[mlir][crunner] Add support for random number generation.

mlir/include/mlir/ExecutionEngine/CRunnerUtils.h

 extern "C" MLIR_CRUNNERUTILS_EXPORT void printNewline();
 
 //===----------------------------------------------------------------------===//
 // Small runtime support library for timing execution and printing GFLOPS
 //===----------------------------------------------------------------------===//
 extern "C" MLIR_CRUNNERUTILS_EXPORT void printFlops(double flops);
 extern "C" MLIR_CRUNNERUTILS_EXPORT double rtclock();
 
+//===----------------------------------------------------------------------===//
+// Runtime support library for random number generation.
+//===----------------------------------------------------------------------===//
+// Uses a seed to initialize a random generator and returns the generator.
+extern "C" MLIR_CRUNNERUTILS_EXPORT void *rtsrand(uint64_t s);
+// Returns a random number in the range of [0, m).
+extern "C" MLIR_CRUNNERUTILS_EXPORT uint64_t rtrand(void *, uint64_t m);
+// Deletes the random number generator.
+extern "C" MLIR_CRUNNERUTILS_EXPORT void rtdrand(void *);
+
 #endif // MLIR_EXECUTIONENGINE_CRUNNERUTILS_H

mlir/lib/ExecutionEngine/CRunnerUtils.cpp

 #include <sys/time.h>
 #else
 #include "malloc.h"
 #endif // _WIN32
 
 #include <cinttypes>
 #include <cstdio>
 #include <cstdlib>
+#include <random>
 #include <string.h>
 
 #ifdef MLIR_CRUNNERUTILS_DEFINE_FUNCTIONS
 
 // Small runtime support "lib" for vector.print lowering.
 // By providing elementary printing methods only, this
 // library can remain fully unaware of low-level implementation
 // details of our vectors. Also useful for direct LLVM IR output.

 extern "C" void mlirAlignedFree(void *ptr) {
 #ifdef _WIN32
   _aligned_free(ptr);
 #else
   free(ptr);
 #endif
 }
 
+extern "C" void *rtsrand(uint64_t s) {
+  // Standard mersenne_twister_engine seeded with s.
+  return new std::mt19937(s);
+}
+
+extern "C" uint64_t rtrand(void *g, uint64_t m) {
+  std::mt19937 *generator = static_cast<std::mt19937 *>(g);
+  std::uniform_int_distribution<uint64_t> distrib(0, m);
+  return distrib(*generator);
+}
+
+extern "C" void rtdrand(void *g) {
+  std::mt19937 *generator = static_cast<std::mt19937 *>(g);
+  delete generator;
+}
+
 #endif // MLIR_CRUNNERUTILS_DEFINE_FUNCTIONS