Speed up hash literals by duping

This commit replaces the `newhashfromarray` instruction with a `duphash`
instruction.  Instead of allocating a new hash from an array stored in
the Instruction Sequences, store a hash directly in the instruction
sequences and dup it on execution.

== Instruction sequence changes ==

```ruby
code = <<-eorby
  { "foo" => "bar", "baz" => "lol" }
eorby

insns = RubyVM::InstructionSequence.compile(code, __FILE__, nil, 0, frozen_string_literal: true)
puts insns.disasm
```

On Ruby 2.5:

```
== disasm: #<ISeq:<compiled>@test.rb:0 (0,0)-(0,36)>====================
0000 putobject        "foo"
0002 putobject        "bar"
0004 putobject        "baz"
0006 putobject        "lol"
0008 newhash          4
0010 leave
```

Ruby 2.6@r66174 3b6321083a2e3525da3b34d08a0b68bac094bd7f:

```
$ ./ruby test.rb
== disasm: #<ISeq:<compiled>@test.rb:0 (0,0)-(0,36)> (catch: FALSE)
0000 newhashfromarray             2, ["foo", "bar", "baz", "lol"]
0003 leave
```

Ruby 2.6 + This commit:

```
$ ./ruby test.rb
== disasm: #<ISeq:<compiled>@test.rb:0 (0,0)-(0,36)> (catch: FALSE)
0000 duphash                      {"foo"=>"bar", "baz"=>"lol"}
0002 leave
```

== Benchmark Results ==

Compared to 2.5.3:

```
$ make benchmark ITEM=hash_literal_small COMPARE_RUBY=/Users/aaron/.rbenv/versions/2.5.3/bin/ruby
generating known_errors.inc
known_errors.inc unchanged
./revision.h unchanged
/Users/aaron/.rbenv/shims/ruby --disable=gems -rrubygems -I./benchmark/lib ./benchmark/benchmark-driver/exe/benchmark-driver \
	            --executables="compare-ruby::/Users/aaron/.rbenv/versions/2.5.3/bin/ruby -I.ext/common --disable-gem" \
	            --executables="built-ruby::./miniruby -I./lib -I. -I.ext/common  -r./prelude --disable-gem" \
	            $(find ./benchmark -maxdepth 1 -name '*hash_literal_small*.yml' -o -name '*hash_literal_small*.rb' | sort)
Calculating -------------------------------------
                     compare-ruby  built-ruby
 hash_literal_small2        1.498       1.877 i/s -       1.000 times in 0.667581s 0.532656s
 hash_literal_small4        1.197       1.642 i/s -       1.000 times in 0.835375s 0.609160s
 hash_literal_small8        0.620       1.215 i/s -       1.000 times in 1.611638s 0.823090s

Comparison:
              hash_literal_small2
          built-ruby:         1.9 i/s
        compare-ruby:         1.5 i/s - 1.25x  slower

              hash_literal_small4
          built-ruby:         1.6 i/s
        compare-ruby:         1.2 i/s - 1.37x  slower

              hash_literal_small8
          built-ruby:         1.2 i/s
        compare-ruby:         0.6 i/s - 1.96x  slower
```

Compared to r66255

```
$ make benchmark ITEM=hash_literal_small COMPARE_RUBY=/Users/aaron/.rbenv/versions/ruby-trunk/bin/ruby
generating known_errors.inc
known_errors.inc unchanged
./revision.h unchanged
/Users/aaron/.rbenv/shims/ruby --disable=gems -rrubygems -I./benchmark/lib ./benchmark/benchmark-driver/exe/benchmark-driver \
	            --executables="compare-ruby::/Users/aaron/.rbenv/versions/ruby-trunk/bin/ruby -I.ext/common --disable-gem" \
	            --executables="built-ruby::./miniruby -I./lib -I. -I.ext/common  -r./prelude --disable-gem" \
	            $(find ./benchmark -maxdepth 1 -name '*hash_literal_small*.yml' -o -name '*hash_literal_small*.rb' | sort)
Calculating -------------------------------------
                     compare-ruby  built-ruby
 hash_literal_small2        1.567       1.831 i/s -       1.000 times in 0.638056s 0.546039s
 hash_literal_small4        1.298       1.652 i/s -       1.000 times in 0.770214s 0.605182s
 hash_literal_small8        0.873       1.216 i/s -       1.000 times in 1.145304s 0.822047s

Comparison:
              hash_literal_small2
          built-ruby:         1.8 i/s
        compare-ruby:         1.6 i/s - 1.17x  slower

              hash_literal_small4
          built-ruby:         1.7 i/s
        compare-ruby:         1.3 i/s - 1.27x  slower

              hash_literal_small8
          built-ruby:         1.2 i/s
        compare-ruby:         0.9 i/s - 1.39x  slower
```

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66258 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 2 deletions

diff --git a/test/ruby/test_jit.rb b/test/ruby/test_jit.rb
index fdcb0726ef..7627b2c048 100644
--- a/test/ruby/test_jit.rb
+++ b/test/ruby/test_jit.rb
@@ -239,8 +239,8 @@ class TestJIT < Test::Unit::TestCase
     assert_compile_once('a = 1; { a: a }', result_inspect: '{:a=>1}', insns: %i[newhash])
   end
 
-  def test_compile_insn_newhashfromarray
-    assert_compile_once('{ a: 1 }', result_inspect: '{:a=>1}', insns: %i[newhashfromarray])
+  def test_compile_insn_duphash
+    assert_compile_once('{ a: 1 }', result_inspect: '{:a=>1}', insns: %i[duphash])
   end
 
   def test_compile_insn_newrange