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Subject: |
[PATCH 2/6] maint: replace bitwise with logical OR |
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Date: |
Tue, 7 Jun 2016 01:37:39 -0500 |
* src/grep.c (main): replace bitwise ORs with logical ORs where it
makes sense (when dealing with boolean conditions as opposed to
bitmasks).
---
src/grep.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/grep.c b/src/grep.c
index d812bae..9776507 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -2623,12 +2623,12 @@ main (int argc, char **argv)
implementation, -q overrides -l and -L, which in turn override -c. */
if (exit_on_match)
list_files = 0;
- if (exit_on_match | list_files)
+ if (exit_on_match || list_files)
{
count_matches = false;
done_on_match = true;
}
- out_quiet = count_matches | done_on_match;
+ out_quiet = count_matches || done_on_match;
if (out_after < 0)
out_after = default_context;
--
2.8.0.rc3
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--- Begin Message ---
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Subject: |
Re: bug#23713: [PATCH 2/6] maint: replace bitwise with logical OR |
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Date: |
Thu, 18 Aug 2016 22:54:54 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 |
Thanks. I see this patch was also installed in June so will close the bug
report.
I have a bone to pick with it, though. For bool expressions without side
effects, bitwise ops are logically equivalent to short-circuit ops. On modern
platforms where operands are trivial, short-circuit ops are often a tad bigger
and can have more branch-prediction overhead, which is a tiny bit worse for
performance. In the examples you the short-circuit ops all generate bigger
machine code on my platform (GCC 6.1 x86-64). So I'm mildly inclined to revert
the change and have pushed the attached. To some extent this is a style issue;
yes, there is a long tradition in C of using short-circuit ops for bool, but I
don't mind too much diverging slightly from the common style in order to make
the point.
For clarity this patch also uses c_isdigit (which uses a switch) instead of &&
though GCC seems to generate the same code either way.
0001-grep-prefer-bitwise-to-short-circuit-when-shorter.patch
Description: Text Data
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