[flang-commits] [flang] [flang][FIRToMemRef] lower `fir.coordinate_of` on static-extent arrays to indexed memref (PR #195404)

[Scott Manley via flang-commits]

================
@@ -867,6 +879,75 @@ Value FIRToMemRef::canonicalizeIndex(Value index,
   return index;
 }
 
+bool FIRToMemRef::isArrayIndexingCoordinateOp(
+    fir::CoordinateOp coordinateOp,
+    FIRToMemRefTypeConverter &typeConverter) const {
+  // The base must be a reference/pointer/heap to a sequence/array type.
+  Type baseType = coordinateOp.getRef().getType();
+  Type unwrapped = fir::dyn_cast_ptrEleTy(baseType);
+  if (!unwrapped)
+    return false;
+
+  auto seqTy = dyn_cast<fir::SequenceType>(unwrapped);
+  if (!seqTy)
+    return false;
+
+  // Restrict to fully static extents — dynamic arrays would need a shape
+  // operand (which coordinate_of lacks) to build a valid memref descriptor.
+  if (fir::hasDynamicSize(seqTy))
+    return false;
+
+  // The element type must be a convertible scalar — no derived types.
+  if (!typeConverter.convertibleMemrefType(baseType))
+    return false;
+
+  return true;
+}
+
+MemRefInfo FIRToMemRef::convertCoordinateArrayOp(
+    Operation *memOp, fir::CoordinateOp coordinateOp, PatternRewriter &rewriter,
+    FIRToMemRefTypeConverter &typeConverter) {
+  Value firBase = coordinateOp.getRef();
+  Location loc = coordinateOp->getLoc();
+  IndexType indexTy = rewriter.getIndexType();
+
+  if (typeConverter.isEmptyArray(firBase.getType()))
+    return failure();
+
+  // Convert the base ref/heap/ptr to a memref.  convertMemrefType reverses the
+  // FIR column-major shape to row-major, keeping it in sync with index reversal
+  // below.
+  rewriter.setInsertionPoint(coordinateOp);
+  FailureOr<Value> converted;
+  if (isa<BlockArgument>(firBase)) {
+    Type memrefTy = typeConverter.convertMemrefType(firBase.getType());
+    converted =
+        fir::ConvertOp::create(rewriter, loc, memrefTy, firBase).getResult();
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rscottmanley wrote:

do we need to check for failure here or?

https://github.com/llvm/llvm-project/pull/195404