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[flang][acc] Use non-boxed value for assumed-size in acc data clause #129804

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[flang][acc] Use non-boxed value for assumed-size in acc data clause #129804

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57 changes: 50 additions & 7 deletions flang/lib/Lower/OpenACC.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -369,6 +369,55 @@ getSymbolFromAccObject(const Fortran::parser::AccObject &accObject) {
llvm::report_fatal_error("Could not find symbol");
}

static mlir::Value getBaseAddr(Fortran::semantics::Symbol &symbol,
const fir::factory::AddrAndBoundsInfo &info) {
if (Fortran::semantics::IsAssumedSizeArray(symbol)) {
// Assumed-size arrays in FIR are represented as:
// func.func @func(%arg0: !fir.ref<!fir.array<?xf64>> {fir.bindc_name = "arr"}) {
// %arr:2 = hlfir.declare %arg0(%shape) ... -> (!fir.box<!fir.array<?xf64>>, !fir.ref<!fir.array<?xf64>>)
// The `rawInput` refers to the #1 output of the `hlfir.declare` operation.
// This is preferred since the Fortran variable properties does not contain
// any useful size information.
return info.rawInput;
}

if (Fortran::semantics::IsOptional(symbol)) {
// When there is an optional argument for which there is a possibility
// to create a descriptor, pick the rawInput instead. This is done to
// avoid materializing the descriptor which leads to following pattern
// generated at the FIR level which adds an extra indirection that makes
// recovering original variable not evident.
// This is the pattern we want to avoid to be generated:
// %1 = fir.declare %arg0 ... {fortran_attrs = #fir.var_attrs<optional>, uniq_name = "_QFsub1Eassumedshapeoptarr"} : (!fir.box<!fir.array<?xf32>>, !fir.dscope) -> !fir.box<!fir.array<?xf32>>
// %2 = fir.is_present %1 : (!fir.box<!fir.array<?xf32>>) -> i1
// %3 = fir.if %2 -> (!fir.box<!fir.array<?xf32>>) {
// %5 = fir.rebox %1 : (!fir.box<!fir.array<?xf32>>) -> !fir.box<!fir.array<?xf32>>
// fir.result %5 : !fir.box<!fir.array<?xf32>>
// } else {
// %5 = fir.absent !fir.box<!fir.array<?xf32>>
// fir.result %5 : !fir.box<!fir.array<?xf32>>
// }
// %4 = acc.copyin var(%3 : !fir.box<!fir.array<?xf32>>) ...
//
// Instead by picking the rawInput we get the following pattern:
// %1 = fir.declare %arg0 ... {fortran_attrs = #fir.var_attrs<optional>, uniq_name = "_QFsub1Eassumedshapeoptarr"} : (!fir.box<!fir.array<?xf32>>, !fir.dscope) -> !fir.box<!fir.array<?xf32>>
// %2 = acc.copyin var(%2 : !fir.box<!fir.array<?xf32>>) ...
if (fir::unwrapRefType(info.addr.getType()) !=
fir::unwrapRefType(info.rawInput.getType())) {
return info.rawInput;
}
}

// The `addr` field refers to the address of the Fortran entity, but with the
// ssa value that when lowered to FIR will include the tied Fortran variable
// properties. Additionally, in cases where `unwrapFirBox` is requested,
// it refers to the address of the data (either result of fir.box_addr or
// result of `fir.if` in case of optional).
// Therefore, use the processed address in all cases by default unless it was
// deemed through the earlier checks in this routine that it is not useful.
return info.addr;
}

template <typename Op>
static void
genDataOperandOperations(const Fortran::parser::AccObjectList &objectList,
Expand Down Expand Up @@ -399,13 +448,7 @@ genDataOperandOperations(const Fortran::parser::AccObjectList &objectList,
/*genDefaultBounds=*/generateDefaultBounds);
LLVM_DEBUG(llvm::dbgs() << __func__ << "\n"; info.dump(llvm::dbgs()));

// If the input value is optional and is not a descriptor, we use the
// rawInput directly.
mlir::Value baseAddr = ((fir::unwrapRefType(info.addr.getType()) !=
fir::unwrapRefType(info.rawInput.getType())) &&
info.isPresent)
? info.rawInput
: info.addr;
mlir::Value baseAddr = getBaseAddr(symbol, info);
Op op = createDataEntryOp<Op>(
builder, operandLocation, baseAddr, asFortran, bounds, structured,
implicit, dataClause, baseAddr.getType(), async, asyncDeviceTypes,
Expand Down
3 changes: 1 addition & 2 deletions flang/test/Lower/OpenACC/acc-bounds.f90
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Expand Up @@ -92,8 +92,7 @@ subroutine acc_undefined_extent(a)
! CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[DECL_ARG0]]#0, %c0{{.*}} : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
! CHECK: %[[UB:.*]] = arith.subi %[[DIMS0]]#1, %c1{{.*}} : index
! CHECK: %[[BOUND:.*]] = acc.bounds lowerbound(%c0{{.*}} : index) upperbound(%[[UB]] : index) extent(%[[DIMS0]]#1 : index) stride(%[[DIMS0]]#2 : index) startIdx(%c1{{.*}} : index) {strideInBytes = true}
! CHECK: %[[ADDR:.*]] = fir.box_addr %[[DECL_ARG0]]#0 : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
! CHECK: %[[PRESENT:.*]] = acc.present varPtr(%[[ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a"}
! CHECK: %[[PRESENT:.*]] = acc.present varPtr(%[[DECL_ARG0]]#1 : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a"}
! CHECK: acc.kernels dataOperands(%[[PRESENT]] : !fir.ref<!fir.array<?xf32>>)

subroutine acc_multi_strides(a)
Expand Down
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