From 62b1f9159667efa63f86d62c419af70af000ceac Mon Sep 17 00:00:00 2001
From: Valentin Clement <clementval@gmail.com>
Date: Tue, 11 Mar 2025 13:59:54 -0700
Subject: [PATCH] [flang][cuda] Allow assumed-size declaration for SHARED
 variable

---
 flang/include/flang/Lower/BoxAnalyzer.h |  5 +++--
 flang/include/flang/Semantics/tools.h   | 10 ++++++++++
 flang/test/Lower/CUDA/cuda-shared01.cuf |  9 +++++++++
 3 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 flang/test/Lower/CUDA/cuda-shared01.cuf

diff --git a/flang/include/flang/Lower/BoxAnalyzer.h b/flang/include/flang/Lower/BoxAnalyzer.h
index 8eca7d66a71bf..cd9037360a56b 100644
--- a/flang/include/flang/Lower/BoxAnalyzer.h
+++ b/flang/include/flang/Lower/BoxAnalyzer.h
@@ -403,8 +403,9 @@ class BoxAnalyzer : public fir::details::matcher<BoxAnalyzer> {
                 continue;
               }
             } else if (subs.ubound().isStar()) {
-              assert(Fortran::semantics::IsNamedConstant(sym) &&
-                     "expect implied shape constant");
+              assert(Fortran::semantics::IsNamedConstant(sym) ||
+                     Fortran::semantics::IsCUDAShared(sym) &&
+                         "expect implied shape constant");
               shapes.push_back(fir::SequenceType::getUnknownExtent());
               continue;
             }
diff --git a/flang/include/flang/Semantics/tools.h b/flang/include/flang/Semantics/tools.h
index 16fd8d158b0e0..31dfad098f3a7 100644
--- a/flang/include/flang/Semantics/tools.h
+++ b/flang/include/flang/Semantics/tools.h
@@ -222,6 +222,16 @@ inline bool HasCUDAAttr(const Symbol &sym) {
   return false;
 }
 
+inline bool IsCUDAShared(const Symbol &sym) {
+  if (const auto *details{sym.GetUltimate().detailsIf<ObjectEntityDetails>()}) {
+    if (details->cudaDataAttr() &&
+        *details->cudaDataAttr() == common::CUDADataAttr::Shared) {
+      return true;
+    }
+  }
+  return false;
+}
+
 inline bool NeedCUDAAlloc(const Symbol &sym) {
   if (IsDummy(sym)) {
     return false;
diff --git a/flang/test/Lower/CUDA/cuda-shared01.cuf b/flang/test/Lower/CUDA/cuda-shared01.cuf
new file mode 100644
index 0000000000000..a4603bed1f0ed
--- /dev/null
+++ b/flang/test/Lower/CUDA/cuda-shared01.cuf
@@ -0,0 +1,9 @@
+
+! RUN: bbc -emit-hlfir -fcuda %s -o - | FileCheck %s
+
+attributes(global) subroutine sharedstar()
+  real, shared :: s(*) ! ok. dynamic shared memory.
+end subroutine
+
+! CHECK-LABEL: func.func @_QPsharedstar()
+! CHECK: hlfir.declare %{{.*}}(%{{.*}}) {data_attr = #cuf.cuda<shared>, uniq_name = "_QFsharedstarEs"} : (!fir.ref<!fir.array<?xf32>>, !fir.shape<1>) -> (!fir.box<!fir.array<?xf32>>, !fir.ref<!fir.array<?xf32>>)