From 271be9bb7df6f3910a929ef7bff55fbd9bc2dee6 Mon Sep 17 00:00:00 2001
From: Anders Lewis <agloo@google.com>
Date: Wed, 7 Jun 2017 13:00:38 -0700
Subject: Split memmove benchmark into separate overlapping (src before dst and
 dst before src) and non-overlapping tests.

Test: Ran benchmarks and verified that runtimes were sensible.
Change-Id: Ia7fbc5596dfdc162fff2364f4ef6dafe5549b907
---
 benchmarks/string_benchmark.cpp | 35 +++++++++++++++++++++++++++++------
 1 file changed, 29 insertions(+), 6 deletions(-)

(limited to 'benchmarks/string_benchmark.cpp')

diff --git a/benchmarks/string_benchmark.cpp b/benchmarks/string_benchmark.cpp
index 41306db1c..aa1e8c9aa 100644
--- a/benchmarks/string_benchmark.cpp
+++ b/benchmarks/string_benchmark.cpp
@@ -58,19 +58,42 @@ static void BM_string_memcpy(benchmark::State& state) {
 }
 BENCHMARK(BM_string_memcpy)->AT_COMMON_SIZES;
 
-static void BM_string_memmove(benchmark::State& state) {
+static void BM_string_memmove_non_overlapping(benchmark::State& state) {
   const size_t nbytes = state.range(0);
-  char* buf = new char[nbytes + 64];
-  memset(buf, 'x', nbytes + 64);
+  std::vector<char> src(nbytes, 'x');
+  std::vector<char> dst(nbytes, 'x');
 
   while (state.KeepRunning()) {
-    memmove(buf, buf + 1, nbytes); // Worst-case overlap.
+    memmove(dst.data(), src.data(), nbytes);
   }
 
   state.SetBytesProcessed(uint64_t(state.iterations()) * uint64_t(nbytes));
-  delete[] buf;
 }
-BENCHMARK(BM_string_memmove)->AT_COMMON_SIZES;
+BENCHMARK(BM_string_memmove_non_overlapping)->AT_COMMON_SIZES;
+
+static void BM_string_memmove_overlap_dst_before_src(benchmark::State& state) {
+  const size_t nbytes = state.range(0);
+  std::vector<char> buf(nbytes + 1, 'x');
+
+  while (state.KeepRunning()) {
+    memmove(buf.data(), buf.data() + 1, nbytes); // Worst-case overlap.
+  }
+
+  state.SetBytesProcessed(uint64_t(state.iterations()) * uint64_t(nbytes));
+}
+BENCHMARK(BM_string_memmove_overlap_dst_before_src)->AT_COMMON_SIZES;
+
+static void BM_string_memmove_overlap_src_before_dst(benchmark::State& state) {
+  const size_t nbytes = state.range(0);
+  std::vector<char> buf(nbytes + 1, 'x');
+
+  while (state.KeepRunning()) {
+    memmove(buf.data() + 1, buf.data(), nbytes); // Worst-case overlap.
+  }
+
+  state.SetBytesProcessed(uint64_t(state.iterations()) * uint64_t(nbytes));
+}
+BENCHMARK(BM_string_memmove_overlap_src_before_dst)->AT_COMMON_SIZES;
 
 static void BM_string_memset(benchmark::State& state) {
   const size_t nbytes = state.range(0);
-- 
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