[MemFunctions] Add validity check.
Summary: Validate the results in addition to benchmarking.
Reviewers: gchatelet
Subscribers: spatel, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76056
diff --git a/MicroBenchmarks/MemFunctions/main.cpp b/MicroBenchmarks/MemFunctions/main.cpp
index 8ffdbb6..ea18445 100644
--- a/MicroBenchmarks/MemFunctions/main.cpp
+++ b/MicroBenchmarks/MemFunctions/main.cpp
@@ -17,11 +17,20 @@
//
//===----------------------------------------------------------------------===//
+#include <cstdlib>
#include <cstring>
+#include <iostream>
#include <vector>
#include "benchmark/benchmark.h"
+// This function prevents the compiler from interfering with `memcmp` and
+// makes sure the function is called.
+int RealMemCmp(const char *p, const char *q, size_t s)
+ __attribute__((no_builtin("memcmp"))) {
+ return memcmp(p, q, s);
+}
+
// Benchmarks `memcmp(p, q, size) OP 0` where n is known at compile time and OP
// is defined by `Pred`. The compiler typically inlines the memcmp + comparion
// to loads and compares.
@@ -44,6 +53,13 @@
for (int i = 0; i < kNumElements; ++i)
Mod().template Change<kSize>(p + i * kSize);
+ // First check the validity of the results.
+ if (Pred::Cmp(RealMemCmp(p, q, kSize)) != Pred::Cmp(memcmp(p, q, kSize))) {
+ std::cerr << "invalid results for Pred=" << Pred::kDisplay
+ << " Mod=" << Mod::kDisplay << " kSize=" << kSize << std::endl;
+ std::exit(1);
+ }
+
benchmark::DoNotOptimize(p);
benchmark::DoNotOptimize(q);
@@ -52,7 +68,7 @@
benchmark::ClobberMemory();
for (int i = 0; i < kNumElements; ++i) {
- int res = Pred()(memcmp(p + i * kSize, q + i * kSize, kSize));
+ bool res = Pred::Cmp(memcmp(p + i * kSize, q + i * kSize, kSize));
benchmark::DoNotOptimize(res);
}
}
@@ -61,37 +77,35 @@
// Predicates.
struct EqZero {
- bool operator()(int v) const { return v == 0; }
+ static bool Cmp(int v) { return v == 0; }
+ inline static constexpr const char kDisplay[] = "EqZero";
};
struct LessThanZero {
- bool operator()(int v) const { return v < 0; }
+ static bool Cmp(int v) { return v < 0; }
+ inline static constexpr const char kDisplay[] = "LessThanZero";
};
struct GreaterThanZero {
- bool operator()(int v) const { return v > 0; }
+ static bool Cmp(int v) { return v > 0; }
+ inline static constexpr const char kDisplay[] = "GreaterThanZero";
};
// Functors to change the first/mid/last or no value.
struct None {
template <int kSize>
void Change(char* const p) const {}
+ inline static constexpr const char kDisplay[] = "None";
};
struct First {
- template <int kSize>
- void Change(char* const p) const {
- p[0] = 128;
- }
+ template <int kSize> void Change(char *const p) const { p[0] = 0xff; }
+ inline static constexpr const char kDisplay[] = "First";
};
struct Mid {
- template <int kSize>
- void Change(char* const p) const {
- p[kSize / 2] = 128;
- }
+ template <int kSize> void Change(char *const p) const { p[kSize / 2] = 0xff; }
+ inline static constexpr const char kDisplay[] = "Mid";
};
struct Last {
- template <int kSize>
- void Change(char* const p) const {
- p[kSize - 1] = 128;
- }
+ template <int kSize> void Change(char *const p) const { p[kSize - 1] = 0xff; }
+ inline static constexpr const char kDisplay[] = "Last";
};
#define MEMCMP_BENCHMARK_PRED_CHANGE(size, pred, change) \
