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CMake script regex match patterns has unnecessary kleenes #1040

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zao opened this issue Jan 6, 2014 · 2 comments
Closed

CMake script regex match patterns has unnecessary kleenes #1040

zao opened this issue Jan 6, 2014 · 2 comments
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@zao
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category: CMake difficulty: easy Good issues for starting out with HPX development type: enhancement
Milestone
0.9.8

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@zao
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zao commented Jan 6, 2014

Several of the string(REGEX MATCH patterns in the CMake scripts surround the pattern with .* on one or both sides. This is unnecessary as this kind of pattern only needs to match the part that it tries to match.

On my FreeBSD machine with Clang 3.3, the pattern in cmake/HPX_Compile.cmake:91 [1] tries to match across 120 kilobytes of linker errors and doesn't terminate in acceptable timescales (still hung after ten minutes of saturation).

Removing the .* parts results in an acceptable sub-second match attempt.

There seems to be more occurrences of unnecessary wildcards in the codebase as well, but none that trigger performance cliffs on my system.

[1] ".*(argument unused during compilation|unknown warning option).*"
@hkaiser
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hkaiser commented Jan 6, 2014

Would you care to provide a patch?

zao added a commit to zao/hpx that referenced this issue Jan 6, 2014
@zao
Remove redundant costly Kleene stars from regex searches
b9d4472 
Some of the string(REGEX MATCH) operations surround the pattern
with ".*", causing the CMake process to effectively wedge when
trying to match on larger (100KiB) bodies of input.

This commit removes those parts without any change in semantics
as MATCH patterns only need to match the actual match.

This should fix bug STEllAR-GROUP#1040.
zao added a commit to zao/hpx that referenced this issue Jan 6, 2014
@zao
Remove redundant costly Kleene stars from regex searches
610dfc4 
Some of the string(REGEX MATCH) operations surround the pattern
with ".*", causing the CMake process to effectively wedge when
trying to match on larger (100KiB) bodies of input.

This commit removes those parts without any change in semantics
as MATCH patterns only need to match the actual match.

This should fix bug STEllAR-GROUP#1040.
@zao zao mentioned this issue Jan 6, 2014
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@K-ballo
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K-ballo commented Jan 6, 2014

Thank you!

@K-ballo K-ballo closed this as completed Jan 6, 2014
@ghost ghost assigned zao Jan 6, 2014
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category: CMake difficulty: easy Good issues for starting out with HPX development type: enhancement
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