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//===-- wasm.cpp ----------------------------------------------------------===//
//
// LDC – the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//
//
// see https://github.com/WebAssembly/tool-conventions/blob/main/BasicCABI.md
//
//===----------------------------------------------------------------------===//
#include "gen/abi/generic.h"
using namespace dmd;
namespace {
Type *getSingleWrappedScalarType(Type *t) {
t = t->toBasetype();
if (auto ts = t->isTypeStruct()) {
if (ts->sym->fields.length != 1)
return nullptr;
return getSingleWrappedScalarType(ts->sym->fields[0]->type);
}
if (auto tsa = t->isTypeSArray()) {
if (tsa->dim->toInteger() != 1)
return nullptr;
return getSingleWrappedScalarType(tsa->nextOf());
}
return t->isscalar()
// some more pointers:
|| t->ty == TY::Tclass || t->ty == TY::Taarray
? t
: nullptr;
}
}
struct WasmTargetABI : TargetABI {
static bool isDirectlyPassedAggregate(Type *t) {
// Structs and static arrays are generally passed byval, except for POD
// aggregates wrapping a single scalar type.
if (!DtoIsInMemoryOnly(t)) // not a struct or static array
return false;
// max scalar type size is 16 (`real`); return early if larger
if (size(t) > 16 || !isPOD(t))
return false;
Type *singleWrappedScalarType = getSingleWrappedScalarType(t);
return singleWrappedScalarType &&
// not passed directly if over-aligned
DtoAlignment(t) <= DtoAlignment(singleWrappedScalarType);
}
bool returnInArg(TypeFunction *tf, bool) override {
if (tf->isref()) {
return false;
}
Type *rt = tf->next->toBasetype();
return passByVal(tf, rt);
}
bool passByVal(TypeFunction *, Type *t) override {
return DtoIsInMemoryOnly(t) && !isDirectlyPassedAggregate(t);
}
void rewriteFunctionType(IrFuncTy &) override {}
};
// The public getter for abi.cpp.
TargetABI *getWasmTargetABI() { return new WasmTargetABI; }
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