core: Fix parsing for hex denseAttrs (#3239)

Fixes #2876.

The original parsing implementation for hex denseAttrs uses format
strings in `struct.unpack_from()`, but the format strings actually do
not include the count of the chunks contained in the bytes list.

This patch fixes this behavior by embedding the number of chunks in the
respective format string.

tests/filecheck/parser-printer/builtin_attrs.mlir

@@ -82,6 +82,9 @@
 
   // CHECK: 3.060000e+02 : f32
 
+  "func.func"() ({}) {function_type = () -> (), value = dense<"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tensor<4x4x3x3xf32>, sym_name = "hex_f32_large_attr"} : () -> ()
+
+  // CHECK: "value" = dense<[[[[9.992968e-02, -1.430319e-01, 1.480872e-01], [-1.135054e-01, -3.655422e-02, -1.524415e-01], [-1.096354e-01, 1.070076e-01, 1.635475e-01]], [[6.201498e-02, 1.377752e-01, 6.284702e-02], [1.423031e-02, -2.755300e-02, -5.018222e-02], [1.126285e-01, 1.467116e-01, -4.841509e-02]], [[1.616688e-01, 6.736130e-02, -1.368682e-01], [5.771752e-02, -1.536790e-01, 5.869561e-02], [-9.142806e-02, -4.854431e-02, -6.135579e-02]], [[-6.997196e-02, 1.221017e-01, 8.880942e-02], [-9.790727e-02, 8.166470e-02, 1.657003e-01], [1.432140e-01, -6.376306e-04, 2.486622e-02]]], [[[-8.931184e-02, -8.708668e-02, -2.310556e-02], [5.971766e-02, 1.079614e-01, -1.042320e-01], [1.297905e-01, -9.458923e-02, 3.385238e-02]], [[1.064524e-01, 7.494444e-02, -1.417377e-02], [-3.528321e-02, -8.690961e-02, 1.572554e-01], [-1.448007e-01, 1.396378e-03, 2.953589e-03]], [[-8.743954e-02, 1.499613e-01, -1.458949e-01], [6.397714e-02, -1.601468e-02, 1.705752e-02], [-8.939862e-02, 1.030373e-01, -4.113474e-02]], [[-1.393882e-01, 1.261400e-01, -1.203568e-01], [-1.384676e-03, -1.290683e-01, 1.208070e-01], [5.880459e-02, 8.035894e-02, 5.368434e-02]]], [[[-1.136149e-01, -1.179534e-01, 7.016367e-02], [1.793486e-02, -1.264111e-01, -8.228018e-02], [-1.767119e-03, 1.541317e-03, -1.610818e-01]], [[-8.073064e-02, 6.758833e-02, 9.321358e-02], [-2.199372e-03, 1.472749e-02, -1.560103e-01], [7.020243e-02, -1.053098e-01, 4.541967e-02]], [[1.396751e-01, 9.858086e-02, 3.462158e-02], [1.098654e-01, 6.237565e-02, 1.037528e-01], [-3.075286e-02, -8.537539e-02, 1.276630e-01]], [[-2.053817e-03, -7.634263e-02, 1.319897e-01], [-1.197378e-01, -1.338271e-01, -1.633589e-01], [1.461712e-01, -1.301150e-01, -1.436527e-01]]], [[[-5.300419e-02, -1.039582e-01, 3.584604e-02], [-6.330036e-02, 2.933902e-02, 1.210629e-01], [-9.744763e-04, -8.533832e-02, 1.634076e-01]], [[-8.803773e-02, 3.552079e-03, 9.822105e-02], [4.169868e-02, 5.665455e-02, 7.129338e-02], [-1.330132e-01, 1.203795e-03, -1.112827e-02]], [[-1.189723e-01, 1.219815e-01, 9.064370e-02], [1.528674e-01, 1.606639e-01, -1.070540e-01], [-8.009027e-02, -7.141336e-02, 1.856669e-02]], [[6.147128e-02, -1.334543e-01, 4.995131e-02], [-4.423932e-02, 4.138951e-02, -4.917079e-02], [1.309356e-01, 2.727993e-02, -1.442297e-01]]]]> : tensor<4x4x3x3xf32>
 
   "func.func"() ({}) {function_type = () -> (), value = "foo", sym_name = "string_attr"} : () -> ()
 

xdsl/parser/attribute_parser.py

@@ -721,24 +721,29 @@ def _parse_builtin_dense_attr_hex(
 
         # Use struct builtin package for unpacking f32, f64
         format_str: str = ""
+        num_chunks = 0
         match element_type:
             case Float32Type():
                 chunk_size = 4
-                format_str = "@f"  # @ in format string implies native endianess
+                num_chunks = len(byte_list) // chunk_size
+                format_str = (
+                    f"@{num_chunks}f"  # @ in format string implies native endianess
+                )
             case Float64Type():
                 chunk_size = 8
-                format_str = "@d"
+                num_chunks = len(byte_list) // chunk_size
+                format_str = f"@{num_chunks}d"
             case IntegerType():
                 if element_type.width.data % 8 != 0:
                     self.raise_error(
                         "Hex strings for dense literals only support integer types that are a multiple of 8 bits"
                     )
                 chunk_size = element_type.width.data // 8
+                num_chunks = len(byte_list) // chunk_size
             case _:
                 self.raise_error(
                     "Hex strings for dense literals are only supported for int, f32 and f64 types"
                 )
-        num_chunks = len(byte_list) // chunk_size
 
         data_values: list[int] | list[float] = []