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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2020/06/02 17:26:37 UTC
[GitHub] [arrow] pitrou commented on a change in pull request #7330: ARROW-8951: [C++] Fix compiler warnings on gcc8 in release builds
pitrou commented on a change in pull request #7330:
URL: https://github.com/apache/arrow/pull/7330#discussion_r434047931
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File path: cpp/src/arrow/util/time.h
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@@ -34,16 +34,8 @@ enum DivideOrMultiply {
};
// TimestampType -> TimestampType
-static std::pair<DivideOrMultiply, int64_t> kTimestampConversionTable[4][4] = {
- // TimestampType::SECOND
- {{MULTIPLY, 1}, {MULTIPLY, 1000}, {MULTIPLY, 1000000}, {MULTIPLY, 1000000000}},
- // TimestampType::MILLI
- {{DIVIDE, 1000}, {MULTIPLY, 1}, {MULTIPLY, 1000}, {MULTIPLY, 1000000}},
- // TimestampType::MICRO
- {{DIVIDE, 1000000}, {DIVIDE, 1000}, {MULTIPLY, 1}, {MULTIPLY, 1000}},
- // TimestampType::NANO
- {{DIVIDE, 1000000000}, {DIVIDE, 1000000}, {DIVIDE, 1000}, {MULTIPLY, 1}},
-};
+ARROW_EXPORT extern const std::pair<DivideOrMultiply, int64_t>
+ kTimestampConversionTable[4][4];
Review comment:
The problem here is that the compiler won't be able to optimize divide-by-constant, which is very slow by default.
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