[flang][openmp] fix OMPFunctionFiltering pass after llvm#87796

Author: jeanPerier

flang/lib/Optimizer/Transforms/OMPFunctionFiltering.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Optimizer/Dialect/FIRDialect.h"
+#include "flang/Optimizer/Dialect/FIROpsSupport.h"
 #include "flang/Optimizer/Transforms/Passes.h"
 
 #include "mlir/Dialect/Func/IR/FuncOps.h"
@@ -66,6 +67,12 @@ class OMPFunctionFilteringPass
         SymbolTable::UseRange funcUses = *funcOp.getSymbolUses(op);
         for (SymbolTable::SymbolUse use : funcUses) {
           Operation *callOp = use.getUser();
+          if (mlir::isa<func::FuncOp>(callOp)) {
+            // Do not delete internal procedures holding the symbol of their
+            // Fortran host procedure as attribute.
+            callOp->removeAttr(fir::getHostSymbolAttrName());
+            continue;
+          }
           // If the callOp has users then replace them with Undef values.
           if (!callOp->use_empty()) {
             SmallVector<Value> undefResults;

flang/test/Lower/OpenMP/function-filtering-3.f90

@@ -0,0 +1,37 @@
+! RUN: %flang_fc1 -fopenmp -flang-experimental-hlfir -emit-llvm %s -o - | FileCheck --check-prefixes=LLVM-HOST %s
+! RUN: %flang_fc1 -fopenmp -emit-hlfir %s -o - | FileCheck --check-prefixes=MLIR-HOST,MLIR-ALL %s
+! RUN: %flang_fc1 -fopenmp -fopenmp-is-target-device -flang-experimental-hlfir -emit-llvm %s -o - | FileCheck --check-prefixes=LLVM-DEVICE %s
+! RUN: %flang_fc1 -fopenmp -fopenmp-is-target-device -emit-hlfir %s -o - | FileCheck --check-prefixes=MLIR-DEVICE,MLIR-ALL %s
+! RUN: bbc -fopenmp -emit-hlfir %s -o - | FileCheck --check-prefixes=MLIR-HOST,MLIR-ALL %s
+! RUN: bbc -fopenmp -fopenmp-is-target-device -emit-hlfir %s -o - | FileCheck --check-prefixes=MLIR-DEVICE,MLIR-ALL %s
+
+! Check that the correct LLVM IR functions are kept for the host and device
+! after running the whole set of translation and transformation passes from
+! Fortran.
+
+! MLIR-HOST: func.func @{{.*}}host_parent_procedure(
+! MLIR-HOST: return
+! MLIR-DEVICE-NOT: func.func {{.*}}host_parent_procedure(
+
+! LLVM-HOST: define {{.*}} @host_parent_procedure{{.*}}(
+! LLVM-DEVICE-NOT: {{.*}} @{{.*}}_host_parent_procedure{{.*}}(
+subroutine host_parent_procedure(x)
+  integer, intent(out) :: x
+  call target_internal_proc(x)
+contains
+! MLIR-ALL: func.func private @_QFhost_parent_procedurePtarget_internal_proc(
+
+! LLVM-HOST: define {{.*}} @_QFhost_parent_procedurePtarget_internal_proc(
+! LLVM-HOST: define {{.*}} @__omp_offloading_{{.*}}QFhost_parent_procedurePtarget_internal_proc{{.*}}(
+
+! FIXME: the last check above should also work on the host, but the offload function
+! is deleted because it is private and all its usages have been removed in the
+! device code. Maybe the private attribute should be removed on internal
+! functions while filtering?
+subroutine target_internal_proc(x)
+  integer, intent(out) :: x
+  !$omp target map(from:x)
+    x = 10
+  !$omp end target
+end subroutine
+end subroutine