[flang-commits] [flang] [flang] Reset all extents to zero for empty hlfir.elemental loops. (PR #124867)

[Slava Zakharin via flang-commits]

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@@ -1759,3 +1759,38 @@ fir::factory::deduceOptimalExtents(mlir::ValueRange extents1,
   }
   return extents;
 }
+
+llvm::SmallVector<mlir::Value> fir::factory::updateRuntimeExtentsForEmptyArrays(
+    fir::FirOpBuilder &builder, mlir::Location loc, mlir::ValueRange extents) {
+  if (extents.size() <= 1)
+    return extents;
+
+  // Try to reduce the number of new zero constant operations.
+  // This just makes MLIR matching easier, if CSE is not run
+  // after this.
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vzakhari wrote:

Addressing Jean's question as well.

Yes, it is not usual for extents to have different data types, because they will likely be casted to `index` somewhere else (e.g. as in elemental codegen, where we use `getIndexExtents`).

I guess I overthought it, and I will remove this code :)

https://github.com/llvm/llvm-project/pull/124867