[llvm-branch-commits] [flang] [flang] support fir.alloca operations inside of omp reduction ops (PR #84952)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-codegen

Author: Tom Eccles (tblah)

<details>
<summary>Changes</summary>

Advise to place the alloca at the start of the first block of whichever region (init or combiner) we are currently inside.

It probably isn't safe to put an alloca inside of a combiner region because this will be executed multiple times. But that would be a bug to fix in Lower/OpenMP.cpp, not here.

OpenMP array reductions 1/6

---
Full diff: https://github.com/llvm/llvm-project/pull/84952.diff


2 Files Affected:

- (modified) flang/lib/Optimizer/Builder/FIRBuilder.cpp (+2) 
- (modified) flang/lib/Optimizer/CodeGen/CodeGen.cpp (+9-2) 


``````````diff
diff --git a/flang/lib/Optimizer/Builder/FIRBuilder.cpp b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
index 12da7412888a3b..f7327a299d9a5e 100644
--- a/flang/lib/Optimizer/Builder/FIRBuilder.cpp
+++ b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
@@ -208,6 +208,8 @@ mlir::Block *fir::FirOpBuilder::getAllocaBlock() {
               .getParentOfType<mlir::omp::OutlineableOpenMPOpInterface>()) {
     return ompOutlineableIface.getAllocaBlock();
   }
+  if (mlir::isa<mlir::omp::ReductionDeclareOp>(getRegion().getParentOp()))
+    return &getRegion().front();
   if (auto accRecipeIface =
           getRegion().getParentOfType<mlir::acc::RecipeInterface>()) {
     return accRecipeIface.getAllocaBlock(getRegion());
diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
index f81a08388da722..123eb6e4e6a255 100644
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -410,8 +410,15 @@ class FIROpConversion : public mlir::ConvertOpToLLVMPattern<FromOp> {
       mlir::ConversionPatternRewriter &rewriter) const {
     auto thisPt = rewriter.saveInsertionPoint();
     mlir::Operation *parentOp = rewriter.getInsertionBlock()->getParentOp();
-    mlir::Block *insertBlock = getBlockForAllocaInsert(parentOp);
-    rewriter.setInsertionPointToStart(insertBlock);
+    if (mlir::isa<mlir::omp::ReductionDeclareOp>(parentOp)) {
+      // ReductionDeclareOp has multiple child regions. We want to get the first
+      // block of whichever of those regions we are currently in
+      mlir::Region *parentRegion = rewriter.getInsertionBlock()->getParent();
+      rewriter.setInsertionPointToStart(&parentRegion->front());
+    } else {
+      mlir::Block *insertBlock = getBlockForAllocaInsert(parentOp);
+      rewriter.setInsertionPointToStart(insertBlock);
+    }
     auto size = genI32Constant(loc, rewriter, 1);
     unsigned allocaAs = getAllocaAddressSpace(rewriter);
     unsigned programAs = getProgramAddressSpace(rewriter);

``````````

</details>


https://github.com/llvm/llvm-project/pull/84952