Importing rustc-1.38.0
diff --git a/src/llvm-project/compiler-rt/test/fuzzer/TableLookupTest.cpp b/src/llvm-project/compiler-rt/test/fuzzer/TableLookupTest.cpp
new file mode 100644
index 0000000..2b40523
--- /dev/null
+++ b/src/llvm-project/compiler-rt/test/fuzzer/TableLookupTest.cpp
@@ -0,0 +1,45 @@
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Make sure the fuzzer eventually finds all possible values of a variable
+// within a range.
+#include <cassert>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <set>
+
+const size_t N = 1 << 12;
+
+// Define an array of counters that will be understood by libFuzzer
+// as extra coverage signal. The array must be:
+// * uint8_t
+// * in the section named __libfuzzer_extra_counters.
+// The target code may declare more than one such array.
+//
+// Use either `Counters[Idx] = 1` or `Counters[Idx]++;`
+// depending on whether multiple occurrences of the event 'Idx'
+// is important to distinguish from one occurrence.
+#ifdef __linux__
+__attribute__((section("__libfuzzer_extra_counters")))
+#endif
+static uint8_t Counters[N];
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+ static std::set<uint16_t> SeenIdx;
+ if (Size != 4) return 0;
+ uint32_t Idx;
+ memcpy(&Idx, Data, 4);
+ Idx %= N;
+ assert(Counters[Idx] == 0); // libFuzzer should reset these between the runs.
+ // Or Counters[Idx]=1 if we don't care how many times this happened.
+ Counters[Idx]++;
+ SeenIdx.insert(Idx);
+ if (SeenIdx.size() == N) {
+ fprintf(stderr, "BINGO: found all values\n");
+ abort();
+ }
+ return 0;
+}
