Add `compiler_verbose` config flag (#1520)

doc/library/config.rst

@@ -556,6 +556,15 @@ import ``pytensor`` and print the config variable, as in:
 
     When ``True``, print the rewrites applied to stdout.
 
+.. attribute:: compiler_verbose
+
+    Bool value: either ``True`` or ``False``
+
+    Default: ``False``
+
+    When ``True``, print detailed information about the compilation of a graph. The type of information printed will
+    vary depending on the computational backend, and some backends may not provide additional information.
+
 .. attribute:: nocleanup
 
     Bool value: either ``True`` or ``False``

pytensor/configdefaults.py

@@ -430,6 +430,13 @@ def add_compile_configvars():
         in_c_key=False,
     )
 
+    config.add(
+        "compiler_verbose",
+        "Print information about compilation steps.",
+        BoolParam(False),
+        in_c_key=False,
+    )
+
     config.add(
         "on_opt_error",
         (

pytensor/configparser.py

@@ -82,6 +82,7 @@ class PyTensorConfigParser:
     optimizer: str
     optimizer_verbose: bool
     optimizer_verbose_ignore: str
+    compiler_verbose: bool
     on_opt_error: str
     nocleanup: bool
     on_unused_input: str

pytensor/link/numba/dispatch/basic.py

@@ -285,10 +285,14 @@ def generate_fallback_impl(op, node=None, storage_map=None, **kwargs):
     """Create a Numba compatible function from a Pytensor `Op`."""
 
     warnings.warn(
-        f"Numba will use object mode to run {op}'s perform method",
+        f"Numba will use object mode to run {op}'s perform method. "
+        f"Set `pytensor.config.compiler_verbose = True` to see more details.",
         UserWarning,
     )
 
+    if config.compiler_verbose:
+        node.dprint(depth=5, print_type=True)
+
     n_outputs = len(node.outputs)
 
     if n_outputs > 1: