[PATCH] D12871: [OpenMP] Target directive host codegen - rebased

[Samuel Antao via cfe-commits]

sfantao added inline comments.

================
Comment at: lib/CodeGen/CGOpenMPRuntime.cpp:3044-3054
@@ +3043,13 @@
+
+      if (auto *VAT = dyn_cast<VariableArrayType>(ElementType.getTypePtr())) {
+        auto VATInfo = CGF.getVLASize(VAT);
+        Size = llvm::ConstantInt::get(
+            CGM.SizeTy,
+            CGM.getContext().getTypeSizeInChars(VATInfo.second).getQuantity());
+        Size = CGF.Builder.CreateNUWMul(Size, VATInfo.first);
+      } else {
+        uint64_t ElementTypeSize =
+            CGM.getContext().getTypeSizeInChars(ElementType).getQuantity();
+        Size = llvm::ConstantInt::get(CGM.SizeTy, ElementTypeSize);
+      }
+
----------------
ABataev wrote:
> Use `getTypeSize(CGF, ElementType)` instead
In some previous review of this patch there was a suggestion to change from `getTypeSize(CGF, ElementType)/8` to `getTypeSizeInChars(ElementType).getQuantity()`. Just double checking if you really want me to revert that.

================
Comment at: lib/CodeGen/CGOpenMPRuntime.cpp:3082-3128
@@ +3081,49 @@
+
+  // Generate the code to launch the target region. The pattern is the
+  // following:
+  //
+  //   ...
+  //   br IfCond (if any), omp_offload, omp_offload_fail
+  //
+  // omp_offload.try:
+  //   ; create arrays for offloading
+  //   error = __tgt_target(...)
+  //   br error, omp_offload_fail, omp_offload_end
+  //
+  // omp_offload.fail:
+  //   host_version(...)
+  //
+  // omp_offload.end:
+  //   ...
+  //
+
+  auto OffloadTryBlock = CGF.createBasicBlock("omp_offload.try");
+  auto OffloadFailBlock = CGF.createBasicBlock("omp_offload.fail");
+  auto ContBlock = CGF.createBasicBlock("omp_offload.end");
+
+  if (IfCond)
+    CGF.EmitBranchOnBoolExpr(IfCond, OffloadTryBlock, OffloadFailBlock,
+                             /*TrueCount=*/0);
+
+  CGF.EmitBlock(OffloadTryBlock);
+
+  unsigned PointerNumVal = BasePointers.size();
+  llvm::Value *PointerNum = CGF.Builder.getInt32(PointerNumVal);
+  llvm::Value *BasePointersArray;
+  llvm::Value *PointersArray;
+  llvm::Value *SizesArray;
+  llvm::Value *MapTypesArray;
+
+  if (PointerNumVal) {
+    llvm::APInt PointerNumAP(32, PointerNumVal, /*isSigned=*/true);
+    QualType PointerArrayType = CGF.getContext().getConstantArrayType(
+        CGF.getContext().VoidPtrTy, PointerNumAP, ArrayType::Normal,
+        /*IndexTypeQuals=*/0);
+
+    BasePointersArray =
+        CGF.CreateMemTemp(PointerArrayType, ".offload_baseptrs").getPointer();
+    PointersArray =
+        CGF.CreateMemTemp(PointerArrayType, ".offload_ptrs").getPointer();
+
+    // If we don't have any VLA types, we can use a constant array for the map
+    // sizes, otherwise we need to fill up the arrays as we do for the pointers.
----------------
ABataev wrote:
> Could you use `emitOMPIfClause()` function instead of this long block?
I don't think I can reuse the current implementation. The reason is that the "else" basic block is always emitted and the "if" basic block needs to have a branch to the "else" basic block, and all these basic blocks are only visible inside `emitOMPIfClause()`. Basically, the if clause codegen would have to be combined with the testing of the return code of the offloading call.

================
Comment at: lib/CodeGen/CGStmtOpenMP.cpp:38
@@ +37,3 @@
+      if (UseOnlyReferences) {
+        LValue LV = MakeNaturalAlignAddrLValue(
+            CreateMemTemp(CurField->getType(), "__vla_size_ref").getPointer(),
----------------
ABataev wrote:
> Use `MakeAddrLValue(CreateMemTemp(CurField->getType(), "__vla_size_ref"), CurField->getType())` instead.
Done!

================
Comment at: lib/CodeGen/CGStmtOpenMP.cpp:117-122
@@ -102,4 +116,8 @@
     if (FD->hasCapturedVLAType()) {
       auto *ExprArg =
           EmitLoadOfLValue(ArgLVal, SourceLocation()).getScalarVal();
+      if (UseOnlyReferences) {
+        auto ExprArgRef = MakeNaturalAlignAddrLValue(ExprArg, FD->getType());
+        ExprArg = EmitLoadOfLValue(ExprArgRef, SourceLocation()).getScalarVal();
+      }
       auto VAT = FD->getCapturedVLAType();
----------------
ABataev wrote:
> ```
> if (UseOnlyReferences)
>   ArgLVal = CGF.EmitLoadOfReferenceLValue(ArgLVal.getAddress(), FD->getType()->casAs<ReferenceType>());
> auto *ExprArg = EmitLoadOfLValue(ArgLVal, SourceLocation()).getScalarVal();
> ```
Done!


http://reviews.llvm.org/D12871