Bug #9227: use opt_aset ?

• Status: Closed
• Assignee: ko1 (Koichi Sasada)
• Target version: 2.1.0
• ruby -v: trunk
• Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN

[tmm1 (Aman Karmani)]

I noticed we have an opt_aset instruction, but nothing is using it. Is there some reason?

diff --git a/compile.c b/compile.c
index 812f692..9d9f14f 100644
--- a/compile.c
+++ b/compile.c
@@ -1955,6 +1955,11 @@ iseq_specialized_instruction(rb_iseq_t *iseq, INSN *iobj)
case idAREF: SP_INSN(aref); return COMPILE_OK;
}
break;

•         case 2:
  

•           switch (ci->mid) {
  

•               case idASET: SP_INSN(aset);   return COMPILE_OK;
  

•           }
  

•           break;
        }
    }
    if (ci->flag & VM_CALL_ARGS_SKIP_SETUP) {
  

[tmm1 (Aman Karmani)]

Maybe some minor improvement on microbenchmarks.

Before patch:

./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.54s user 0.02s system 99% cpu 1.572 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.58s user 0.02s system 99% cpu 1.608 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.54s user 0.02s system 99% cpu 1.565 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.57s user 0.02s system 99% cpu 1.605 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.54s user 0.02s system 99% cpu 1.569 total

After patch:

./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.51s user 0.02s system 99% cpu 1.535 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.52s user 0.02s system 99% cpu 1.545 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.49s user 0.02s system 99% cpu 1.515 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.54s user 0.02s system 99% cpu 1.567 total
./miniruby -I. benchmark/bm_so_k_nucleotide.rb > /dev/null 1.50s user 0.02s system 99% cpu 1.530 total

[ko1 (Koichi Sasada)]

• Assignee set to ko1 (Koichi Sasada)

I forget why I remove it.
Maybe I can't measure improvement (and possible to have trouble with this insn).

If there are no regression, I don't against to use it.

[tmm1 (Aman Karmani)]

I did some more microbenchmarks. In the Array#[Fixnum]= case, the new instruction makes a huge difference.

Before:
array aset 1.430000 0.000000 1.430000 ( 1.430370)
array aset 1.430000 0.000000 1.430000 ( 1.429422)
array aset 1.520000 0.000000 1.520000 ( 1.544912)
array aset 1.440000 0.000000 1.440000 ( 1.444454)

After:
array aset 0.910000 0.000000 0.910000 ( 0.908866)
array aset 0.910000 0.000000 0.910000 ( 0.910356)
array aset 0.890000 0.000000 0.890000 ( 0.891267)
array aset 0.920000 0.000000 0.920000 ( 0.921012)

Benchmark:

require 'benchmark'
Benchmark.bmbm(20) do |b|
ary = [1,2,3,4]
b.report('array aset') do
10_000_000.times do
ary[2] = 2
ary[3] = 3
end
end
end

Here's a copy of the patch that applies on trunk:

diff --git a/compile.c b/compile.c
index af11baf..25e3652 100644
--- a/compile.c
+++ b/compile.c
@@ -1955,6 +1955,11 @@ iseq_specialized_instruction(rb_iseq_t *iseq, INSN *iobj)
case idAREF: SP_INSN(aref); return COMPILE_OK;
}
break;

•     case 2:
  

•   switch (ci->mid) {
  

•     case idASET:	 SP_INSN(aset);	  return COMPILE_OK;
  

•   }
  

•   break;
    }
  

  }
  if (ci->flag & VM_CALL_ARGS_SKIP_SETUP) {

[ko1 (Koichi Sasada)]

OK. Please enable it.

[tmm1 (Aman Karmani)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r44136.
Aman, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

compile.c: add opt_aset instruction for faster Hash#[]= and Array#[]=

• compile.c (iseq_specialized_instruction): emit opt_aset instruction
  to optimize Hash#[]= and Array#[]= when called with Fixnum argument.
  [Bug #9227] [ruby-core:58956]