[flang] Load unlimited polymorphic box the same way as other

[clementval]

Summary

Unlimited polymorphic descriptor have a set size and can be loaded the
same way as polymorphic or monomorphic descriptors. The descriptor
code gen as been set in D138587.
Of course, the data hold by those descriptors have an unknown size
at compile time.

Depends on D141383

[PeteSteinfeld]

I was not able to load this patch onto my system. Does something need to be merged? I got the following message:

This diff is against commit 793ef93e8049dd8217f3f90881c7395e691c4226, but
the commit is nowhere in the working copy. Try to apply it against the
current working copy state? (b05c71814c3b9f91a2e00af891d67a83790a109c)

[clementval]

In D141390#4039979, @PeteSteinfeld wrote:

I was not able to load this patch onto my system. Does something need to be merged? I got the following message:

This diff is against commit 793ef93e8049dd8217f3f90881c7395e691c4226, but
the commit is nowhere in the working copy. Try to apply it against the
current working copy state? (b05c71814c3b9f91a2e00af891d67a83790a109c)

Forgot to add a dependency on a previous patch.

[PeteSteinfeld]

You probably just need to remove line 3016 from CodeGen.cpp.

flang/lib/Optimizer/CodeGen/CodeGen.cpp

3015–3016

I get a warning on this line because eleTy is not used anywhere, and the build options turn warnings into errors.

[clementval]

Remove unused variable

flang/lib/Optimizer/CodeGen/CodeGen.cpp

3015–3016

Makes sense. Some buildbot have that as well. Will remove it.

[PeteSteinfeld]

All builds and tests correctly and looks good.

[jeanPerier]

LGTM

flang/lib/Optimizer/CodeGen/CodeGen.cpp

matchAndRewrite(fir::LoadOp load, OpAdaptor adaptor,
     if (auto boxTy = load.getType().dyn_cast<fir::BaseBoxType>()) {
       // fir.box is a special case because it is considered as an ssa values in
       // fir, but it is lowered as a pointer to a descriptor. So
       // fir.ref<fir.box> and fir.box end up being the same llvm types and
       // loading a fir.ref<fir.box> is implemented as taking a snapshot of the
       // descriptor value into a new descriptor temp.
       auto inputBoxStorage = adaptor.getOperands()[0];
       mlir::Location loc = load.getLoc();
       fir::SequenceType seqTy = fir::unwrapUntilSeqType(boxTy);
-      mlir::Type eleTy = fir::unwrapPassByRefType(boxTy);
-      // fir.box of assumed rank and polymorphic entities do not have a storage
+      // fir.box of assumed rank do not have a storage
       // size that is know at compile time. The copy needs to be runtime driven
       // depending on the actual dynamic rank or type.
-      if (eleTy.isa<mlir::NoneType>() || (seqTy && seqTy.hasUnknownShape()))
-        TODO(loc, "loading polymorphic or assumed rank fir.box");
+      if (seqTy && seqTy.hasUnknownShape())
+        TODO(loc, "loading or assumed rank fir.box");
       mlir::Type boxPtrTy = inputBoxStorage.getType();
       auto boxValue = rewriter.create<mlir::LLVM::LoadOp>(
           loc, boxPtrTy.cast<mlir::LLVM::LLVMPointerType>().getElementType(),
           inputBoxStorage);
       auto newBoxStorage =
           genAllocaWithType(loc, boxPtrTy, defaultAlign, rewriter);
       rewriter.create<mlir::LLVM::StoreOp>(loc, boxValue, newBoxStorage);
       rewriter.replaceOp(load, newBoxStorage.getResult());

flang/test/Fir/polymorphic.fir

 // CHECK-LABEL: define void @_QQmain() {
 // CHECK: %[[CLASS_NONE:.*]] = alloca { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }
 // CHECK: %[[DESC:.*]] = alloca { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, i64 1
 // CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr @_QMmod1Ea, i64 ptrtoint (ptr getelementptr (%_QMmod1TtK2, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 1, i8 1, ptr @_QMmod1E.dt.t.2, [1 x i64] undef }, ptr %[[CLASS_NONE]], align 8
 // CHECK: %[[LOAD:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %[[CLASS_NONE]]
 // CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[LOAD]], ptr %[[DESC]]
 // CHECK: call void @_QMmod1Psub1(ptr %[[DESC]])
 
+fir.global @_QMmod2Ep : !fir.class<!fir.ptr<none>> {
+  %0 = fir.zero_bits !fir.ptr<none>
+  %1 = fir.embox %0 : (!fir.ptr<none>) -> !fir.class<!fir.ptr<none>>
+  fir.has_value %1 : !fir.class<!fir.ptr<none>>
+}
+func.func @_QMmod2Pinitp(%arg0: !fir.ref<!fir.class<!fir.ptr<none>>> {fir.bindc_name = "target"}) {
+  %0 = fir.address_of(@_QMmod2Ep) : !fir.ref<!fir.class<!fir.ptr<none>>>
+  %1 = fir.load %arg0 : !fir.ref<!fir.class<!fir.ptr<none>>>
+  %2 = fir.convert %0 : (!fir.ref<!fir.class<!fir.ptr<none>>>) -> !fir.ref<!fir.box<none>>
+  %3 = fir.convert %1 : (!fir.class<!fir.ptr<none>>) -> !fir.box<none>
+  %4 = fir.call @_FortranAPointerAssociate(%2, %3) fastmath<contract> : (!fir.ref<!fir.box<none>>, !fir.box<none>) -> none
+  return
+}
+func.func private @_FortranAPointerAssociate(!fir.ref<!fir.box<none>>, !fir.box<none>) -> none attributes {fir.runtime}
+
+// CHECK-LABEL: define void @_QMmod2Pinitp(
+// CHECK-SAME: ptr %[[ARG0:.*]]) {
+// CHECK: %[[ALLOCA_CLASS_NONE:.*]] = alloca { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }
+// CHECK: %[[LOAD:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %[[ARG0]]
+// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[LOAD]], ptr %[[ALLOCA_CLASS_NONE]]
+// CHECK: %{{.*}} = call {} @_FortranAPointerAssociate(ptr @_QMmod2Ep, ptr %[[ALLOCA_CLASS_NONE]])
+// CHECK: ret void
+