[Openmp-commits] [clang] [openmp] Fix ordering of processing of map clauses when mapping a struct. (PR #72410)

via Openmp-commits openmp-commits at lists.llvm.org
Wed Nov 15 08:41:28 PST 2023


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Gheorghe-Teodor Bercea (doru1004)

<details>
<summary>Changes</summary>

Mapping a struct, if done in the wrong order, can overwrite the pointer attachment details. This fixes this problem.

Original failing example:

```
#include <stdio.h>
#include <stdlib.h>

struct Descriptor {
  int *datum;
  long int x;
  int xi;
  long int arr[1][30];
};

int main() {
  Descriptor dat = Descriptor();
  dat.datum = (int *)malloc(sizeof(int)*10);
  dat.xi = 3;
  dat.arr[0][0] = 1;

  #pragma omp target enter data map(to: dat.datum[:10]) map(to: dat)

  #pragma omp target
  {
    dat.xi = 4;
    dat.datum[dat.arr[0][0]] = dat.xi;
  }

  #pragma omp target exit data map(from: dat)

 return 0;
}
```

Previous attempt at fixing this: https://github.com/llvm/llvm-project/pull/70821

---
Full diff: https://github.com/llvm/llvm-project/pull/72410.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CGOpenMPRuntime.cpp (+37-7) 
- (added) openmp/libomptarget/test/offloading/struct_mapping_with_pointers.cpp (+114) 


``````````diff
diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index d2be8141a3a4b31..50518c46152bbaf 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -7731,6 +7731,8 @@ class MappableExprsHandler {
               IsImplicit, Mapper, VarRef, ForDeviceAddr);
         };
 
+    // Iterate over all non-section maps first to avoid overwriting pointer
+    // attachment.
     for (const auto *Cl : Clauses) {
       const auto *C = dyn_cast<OMPMapClause>(Cl);
       if (!C)
@@ -7742,15 +7744,42 @@ class MappableExprsHandler {
       else if (C->getMapType() == OMPC_MAP_alloc)
         Kind = Allocs;
       const auto *EI = C->getVarRefs().begin();
-      for (const auto L : C->component_lists()) {
-        const Expr *E = (C->getMapLoc().isValid()) ? *EI : nullptr;
-        InfoGen(std::get<0>(L), Kind, std::get<1>(L), C->getMapType(),
-                C->getMapTypeModifiers(), std::nullopt,
-                /*ReturnDevicePointer=*/false, C->isImplicit(), std::get<2>(L),
-                E);
-        ++EI;
+      if (*EI && !isa<OMPArraySectionExpr>(*EI)) {
+        for (const auto L : C->component_lists()) {
+          const Expr *E = (C->getMapLoc().isValid()) ? *EI : nullptr;
+          InfoGen(std::get<0>(L), Kind, std::get<1>(L), C->getMapType(),
+                  C->getMapTypeModifiers(), std::nullopt,
+                  /*ReturnDevicePointer=*/false, C->isImplicit(), std::get<2>(L),
+                  E);
+          ++EI;
+        }
+      }
+    }
+
+    // Process the maps with sections.
+    for (const auto *Cl : Clauses) {
+      const auto *C = dyn_cast<OMPMapClause>(Cl);
+      if (!C)
+        continue;
+      MapKind Kind = Other;
+      if (llvm::is_contained(C->getMapTypeModifiers(),
+                             OMPC_MAP_MODIFIER_present))
+        Kind = Present;
+      else if (C->getMapType() == OMPC_MAP_alloc)
+        Kind = Allocs;
+      const auto *EI = C->getVarRefs().begin();
+      if (*EI && isa<OMPArraySectionExpr>(*EI)) {
+        for (const auto L : C->component_lists()) {
+          const Expr *E = (C->getMapLoc().isValid()) ? *EI : nullptr;
+          InfoGen(std::get<0>(L), Kind, std::get<1>(L), C->getMapType(),
+                  C->getMapTypeModifiers(), std::nullopt,
+                  /*ReturnDevicePointer=*/false, C->isImplicit(), std::get<2>(L),
+                  E);
+          ++EI;
+        }
       }
     }
+
     for (const auto *Cl : Clauses) {
       const auto *C = dyn_cast<OMPToClause>(Cl);
       if (!C)
@@ -7767,6 +7796,7 @@ class MappableExprsHandler {
         ++EI;
       }
     }
+
     for (const auto *Cl : Clauses) {
       const auto *C = dyn_cast<OMPFromClause>(Cl);
       if (!C)
diff --git a/openmp/libomptarget/test/offloading/struct_mapping_with_pointers.cpp b/openmp/libomptarget/test/offloading/struct_mapping_with_pointers.cpp
new file mode 100644
index 000000000000000..c7ce4bade8de9a2
--- /dev/null
+++ b/openmp/libomptarget/test/offloading/struct_mapping_with_pointers.cpp
@@ -0,0 +1,114 @@
+// clang-format off
+// RUN: %libomptarget-compilexx-generic && env LIBOMPTARGET_DEBUG=1 %libomptarget-run-generic 2>&1 | %fcheck-generic
+// clang-format on
+
+#include <stdio.h>
+#include <stdlib.h>
+
+struct Descriptor {
+  int *datum;
+  long int x;
+  int *more_datum;
+  int xi;
+  int val_datum, val_more_datum;
+  long int arr[1][30];
+  int val_arr;
+};
+
+int main() {
+  Descriptor dat = Descriptor();
+  dat.datum = (int *)malloc(sizeof(int) * 10);
+  dat.more_datum = (int *)malloc(sizeof(int) * 20);
+  dat.xi = 3;
+  dat.arr[0][0] = 1;
+
+  dat.datum[7] = 7;
+  dat.more_datum[17] = 17;
+
+  /// The struct is mapped with type 0x0 when the pointer fields are mapped.
+  /// The struct is also map explicitely by the user. The second mapping by
+  /// the user must not overwrite the mapping set up for the pointer fields
+  /// when mapping the struct happens after the mapping of the pointers.
+
+  // clang-format off
+  // CHECK: Libomptarget --> Entry  0: Base=[[DAT_HST_PTR_BASE:0x.*]], Begin=[[DAT_HST_PTR_BASE]], Size=288, Type=0x0, Name=unknown
+  // CHECK: Libomptarget --> Entry  1: Base=[[DAT_HST_PTR_BASE]], Begin=[[DAT_HST_PTR_BASE]], Size=288, Type=0x1000000000001, Name=unknown
+  // CHECK: Libomptarget --> Entry  2: Base=[[DAT_HST_PTR_BASE]], Begin=[[DATUM_HST_PTR_BASE:0x.*]], Size=40, Type=0x1000000000011, Name=unknown
+  // CHECK: Libomptarget --> Entry  3: Base=[[MORE_DATUM_HST_PTR_BASE:0x.*]], Begin=[[MORE_DATUM_HST_PTR_BEGIN:0x.*]], Size=80, Type=0x1000000000011, Name=unknown
+  // clang-format on
+
+  /// The struct will be mapped in the same order as the above entries.
+
+  /// First argument is the struct itself and it will be mapped once.
+
+  // clang-format off
+  // CHECK: Libomptarget --> Looking up mapping(HstPtrBegin=[[DAT_HST_PTR_BASE]], Size=288)...
+  // CHECK: PluginInterface --> MemoryManagerTy::allocate: size 288 with host pointer [[DAT_HST_PTR_BASE]].
+  // CHECK: Libomptarget --> Creating new map entry with HstPtrBase=[[DAT_HST_PTR_BASE]], HstPtrBegin=[[DAT_HST_PTR_BASE]], TgtAllocBegin=[[DAT_DEVICE_PTR_BASE:0x.*]], TgtPtrBegin=[[DAT_DEVICE_PTR_BASE]], Size=288, DynRefCount=1, HoldRefCount=0, Name=unknown
+  // CHECK: Libomptarget --> Moving 288 bytes (hst:[[DAT_HST_PTR_BASE]]) -> (tgt:[[DAT_DEVICE_PTR_BASE]])
+  // clang-format on
+
+  /// Second argument is dat.datum:
+  // clang-format off
+  // CHECK: Libomptarget --> Looking up mapping(HstPtrBegin=[[DATUM_HST_PTR_BASE]], Size=40)...
+  // CHECK: PluginInterface --> MemoryManagerTy::allocate: size 40 with host pointer [[DATUM_HST_PTR_BASE]].
+  // CHECK: Libomptarget --> Creating new map entry with HstPtrBase=[[DATUM_HST_PTR_BASE]], HstPtrBegin=[[DATUM_HST_PTR_BASE]], TgtAllocBegin=[[DATUM_DEVICE_PTR_BASE:0x.*]], TgtPtrBegin=[[DATUM_DEVICE_PTR_BASE]], Size=40, DynRefCount=1, HoldRefCount=0, Name=unknown
+  // CHECK: Libomptarget --> Moving 40 bytes (hst:[[DATUM_HST_PTR_BASE]]) -> (tgt:[[DATUM_DEVICE_PTR_BASE]])
+  // clang-format on
+
+  /// Third argument is dat.more_datum:
+  // clang-format off
+  // CHECK: Libomptarget --> Looking up mapping(HstPtrBegin=[[MORE_DATUM_HST_PTR_BEGIN]], Size=80)...
+  // CHECK: PluginInterface --> MemoryManagerTy::allocate: size 80 with host pointer [[MORE_DATUM_HST_PTR_BEGIN]].
+  // CHECK: Libomptarget --> Creating new map entry with HstPtrBase=[[MORE_DATUM_HST_PTR_BEGIN]], HstPtrBegin=[[MORE_DATUM_HST_PTR_BEGIN]], TgtAllocBegin=[[MORE_DATUM_DEVICE_PTR_BEGIN:0x.*]], TgtPtrBegin=[[MORE_DATUM_DEVICE_PTR_BEGIN]], Size=80, DynRefCount=1, HoldRefCount=0, Name=unknown
+  // CHECK: Libomptarget --> Moving 80 bytes (hst:[[MORE_DATUM_HST_PTR_BEGIN]]) -> (tgt:[[MORE_DATUM_DEVICE_PTR_BEGIN]])
+  // clang-format on
+
+#pragma omp target enter data map(to : dat.datum[ : 10])                       \
+    map(to : dat.more_datum[ : 20]) map(to : dat)
+
+  /// Checks induced by having a target region:
+  // clang-format off
+  // CHECK: Libomptarget --> Entry  0: Base=[[DAT_HST_PTR_BASE]], Begin=[[DAT_HST_PTR_BASE]], Size=288, Type=0x223, Name=unknown
+  // CHECK: Libomptarget --> Mapping exists (implicit) with HstPtrBegin=[[DAT_HST_PTR_BASE]], TgtPtrBegin=[[DAT_DEVICE_PTR_BASE]], Size=288, DynRefCount=2 (incremented), HoldRefCount=0, Name=unknown
+  // CHECK: Libomptarget --> Obtained target argument [[DAT_DEVICE_PTR_BASE]] from host pointer [[DAT_HST_PTR_BASE]]
+  // clang-format on
+
+#pragma omp target
+  {
+    dat.xi = 4;
+    dat.datum[7]++;
+    dat.more_datum[17]++;
+    dat.val_datum = dat.datum[7];
+    dat.val_more_datum = dat.more_datum[17];
+    dat.datum[dat.arr[0][0]] = dat.xi;
+    dat.val_arr = dat.datum[dat.arr[0][0]];
+  }
+
+  /// Post-target region checks:
+  // clang-format off
+  // CHECK: Libomptarget --> Mapping exists with HstPtrBegin=[[DAT_HST_PTR_BASE]], TgtPtrBegin=[[DAT_DEVICE_PTR_BASE]], Size=288, DynRefCount=1 (decremented), HoldRefCount=0
+  // clang-format on
+
+#pragma omp target exit data map(from : dat)
+
+  /// Target data end checks:
+  // clang-format off
+  // CHECK: Libomptarget --> Mapping exists with HstPtrBegin=[[DAT_HST_PTR_BASE]], TgtPtrBegin=[[DAT_DEVICE_PTR_BASE]], Size=288, DynRefCount=0 (decremented, delayed deletion), HoldRefCount=0
+  // CHECK: Libomptarget --> Moving 288 bytes (tgt:[[DAT_DEVICE_PTR_BASE]]) -> (hst:[[DAT_HST_PTR_BASE]])
+  // clang-format on
+
+  // CHECK: dat.xi = 4
+  // CHECK: dat.val_datum = 8
+  // CHECK: dat.val_more_datum = 18
+  // CHECK: dat.datum[dat.arr[0][0]] = 0
+  // CHECK: dat.val_arr = 4
+
+  printf("dat.xi = %d\n", dat.xi);
+  printf("dat.val_datum = %d\n", dat.val_datum);
+  printf("dat.val_more_datum = %d\n", dat.val_more_datum);
+  printf("dat.datum[dat.arr[0][0]] = %d\n", dat.datum[dat.arr[0][0]]);
+  printf("dat.val_arr = %d\n", dat.val_arr);
+
+  return 0;
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/72410


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