[InstrProf] Use atomic profile counter updates for TSan

Thread sanitizer instrumentation fails to skip all loads and stores to
profile counters. This can happen if profile counter updates are merged:

  %.sink = phi i64* ...
  %pgocount5 = load i64, i64* %.sink
  %27 = add i64 %pgocount5, 1
  %28 = bitcast i64* %.sink to i8*
  call void @__tsan_write8(i8* %28)
  store i64 %27, i64* %.sink

To suppress TSan diagnostics about racy counter updates, make the
counter updates atomic when TSan is enabled. If there's general interest
in this mode it can be surfaced as a clang/swift driver option.

Testing: check-{llvm,clang,profile}

rdar://40477803

Differential Revision: https://reviews.llvm.org/D50867

llvm-svn: 339955

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/test/Instrumentation/InstrProfiling/atomic-updates.ll b/llvm/test/Instrumentation/InstrProfiling/atomic-updates.ll
new file mode 100644
index 00000000000..7230a205dff
--- /dev/null
+++ b/llvm/test/Instrumentation/InstrProfiling/atomic-updates.ll
@@ -0,0 +1,14 @@
+; RUN: opt < %s -S -instrprof -instrprof-atomic-counter-update-all | FileCheck %s
+
+target triple = "x86_64-apple-macosx10.10.0"
+
+@__profn_foo = hidden constant [3 x i8] c"foo"
+
+; CHECK-LABEL: define void @foo
+; CHECK-NEXT: atomicrmw add i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_foo, i64 0, i64 0), i64 1 monotonic
+define void @foo() {
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 0, i32 1, i32 0)
+  ret void
+}
+
+declare void @llvm.instrprof.increment(i8*, i64, i32, i32)