[flang-commits] [flang] [flang] Do not instantiate components in initial targets as objects (PR #75778)

[via flang-commits]

https://github.com/jeanPerier created https://github.com/llvm/llvm-project/pull/75778

Lowering was instantiating component symbols (but the last) in initial target designator as if they were whole objects, leading to collisions and bugs.

Fixes https://github.com/llvm/llvm-project/issues/75728

>From 6ac3b85c87008bef97c04a549a727248e40bb80e Mon Sep 17 00:00:00 2001
From: Jean Perier <jperier at nvidia.com>
Date: Mon, 18 Dec 2023 01:19:39 -0800
Subject: [PATCH] [flang] Do not instantiate components in initial targets as
 objects

Lowering was instantiating component symbols (but the last) in
initial target designator as if they were whole objects, leading to
collisions and bugs.

Fixes https://github.com/llvm/llvm-project/issues/75728
---
 flang/lib/Lower/ConvertVariable.cpp             |  4 ++++
 .../Lower/HLFIR/initial-target-component.f90    | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 flang/test/Lower/HLFIR/initial-target-component.f90

diff --git a/flang/lib/Lower/ConvertVariable.cpp b/flang/lib/Lower/ConvertVariable.cpp
index 364de33d00a627..ad44de71ee828a 100644
--- a/flang/lib/Lower/ConvertVariable.cpp
+++ b/flang/lib/Lower/ConvertVariable.cpp
@@ -238,6 +238,10 @@ mlir::Value Fortran::lower::genInitialDataTarget(
         /*nonDeferredParams=*/std::nullopt);
   // Pointer initial data target, and NULL(mold).
   for (const auto &sym : Fortran::evaluate::CollectSymbols(initialTarget)) {
+    // Derived type component symbols should not be instantiated as objects
+    // on their own.
+    if (sym->owner().IsDerivedType())
+      continue;
     // Length parameters processing will need care in global initializer
     // context.
     if (hasDerivedTypeWithLengthParameters(sym))
diff --git a/flang/test/Lower/HLFIR/initial-target-component.f90 b/flang/test/Lower/HLFIR/initial-target-component.f90
new file mode 100644
index 00000000000000..cfee3adbc70beb
--- /dev/null
+++ b/flang/test/Lower/HLFIR/initial-target-component.f90
@@ -0,0 +1,17 @@
+! Test https://github.com/llvm/llvm-project/issues/75728 fix.
+! RUN: bbc -emit-hlfir -o - -I nw %s | FileCheck %s
+
+subroutine test()
+  type t
+    complex :: z
+  end type
+  type(t), target, save :: obj
+  real, pointer :: p => obj%z%re
+end subroutine
+! CHECK-LABEL:   fir.global internal @_QFtestEp : !fir.box<!fir.ptr<f32>> {
+! CHECK-NEXT:      %[[VAL_0:.*]] = fir.address_of(@_QFtestEobj) : !fir.ref<!fir.type<_QFtestTt{z:!fir.complex<4>}>>
+! CHECK-NEXT:      %[[VAL_1:.*]]:2 = hlfir.declare %[[VAL_0]] {fortran_attrs = #fir.var_attrs<target>, uniq_name = "_QFtestEobj"} : (!fir.ref<!fir.type<_QFtestTt{z:!fir.complex<4>}>>) -> (!fir.ref<!fir.type<_QFtestTt{z:!fir.complex<4>}>>, !fir.ref<!fir.type<_QFtestTt{z:!fir.complex<4>}>>)
+! CHECK-NEXT:      %[[VAL_2:.*]] = hlfir.designate %[[VAL_1]]#0{"z"}  real : (!fir.ref<!fir.type<_QFtestTt{z:!fir.complex<4>}>>) -> !fir.ref<f32>
+! CHECK-NEXT:      %[[VAL_3:.*]] = fir.embox %[[VAL_2]] : (!fir.ref<f32>) -> !fir.box<f32>
+! CHECK-NEXT:      %[[VAL_4:.*]] = fir.rebox %[[VAL_3]] : (!fir.box<f32>) -> !fir.box<!fir.ptr<f32>>
+! CHECK-NEXT:      fir.has_value %[[VAL_4]] : !fir.box<!fir.ptr<f32>>