From: Egor Bogatov <egorbo@gmail.com>
Date: Fri, 10 Feb 2023 11:28:13 +0000 (+0100)
Subject: Remove contention from HandleHistogramProfileRand (#81932)
X-Git-Tag: accepted/tizen/unified/riscv/20231226.055536~4109
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0d95bf1c5ead1227762914495f7206e315c3fc16;p=platform%2Fupstream%2Fdotnet%2Fruntime.git

Remove contention from HandleHistogramProfileRand (#81932)
---

diff --git a/src/coreclr/vm/jithelpers.cpp b/src/coreclr/vm/jithelpers.cpp
index 2628f56..a6d41ca 100644
--- a/src/coreclr/vm/jithelpers.cpp
+++ b/src/coreclr/vm/jithelpers.cpp
@@ -5407,12 +5407,12 @@ void JIT_PartialCompilationPatchpoint(int* counter, int ilOffset)
 
 static unsigned HandleHistogramProfileRand()
 {
-    // generate a random number (xorshift32)
+    // Generate a random number (xorshift32)
     //
-    // intentionally simple so we can have multithreaded
-    // access w/o tearing state.
+    // Intentionally simple for faster random. It's stored in TLS to avoid
+    // multithread contention.
     //
-    static volatile unsigned s_rng = 100;
+    static thread_local unsigned s_rng = 100;
 
     unsigned x = s_rng;
     x ^= x << 13;