[Mlir-commits] [mlir] [mlir][OpenMP] implement SIMD reduction (PR #146671)

[Sergio Afonso]

================
@@ -2921,6 +2948,50 @@ convertOmpSimd(Operation &opInst, llvm::IRBuilderBase &builder,
                             : nullptr,
                         order, simdlen, safelen);
 
+  // We now need to reduce the per-simd-lane reduction variable into the
+  // original variable. This works a bit differently to other reductions (e.g.
+  // wsloop) because we don't need to call into the OpenMP runtime to handle
+  // threads: everything happened in this one thread.
+  for (auto [i, tuple] : llvm::enumerate(
+           llvm::zip(reductionDecls, isByRef, simdOp.getReductionVars(),
+                     privateReductionVariables))) {
+    auto [decl, byRef, reductionVar, privateReductionVar] = tuple;
+
+    OwningReductionGen gen = makeReductionGen(decl, builder, moduleTranslation);
+    llvm::Value *originalVariable = moduleTranslation.lookupValue(reductionVar);
+    llvm::Type *reductionType = moduleTranslation.convertType(decl.getType());
+
+    // We have one less load for by-ref case because that load is now inside of
+    // the reduction region
+    llvm::Value *redValue = originalVariable;
+    if (!byRef)
+      redValue =
+          builder.CreateLoad(reductionType, redValue, "red.value." + Twine(i));
+    llvm::Value *privateRedValue = builder.CreateLoad(
+        reductionType, privateReductionVar, "red.private.value." + Twine(i));
+    llvm::Value *reduced;
+
+    auto res = gen(builder.saveIP(), redValue, privateRedValue, reduced);
+    if (failed(handleError(res, opInst)))
+      return failure();
+    builder.restoreIP(res.get());
+
+    // for by-ref case, the store is inside of the reduction region
+    if (!byRef)
+      builder.CreateStore(reduced, originalVariable);
+  }
+
+  // After the construct, deallocate private reduction variables
----------------
skatrak wrote:

```suggestion
  // After the construct, deallocate private reduction variables.
```

https://github.com/llvm/llvm-project/pull/146671