[Stats] Add ALWAYS_ENABLED_STATISTIC enabled regardless of LLVM_ENABLE_STATS.

The intended usage is to measure relatively expensive operations. So the
cost of the statistic is negligible compared to the cost of a measured
operation and can be enabled all the time without impairing the
compilation time.

rdar://problem/55715134

Reviewers: dsanders, bogner, rtereshin

Reviewed By: dsanders

Subscribers: hiraditya, jkorous, dexonsmith, ributzka, cfe-commits, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68252

llvm-svn: 374490

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/StatisticTest.cpp b/llvm/unittests/ADT/StatisticTest.cpp
index 1b5530fb729..eb7a947224d 100644
--- a/llvm/unittests/ADT/StatisticTest.cpp
+++ b/llvm/unittests/ADT/StatisticTest.cpp
@@ -17,6 +17,7 @@ namespace {
 #define DEBUG_TYPE "unittest"
 STATISTIC(Counter, "Counts things");
 STATISTIC(Counter2, "Counts other things");
+ALWAYS_ENABLED_STATISTIC(AlwaysCounter, "Counts things always");
 
 #if LLVM_ENABLE_STATS
 static void
@@ -43,6 +44,12 @@ TEST(StatisticTest, Count) {
 #else
   EXPECT_EQ(Counter, 0u);
 #endif
+
+  AlwaysCounter = 0;
+  EXPECT_EQ(AlwaysCounter, 0u);
+  AlwaysCounter++;
+  ++AlwaysCounter;
+  EXPECT_EQ(AlwaysCounter, 2u);
 }
 
 TEST(StatisticTest, Assign) {
@@ -54,6 +61,9 @@ TEST(StatisticTest, Assign) {
 #else
   EXPECT_EQ(Counter, 0u);
 #endif
+
+  AlwaysCounter = 2;
+  EXPECT_EQ(AlwaysCounter, 2u);
 }
 
 TEST(StatisticTest, API) {