ruby-dev

なかだです。

At Sun, 15 Jul 2007 23:37:08 +0900,
Tanaka Akira wrote in [ruby-dev:31236]:
> ふと test_integer.rb の実行を callgrind をかけて、bignum.c
> を眺めていると、rb_big_pow の中に実行されない部分があるのに
> 気がつきました。そしてしばらく眺めた結果、n という変数はずっ
> と 1 なことに気がついてしまいました。なにか変だと思うんです
> が、どうなんでしょう?

たしかに不要のようです。

>                 if (!z) {
>                     SIGNED_VALUE n2 = n * n; // 1 * 1 は 1
>                     if (!POSFIXABLE(n2) || (n2 / n != n)) { // 条件は成立しない
>                         z = bigtrunc(bigsqr(rb_int2big(n))); // ここは実行されない
>                     }
>                     else {
>                         n = n2; // ここで 1 を代入
>                     }
>                 }
>                 else {
>                     z = bigtrunc(bigsqr(z));
>                 }
>                 if (yy & mask) {
>                     if (!z) z = rb_int2big(n); // rb_int2bigには常に 1 を渡す
>                     z = bigtrunc(rb_big_mul0(z, x));

本来ならここでnにxを掛けるはずなのですが、xはBignumなのでBignum
であるzを最初から使うことになり、Fixnum相当のnは使われることが
なくなってしまった、ということかと思います。

-- 
--- 僕の前にBugはない。
--- 僕の後ろにBugはできる。
    中田 伸悦

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[#31101] exception when converting block arg — "Yusuke ENDOH" <mame@...>

[#31102] [*0];0 dumps core — "Yusuke ENDOH" <mame@...>

[#31104] v0,(*,v1,) = 0 dumps core — Tanaka Akira <akr@...>

[#31107] *v1,(*) = 0: Stack consistency error — Tanaka Akira <akr@...>

[#31109] assignment syntax — Tanaka Akira <akr@...>

[#31110] ary[]+=1 dumps core — "Yusuke ENDOH" <mame@...>

[#31118] 0..$1=0 dumps core — "Yusuke ENDOH" <mame@...>

[#31119] loop{x+=1&&next} dumps core — "Yusuke ENDOH" <mame@...>

[#31132] (v,) = [[]] — Tanaka Akira <akr@...>

[#31136] *a = *nil — Tanaka Akira <akr@...>

[#31138] nil.to_splat — Tanaka Akira <akr@...>

[#31140] ripper.y:3235: error: syntax error before '}' token — pegacorn <subscriber.jp@...>

[#31141] SEGV by m {|(*,v)|} — Tanaka Akira <akr@...>

[#31142] yield :k=>:v, *[] — Tanaka Akira <akr@...>

[#31143] m {|(*,(*)),|} — Tanaka Akira <akr@...>

[#31145] make test result — SASADA Koichi <ko1@...>

[#31147] Proc from yield — Tanaka Akira <akr@...>

[#31148] lib/irb/completion.rb needs .to_s — "NARUSE, Yui" <naruse@...>

[#31149] net/http: path.empty? was removed when path is nil — "NARUSE, Yui" <naruse@...>

[#31151] trunk: rdoc: format.rb 処理中に Bus error — pegacorn <subscriber.jp@...>

[#31153] syntax error: m {|(*,a,b)|} — Tanaka Akira <akr@...>

[#31160] Stack consistency error: m {|(v,(*))|} — Tanaka Akira <akr@...>

[#31162] rb_eval_string("lambda{}") dumps core — Masahiro Sakai (酒井政裕) <masahiro.sakai@...>

[#31163] Invalid read of size 4: valgrind ./ruby -ve 'print "a"' — Tanaka Akira <akr@...>

[#31164] ruby_set_current_source remains in intern.h — Masahiro Sakai (酒井政裕) <masahiro.sakai@...>

[#31166] is_ruby_native_thread() — Masahiro Sakai (酒井政裕) <masahiro.sakai@...>

[#31168] 構造体オブジェクトのcloneメソッド呼び出しでメモリリーク発生 — m-ohkubo@... (Mitsuhiko OHKUBO)

[#31177] [Fwd: Netrc?] — Shugo Maeda <shugo@...>

[#31189] 0x3fffffff.succ — Tanaka Akira <akr@...>

[#31190] 0x3fffffffffffffff.succ — Tanaka Akira <akr@...>

[#31197] ary.flatten("") — Tanaka Akira <akr@...>

[#31198] (0...0).max — Tanaka Akira <akr@...>

[#31199] Re: [ruby-cvs:19979] Ruby:r12743 (trunk): * range.c (range_max): use FIX2LONG instead of FIX2INT to avoid — "U.Nakamura" <usa@...>

[#31208] mswin32 on cygwin zsh/bash — "NAKAMURA, Hiroshi" <nakahiro@...>

[#31210] (-0x40000000)/(-1) — Tanaka Akira <akr@...>

[#31211] ruby_1_8_6がtest_condvar_wait_not_owner(TC_Thread)で1F — Kazuhiro NISHIYAMA <zn@...>

[#31212] 0.round — Tanaka Akira <akr@...>

[#31213] 24 ** 7 — Tanaka Akira <akr@...>

[#31214] Warning: OpenSSL::PKCS7::PKCS7 is deprecated after Ruby 1.9; use OpenSSL::PKCS7 instead — Kazuhiro NISHIYAMA <zn@...>

[#31215] 65538 ** 2 — Tanaka Akira <akr@...>

[#31216] 1.8 floating point exception: 0 ** 2 — Tanaka Akira <akr@...>

[#31217] trunk: generator.c:150: warning: unsigned int format, long int arg (arg 3) — pegacorn <subscriber.jp@...>

[#31221] Base64.b64encode len bug — "Kazuhiro NISHIYAMA" <zn@...>

[#31222] trunk: バグを指摘している警告 — pegacorn <subscriber.jp@...>

[#31225] Invalid read/write by ~big_zero. — Tanaka Akira <akr@...>

[#31229] ~big_zero after big_zero % big_neg — Tanaka Akira <akr@...>

[#31236] rb_big_pow — Tanaka Akira <akr@...>

[#31242] p(65536**(1<<29)) stalls — "Yusuke ENDOH" <mame@...>

[#31243] ruby -ne ! dumps core — "Yusuke ENDOH" <mame@...>

[#31244] shift — Tanaka Akira <akr@...>

[#31252] [()] dumps core — "Yusuke ENDOH" <mame@...>

[#31253] [PATCH] Problem with ruby 1.8.6-p36 (and p39) on Tiger — "Vincent Isambart" <vincent.isambart@...>

[#31261] [ruby-bugs-12398] Redefining Exception#backtrace and unhandled exception bug — Nobuyoshi Nakada <nobu@...>

[#31263] !_=() and 0..() dump core — "Yusuke ENDOH" <mame@...>

[#31264] +:x doesn't raise exception — "Yusuke ENDOH" <mame@...>

[#31265] "ab".rindex(/ab/, 0) => nil — Tanaka Akira <akr@...>

[#31271] (1 << 0x40000000)[0x40000000] — Tanaka Akira <akr@...>

[#31285] p()#=>[] — eklerni <eklerni@...>

[#31292] ParseDate.parsedate("Tuesday, July 6th, 2007, 18:35:20 UTC") — Tanaka Akira <akr@...>

[#31293] a = -(1) : warning: empty expression — Tanaka Akira <akr@...>

[#31296] ("a".."z")==="g"#=>false — eklerni <eklerni@...>

[#31298] retryの使い方 — eklerni <eklerni@...>

[#31304] rb_thread_statusが未定義? — Kentaro KAWAMOTO <kentaro.kawamoto@...>

[#31312] faster Bignum#to_s — "Yusuke ENDOH" <mame@...>

[#31318] URI and RFC 3986 (Re: URI::merge bug?) — Nobuyoshi Nakada <nobu@...>

[#31319] DelegatorおよびWeakRefのメモリ使用量 — "GO Noguchi" <gonoguti@...>

[ruby-dev:31237] Re: rb_big_pow

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[#31107] v1,() = 0: Stack consistency error — Tanaka Akira <akr@...>

[#31136] a = nil — Tanaka Akira <akr@...>

[#31143] m {|(,()),|} — Tanaka Akira <akr@...>