[ruby-core:55021] [ruby-trunk - Bug #8358] TestSprintf#test_float test failuer on mingw32

Issue #8358 has been updated by h.shirosaki (Hiroshi Shirosaki).


The author describes that it is necessary to specify double-precision (53-bit) rounding precision before invoking strtod or dtoa.
https://github.com/ruby/ruby/blob/trunk/util.c#L526

So that I created a patch to set _PC_53 temporally when calling strtod, dtoa and hdtoa on mingw x86.

It seems that __SSE2_MATH__ is defined only if compiling with -msse2 -mfpmath=sse. In the case it avoids to set _PC_53.

This patch would also fix #8299.

https://gist.github.com/shirosaki/5596940
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Bug #8358: TestSprintf#test_float test failuer on mingw32
https://bugs.ruby-lang.org/issues/8358#change-39368

Author: phasis68 (Heesob Park)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.1.0dev (2013-05-01) [i386-mingw32]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


I noticed TestSprintf#test_float
http://ci.rubyinstaller.org/job/ruby-trunk-x86-test-all/1287/console
  1) Failure:
TestSprintf#test_float [C:/Users/Worker/Jenkins/workspace/ruby-trunk-x86-build/test/ruby/test_sprintf.rb:193]:
[ruby-dev:42551].
<"0x1p+2"> expected but was
<"0x1p+1">.

This failure is due to r40404.

And Actually, this issue is almost same to bug #8299.
ruby_hdtoa function requires 53-bit precision 
but mingw32 compiler is 64-bit precision.

There are 2 possible workarounds.

1. adding  -msse2 -mfpmath=sse flag when compiling.
2. adding  _control87(_PC_53, _MCW_PC) when running.



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