File 0071-HiPE-Fix-off-by-one-in-register-allocators.patch of Package erlang

From 3cf6a85eb32e173b533de47bcd530364ceb20dc5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Magnus=20L=C3=A5ng?= <margnus1@telia.com>
Date: Thu, 23 Mar 2017 22:03:03 +0100
Subject: [PATCH] HiPE: Fix off-by-one in register allocators

hipe_regalloc_loop considers SpillLimit to be an inclusive lower bound,
the allocators considered it to be an exclusive lower bound. The
allocators are changed to also consider it an inclusive lower bound.

This caused the register allocators to occasionally spill the first
"unspillable" temporary. This caused a failure in a newly added
assertion when hipe-compiling dets_v9 on x86.
---
 lib/hipe/regalloc/hipe_coalescing_regalloc.erl     | 2 +-
 lib/hipe/regalloc/hipe_graph_coloring_regalloc.erl | 6 +++---
 lib/hipe/regalloc/hipe_optimistic_regalloc.erl     | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/hipe/regalloc/hipe_coalescing_regalloc.erl b/lib/hipe/regalloc/hipe_coalescing_regalloc.erl
index e8ccbec9f..b8f0a1974 100644
--- a/lib/hipe/regalloc/hipe_coalescing_regalloc.erl
+++ b/lib/hipe/regalloc/hipe_coalescing_regalloc.erl
@@ -914,7 +914,7 @@ findCheapest([Node|Nodes], IG, Cost, Cheapest, SpillLimit) ->
 %% limit are extremely expensive.
 
 getCost(Node, IG, SpillLimit) ->
-  case Node > SpillLimit of
+  case Node >= SpillLimit of
     true -> inf;
     false -> hipe_ig:node_spill_cost(Node, IG)
   end.
diff --git a/lib/hipe/regalloc/hipe_graph_coloring_regalloc.erl b/lib/hipe/regalloc/hipe_graph_coloring_regalloc.erl
index 07aa812f4..f82d3a2cb 100644
--- a/lib/hipe/regalloc/hipe_graph_coloring_regalloc.erl
+++ b/lib/hipe/regalloc/hipe_graph_coloring_regalloc.erl
@@ -209,8 +209,8 @@ color(IG, Spill, PhysRegs, SpillIx, SpillLimit, NumNodes, Target,
 
   %% Any nodes above the spillimit must be colored first...
   MustNotSpill = 
-    if NumNodes > SpillLimit+1 ->
-	sort_on_degree(lists:seq(SpillLimit+1,NumNodes-1) -- Low,IG);
+    if NumNodes > SpillLimit ->
+	sort_on_degree(lists:seq(SpillLimit,NumNodes-1) -- Low,IG);
        true -> []
     end,
       
@@ -401,7 +401,7 @@ spill_costs([{N,Info}|Ns], IG, Vis, Spill, SpillLimit, Target) ->
 	    true ->
 	      spill_costs(Ns, IG, Vis, Spill, SpillLimit, Target);
 	    false ->
-	      if N > SpillLimit ->
+	      if N >= SpillLimit ->
 		  spill_costs(Ns, IG, Vis, Spill, SpillLimit, Target);
 		 true ->
 		  [{spill_cost_of(N,Spill)/Deg,N} | 
diff --git a/lib/hipe/regalloc/hipe_optimistic_regalloc.erl b/lib/hipe/regalloc/hipe_optimistic_regalloc.erl
index b96920cbc..a019c46b9 100644
--- a/lib/hipe/regalloc/hipe_optimistic_regalloc.erl
+++ b/lib/hipe/regalloc/hipe_optimistic_regalloc.erl
@@ -1933,7 +1933,7 @@ findCheapest([Node|Nodes], IG, Cost, Cheapest, SpillLimit) ->
 %% limit are extremely expensive.
 
 getCost(Node, IG, SpillLimit) ->
-  case Node > SpillLimit of
+  case Node >= SpillLimit of
     true -> inf;
     false ->
       SpillCost = hipe_ig:node_spill_cost(Node, IG),
-- 
2.12.2