[flang-commits] [flang] [flang] Simple folding for hlfir.shape_of. (PR #119649)

[Slava Zakharin via flang-commits]

https://github.com/vzakhari created https://github.com/llvm/llvm-project/pull/119649

This folding makes sure there are no hlfir.shape_of users
of hlfir.elemental - this may enable more InlineElementals matches,
because it is looking for exactly two uses of an hlfir.elemental.


>From a60cdbb05d43bfc8c9ca7e392825e47a96b1224e Mon Sep 17 00:00:00 2001
From: Slava Zakharin <szakharin at nvidia.com>
Date: Wed, 11 Dec 2024 15:01:44 -0800
Subject: [PATCH] [flang] Simple folding for hlfir.shape_of.

This folding makes sure there are no hlfir.shape_of users
of hlfir.elemental - this may enable more InlineElementals matches,
because it is looking for exactly two uses of an hlfir.elemental.
---
 .../include/flang/Optimizer/HLFIR/HLFIROps.td  |  1 +
 flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp      |  9 +++++++++
 flang/test/HLFIR/shapeof.fir                   | 18 ++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/flang/include/flang/Optimizer/HLFIR/HLFIROps.td b/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
index f11162dc0d95e1..48764580d526d2 100644
--- a/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
+++ b/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
@@ -1205,6 +1205,7 @@ def hlfir_ShapeOfOp : hlfir_Op<"shape_of", [Pure]> {
   }];
 
   let builders = [OpBuilder<(ins "mlir::Value":$expr)>];
+  let hasFolder = 1;
 }
 
 def hlfir_GetExtentOp : hlfir_Op<"get_extent", [Pure]> {
diff --git a/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp b/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
index ad53527f43441b..82aac7cafa1d0e 100644
--- a/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
+++ b/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
@@ -1704,6 +1704,15 @@ hlfir::ShapeOfOp::canonicalize(ShapeOfOp shapeOf,
   return llvm::LogicalResult::success();
 }
 
+mlir::OpFoldResult hlfir::ShapeOfOp::fold(FoldAdaptor adaptor) {
+  if (matchPattern(getExpr(), mlir::m_Op<hlfir::ElementalOp>())) {
+    auto elementalOp =
+        mlir::cast<hlfir::ElementalOp>(getExpr().getDefiningOp());
+    return elementalOp.getShape();
+  }
+  return {};
+}
+
 //===----------------------------------------------------------------------===//
 // GetExtent
 //===----------------------------------------------------------------------===//
diff --git a/flang/test/HLFIR/shapeof.fir b/flang/test/HLFIR/shapeof.fir
index b91efc276b62e2..43e22dd320c18b 100644
--- a/flang/test/HLFIR/shapeof.fir
+++ b/flang/test/HLFIR/shapeof.fir
@@ -27,3 +27,21 @@ func.func @shapeof2(%arg0: !hlfir.expr<?x2xi32>) -> !fir.shape<2> {
 // CHECK-ALL:          %[[EXPR:.*]]: !hlfir.expr<?x2xi32>
 // CHECK-ALL-NEXT:   %[[SHAPE:.*]] = hlfir.shape_of %[[EXPR]] : (!hlfir.expr<?x2xi32>) -> !fir.shape<2>
 // CHECK-ALL-NEXT:   return %[[SHAPE]]
+
+// Checks hlfir.elemental -> hlfir.shape_of folding
+func.func @shapeof_fold1(%extent: index) -> !fir.shape<1> {
+  %shape1 = fir.shape %extent : (index) -> !fir.shape<1>
+  %elem = hlfir.elemental %shape1 : (!fir.shape<1>) -> !hlfir.expr<?xindex> {
+    hlfir.yield_element %extent : index
+  }
+  %shape2 = hlfir.shape_of %elem : (!hlfir.expr<?xindex>) -> !fir.shape<1>
+  return %shape2 : !fir.shape<1>
+}
+// CHECK-ALL-LABEL:   func.func @shapeof_fold1(
+// CHECK-ALL-SAME:        %[[VAL_0:.*]]: index) -> !fir.shape<1> {
+// CHECK-CANON-NEXT:    %[[VAL_1:.*]] = fir.shape %[[VAL_0]] : (index) -> !fir.shape<1>
+// CHECK-CANON-NEXT:    %[[VAL_2:.*]] = hlfir.elemental %[[VAL_1]] : (!fir.shape<1>) -> !hlfir.expr<?xindex> {
+// CHECK-CANON-NEXT:      hlfir.yield_element %[[VAL_0]] : index
+// CHECK-CANON-NEXT:    }
+// CHECK-CANON-NEXT:    return %[[VAL_1]] : !fir.shape<1>
+// CHECK-CANON-NEXT:  }