[flang-commits] [flang] [flang][runtime] Better non-repeatable RANDOM_INIT() (PR #67363)
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Mon Sep 25 12:59:11 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-flang-runtime
<details>
<summary>Changes</summary>
Use a higher-frequency clock base when initializing the pseudo-random number generator to implement
CALL RANDOM_INIT(REPEATABLE=.FALSE.)
---
Full diff: https://github.com/llvm/llvm-project/pull/67363.diff
1 Files Affected:
- (modified) flang/runtime/random.cpp (+4-2)
``````````diff
diff --git a/flang/runtime/random.cpp b/flang/runtime/random.cpp
index b7175d6b63c35f8..93113657bdecbca 100644
--- a/flang/runtime/random.cpp
+++ b/flang/runtime/random.cpp
@@ -20,10 +20,10 @@
#include <algorithm>
#include <cmath>
#include <cstdint>
-#include <ctime>
#include <limits>
#include <memory>
#include <random>
+#include <time.h>
namespace Fortran::runtime {
@@ -100,7 +100,9 @@ void RTNAME(RandomInit)(bool repeatable, bool /*image_distinct*/) {
if (repeatable) {
generator.seed(0);
} else {
- generator.seed(std::time(nullptr));
+ timespec ts;
+ clock_gettime(CLOCK_REALTIME, &ts);
+ generator.seed(ts.tv_sec & ts.tv_nsec);
}
}
}
``````````
</details>
https://github.com/llvm/llvm-project/pull/67363
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