[Frontend] Print out config when autotune fails (#5117)

Printing out config when autotune fails under `TRITON_PRINT_AUTOTUNING `. This will
allow kernel developers to narrow down a problematic config and remove
it to unblock themselves. This could also help compiler developers focus
on debugging that config.

Author: htyu

python/triton/runtime/autotuner.py

@@ -131,6 +131,10 @@ def _post_hook(kwargs, exception):
     def _bench(self, *args, config, **meta):
         from ..compiler.errors import CompileTimeAssertionFailure
 
+        verbose = os.environ.get("TRITON_PRINT_AUTOTUNING", None) == "1"
+        if verbose:
+            print(f"Autotuning kernel {self.base_fn.__name__} with config {config}")
+
         # check for conflicts, i.e. meta-parameters both provided
         # as kwargs and by the autotuner
         conflicts = meta.keys() & config.kwargs.keys()
@@ -161,7 +165,9 @@ def kernel_call():
 
         try:
             return self.do_bench(kernel_call, quantiles=(0.5, 0.2, 0.8))
-        except (OutOfResources, CompileTimeAssertionFailure, PTXASError):
+        except (OutOfResources, CompileTimeAssertionFailure, PTXASError) as e:
+            if verbose:
+                print(f"Autotuning failed with {e}")
             return [float("inf"), float("inf"), float("inf")]
 
     def run(self, *args, **kwargs):