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[Flang] Cray pointer Lowering
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This patch is to add cray pointer (aka integer pointer) support to flang. Syntax and semantic checking were already available in flang.
Cray pointers reference (https://gcc.gnu.org/onlinedocs/gfortran/Cray-pointers.html)

In order to implement the feature we create the following sequence for a simple scalar load and store:

```
integer pte, i
pointer(ptr, pte)
i = pte
```

```
    %1 = fir.alloca i32 {bindc_name = "i", uniq_name = "_QFEi"}
    %2 = fir.alloca i32 {bindc_name = "pte", uniq_name = "_QFEpte"}
    %3 = fir.alloca i64 {bindc_name = "ptr", uniq_name = "_QFEptr"}
    ...
    %7 = fir.embox %3 : (!fir.ref<i64>) -> !fir.box<i64>
    %8 = fir.box_addr %7 : (!fir.box<i64>) -> !fir.ref<i64>
    %9 = fir.convert %8 : (!fir.ref<i64>) -> !fir.ref<!fir.ptr<i32>>
    %10 = fir.load %9 : !fir.ref<!fir.ptr<i32>>
    %11 = fir.load %10 : !fir.ptr<i32>
    fir.store %11 to %1 : !fir.ref<i32>
```

```
  integer pte, i
  pointer(ptr, pte)
  pte = i
```

```
    %1 = fir.alloca i32 {bindc_name = "i", uniq_name = "_QFEi"}
    %2 = fir.alloca i32 {bindc_name = "pte", uniq_name = "_QFEpte"}
    %3 = fir.alloca i64 {bindc_name = "ptr", uniq_name = "_QFEptr"}

    %7 = fir.load %1 : !fir.ref<i32>
    %8 = fir.embox %3 : (!fir.ref<i64>) -> !fir.box<i64>
    %9 = fir.box_addr %8 : (!fir.box<i64>) -> !fir.ref<i64>
    %10 = fir.convert %9 : (!fir.ref<i64>) -> !fir.ref<!fir.ptr<i32>>
    %11 = fir.load %10 : !fir.ref<!fir.ptr<i32>>
    fir.store %7 to %11 : !fir.ptr<i32>
```
The sequence is very similar for array element cases with the addition of fir.coordinate_of for the specific element.
The whole array case is slightly different but uses the same sequence before the fir.array_load and fir.array_merge_store.

Reviewed By: kkwli0

Differential Revision: https://reviews.llvm.org/D151478
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@madanial0
madanial0 committed Aug 22, 2023
1 parent d3d4d78 commit a1c736e
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Showing 4 changed files with 519 additions and 2 deletions.
4 changes: 4 additions & 0 deletions flang/include/flang/Lower/ConvertExpr.h
View file
Expand Up @@ -234,6 +234,10 @@ inline mlir::NamedAttribute getAdaptToByRefAttr(fir::FirOpBuilder &builder) {
builder.getUnitAttr()};
}

Fortran::semantics::SymbolRef getPointer(Fortran::semantics::SymbolRef sym);
mlir::Value addCrayPointerInst(mlir::Location loc, fir::FirOpBuilder &builder,
mlir::Value ptrVal, mlir::Type ptrTy,
mlir::Type pteTy);
} // namespace Fortran::lower

#endif // FORTRAN_LOWER_CONVERTEXPR_H
20 changes: 20 additions & 0 deletions flang/lib/Lower/Bridge.cpp
View file
Expand Up @@ -3578,6 +3578,26 @@ class FirConverter : public Fortran::lower::AbstractConverter {
// to a result variable of one of the other types requires
// conversion to the actual type.
mlir::Type toTy = genType(assign.lhs);

// If Cray pointee, need to handle the address
// Array is handled in genCoordinateOp.
if (sym->test(Fortran::semantics::Symbol::Flag::CrayPointee) &&
sym->Rank() == 0) {
// get the corresponding Cray pointer

auto ptrSym = Fortran::lower::getPointer(*sym);
fir::ExtendedValue ptr =
getSymbolExtendedValue(ptrSym, nullptr);
mlir::Value ptrVal = fir::getBase(ptr);
mlir::Type ptrTy = genType(*ptrSym);

fir::ExtendedValue pte =
getSymbolExtendedValue(*sym, nullptr);
mlir::Value pteVal = fir::getBase(pte);
mlir::Value cnvrt = Fortran::lower::addCrayPointerInst(
loc, *builder, ptrVal, ptrTy, pteVal.getType());
addr = builder->create<fir::LoadOp>(loc, cnvrt);
}
mlir::Value cast =
isVector ? val
: builder->convertWithSemantics(loc, toTy, val);
Expand Down
93 changes: 91 additions & 2 deletions flang/lib/Lower/ConvertExpr.cpp
View file
Expand Up @@ -849,7 +849,7 @@ class ScalarExprLowering {
ExtValue genval(Fortran::semantics::SymbolRef sym) {
mlir::Location loc = getLoc();
ExtValue var = gen(sym);
if (const fir::UnboxedValue *s = var.getUnboxed())
if (const fir::UnboxedValue *s = var.getUnboxed()) {
if (fir::isa_ref_type(s->getType())) {
// A function with multiple entry points returning different types
// tags all result variables with one of the largest types to allow
Expand All @@ -861,9 +861,23 @@ class ScalarExprLowering {
if (addr.getType() != resultType)
addr = builder.createConvert(loc, builder.getRefType(resultType),
addr);
} else if (sym->test(Fortran::semantics::Symbol::Flag::CrayPointee)) {
// get the corresponding Cray pointer
auto ptrSym = Fortran::lower::getPointer(sym);
ExtValue ptr = gen(ptrSym);
mlir::Value ptrVal = fir::getBase(ptr);
mlir::Type ptrTy = converter.genType(*ptrSym);

ExtValue pte = gen(sym);
mlir::Value pteVal = fir::getBase(pte);

mlir::Value cnvrt = Fortran::lower::addCrayPointerInst(
loc, builder, ptrVal, ptrTy, pteVal.getType());
addr = builder.create<fir::LoadOp>(loc, cnvrt);
}
return genLoad(addr);
}
}
return var;
}

Expand Down Expand Up @@ -1553,6 +1567,21 @@ class ScalarExprLowering {
args.push_back(builder.create<mlir::arith::SubIOp>(loc, ty, val, lb));
}
mlir::Value base = fir::getBase(array);

auto baseSym = getFirstSym(aref);
if (baseSym.test(Fortran::semantics::Symbol::Flag::CrayPointee)) {
// get the corresponding Cray pointer
auto ptrSym = Fortran::lower::getPointer(baseSym);

fir::ExtendedValue ptr = gen(ptrSym);
mlir::Value ptrVal = fir::getBase(ptr);
mlir::Type ptrTy = ptrVal.getType();

mlir::Value cnvrt = Fortran::lower::addCrayPointerInst(
loc, builder, ptrVal, ptrTy, base.getType());
base = builder.create<fir::LoadOp>(loc, cnvrt);
}

mlir::Type eleTy = fir::dyn_cast_ptrOrBoxEleTy(base.getType());
if (auto classTy = eleTy.dyn_cast<fir::ClassType>())
eleTy = classTy.getEleTy();
Expand Down Expand Up @@ -5632,7 +5661,8 @@ class ArrayExprLowering {
}

/// Base case of generating an array reference,
CC genarr(const ExtValue &extMemref, ComponentPath &components) {
CC genarr(const ExtValue &extMemref, ComponentPath &components,
mlir::Value CrayPtr = nullptr) {
mlir::Location loc = getLoc();
mlir::Value memref = fir::getBase(extMemref);
mlir::Type arrTy = fir::dyn_cast_ptrOrBoxEleTy(memref.getType());
Expand Down Expand Up @@ -5777,6 +5807,16 @@ class ArrayExprLowering {
}
auto arrLoad = builder.create<fir::ArrayLoadOp>(
loc, arrTy, memref, shape, slice, fir::getTypeParams(extMemref));

if (CrayPtr) {
mlir::Type ptrTy = CrayPtr.getType();
mlir::Value cnvrt = Fortran::lower::addCrayPointerInst(
loc, builder, CrayPtr, ptrTy, memref.getType());
auto addr = builder.create<fir::LoadOp>(loc, cnvrt);
arrLoad = builder.create<fir::ArrayLoadOp>(loc, arrTy, addr, shape, slice,
fir::getTypeParams(extMemref));
}

mlir::Value arrLd = arrLoad.getResult();
if (isProjectedCopyInCopyOut()) {
// Semantics are projected copy-in copy-out.
Expand Down Expand Up @@ -6930,6 +6970,21 @@ class ArrayExprLowering {
return genImplicitArrayAccess(x.GetComponent(), components);
}

CC genImplicitArrayAccess(const Fortran::semantics::Symbol &x,
ComponentPath &components) {
mlir::Value ptrVal = nullptr;
if (x.test(Fortran::semantics::Symbol::Flag::CrayPointee)) {
auto ptrSym = Fortran::lower::getPointer(x);
ExtValue ptr = converter.getSymbolExtendedValue(ptrSym);
ptrVal = fir::getBase(ptr);
}
components.reversePath.push_back(ImplicitSubscripts{});
ExtValue exv = asScalarRef(x);
lowerPath(exv, components);
auto lambda = genarr(exv, components, ptrVal);
return [=](IterSpace iters) { return lambda(components.pc(iters)); };
}

template <typename A>
CC genAsScalar(const A &x) {
mlir::Location loc = getLoc();
Expand Down Expand Up @@ -7573,3 +7628,37 @@ void Fortran::lower::createArrayMergeStores(
esp.resetBindings();
esp.incrementCounter();
}

Fortran::semantics::SymbolRef
Fortran::lower::getPointer(Fortran::semantics::SymbolRef sym) {
assert(!sym->owner().crayPointers().empty() &&
"empty Cray pointer/pointee map");
for (const auto &[pointee, pointer] : sym->owner().crayPointers()) {
if (pointee == sym->name()) {
Fortran::semantics::SymbolRef v{pointer.get()};
return v;
}
}
llvm_unreachable("corresponding Cray pointer cannot be found");
}

mlir::Value Fortran::lower::addCrayPointerInst(mlir::Location loc,
fir::FirOpBuilder &builder,
mlir::Value ptrVal,
mlir::Type ptrTy,
mlir::Type pteTy) {

mlir::Value empty;
mlir::ValueRange emptyRange;
auto boxTy = fir::BoxType::get(ptrTy);
auto box = builder.create<fir::EmboxOp>(loc, boxTy, ptrVal, empty, empty,
emptyRange);
mlir::Value addrof =
(ptrTy.isa<fir::ReferenceType>())
? builder.create<fir::BoxAddrOp>(loc, ptrTy, box)
: builder.create<fir::BoxAddrOp>(loc, builder.getRefType(ptrTy), box);

auto refPtrTy =
builder.getRefType(fir::PointerType::get(fir::dyn_cast_ptrEleTy(pteTy)));
return builder.createConvert(loc, refPtrTy, addrof);
}

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