ldc/gen/toconstelem.cpp
Martin Kinkelin fe146c41e8 Enable toConstElem for some SliceExp
Porting dlang/dmd#13358 to fix dmd-testsuite's compilable/test21414.d.
2021-12-21 04:07:06 +01:00

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//===-- toconstelem.cpp ---------------------------------------------------===//
//
// LDC the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//
#include "dmd/ctfe.h"
#include "dmd/errors.h"
#include "dmd/template.h"
#include "gen/arrays.h"
#include "gen/binops.h"
#include "gen/classes.h"
#include "gen/complex.h"
#include "gen/irstate.h"
#include "gen/llvm.h"
#include "gen/llvmhelpers.h"
#include "gen/logger.h"
#include "gen/structs.h"
#include "gen/tollvm.h"
#include "gen/typinf.h"
#include "ir/irfunction.h"
#include "ir/irtypeclass.h"
#include "ir/irtypestruct.h"
/// Emits an LLVM constant corresponding to the expression (or an error if
/// impossible).
class ToConstElemVisitor : public Visitor {
IRState *p;
LLConstant *result;
public:
explicit ToConstElemVisitor(IRState *p_) : p(p_) {}
// Import all functions from class Visitor
using Visitor::visit;
//////////////////////////////////////////////////////////////////////////////
LLConstant *process(Expression *e) {
result = nullptr;
e->accept(this);
return result;
}
//////////////////////////////////////////////////////////////////////////////
void fatalError() {
result = nullptr;
if (!global.gag) {
fatal();
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(VarExp *e) override {
IF_LOG Logger::print("VarExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
if (SymbolDeclaration *sdecl = e->var->isSymbolDeclaration()) {
// This is the static initialiser (init symbol) for aggregates.
// Exclude void[]-typed `__traits(initSymbol)` (LDC extension).
if (sdecl->type->toBasetype()->ty == TY::Tstruct) {
const auto sd = sdecl->dsym->isStructDeclaration();
assert(sd);
IF_LOG Logger::print("Sym: sd=%s\n", sd->toChars());
DtoResolveStruct(sd);
result = getIrAggr(sd)->getDefaultInit();
return;
}
}
if (TypeInfoDeclaration *ti = e->var->isTypeInfoDeclaration()) {
result = DtoTypeInfoOf(e->loc, ti->tinfo, /*base=*/false);
result = DtoBitCast(result, DtoType(e->type));
return;
}
VarDeclaration *vd = e->var->isVarDeclaration();
if (vd && vd->isConst() && vd->_init) {
if (vd->inuse) {
e->error("recursive reference `%s`", e->toChars());
result = nullptr;
} else {
vd->inuse++;
// return the initializer
result = DtoConstInitializer(e->loc, e->type, vd->_init);
vd->inuse--;
}
}
// fail
else {
e->error("non-constant expression `%s`", e->toChars());
result = nullptr;
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(IntegerExp *e) override {
IF_LOG Logger::print("IntegerExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
LLType *t = DtoType(e->type);
if (isaPointer(t)) {
Logger::println("pointer");
LLConstant *i = LLConstantInt::get(
DtoSize_t(), static_cast<uint64_t>(e->getInteger()), false);
result = llvm::ConstantExpr::getIntToPtr(i, t);
} else {
assert(llvm::isa<LLIntegerType>(t));
result = LLConstantInt::get(t, static_cast<uint64_t>(e->getInteger()),
!e->type->isunsigned());
assert(result);
IF_LOG Logger::cout() << "value = " << *result << '\n';
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(RealExp *e) override {
IF_LOG Logger::print("RealExp::toConstElem: %s @ %s | %La\n", e->toChars(),
e->type->toChars(), e->value);
LOG_SCOPE;
Type *t = e->type->toBasetype();
result = DtoConstFP(t, e->value);
}
//////////////////////////////////////////////////////////////////////////////
void visit(NullExp *e) override {
IF_LOG Logger::print("NullExp::toConstElem(type=%s): %s\n",
e->type->toChars(), e->toChars());
LOG_SCOPE;
LLType *t = DtoType(e->type);
if (e->type->ty == TY::Tarray) {
assert(isaStruct(t));
result = llvm::ConstantAggregateZero::get(t);
} else {
result = LLConstant::getNullValue(t);
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(ComplexExp *e) override {
IF_LOG Logger::print("ComplexExp::toConstElem(): %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
result = DtoConstComplex(e->type, e->value.re, e->value.im);
}
//////////////////////////////////////////////////////////////////////////////
void visit(StringExp *e) override {
IF_LOG Logger::print("StringExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
Type *const t = e->type->toBasetype();
if (auto ts = t->isTypeSArray()) {
bool zeroTerm = ts->dim->toInteger() == e->numberOfCodeUnits() + 1;
result = buildStringLiteralConstant(e, zeroTerm);
return;
}
llvm::GlobalVariable *gvar = p->getCachedStringLiteral(e);
LLConstant *arrptr = DtoGEP(gvar, 0u, 0u);
if (t->ty == TY::Tpointer) {
result = DtoBitCast(arrptr, DtoType(t));
} else if (t->ty == TY::Tarray) {
LLConstant *clen =
LLConstantInt::get(DtoSize_t(), e->numberOfCodeUnits(), false);
result = DtoConstSlice(clen, arrptr, e->type);
} else {
llvm_unreachable("Unknown type for StringExp.");
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(AddExp *e) override {
IF_LOG Logger::print("AddExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
// add to pointer
Type *t1b = e->e1->type->toBasetype();
if (t1b->ty == TY::Tpointer && e->e2->type->isintegral()) {
llvm::Constant *ptr = toConstElem(e->e1, p);
dinteger_t idx = undoStrideMul(e->loc, t1b, e->e2->toInteger());
result = llvm::ConstantExpr::getGetElementPtr(getPointeeType(ptr), ptr,
DtoConstSize_t(idx));
return;
}
visit(static_cast<Expression *>(e));
}
void visit(MinExp *e) override {
IF_LOG Logger::print("MinExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
Type *t1b = e->e1->type->toBasetype();
if (t1b->ty == TY::Tpointer && e->e2->type->isintegral()) {
llvm::Constant *ptr = toConstElem(e->e1, p);
dinteger_t idx = undoStrideMul(e->loc, t1b, e->e2->toInteger());
llvm::Constant *negIdx = llvm::ConstantExpr::getNeg(DtoConstSize_t(idx));
result = llvm::ConstantExpr::getGetElementPtr(getPointeeType(ptr), ptr,
negIdx);
return;
}
visit(static_cast<Expression *>(e));
}
//////////////////////////////////////////////////////////////////////////////
void visit(SliceExp *e) override {
IF_LOG Logger::print("SliceExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
if (e->type->equivalent(e->e1->type)) {
if (!e->lwr && !e->upr) {
result = toConstElem(e->e1, p);
return;
}
if (auto se = e->e1->isStringExp())
if (auto lwr = e->lwr->isIntegerExp())
if (auto upr = e->upr->isIntegerExp())
if (lwr->toInteger() == 0 && upr->toInteger() == se->len) {
result = toConstElem(se, p);
return;
}
}
visit(static_cast<Expression *>(e));
}
//////////////////////////////////////////////////////////////////////////////
void visit(CastExp *e) override {
IF_LOG Logger::print("CastExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
LLType *lltype = DtoType(e->type);
Type *tb = e->to->toBasetype();
// string literal to dyn array:
// reinterpret the string data as an array, calculate the length
if (e->e1->op == TOKstring && tb->ty == TY::Tarray) {
#if 0
StringExp *strexp = static_cast<StringExp*>(e1);
size_t datalen = strexp->sz * strexp->len;
Type* eltype = tb->nextOf()->toBasetype();
if (datalen % eltype->size() != 0) {
error("the sizes don't line up");
return e1->toConstElem(p);
}
size_t arrlen = datalen / eltype->size();
#endif
e->error("ct cast of `string` to dynamic array not fully implemented");
result = nullptr;
}
// pointer to pointer
else if (tb->ty == TY::Tpointer &&
e->e1->type->toBasetype()->ty == TY::Tpointer) {
result = llvm::ConstantExpr::getBitCast(toConstElem(e->e1, p), lltype);
}
// global variable to pointer
else if (tb->ty == TY::Tpointer && e->e1->op == TOKvar) {
VarDeclaration *vd =
static_cast<VarExp *>(e->e1)->var->isVarDeclaration();
assert(vd);
DtoResolveVariable(vd);
LLConstant *value =
isIrGlobalCreated(vd) ? isaConstant(getIrGlobal(vd)->value) : nullptr;
if (!value) {
goto Lerr;
}
Type *type = vd->type->toBasetype();
if (type->ty == TY::Tarray || type->ty == TY::Tdelegate) {
value = DtoGEP(value, 0u, 1u);
}
result = DtoBitCast(value, DtoType(tb));
} else if (tb->ty == TY::Tclass && e->e1->type->ty == TY::Tclass &&
e->e1->op == TOKclassreference) {
auto cd = static_cast<ClassReferenceExp *>(e->e1)->originalClass();
llvm::Constant *instance = toConstElem(e->e1, p);
if (InterfaceDeclaration *it =
static_cast<TypeClass *>(tb)->sym->isInterfaceDeclaration()) {
assert(it->isBaseOf(cd, NULL));
IrTypeClass *typeclass = getIrType(cd->type)->isClass();
// find interface impl
size_t i_index = typeclass->getInterfaceIndex(it);
assert(i_index != ~0UL);
// offset pointer
instance = DtoGEP(instance, 0, i_index);
}
result = DtoBitCast(instance, DtoType(tb));
} else {
goto Lerr;
}
return;
Lerr:
e->error("cannot cast `%s` to `%s` at compile time", e->e1->type->toChars(),
e->type->toChars());
fatalError();
}
//////////////////////////////////////////////////////////////////////////////
void visit(SymOffExp *e) override {
IF_LOG Logger::println("SymOffExp::toConstElem: %s @ %s", e->toChars(),
e->type->toChars());
LOG_SCOPE;
llvm::Constant *base = DtoConstSymbolAddress(e->loc, e->var);
if (base == nullptr) {
result = nullptr;
return;
}
if (e->offset == 0) {
result = base;
} else {
const unsigned elemSize =
gDataLayout->getTypeStoreSize(base->getType()->getContainedType(0));
IF_LOG Logger::println("adding offset: %llu (elem size: %u)",
static_cast<unsigned long long>(e->offset),
elemSize);
if (e->offset % elemSize == 0) {
// We can turn this into a "nice" GEP.
result = llvm::ConstantExpr::getGetElementPtr(
getPointeeType(base), base, DtoConstSize_t(e->offset / elemSize));
} else {
// Offset isn't a multiple of base type size, just cast to i8* and
// apply the byte offset.
auto voidPtrType = getVoidPtrType();
result = llvm::ConstantExpr::getGetElementPtr(
voidPtrType->getElementType(), DtoBitCast(base, voidPtrType),
DtoConstSize_t(e->offset));
}
}
result = DtoBitCast(result, DtoType(e->type));
}
//////////////////////////////////////////////////////////////////////////////
void visit(AddrExp *e) override {
IF_LOG Logger::println("AddrExp::toConstElem: %s @ %s", e->toChars(),
e->type->toChars());
LOG_SCOPE;
// FIXME: this should probably be generalized more so we don't
// need to have a case for each thing we can take the address of
// address of global variable
if (auto vexp = e->e1->isVarExp()) {
LLConstant *c = DtoConstSymbolAddress(e->loc, vexp->var);
result = c ? DtoBitCast(c, DtoType(e->type)) : nullptr;
return;
}
// address of indexExp
if (auto iexp = e->e1->isIndexExp()) {
// indexee must be global static array var
VarExp *vexp = iexp->e1->isVarExp();
assert(vexp);
VarDeclaration *vd = vexp->var->isVarDeclaration();
assert(vd);
assert(vd->type->toBasetype()->ty == TY::Tsarray);
DtoResolveVariable(vd);
assert(isIrGlobalCreated(vd));
// get index
LLConstant *index = toConstElem(iexp->e2, p);
assert(index->getType() == DtoSize_t());
// gep
LLConstant *idxs[2] = {DtoConstSize_t(0), index};
LLConstant *val = isaConstant(getIrGlobal(vd)->value);
val = DtoBitCast(val, DtoType(vd->type->pointerTo()));
LLConstant *gep = llvm::ConstantExpr::getGetElementPtr(
getPointeeType(val), val, idxs, true);
// bitcast to requested type
assert(e->type->toBasetype()->ty == TY::Tpointer);
result = DtoBitCast(gep, DtoType(e->type));
return;
}
if (auto se = e->e1->isStructLiteralExp()) {
result = p->getStructLiteralConstant(se);
if (result) {
IF_LOG Logger::cout()
<< "Returning existing global: " << *result << '\n';
return;
}
auto globalVar = new llvm::GlobalVariable(
p->module, DtoType(se->type), false,
llvm::GlobalValue::InternalLinkage, nullptr, ".structliteral");
globalVar->setAlignment(LLMaybeAlign(DtoAlignment(se->type)));
p->setStructLiteralConstant(se, globalVar);
llvm::Constant *constValue = toConstElem(se, p);
constValue = p->setGlobalVarInitializer(globalVar, constValue, nullptr);
p->setStructLiteralConstant(se, constValue);
result = constValue;
return;
}
if (e->e1->op == TOKslice || e->e1->op == TOKdotvar) {
visit(static_cast<Expression *>(e));
return;
}
llvm_unreachable("unsupported AddrExp in ToConstElemVisitor");
}
//////////////////////////////////////////////////////////////////////////////
void visit(FuncExp *e) override {
IF_LOG Logger::print("FuncExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
FuncLiteralDeclaration *fd = e->fd;
assert(fd);
if (fd->tok == TOKreserved && e->type->ty == TY::Tpointer) {
// This is a lambda that was inferred to be a function literal instead
// of a delegate, so set tok here in order to get correct types/mangling.
// Horrible hack, but DMD does the same thing in FuncExp::toElem and
// other random places.
fd->tok = TOKfunction;
fd->vthis = nullptr;
}
if (fd->tok != TOKfunction) {
assert(fd->tok == TOKdelegate || fd->tok == TOKreserved);
// Only if the function doesn't access its nested context, we can emit a
// constant delegate with context pointer being null.
// FIXME: Find a proper way to check whether the context is used.
// For now, just enable it for literals declared at module scope.
if (!fd->toParent2()->isModule()) {
e->error("non-constant nested delegate literal expression `%s`",
e->toChars());
fatalError();
return;
}
}
// We need to actually codegen the function here, as literals are not
// added to the module member list.
Declaration_codegen(fd, p);
result = DtoCallee(fd, false);
assert(result);
if (fd->tok != TOKfunction) {
auto contextPtr = getNullPtr(getVoidPtrType());
result = LLConstantStruct::getAnon(gIR->context(), {contextPtr, result});
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(ArrayLiteralExp *e) override {
IF_LOG Logger::print("ArrayLiteralExp::toConstElem: %s @ %s\n",
e->toChars(), e->type->toChars());
LOG_SCOPE;
// extract D types
Type *bt = e->type->toBasetype();
Type *elemt = bt->nextOf();
// build llvm array type
LLArrayType *arrtype =
LLArrayType::get(DtoMemType(elemt), e->elements->length);
// dynamic arrays can occur here as well ...
bool dyn = (bt->ty != TY::Tsarray);
llvm::Constant *initval = arrayLiteralToConst(p, e);
// if static array, we're done
if (!dyn) {
result = initval;
return;
}
bool canBeConst = e->type->isConst() || e->type->isImmutable();
auto gvar = new llvm::GlobalVariable(
gIR->module, initval->getType(), canBeConst,
llvm::GlobalValue::InternalLinkage, initval, ".dynarrayStorage");
gvar->setUnnamedAddr(canBeConst ? llvm::GlobalValue::UnnamedAddr::Global
: llvm::GlobalValue::UnnamedAddr::None);
llvm::Constant *store = DtoBitCast(gvar, getPtrToType(arrtype));
if (bt->ty == TY::Tpointer) {
// we need to return pointer to the static array.
result = store;
return;
}
// build a constant dynamic array reference with the .ptr field pointing
// into store
LLConstant *globalstorePtr = DtoGEP(store, 0u, 0u);
result = DtoConstSlice(DtoConstSize_t(e->elements->length), globalstorePtr);
}
//////////////////////////////////////////////////////////////////////////////
void visit(StructLiteralExp *e) override {
// type can legitimately be null for ClassReferenceExp::value.
IF_LOG Logger::print("StructLiteralExp::toConstElem: %s @ %s\n",
e->toChars(), e->type ? e->type->toChars() : "(null)");
LOG_SCOPE;
if (e->useStaticInit) {
DtoResolveStruct(e->sd);
result = getIrAggr(e->sd)->getDefaultInit();
} else {
// make sure the struct is resolved
DtoResolveStruct(e->sd);
std::map<VarDeclaration *, llvm::Constant *> varInits;
const size_t nexprs = e->elements->length;
for (size_t i = 0; i < nexprs; i++) {
if (auto elem = (*e->elements)[i]) {
LLConstant *c = toConstElem(elem, p);
// extend i1 to i8
if (c->getType() == LLType::getInt1Ty(p->context()))
c = llvm::ConstantExpr::getZExt(c, LLType::getInt8Ty(p->context()));
varInits[e->sd->fields[i]] = c;
}
}
result = getIrAggr(e->sd)->createInitializerConstant(varInits);
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(ClassReferenceExp *e) override {
IF_LOG Logger::print("ClassReferenceExp::toConstElem: %s @ %s\n",
e->toChars(), e->type->toChars());
LOG_SCOPE;
ClassDeclaration *origClass = e->originalClass();
DtoResolveClass(origClass);
StructLiteralExp *value = e->value;
result = p->getStructLiteralConstant(value);
if (result) {
IF_LOG Logger::cout() << "Using existing global: " << *result << '\n';
} else {
auto globalVar = new llvm::GlobalVariable(
p->module, getIrType(origClass->type)->isClass()->getMemoryLLType(),
false, llvm::GlobalValue::InternalLinkage, nullptr, ".classref");
p->setStructLiteralConstant(value, globalVar);
std::map<VarDeclaration *, llvm::Constant *> varInits;
// Unfortunately, ClassReferenceExp::getFieldAt is badly broken it
// places the base class fields _after_ those of the subclass.
{
const size_t nexprs = value->elements->length;
std::stack<ClassDeclaration *> classHierachy;
ClassDeclaration *cur = origClass;
while (cur) {
classHierachy.push(cur);
cur = cur->baseClass;
}
size_t i = 0;
while (!classHierachy.empty()) {
cur = classHierachy.top();
classHierachy.pop();
for (size_t j = 0; j < cur->fields.length; ++j) {
if (auto elem = (*value->elements)[i]) {
VarDeclaration *field = cur->fields[j];
IF_LOG Logger::println("Getting initializer for: %s",
field->toChars());
LOG_SCOPE;
varInits[field] = toConstElem(elem, p);
}
++i;
}
}
(void)nexprs;
assert(i == nexprs);
}
llvm::Constant *constValue =
getIrAggr(origClass)->createInitializerConstant(varInits);
constValue = p->setGlobalVarInitializer(globalVar, constValue, nullptr);
p->setStructLiteralConstant(value, constValue);
result = constValue;
}
if (e->type->ty == TY::Tclass) {
ClassDeclaration *targetClass = static_cast<TypeClass *>(e->type)->sym;
if (InterfaceDeclaration *it = targetClass->isInterfaceDeclaration()) {
assert(it->isBaseOf(origClass, NULL));
// find interface impl
size_t i_index =
getIrType(origClass->type)->isClass()->getInterfaceIndex(it);
assert(i_index != ~0UL);
// offset pointer
result = DtoGEP(result, 0, i_index);
}
}
assert(e->type->ty == TY::Tclass || e->type->ty == TY::Tenum);
result = DtoBitCast(result, DtoType(e->type));
}
//////////////////////////////////////////////////////////////////////////////
void visit(VectorExp *e) override {
IF_LOG Logger::print("VectorExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
LOG_SCOPE;
TypeVector *tv = static_cast<TypeVector *>(e->to->toBasetype());
assert(tv->ty == TY::Tvector);
const auto elemCount =
static_cast<TypeSArray *>(tv->basetype)->dim->toInteger();
// Array literals are assigned element-for-element; other expressions splat
// across the whole vector.
if (auto ale = e->e1->isArrayLiteralExp()) {
llvm::SmallVector<llvm::Constant *, 16> elements;
elements.reserve(elemCount);
for (size_t i = 0; i < elemCount; ++i) {
elements.push_back(toConstElem(indexArrayLiteral(ale, i), p));
}
result = llvm::ConstantVector::get(elements);
} else {
// The AST for
// static immutable ubyte16 vec1 = 123;
// differs from
// static immutable ubyte[16] vec1 = 123;
// In the vector case the AST contains an IntegerExp (of type int) and a
// CastExp to type ubyte. In the static array case the AST only contains
// an IntegerExp of type ubyte. Simply call optimize to get rid of the
// cast.
// FIXME: Check DMD source to understand why two different ASTs are
// constructed.
#if LDC_LLVM_VER >= 1200
const auto elementCount = llvm::ElementCount::getFixed(elemCount);
#elif LDC_LLVM_VER >= 1100
const auto elementCount = llvm::ElementCount(elemCount, false);
#else
const auto elementCount = elemCount;
#endif
result = llvm::ConstantVector::getSplat(
elementCount, toConstElem(e->e1->optimize(WANTvalue), p));
}
}
//////////////////////////////////////////////////////////////////////////////
void visit(TypeidExp *e) override {
IF_LOG Logger::print("TypeidExp::toConstElem: %s @ %s\n", e->toChars(),
e->type->toChars());
Type *t = isType(e->obj);
if (!t) {
visit(static_cast<Expression *>(e));
return;
}
result = DtoTypeInfoOf(e->loc, t, /*base=*/false);
result = DtoBitCast(result, DtoType(e->type));
}
//////////////////////////////////////////////////////////////////////////////
void visit(Expression *e) override {
e->error("expression `%s` is not a constant", e->toChars());
fatalError();
}
};
LLConstant *toConstElem(Expression *e, IRState *p) {
auto ce = ToConstElemVisitor(p).process(e);
if (!ce) {
// error case; never return null
ce = llvm::UndefValue::get(DtoType(e->type));
}
return ce;
}
LLConstant *tryToConstElem(Expression *e, IRState *p) {
const auto errors = global.startGagging();
auto ce = ToConstElemVisitor(p).process(e);
if (global.endGagging(errors)) {
return nullptr;
}
assert(ce);
return ce;
}