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[Flang] Handle %VAL arguments correctly #157186

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Merged
merged 4 commits into from
Sep 9, 2025
Merged

[Flang] Handle %VAL arguments correctly #157186

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d7f5c64
[Flang] Handle %VAL arguments correctly
ceseo Sep 5, 2025
747ede1
Remove unnecessary temporary storage creation
ceseo Sep 8, 2025
b65fad2
Fix the testcase to reflect latest changes
ceseo Sep 8, 2025
cf32305
Add a new test to check passing %VAL to a VALUE argument
ceseo Sep 8, 2025
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31 changes: 26 additions & 5 deletions flang/lib/Lower/ConvertCall.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -494,10 +494,19 @@ Fortran::lower::genCallOpAndResult(
// arguments of any type and vice versa.
mlir::Value cast;
auto *context = builder.getContext();
if (mlir::isa<fir::BoxProcType>(snd) &&
mlir::isa<mlir::FunctionType>(fst.getType())) {
auto funcTy = mlir::FunctionType::get(context, {}, {});
auto boxProcTy = builder.getBoxProcType(funcTy);

// Special handling for %VAL arguments: internal procedures expect
// reference parameters. When %VAL is used, the argument should be
// passed by value. Pass the originally loaded value.
if (fir::isa_ref_type(snd) && !fir::isa_ref_type(fst.getType()) &&
fir::dyn_cast_ptrEleTy(snd) == fst.getType()) {
auto loadOp = mlir::cast<fir::LoadOp>(fst.getDefiningOp());
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Thanks for the update. Please could you keep the old code creating the temporary as a fallback. I'm not 100% certain that there will always be a load here. If the cast failed that would be a compiler crash. I'd rather have 2 lines of dead code than a compiler crash for some obscure untested case.

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I think that's the case because hlfir::loadTrivialScalar always creates fir::LoadOp for scalar trivial variables coming from hlfir.declare.

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Checking I understand the reasoning here: do you mean it will have always taken this path, and that means it must be a load op?

llvm-project/flang/lib/Lower/ConvertCall.cpp

Line 1613 in 747ede1

hlfir::Entity value = hlfir::loadTrivialScalar(loc, builder, actual);

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Yes, correct.

mlir::Value originalStorage = loadOp.getMemref();
cast = originalStorage;
} else if (mlir::isa<fir::BoxProcType>(snd) &&
mlir::isa<mlir::FunctionType>(fst.getType())) {
mlir::FunctionType funcTy = mlir::FunctionType::get(context, {}, {});
fir::BoxProcType boxProcTy = builder.getBoxProcType(funcTy);
if (mlir::Value host = argumentHostAssocs(converter, fst)) {
cast = fir::EmboxProcOp::create(builder, loc, boxProcTy,
llvm::ArrayRef<mlir::Value>{fst, host});
Expand Down Expand Up @@ -1637,7 +1646,19 @@ void prepareUserCallArguments(
(*cleanup)();
break;
}
caller.placeInput(arg, builder.createConvert(loc, argTy, value));
// For %VAL arguments, we should pass the value directly without
// conversion to reference types. If argTy is different from value type,
// it might be due to signature mismatch with internal procedures.
if (argTy == value.getType())
caller.placeInput(arg, value);
else if (fir::isa_ref_type(argTy) &&
fir::dyn_cast_ptrEleTy(argTy) == value.getType()) {
auto loadOp = mlir::cast<fir::LoadOp>(value.getDefiningOp());
mlir::Value originalStorage = loadOp.getMemref();
caller.placeInput(arg, originalStorage);
} else
caller.placeInput(arg, builder.createConvert(loc, argTy, value));

} break;
case PassBy::BaseAddressValueAttribute:
case PassBy::CharBoxValueAttribute:
Expand Down
16 changes: 16 additions & 0 deletions flang/test/Lower/percent-val-actual-argument.f90
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@@ -0,0 +1,16 @@
! RUN: flang -fc1 -emit-hlfir %s -o - | FileCheck %s

program main
logical::a1
data a1/.true./
call sa(%val(a1))
! CHECK: %[[A1_ADDR:.*]] = fir.address_of(@_QFEa1) : !fir.ref<!fir.logical<4>>
! CHECK: %[[A1_DECL:.*]]:2 = hlfir.declare %[[A1_ADDR]] {uniq_name = "_QFEa1"} : (!fir.ref<!fir.logical<4>>) -> (!fir.ref<!fir.logical<4>>, !fir.ref<!fir.logical<4>>)
! CHECK: fir.call @_QPsa(%[[A1_DECL]]#0) fastmath<contract> : (!fir.ref<!fir.logical<4>>) -> ()
! CHECK: func.func @_QPsa(%[[SA_ARG:.*]]: !fir.ref<!fir.logical<4>> {fir.bindc_name = "x1"}) {
write(6,*) "a1 = ", a1
end program main

subroutine sa(x1)
logical::x1
end subroutine sa
17 changes: 17 additions & 0 deletions flang/test/Lower/percent-val-value-argument.f90
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@@ -0,0 +1,17 @@
! RUN: flang -fc1 -emit-hlfir %s -o - | FileCheck %s

program main
logical::a1
data a1/.true./
call sb(%val(a1))
! CHECK: %[[A1_ADDR:.*]] = fir.address_of(@_QFEa1) : !fir.ref<!fir.logical<4>>
! CHECK: %[[A1_DECL:.*]]:2 = hlfir.declare %[[A1_ADDR]] {uniq_name = "_QFEa1"} : (!fir.ref<!fir.logical<4>>) -> (!fir.ref<!fir.logical<4>>, !fir.ref<!fir.logical<4>>)
! CHECK: %[[A1_LOADED:.*]] = fir.load %[[A1_DECL]]#0 : !fir.ref<!fir.logical<4>>
! CHECK: fir.call @_QFPsb(%[[A1_LOADED]]) fastmath<contract> : (!fir.logical<4>) -> ()
! CHECK: func.func private @_QFPsb(%[[SB_ARG:.*]]: !fir.logical<4> {fir.bindc_name = "x1"})
write(6,*) "a1 = ", a1
contains
subroutine sb(x1)
logical, value :: x1
end subroutine sb
end program main