From f5fc83ce1382b0e5d3f5475a8aa1b3f1fe250e61 Mon Sep 17 00:00:00 2001
From: Jameson Nash <vtjnash@gmail.com>
Date: Wed, 17 May 2017 15:25:54 -0400
Subject: [PATCH] inference: prohibit inlining of methods (un)specialized on
 Unions

TODO: this is helping to avoid a type-system bug mis-computing sparams during intersection,
but that can already cause significant problems elsewhere too
---
 base/inference.jl | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/base/inference.jl b/base/inference.jl
index a98e0c8842c91..3bd9f8db9f85f 100644
--- a/base/inference.jl
+++ b/base/inference.jl
@@ -3076,6 +3076,7 @@ end
 #### finalize and record the result of running type inference ####
 
 function isinlineable(m::Method, src::CodeInfo)
+    # compute the cost (size) of inlining this code
     inlineable = false
     cost = 1000
     if m.module === _topmod(m.module)
@@ -3168,7 +3169,25 @@ function optimize(me::InferenceState)
     end
 
     # determine and cache inlineability
-    if !me.src.inlineable && !force_noinline && isdefined(me.linfo, :def)
+    if !force_noinline
+        # don't keep ASTs for functions specialized on a Union argument
+        # TODO: this helps avoid a type-system bug mis-computing sparams during intersection
+        sig = unwrap_unionall(me.linfo.specTypes)
+        if isa(sig, DataType) && sig.name === Tuple.name
+            for P in sig.parameters
+                P = unwrap_unionall(P)
+                if isa(P, Union)
+                    force_noinline = true
+                    break
+                end
+            end
+        else
+            force_noinline = true
+        end
+    end
+    if force_noinline
+        me.src.inlineable = false
+    elseif !me.src.inlineable && isdefined(me.linfo, :def)
         me.src.inlineable = isinlineable(me.linfo.def, me.src)
     end
     me.src.inferred = true