[compiler-rt] [llvm] [MemProf] Change histogram storage from uint64_t to uint16_t (PR #147854)

[Snehasish Kumar via llvm-commits]

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@@ -0,0 +1,35 @@
+#include <cstdint>
+#include <vector>
+
+#include "profile/MemProfData.inc"
+#include "gtest/gtest.h"
+
+namespace llvm {
+namespace memprof {
+namespace {
+TEST(MemProf, F16EncodeDecode) {
+  const std::vector<uint64_t> TestCases = {
+      0, 100, 4095, 4096, 5000, 8191, 65535, 1000000, 134213640, 200000000,
+  };
+
+  for (const uint64_t TestCase : TestCases) {
+    const uint16_t Encoded = encodeHistogramCount(TestCase);
+    const uint64_t Decoded = decodeHistogramCount(Encoded);
+
+    const uint64_t MaxRepresentable = static_cast<uint64_t>(MaxMantissa)
+                                      << MaxExponent;
+
+    if (TestCase >= MaxRepresentable) {
+      EXPECT_EQ(Decoded, MaxRepresentable);
+    } else if (TestCase == 0) {
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snehasish wrote:

Done.

https://github.com/llvm/llvm-project/pull/147854