wgtmac commented on a change in pull request #917:
URL: https://github.com/apache/orc/pull/917#discussion_r718126855
##########
File path: c++/include/orc/orc-config.hh.in
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@@ -75,4 +75,38 @@
}
#endif
+#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__)
+ namespace orc {
+ /**
+ * Compute value * repetitions, return false if overflow, return true
otherwise
+ * and save the result at the address pointed to by result
+ * imitates the jdk Math.multiplyExact implementation
+ * but this method makes the assumption that repetitions > 1
+ */
+ static bool multiplyExact(int64_t value, int64_t repetitions, int64_t*
result) {
+ int64_t r = value * repetitions;
+ if (((value < 0 ? -value : value) | repetitions) >> 31 != 0 && r /
repetitions != value) {
+ return false;
+ }
+ *result = r;
+ return true;
+ }
Review comment:
`#ifdef _MSC_VER` is enough to assert that it is on Windows. You may
also leverage cmake_modules/CheckSourceCompiles.cmake to figure out if the gcc
builtin functions are available or not. BTW, orc-config.hh.in is to address
capability of older c++ standards. If would be better to handle these kinds of
functions in Adaptor.hh.in.
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