Files
clang-p2996/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
Sirui Mu 8ba62fdb3d [CIR] Function calls with aggregate arguments and return values (#143377)
This patch updates cir.call operation and allows function calls with
aggregate arguments and return values.

It seems that C++ class support is still at a minimum now. I tried to
make a call to a C++ function with an argument of aggregate type but it
failed because the initialization of C++ class / struct is NYI. I also
tried to inline this part of support into this patch, but the mixed
patch quickly blows in size and becomes unsuitable for review. Thus,
tests for calling functions with aggregate arguments are added only for
C for now.
2025-06-13 16:47:56 +08:00

378 lines
13 KiB
C++

//===- CIRGenExprAggregrate.cpp - Emit CIR Code from Aggregate Expressions ===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Aggregate Expr nodes as CIR code.
//
//===----------------------------------------------------------------------===//
#include "CIRGenBuilder.h"
#include "CIRGenFunction.h"
#include "CIRGenValue.h"
#include "clang/CIR/Dialect/IR/CIRAttrs.h"
#include "clang/AST/Expr.h"
#include "clang/AST/StmtVisitor.h"
#include <cstdint>
using namespace clang;
using namespace clang::CIRGen;
namespace {
class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
CIRGenFunction &cgf;
AggValueSlot dest;
// Calls `fn` with a valid return value slot, potentially creating a temporary
// to do so. If a temporary is created, an appropriate copy into `Dest` will
// be emitted, as will lifetime markers.
//
// The given function should take a ReturnValueSlot, and return an RValue that
// points to said slot.
void withReturnValueSlot(const Expr *e,
llvm::function_ref<RValue(ReturnValueSlot)> fn);
AggValueSlot ensureSlot(mlir::Location loc, QualType t) {
if (!dest.isIgnored())
return dest;
cgf.cgm.errorNYI(loc, "Slot for ignored address");
return dest;
}
public:
AggExprEmitter(CIRGenFunction &cgf, AggValueSlot dest)
: cgf(cgf), dest(dest) {}
/// Given an expression with aggregate type that represents a value lvalue,
/// this method emits the address of the lvalue, then loads the result into
/// DestPtr.
void emitAggLoadOfLValue(const Expr *e);
void emitArrayInit(Address destPtr, cir::ArrayType arrayTy, QualType arrayQTy,
Expr *exprToVisit, ArrayRef<Expr *> args,
Expr *arrayFiller);
/// Perform the final copy to DestPtr, if desired.
void emitFinalDestCopy(QualType type, const LValue &src);
void emitInitializationToLValue(Expr *e, LValue lv);
void emitNullInitializationToLValue(mlir::Location loc, LValue lv);
void Visit(Expr *e) { StmtVisitor<AggExprEmitter>::Visit(e); }
void VisitCallExpr(const CallExpr *e);
void VisitDeclRefExpr(DeclRefExpr *e) { emitAggLoadOfLValue(e); }
void VisitInitListExpr(InitListExpr *e);
void VisitCXXConstructExpr(const CXXConstructExpr *e);
void visitCXXParenListOrInitListExpr(Expr *e, ArrayRef<Expr *> args,
FieldDecl *initializedFieldInUnion,
Expr *arrayFiller);
};
} // namespace
static bool isTrivialFiller(Expr *e) {
if (!e)
return true;
if (isa<ImplicitValueInitExpr>(e))
return true;
if (auto *ile = dyn_cast<InitListExpr>(e)) {
if (ile->getNumInits())
return false;
return isTrivialFiller(ile->getArrayFiller());
}
if (const auto *cons = dyn_cast_or_null<CXXConstructExpr>(e))
return cons->getConstructor()->isDefaultConstructor() &&
cons->getConstructor()->isTrivial();
return false;
}
/// Given an expression with aggregate type that represents a value lvalue, this
/// method emits the address of the lvalue, then loads the result into DestPtr.
void AggExprEmitter::emitAggLoadOfLValue(const Expr *e) {
LValue lv = cgf.emitLValue(e);
// If the type of the l-value is atomic, then do an atomic load.
assert(!cir::MissingFeatures::opLoadStoreAtomic());
emitFinalDestCopy(e->getType(), lv);
}
void AggExprEmitter::emitArrayInit(Address destPtr, cir::ArrayType arrayTy,
QualType arrayQTy, Expr *e,
ArrayRef<Expr *> args, Expr *arrayFiller) {
CIRGenBuilderTy &builder = cgf.getBuilder();
const mlir::Location loc = cgf.getLoc(e->getSourceRange());
const uint64_t numInitElements = args.size();
const QualType elementType =
cgf.getContext().getAsArrayType(arrayQTy)->getElementType();
if (elementType.isDestructedType()) {
cgf.cgm.errorNYI(loc, "dtorKind NYI");
return;
}
const QualType elementPtrType = cgf.getContext().getPointerType(elementType);
const mlir::Type cirElementType = cgf.convertType(elementType);
const cir::PointerType cirElementPtrType =
builder.getPointerTo(cirElementType);
auto begin = builder.create<cir::CastOp>(loc, cirElementPtrType,
cir::CastKind::array_to_ptrdecay,
destPtr.getPointer());
const CharUnits elementSize =
cgf.getContext().getTypeSizeInChars(elementType);
const CharUnits elementAlign =
destPtr.getAlignment().alignmentOfArrayElement(elementSize);
// The 'current element to initialize'. The invariants on this
// variable are complicated. Essentially, after each iteration of
// the loop, it points to the last initialized element, except
// that it points to the beginning of the array before any
// elements have been initialized.
mlir::Value element = begin;
// Don't build the 'one' before the cycle to avoid
// emmiting the redundant `cir.const 1` instrs.
mlir::Value one;
// Emit the explicit initializers.
for (uint64_t i = 0; i != numInitElements; ++i) {
// Advance to the next element.
if (i > 0) {
one = builder.getConstantInt(loc, cgf.PtrDiffTy, i);
element = builder.createPtrStride(loc, begin, one);
}
const Address address = Address(element, cirElementType, elementAlign);
const LValue elementLV = cgf.makeAddrLValue(address, elementType);
emitInitializationToLValue(args[i], elementLV);
}
const uint64_t numArrayElements = arrayTy.getSize();
// Check whether there's a non-trivial array-fill expression.
const bool hasTrivialFiller = isTrivialFiller(arrayFiller);
// Any remaining elements need to be zero-initialized, possibly
// using the filler expression. We can skip this if the we're
// emitting to zeroed memory.
if (numInitElements != numArrayElements &&
!(dest.isZeroed() && hasTrivialFiller &&
cgf.getTypes().isZeroInitializable(elementType))) {
// Advance to the start of the rest of the array.
if (numInitElements) {
one = builder.getConstantInt(loc, cgf.PtrDiffTy, 1);
element = builder.create<cir::PtrStrideOp>(loc, cirElementPtrType,
element, one);
}
// Allocate the temporary variable
// to store the pointer to first unitialized element
const Address tmpAddr = cgf.createTempAlloca(
cirElementPtrType, cgf.getPointerAlign(), loc, "arrayinit.temp");
LValue tmpLV = cgf.makeAddrLValue(tmpAddr, elementPtrType);
cgf.emitStoreThroughLValue(RValue::get(element), tmpLV);
// TODO(CIR): Replace this part later with cir::DoWhileOp
for (unsigned i = numInitElements; i != numArrayElements; ++i) {
cir::LoadOp currentElement = builder.createLoad(loc, tmpAddr);
// Emit the actual filler expression.
const LValue elementLV = cgf.makeAddrLValue(
Address(currentElement, cirElementType, elementAlign), elementType);
if (arrayFiller)
emitInitializationToLValue(arrayFiller, elementLV);
else
emitNullInitializationToLValue(loc, elementLV);
// Advance pointer and store them to temporary variable
one = builder.getConstantInt(loc, cgf.PtrDiffTy, 1);
cir::PtrStrideOp nextElement =
builder.createPtrStride(loc, currentElement, one);
cgf.emitStoreThroughLValue(RValue::get(nextElement), tmpLV);
}
}
}
/// Perform the final copy to destPtr, if desired.
void AggExprEmitter::emitFinalDestCopy(QualType type, const LValue &src) {
// If dest is ignored, then we're evaluating an aggregate expression
// in a context that doesn't care about the result. Note that loads
// from volatile l-values force the existence of a non-ignored
// destination.
if (dest.isIgnored())
return;
cgf.cgm.errorNYI("emitFinalDestCopy: non-ignored dest is NYI");
}
void AggExprEmitter::emitInitializationToLValue(Expr *e, LValue lv) {
const QualType type = lv.getType();
if (isa<ImplicitValueInitExpr, CXXScalarValueInitExpr>(e)) {
const mlir::Location loc = e->getSourceRange().isValid()
? cgf.getLoc(e->getSourceRange())
: *cgf.currSrcLoc;
return emitNullInitializationToLValue(loc, lv);
}
if (isa<NoInitExpr>(e))
return;
if (type->isReferenceType())
cgf.cgm.errorNYI("emitInitializationToLValue ReferenceType");
switch (cgf.getEvaluationKind(type)) {
case cir::TEK_Complex:
cgf.cgm.errorNYI("emitInitializationToLValue TEK_Complex");
break;
case cir::TEK_Aggregate:
cgf.emitAggExpr(e, AggValueSlot::forLValue(lv, AggValueSlot::IsDestructed,
AggValueSlot::IsNotAliased,
AggValueSlot::MayOverlap,
dest.isZeroed()));
return;
case cir::TEK_Scalar:
if (lv.isSimple())
cgf.emitScalarInit(e, cgf.getLoc(e->getSourceRange()), lv);
else
cgf.emitStoreThroughLValue(RValue::get(cgf.emitScalarExpr(e)), lv);
return;
}
}
void AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *e) {
AggValueSlot slot = ensureSlot(cgf.getLoc(e->getSourceRange()), e->getType());
cgf.emitCXXConstructExpr(e, slot);
}
void AggExprEmitter::emitNullInitializationToLValue(mlir::Location loc,
LValue lv) {
const QualType type = lv.getType();
// If the destination slot is already zeroed out before the aggregate is
// copied into it, we don't have to emit any zeros here.
if (dest.isZeroed() && cgf.getTypes().isZeroInitializable(type))
return;
if (cgf.hasScalarEvaluationKind(type)) {
// For non-aggregates, we can store the appropriate null constant.
mlir::Value null = cgf.cgm.emitNullConstant(type, loc);
if (lv.isSimple()) {
cgf.emitStoreOfScalar(null, lv, /* isInitialization */ true);
return;
}
cgf.cgm.errorNYI("emitStoreThroughBitfieldLValue");
return;
}
// There's a potential optimization opportunity in combining
// memsets; that would be easy for arrays, but relatively
// difficult for structures with the current code.
cgf.emitNullInitialization(loc, lv.getAddress(), lv.getType());
}
void AggExprEmitter::VisitCallExpr(const CallExpr *e) {
if (e->getCallReturnType(cgf.getContext())->isReferenceType()) {
cgf.cgm.errorNYI(e->getSourceRange(), "reference return type");
return;
}
withReturnValueSlot(
e, [&](ReturnValueSlot slot) { return cgf.emitCallExpr(e, slot); });
}
void AggExprEmitter::withReturnValueSlot(
const Expr *e, llvm::function_ref<RValue(ReturnValueSlot)> fn) {
QualType retTy = e->getType();
assert(!cir::MissingFeatures::aggValueSlotDestructedFlag());
bool requiresDestruction =
retTy.isDestructedType() == QualType::DK_nontrivial_c_struct;
if (requiresDestruction)
cgf.cgm.errorNYI(
e->getSourceRange(),
"withReturnValueSlot: return value requiring destruction is NYI");
// If it makes no observable difference, save a memcpy + temporary.
//
// We need to always provide our own temporary if destruction is required.
// Otherwise, fn will emit its own, notice that it's "unused", and end its
// lifetime before we have the chance to emit a proper destructor call.
assert(!cir::MissingFeatures::aggValueSlotAlias());
assert(!cir::MissingFeatures::aggValueSlotGC());
Address retAddr = dest.getAddress();
assert(!cir::MissingFeatures::emitLifetimeMarkers());
assert(!cir::MissingFeatures::aggValueSlotVolatile());
assert(!cir::MissingFeatures::aggValueSlotDestructedFlag());
fn(ReturnValueSlot(retAddr));
}
void AggExprEmitter::VisitInitListExpr(InitListExpr *e) {
if (e->hadArrayRangeDesignator())
llvm_unreachable("GNU array range designator extension");
if (e->isTransparent())
return Visit(e->getInit(0));
visitCXXParenListOrInitListExpr(
e, e->inits(), e->getInitializedFieldInUnion(), e->getArrayFiller());
}
void AggExprEmitter::visitCXXParenListOrInitListExpr(
Expr *e, ArrayRef<Expr *> args, FieldDecl *initializedFieldInUnion,
Expr *arrayFiller) {
const AggValueSlot dest =
ensureSlot(cgf.getLoc(e->getSourceRange()), e->getType());
if (e->getType()->isConstantArrayType()) {
cir::ArrayType arrayTy =
cast<cir::ArrayType>(dest.getAddress().getElementType());
emitArrayInit(dest.getAddress(), arrayTy, e->getType(), e, args,
arrayFiller);
return;
}
cgf.cgm.errorNYI(
"visitCXXParenListOrInitListExpr Record or VariableSizeArray type");
}
void CIRGenFunction::emitAggExpr(const Expr *e, AggValueSlot slot) {
AggExprEmitter(*this, slot).Visit(const_cast<Expr *>(e));
}
LValue CIRGenFunction::emitAggExprToLValue(const Expr *e) {
assert(hasAggregateEvaluationKind(e->getType()) && "Invalid argument!");
Address temp = createMemTemp(e->getType(), getLoc(e->getSourceRange()));
LValue lv = makeAddrLValue(temp, e->getType());
emitAggExpr(e, AggValueSlot::forLValue(lv, AggValueSlot::IsNotDestructed,
AggValueSlot::IsNotAliased,
AggValueSlot::DoesNotOverlap));
return lv;
}