[flang-commits] [flang] [flang] Fix `getTypeSizeAndAlignment` for packed/tail-padded `RecordType` and `TRANSFER` gate (PR #220377)

[Daniel Chen via flang-commits]

================
@@ -102,4 +102,64 @@ module attributes { dlti.dl_spec = #dlti.dl_spec< i1 = dense<8> : vector<2xi64>,
   // CHECK:         %[[C:.*]] = arith.constant 16 : index
   // CHECK:         return %[[C]]
   // CHECK-NOT:     fir.box_elesize
+
+  // Fold: packed derived type -- fir.type<tp<{i:i32,d:f64}>>.
+  // This is the exact example from MattPD's review: on x86-64
+  // (f64 ABI align=8B) the non-packed size is 16B and the packed
+  // size is 12B (i32 allocSize=4B + f64 allocSize=alignTo(8,8)=8B,
+  // no inter-field gap, no tail padding).
+  // The element distance must be 12, not 16.
+  func.func @fold_packed_record(%arg0: !fir.box<!fir.type<tp<{i:i32,d:f64}>>>) -> index {
+    %0 = fir.box_elesize %arg0 : (!fir.box<!fir.type<tp<{i:i32,d:f64}>>>) -> index
+    return %0 : index
+  }
+  // CHECK-LABEL: func.func @fold_packed_record(
+  // CHECK:         %[[C:.*]] = arith.constant 12 : index
+  // CHECK:         return %[[C]]
+  // CHECK-NOT:     fir.box_elesize
+
+  // Fold: packed derived type with a wider alignment gap.
+  // On x86-64: i32 store=4B, complex<f64> store=16B.
+  // Non-packed: alignTo(4,4)=4 + alignTo(4,8)+alignTo(16,8)=24, tail=24 -> 24B.
+  // Packed:     4 + 16 = 20B, align=1.
+  // The element distance must be 20, not 24.
+  func.func @fold_packed_record2(%arg0: !fir.box<!fir.type<tp2<{i:i32,z:complex<f64>}>>>) -> index {
+    %0 = fir.box_elesize %arg0 : (!fir.box<!fir.type<tp2<{i:i32,z:complex<f64>}>>>) -> index
+    return %0 : index
+  }
+  // CHECK-LABEL: func.func @fold_packed_record2(
+  // CHECK:         %[[C:.*]] = arith.constant 20 : index
+  // CHECK:         return %[[C]]
+  // CHECK-NOT:     fir.box_elesize
+
+  // Fold: tail-padded record type -- fir.type<tpad{a:i32,b:i8}>.
+  // The field loop gives size=5, align=4; after tail-padding,
+  // getTypeSizeAndAlignment returns {8, 4}.  The element stride of a
+  // fir.box<fir.array<?x...>> must be the allocation size (8), not the
+  // raw typed size (5).
+  // Use a distinct type name (tpad) to avoid redefining the packed type (tp)
+  // used above.
+  func.func @fold_tail_padded_record(%arg0: !fir.box<!fir.array<?x!fir.type<tpad{a:i32,b:i8}>>>) -> index {
+    %0 = fir.box_elesize %arg0 : (!fir.box<!fir.array<?x!fir.type<tpad{a:i32,b:i8}>>>) -> index
+    return %0 : index
+  }
+  // CHECK-LABEL: func.func @fold_tail_padded_record(
+  // CHECK:         %[[C:.*]] = arith.constant 8 : index
----------------
DanielCChen wrote:

Fixed.

https://github.com/llvm/llvm-project/pull/220377