[llvm-branch-commits] [mlir] [flang][OpenMP] Translate OpenMP scopes when compiling for target device (PR #130078)

[Kareem Ergawy via llvm-branch-commits]

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@@ -5255,6 +5283,51 @@ convertTargetOpsInNest(Operation *op, llvm::IRBuilderBase &builder,
               return WalkResult::interrupt();
             return WalkResult::skip();
           }
+
+          // Non-target ops might nest target-related ops, therefore, we
+          // translate them as non-OpenMP scopes. Translating them is needed by
+          // nested target-related ops since they might LLVM values defined in
+          // their parent non-target ops.
+          if (isa<omp::OpenMPDialect>(oper->getDialect()) &&
+              oper->getParentOfType<LLVM::LLVMFuncOp>() &&
+              !oper->getRegions().empty()) {
+
+            // TODO Handle other ops with entry block args.
+            llvm::TypeSwitch<Operation &>(*oper)
+                .Case([&](omp::WsloopOp wsloopOp) {
+                  forwardPrivateArgs(wsloopOp, moduleTranslation);
+                  forwardReductionArgs(wsloopOp, moduleTranslation);
+                })
+                .Case([&](omp::ParallelOp parallelOp) {
+                  forwardPrivateArgs(parallelOp, moduleTranslation);
+                  forwardReductionArgs(parallelOp, moduleTranslation);
+                })
+                .Case([&](omp::TaskOp taskOp) {
+                  forwardPrivateArgs(taskOp, moduleTranslation);
+                });
+
+            if (auto loopNest = dyn_cast<omp::LoopNestOp>(oper)) {
+              for (auto iv : loopNest.getIVs()) {
+                // Create fake allocas just to maintain IR validity.
+                moduleTranslation.mapValue(
+                    iv, builder.CreateAlloca(
+                            moduleTranslation.convertType(iv.getType())));
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ergawy wrote:

I think `undef` is a better idea than using a fake `alloca`, less confusing. Did that.

https://github.com/llvm/llvm-project/pull/130078