Add an inference option to ignore the recursion hardlimit

We currently very aggressively limit recursion if we came from
a union split. The reason for this choice is to avoid accidental
exponential inference times from excessive exploration of the call
graph. Unfortunately, certain packages like Diffractor really like
triggering the recursion heuristic at the moment, causing any unions
to immediately cause imprecise inference. In the fullness of time,
we should improve the recursion heuristic to do better in this case,
but for the time being, add an inference option that simply lets
it ignore the hardlimit recursion case and proceed anyway.

base/compiler/abstractinterpretation.jl

@@ -688,7 +688,7 @@ function edge_matches_sv(frame::InferenceState, method::Method, @nospecialize(si
     if callee_method2 !== inf_method2
         return false
     end
-    if !hardlimit
+    if !hardlimit || InferenceParams(sv.interp).ignore_recursion_hardlimit
         # if this is a soft limit,
         # also inspect the parent of this edge,
         # to see if they are the same Method as sv

base/compiler/types.jl

@@ -141,6 +141,7 @@ struct InferenceParams
     aggressive_constant_propagation::Bool
     unoptimize_throw_blocks::Bool
     assume_bindings_static::Bool
+    ignore_recursion_hardlimit::Bool
 
     function InferenceParams(
         max_methods::Int,
@@ -151,7 +152,8 @@ struct InferenceParams
         ipo_constant_propagation::Bool,
         aggressive_constant_propagation::Bool,
         unoptimize_throw_blocks::Bool,
-        assume_bindings_static::Bool)
+        assume_bindings_static::Bool,
+        ignore_recursion_hardlimit::Bool)
         return new(
             max_methods,
             max_union_splitting,
@@ -161,7 +163,8 @@ struct InferenceParams
             ipo_constant_propagation,
             aggressive_constant_propagation,
             unoptimize_throw_blocks,
-            assume_bindings_static)
+            assume_bindings_static,
+            ignore_recursion_hardlimit)
     end
 end
 function InferenceParams(
@@ -174,7 +177,8 @@ function InferenceParams(
         #=ipo_constant_propagation::Bool=# true,
         #=aggressive_constant_propagation::Bool=# false,
         #=unoptimize_throw_blocks::Bool=# true,
-        #=assume_bindings_static::Bool=# false);
+        #=assume_bindings_static::Bool=# false,
+        #=ignore_recursion_hardlimit::Bool=# false);
     max_methods::Int = params.max_methods,
     max_union_splitting::Int = params.max_union_splitting,
     max_apply_union_enum::Int = params.max_apply_union_enum,
@@ -183,7 +187,8 @@ function InferenceParams(
     ipo_constant_propagation::Bool = params.ipo_constant_propagation,
     aggressive_constant_propagation::Bool = params.aggressive_constant_propagation,
     unoptimize_throw_blocks::Bool = params.unoptimize_throw_blocks,
-    assume_bindings_static::Bool = params.assume_bindings_static)
+    assume_bindings_static::Bool = params.assume_bindings_static,
+    ignore_recursion_hardlimit::Bool = params.ignore_recursion_hardlimit)
     return InferenceParams(
         max_methods,
         max_union_splitting,
@@ -193,7 +198,8 @@ function InferenceParams(
         ipo_constant_propagation,
         aggressive_constant_propagation,
         unoptimize_throw_blocks,
-        assume_bindings_static)
+        assume_bindings_static,
+        ignore_recursion_hardlimit)
 end
 
 """