File 2072-Optimize-expression-comparing-a-boolean-to-false.patch of Package erlang

From 50a2d448e775668a5cbd835c9ff5eae6058f8739 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 16 Apr 2019 10:42:57 +0200
Subject: [PATCH 2/4] Optimize expression comparing a boolean to 'false'

---
 lib/compiler/src/beam_ssa_type.erl | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl
index a1c10c7a34..82371f4ba3 100644
--- a/lib/compiler/src/beam_ssa_type.erl
+++ b/lib/compiler/src/beam_ssa_type.erl
@@ -552,6 +552,17 @@ simplify(#b_set{op={bif,'=:='},args=[A1,_A2]=Args}=I, Ts) ->
                 {true,#t_atom{elements=[true]}} ->
                     %% Bool =:= true  ==>  Bool
                     A1;
+                {true,#t_atom{elements=[false]}} ->
+                    %% Bool =:= false ==> not Bool
+                    %%
+                    %% This will be further optimized to eliminate the
+                    %% 'not', swapping the success and failure
+                    %% branches in the br instruction. If A1 comes
+                    %% from a type test (such as is_atom/1) or a
+                    %% comparison operator (such as >=) that can be
+                    %% translated to test instruction, this
+                    %% optimization will eliminate one instruction.
+                    simplify(I#b_set{op={bif,'not'},args=[A1]}, Ts);
                 {_,_} ->
                     eval_bif(I, Ts)
             end
-- 
2.16.4