Expression value = checkExpression(type, ctx.constant());
setInitialMemoryFromConstant(globalObject, 0, value);
// TODO: mark the global as constant, if possible.
constantMap.put(name, globalObject);
}

@Override
public Expression visitGlobalDef(GlobalDefContext ctx) {
final String name = globalIdent(ctx.GlobalIdent());
final MemoryObject globalObject = (MemoryObject) constantMap.get(name);
final Type type = parseType(ctx.type());
final boolean isExternal = ctx.externalLinkage() != null;
final boolean hasInitializer = ctx.constant() != null;

check (!(isExternal && hasInitializer), "External global cannot have initializer: %s", ctx);
check (isExternal || hasInitializer, "Global without initializer; %s", ctx);

final Expression value = hasInitializer ? checkExpression(type, ctx.constant()) : makeNonDetOfType(type);
setInitialMemoryFromConstant(globalObject, 0, value);
return null;
}

Expand Down Expand Up @@ -295,7 +301,7 @@ private Block getBlock(String label) {
}

private List<Metadata> parseMetadataAttachment(List<MetadataAttachmentContext> metadataAttachmentContexts) {
if (metadataAttachmentContexts.size() == 0) {
if (metadataAttachmentContexts.isEmpty()) {
return List.of();
}

Expand Down Expand Up @@ -1271,6 +1277,32 @@ public Expression visitFilenameField(FilenameFieldContext ctx) {
// ----------------------------------------------------------------------------------------------------------------
// Helpers

public Expression makeNonDetOfType(Type type) {
if (type instanceof ArrayType arrayType) {
final List<Expression> entries = new ArrayList<>(arrayType.getNumElements());
for (int i = 0; i < arrayType.getNumElements(); i++) {
entries.add(makeNonDetOfType(arrayType.getElementType()));
}
return expressions.makeArray(arrayType.getElementType(), entries, true);
} else if (type instanceof AggregateType structType) {
final List<Expression> elements = new ArrayList<>(structType.getDirectFields().size());
for (Type fieldType : structType.getDirectFields()) {
elements.add(makeNonDetOfType(fieldType));
}
return expressions.makeConstruct(elements);
} else if (type instanceof IntegerType intType) {
final INonDet value = new INonDet(program.getConstants().size(), intType, true);
value.setMin(intType.getMinimumValue(true));
value.setMax(intType.getMaximumValue(true));
program.addConstant(value);
return value;
} else if (type instanceof BooleanType) {
return new BNonDet(types.getBooleanType());
} else {
throw new UnsupportedOperationException("Cannot create non-deterministic value of type " + type);
}
}

private void check(boolean condition, String message, ParserRuleContext context) {
if (!condition) {
throw new ParsingException(String.format(message, context.getText()));
Expand Down

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