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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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16 changes: 7 additions & 9 deletions flang/lib/Lower/ConvertCall.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -497,13 +497,12 @@ Fortran::lower::genCallOpAndResult(

// Special handling for %VAL arguments: internal procedures expect
// reference parameters. When %VAL is used, the argument should be
// passed by value. So we need to create a temporary variable and
// pass its address to avoid a type conversion error.
// 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()) {
mlir::Value temp = builder.createTemporary(loc, fst.getType());
builder.create<fir::StoreOp>(loc, fst, temp);
cast = temp;
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, {}, {});
Expand Down Expand Up @@ -1654,10 +1653,9 @@ void prepareUserCallArguments(
caller.placeInput(arg, value);
else if (fir::isa_ref_type(argTy) &&
fir::dyn_cast_ptrEleTy(argTy) == value.getType()) {
// We're trying to convert value to reference - create temporary
mlir::Value temp = builder.createTemporary(loc, value.getType());
builder.create<fir::StoreOp>(loc, value, temp);
caller.placeInput(arg, temp);
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));

Expand Down