Bug #6370: NaNTest failed for Ruby 1.9.3 P194

• Status: Closed
• Assignee: luislavena (Luis Lavena)
• Target version: -
• ruby -v: ruby 1.9.3p194 (2012-04-20) [x64-mingw32]

[[e-mail] (ray linn)]

The Ruby 1.9.3 is compibled by GCC 4.7.0 (MinGW64) under Windows64. Configure line is as following:

.configure --build=x86_64-w64-mingw32 CFLAGS="-Ofast -mieee-fp -I/usr/local/include" CPPFLAGS="-Ofast -mieee-fp -I/usr/local/include" LDFLAGS="-L/usr/local/lib"

When compiled complete, run make test, it reports:
not ok float 15 -- C:/msys/1.0/home/beta/ruby-1.9.3-p194/sample/test.rb:1410:in nan_test' not ok float 20 -- C:/msys/1.0/home/beta/ruby-1.9.3-p194/sample/test.rb:1410:in nan_test'
not ok float 25 -- C:/msys/1.0/home/beta/ruby-1.9.3-p194/sample/test.rb:1410:in nan_test' not ok float 30 -- C:/msys/1.0/home/beta/ruby-1.9.3-p194/sample/test.rb:1410:in nan_test'
not ok float 35 -- C:/msys/1.0/home/beta/ruby-1.9.3-p194/sample/test.rb:1410:in nan_test' not ok float 40 -- C:/msys/1.0/home/beta/ruby-1.9.3-p194/sample/test.rb:1410:in nan_test'
not ok float 45 -- C:/msys/1.0/home/beta/ruby-1.9.3-p194/sample/test.rb:1410:in `nan_test'
not ok/test: 903 failed 7

marked these 7 lines could pass the test

#nan_test(nan, 0)
#nan_test(nan, 1)
#nan_test(nan, -1)
#nan_test(nan, 1000)
#nan_test(nan, -1000)
#nan_test(nan, 1_000_000_000_000)
#nan_test(nan, -1_000_000_000_000)

[mame (Yusuke Endoh)]

Could you run the following script and show the result?

nan = 0.0 / 0
p nan
p [nan].pack("D")
p nan <=> 0
p nan != 0
p nan < 0
p nan > 0
p nan <= 0
p nan >= 0

--
Yusuke Endoh [e-mail]

[[e-mail] (ray linn)]

Here is the result:

beta@beta-PC ~
$ ruby test.rb
NaN
"\x00\x00\x00\x00\x00\x00\xF8\xFF"
nil
false
false
false
false
false

[mame (Yusuke Endoh)]

• Status changed from Open to Assigned
• Assignee set to luislavena (Luis Lavena)

I have no idea why (nan != 0) is evaluated to false.
Luis, Usa-san, Hongli Lai, can you reproduce it?

--
Yusuke Endoh [e-mail]

[phasis68 (Heesob Park)]

I can reproduce this issue on GCC 4.7.0 Mingw32.

The optimization flag -Ofast is the root cause of this issue.
Accoring to the manual, -Ofast is same to -O3 and -ffast-math.
And -ffast-math sets -fno-math-errno, -funsafe-math-optimizations, -ffinite-math-only, -fno-rounding-math, -fno-signaling-nans and -fcx-limited-range.

The flag -ffinite-math-only means
"Allow optimizations for floating-point arithmetic that assume that arguments and results are not NaNs or +-Infs."
So the nan test is not worked as expected.

The workaround is adding -fno-finite-math-only in case of -Ofast flag.

[nobu (Nobuyoshi Nakada)]

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

This issue was solved with changeset r35497.
ray, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• configure.in (optflags): disable unsafe optimizations.
  [ruby-core:44679][Bug #6370]

[mame (Yusuke Endoh)]

Heesob Park, thank you!

And I'm very sorry. I made a mistake with your name in [ruby-core:44692].

--
Yusuke Endoh [e-mail]