From b9c18a2460a038e3c30db13da150c1c00249517c Mon Sep 17 00:00:00 2001
From: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Tue, 18 Sep 2018 16:30:49 -0400
Subject: [PATCH] always obey inline declarations if the calling signature is
 concrete

This implements the suggestion in
https://github.com/JuliaLang/julia/pull/27857#issuecomment-421109530
---
 base/compiler/optimize.jl | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/base/compiler/optimize.jl b/base/compiler/optimize.jl
index 870b83d50745f..6a202b40a3024 100644
--- a/base/compiler/optimize.jl
+++ b/base/compiler/optimize.jl
@@ -230,15 +230,19 @@ function optimize(opt::OptimizationState, @nospecialize(result))
     if force_noinline
         opt.src.inlineable = false
     elseif isa(def, Method)
-        bonus = 0
-        if result ⊑ Tuple && !isbitstype(widenconst(result))
-            bonus = opt.params.inline_tupleret_bonus
-        end
-        if opt.src.inlineable
-            # For functions declared @inline, increase the cost threshold 20x
-            bonus += opt.params.inline_cost_threshold*19
+        if opt.src.inlineable && isdispatchtuple(opt.linfo.specTypes)
+            # obey @inline declaration if a dispatch barrier would not help
+        else
+            bonus = 0
+            if result ⊑ Tuple && !isbitstype(widenconst(result))
+                bonus = opt.params.inline_tupleret_bonus
+            end
+            if opt.src.inlineable
+                # For functions declared @inline, increase the cost threshold 20x
+                bonus += opt.params.inline_cost_threshold*19
+            end
+            opt.src.inlineable = isinlineable(def, opt, bonus)
         end
-        opt.src.inlineable = isinlineable(def, opt, bonus)
     end
     nothing
 end