From bdba755f8532624f4b25bc801e175bbcc6ce82af Mon Sep 17 00:00:00 2001 From: Vedant Kumar Date: Mon, 20 Jun 2016 21:24:26 +0000 Subject: [PATCH] [tsan] Do not instrument accesses to the gcov counters array There is a known intended race here. This is a follow-up to r264805, which disabled tsan instrumentation for updates to instrprof counters. For more background on this please see the discussion in D18164. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273202 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Instrumentation/ThreadSanitizer.cpp | 4 ++++ .../ThreadSanitizer/do-not-instrument-memory-access.ll | 8 ++++++++ 2 files changed, 12 insertions(+) diff --git a/lib/Transforms/Instrumentation/ThreadSanitizer.cpp b/lib/Transforms/Instrumentation/ThreadSanitizer.cpp index eed77b701e3..22a26d49374 100644 --- a/lib/Transforms/Instrumentation/ThreadSanitizer.cpp +++ b/lib/Transforms/Instrumentation/ThreadSanitizer.cpp @@ -271,6 +271,10 @@ static bool shouldInstrumentReadWriteFromAddress(Value *Addr) { /*AddSegment=*/false))) return false; } + + // Check if the global is in the GCOV counters array. + if (GV->getName() == "__llvm_gcov_ctr") + return false; } return true; } diff --git a/test/Instrumentation/ThreadSanitizer/do-not-instrument-memory-access.ll b/test/Instrumentation/ThreadSanitizer/do-not-instrument-memory-access.ll index 5559441d0ad..e734a382a9c 100644 --- a/test/Instrumentation/ThreadSanitizer/do-not-instrument-memory-access.ll +++ b/test/Instrumentation/ThreadSanitizer/do-not-instrument-memory-access.ll @@ -1,5 +1,6 @@ ; This test checks that we are not instrumenting unwanted acesses to globals: ; - Instruction profiler counter instrumentation has known intended races. +; - The gcov counters array has a known intended race. ; ; RUN: opt < %s -tsan -S | FileCheck %s @@ -10,11 +11,18 @@ target triple = "x86_64-apple-macosx10.9" @__profc_test_bitcast = private global [2 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8 @__profc_test_bitcast_foo = private global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8 +@__llvm_gcov_ctr = internal global [1 x i64] zeroinitializer + define i32 @test_gep() sanitize_thread { entry: %pgocount = load i64, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_test_gep, i64 0, i64 0) %0 = add i64 %pgocount, 1 store i64 %0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_test_gep, i64 0, i64 0) + + %gcovcount = load i64, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__llvm_gcov_ctr, i64 0, i64 0) + %1 = add i64 %gcovcount, 1 + store i64 %1, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__llvm_gcov_ctr, i64 0, i64 0) + ret i32 1 }