[Flang][MLIR][OpenMP] Temporarily re-add basic handling of uses in target regions to avoid gfortran test-suite regressions

This was a regression introduced by myself in:

 6a62707

where I too hastily removed the basic handling of implicit captures
we have currently. This will be superseded by all implicit captures
being added to target operations map_info entries in a soon landing
series of patches, however, that is currently not the case so we must
continue to do some basic handling of these captures for the time
being. This patch re-adds that behaviour to avoid regressions.

Unfortunately this means some test changes as well as
getUsedValuesDefinedAbove grabs constants used outside
of the target region which aren't handled particularly
well currently.

Author: agozillon

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -32,6 +32,7 @@
 #include "llvm/TargetParser/Triple.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 
+#include <any>
 #include <optional>
 #include <utility>
 
@@ -2407,6 +2408,23 @@ convertOmpTarget(Operation &opInst, llvm::IRBuilderBase &builder,
       kernelInput.push_back(mapData.OriginalValue[i]);
   }
 
+  // Do some very basic handling of implicit captures that are caught
+  // by use in the target region.
+  // TODO/FIXME: Remove on addition of IsolatedFromAbove patch series
+  // as this will become redundant and perhaps erroneous in cases
+  // where more complex implicit capture semantics are required.
+  llvm::SetVector<Value> uses;
+  getUsedValuesDefinedAbove(targetRegion, uses);
+
+  for (mlir::Value use : uses) {
+    llvm::Value *useValue = moduleTranslation.lookupValue(use);
+    if (useValue &&
+        !std::any_of(
+            mapData.OriginalValue.begin(), mapData.OriginalValue.end(),
+            [&](llvm::Value *mapValue) { return mapValue == useValue; }))
+      kernelInput.push_back(useValue);
+  }
+
   builder.restoreIP(moduleTranslation.getOpenMPBuilder()->createTarget(
       ompLoc, allocaIP, builder.saveIP(), entryInfo, defaultValTeams,
       defaultValThreads, kernelInput, genMapInfoCB, bodyCB, argAccessorCB));

openmp/libomptarget/test/offloading/fortran/basic-target-region-1D-array-section.f90

@@ -14,10 +14,11 @@ program main
     integer :: write_arr(10) =  (/0,0,0,0,0,0,0,0,0,0/)
     integer :: read_arr(10) = (/1,2,3,4,5,6,7,8,9,10/)
     integer :: i = 2
-
-    !$omp target map(to:read_arr(2:5)) map(from:write_arr(2:5)) map(tofrom:i)
-        do i = 2, 5
+    integer :: j = 5
+    !$omp target map(to:read_arr(2:5)) map(from:write_arr(2:5)) map(to:i,j)
+        do while (i <= j)
             write_arr(i) = read_arr(i)
+            i = i + 1
         end do
     !$omp end target
 

openmp/libomptarget/test/offloading/fortran/basic-target-region-3D-array-section.f90

@@ -14,6 +14,7 @@ program main
     integer :: inArray(3,3,3)
     integer :: outArray(3,3,3)
     integer :: i, j, k 
+    integer :: j2 = 3, k2 = 3
 
     do i = 1, 3
       do j = 1, 3
@@ -24,11 +25,16 @@ program main
        end do
     end do
 
-!$omp target map(tofrom:inArray(1:3, 1:3, 2:2), outArray(1:3, 1:3, 1:3), j, k)
-    do j = 1, 3
-      do k = 1, 3
+j = 1
+k = 1 
+!$omp target map(tofrom:inArray(1:3, 1:3, 2:2), outArray(1:3, 1:3, 1:3), j, k, j2, k2)
+    do while (j <= j2)
+      k = 1
+      do while (k <= k2)
         outArray(k, j, 2) = inArray(k, j, 2)
+        k = k + 1
       end do
+      j = j + 1
     end do
 !$omp end target
 

openmp/libomptarget/test/offloading/fortran/basic-target-region-3D-array.f90

@@ -10,9 +10,9 @@
 
 ! RUN: %libomptarget-compile-fortran-run-and-check-generic
 program main
-    implicit none
     integer :: x(2,2,2)
-    integer :: i = 1, j = 1, k = 1
+    integer :: i, j, k
+    integer :: i2 = 2, j2 = 2, k2 = 2
     integer :: counter = 1
     do i = 1, 2
         do j = 1, 2
@@ -22,14 +22,23 @@ program main
         end do
     end do
 
-!$omp target map(tofrom:x, i, j, k, counter)
-    do i = 1, 2
-        do j = 1, 2
-          do k = 1, 2
+i = 1
+j = 1 
+k = 1
+
+!$omp target map(tofrom:x, counter) map(to: i, j, k, i2, j2, k2)
+    do while (i <= i2)
+      j = 1
+        do while (j <= j2)
+          k = 1
+          do while (k <= k2)
             x(i, j, k) = counter
             counter = counter + 1
+            k = k + 1
           end do
+          j = j + 1
         end do
+        i = i + 1
     end do
 !$omp end target