[WIP][OpenMP] Enable ATTACH-style maps for mappers.

This is a follow-up to llvm#153683.

The change is experimental for now as it simply enables the
`ATTACH`-style maps, and updates a few libomptarget tests.

clang tests haven't been updated yet.

Also, we might need to add some new "implicit" maps. It's not clear
if/whether any implicit maps should be added for a list-item mapped via
a mapper, either default or non-default.

Author: abhinavgaba

clang/lib/CodeGen/CGOpenMPRuntime.cpp

@@ -9172,7 +9172,27 @@ class MappableExprsHandler {
 
   /// Constructor for the declare mapper directive.
   MappableExprsHandler(const OMPDeclareMapperDecl &Dir, CodeGenFunction &CGF)
-      : CurDir(&Dir), CGF(CGF), AttachPtrComparator(*this) {}
+      : CurDir(&Dir), CGF(CGF), AttachPtrComparator(*this) {
+    auto CollectAttachPtrExprsForClauseComponents = [this](const auto *C) {
+      for (auto L : C->component_lists()) {
+        OMPClauseMappableExprCommon::MappableExprComponentListRef Components =
+            std::get<1>(L);
+        if (!Components.empty())
+          collectAttachPtrExprInfo(Components, CurDir);
+      }
+    };
+
+    // Populate the AttachPtrExprMap for all component lists from map-related
+    // clauses in the declare mapper directive.
+    for (const auto *Cl : Dir.clauses()) {
+      if (const auto *C = dyn_cast<OMPMapClause>(Cl))
+        CollectAttachPtrExprsForClauseComponents(C);
+      else if (const auto *C = dyn_cast<OMPToClause>(Cl))
+        CollectAttachPtrExprsForClauseComponents(C);
+      else if (const auto *C = dyn_cast<OMPFromClause>(Cl))
+        CollectAttachPtrExprsForClauseComponents(C);
+    }
+  }
 
   /// Generate code for the combined entry if we have a partially mapped struct
   /// and take care of the mapping flags of the arguments corresponding to

offload/test/mapping/declare_mapper_nested_mappers.cpp

@@ -7,7 +7,8 @@ typedef struct {
   int a;
   double *b;
 } C;
-#pragma omp declare mapper(id1 : C s) map(to : s.a) map(from : s.b[0 : 2])
+#pragma omp declare mapper(id1 : C s) map(to : s.a) map(alloc : s.b)           \
+    map(from : s.b[0 : 2])
 
 typedef struct {
   int e;
@@ -16,7 +17,7 @@ typedef struct {
   short *g;
 } D;
 #pragma omp declare mapper(default : D r) map(from : r.e)                      \
-    map(mapper(id1), tofrom : r.f) map(tofrom : r.g[0 : r.h])
+    map(mapper(id1), tofrom : r.f) map(alloc : r.g) map(tofrom : r.g[0 : r.h])
 
 int main() {
   constexpr int N = 10;
@@ -56,7 +57,7 @@ int main() {
     spp[0][0].f.b[1] = 40;
     spp[0][0].g[1] = 50;
   }
-    printf("%d %d %d %d\n", spp00fa, spp00fb_r, spp00fg1, spp00fg_r);
+  printf("%d %d %d %d\n", spp00fa, spp00fb_r, spp00fg1, spp00fg_r);
   // CHECK: 222 0 30 0
   printf("%d %d %4.5f %d %d %d\n", spp[0][0].e, spp[0][0].f.a, spp[0][0].f.b[1],
          spp[0][0].f.b == &x[0] ? 1 : 0, spp[0][0].g[1],

offload/test/mapping/declare_mapper_target.cpp

@@ -10,7 +10,7 @@ class C {
   int *a;
 };
 
-#pragma omp declare mapper(id : C s) map(s.a[0 : NUM])
+#pragma omp declare mapper(id : C s) map(alloc : s.a) map(s.a[0 : NUM])
 
 int main() {
   C c;

offload/test/mapping/declare_mapper_target_data.cpp

@@ -10,7 +10,7 @@ class C {
   int *a;
 };
 
-#pragma omp declare mapper(id : C s) map(s.a[0 : NUM])
+#pragma omp declare mapper(id : C s) map(alloc : s.a) map(s.a[0 : NUM])
 
 int main() {
   C c;

offload/test/mapping/declare_mapper_target_data_enter_exit.cpp

@@ -10,7 +10,7 @@ class C {
   int *a;
 };
 
-#pragma omp declare mapper(id : C s) map(s.a[0 : NUM])
+#pragma omp declare mapper(id : C s) map(alloc : s.a) map(s.a[0 : NUM])
 
 int main() {
   C c;

offload/test/mapping/declare_mapper_target_update.cpp

@@ -10,7 +10,7 @@ class C {
   int *a;
 };
 
-#pragma omp declare mapper(id : C s) map(s.a[0 : NUM])
+#pragma omp declare mapper(id : C s) map(alloc : s.a) map(s.a[0 : NUM])
 
 int main() {
   C c;