[flang-commits] [flang] [llvm] [mlir] [OpenMP] Honor barrier and last iteration flags in loop lowering (PR #224040)

[Tom Eccles via flang-commits]

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@@ -6612,11 +6612,32 @@ static void workshareLoopTargetCallback(
   CLI->invalidate();
 }
 
-OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::applyWorkshareLoopTarget(
+OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::applyWorkshareLoopTarget(
     DebugLoc DL, CanonicalLoopInfo *CLI, InsertPointTy AllocaIP,
-    WorksharingLoopType LoopType, bool NoLoop) {
+    bool NeedsBarrier, WorksharingLoopType LoopType, bool NoLoop,
+    bool NeedsLastIter) {
   uint32_t SrcLocStrSize;
   Constant *SrcLocStr = getOrCreateSrcLocStr(DL, SrcLocStrSize);
+
+  // Mirrors host runtime reporting of last iteration by in-body computation.
+  if (NeedsLastIter) {
+    Type *I32Type = Type::getInt32Ty(M.getContext());
+    Builder.restoreIP(AllocaIP);
+    AllocaInst *PLastIter =
+        Builder.CreateAlloca(I32Type, nullptr, "p.lastiter");
+    Builder.CreateStore(ConstantInt::get(I32Type, 0), PLastIter);
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tblah wrote:

The workshare loop might be executed multiple times but PLastIter is only initialised once. This store should probably be immediately before the loop.

https://github.com/llvm/llvm-project/pull/224040