add a test

Author: SusanTan

flang/lib/Lower/Bridge.cpp

@@ -3274,19 +3274,19 @@ class FirConverter : public Fortran::lower::AbstractConverter {
       for (auto *e : prologue)  sunk.insert(e);
       for (auto *e : epilogue)  sunk.insert(e);
 
-      auto emit = [&](llvm::SmallVector<Fortran::lower::pft::Evaluation *> &lst) {
-        for (auto *e : lst) genFIR(*e);
-      };
+      auto sink =
+          [&](llvm::SmallVector<Fortran::lower::pft::Evaluation *> &lst) {
+            for (auto *e : lst)
+              genFIR(*e);
+          };
 
-      // Sink prologue
-      emit(prologue);
+      sink(prologue);
 
       // Lower innermost loop body, skipping sunk
       for (Fortran::lower::pft::Evaluation &e : innermostLoopEval->getNestedEvaluations())
         if (!sunk.contains(&e)) genFIR(e);
 
-      // Sink epilogue
-      emit(epilogue);
+      sink(epilogue);
     } else {
       // Normal lowering
       for (Fortran::lower::pft::Evaluation &e : curEval->getNestedEvaluations())

flang/test/Lower/OpenACC/acc-loop-collapse-force-lowering.f90

@@ -0,0 +1,41 @@
+! RUN: bbc -fopenacc -emit-hlfir %s -o - | FileCheck %s
+
+! Verify collapse(force:2) sinks prologue (between loops) and epilogue (after inner loop)
+! into the acc.loop region body.
+
+subroutine collapse_force_sink(n, m)
+  integer, intent(in) :: n, m
+  real, dimension(n,m) :: a
+  real, dimension(n) :: bb, cc
+  integer :: i, j
+
+  !$acc parallel loop collapse(force:2)
+  do i = 1, n
+    bb(i) = 4.2     ! prologue (between loops)
+    do j = 1, m
+      a(i,j) = a(i,j) + 2.0
+    end do
+    cc(i) = 7.3     ! epilogue (after inner loop)
+  end do
+  !$acc end parallel loop
+end subroutine
+
+! CHECK: func.func @_QPcollapse_force_sink(
+! CHECK: acc.parallel
+! Ensure outer acc.loop is combined(parallel)
+! CHECK: acc.loop combined(parallel)
+! Prologue: constant 4.2 and an assign before inner loop
+! CHECK: arith.constant 4.200000e+00
+! CHECK: hlfir.assign
+! Inner loop and its body include 2.0 add and an assign
+! CHECK: acc.loop
+! CHECK: arith.constant 2.000000e+00
+! CHECK: arith.addf
+! CHECK: hlfir.assign
+! Epilogue: constant 7.3 and an assign after inner loop
+! CHECK: arith.constant 7.300000e+00
+! CHECK: hlfir.assign
+! And the outer acc.loop has collapse = [2]
+! CHECK: } attributes {collapse = [2]
+
+