core: Adding option to print full precision fp (#3381)

`mlir-opt` attempts to print floats as 6dp scientific notation, but
round-trips to ensure there is no precision loss and the printed number
will bitwise reproduce exactly. If this fails, it will choose a
different printing method to ensure bit-reproducible printing for a
given precision of fp types.

This PR takes the approach of mlir-opt: attempt to print to scientific
6dp notation iff the resulting string is losslessly reproducible, or
else print to full precision using repr. This has the advantage of not
affecting a vast number of filechecks, mirroring upstream, and not
having a flag for either full or reduced precision.

---------

Co-authored-by: n-io <[email protected]>

xdsl/printer.py

@@ -560,10 +560,17 @@ def print_attribute(self, attribute: Attribute) -> None:
             return
 
         if isinstance(attribute, FloatAttr):
-            attr = cast(AnyFloatAttr, attribute)
-            self.print_float(attr)
-            self.print_string(" : ")
-            self.print_attribute(attr.type)
+            value = attribute.value
+            attr_type = cast(
+                FloatAttr[Float16Type | Float32Type | Float64Type], attribute
+            ).type
+            # to mirror mlir-opt, attempt to print scientific notation iff the value parses losslessly
+            float_str = f"{value.data:.6e}"
+            if float(float_str) == value.data:
+                self.print_string(f"{float_str} : ")
+            else:
+                self.print_string(f"{repr(value.data)} : ")
+            self.print_attribute(attr_type)
             return
 
         # Complex types have MLIR shorthands but XDSL does not.
@@ -623,7 +630,11 @@ def print_one_elem(val: Attribute):
                 if isinstance(val, IntegerAttr):
                     self.print_string(f"{val.value.data}")
                 elif isinstance(val, FloatAttr):
-                    self.print_float(cast(AnyFloatAttr, val))
+                    float_str = f"{val.value.data:.6e}"
+                    if float(float_str) == val.value.data:
+                        self.print_string(float_str)
+                    else:
+                        self.print_string(f"{repr(val.value.data)}")
                 else:
                     raise Exception(
                         "unexpected attribute type "