From 535b6f936157d6fec5b074a149200f81e6bcbb9d Mon Sep 17 00:00:00 2001
From: Alexey Samsonov <vonosmas@gmail.com>
Date: Thu, 17 Jul 2014 18:48:12 +0000
Subject: [PATCH] [ASan] Don't instrument load/stores with !nosanitize
 metadata.

This is used to avoid instrumentation of instructions added by UBSan
in Clang frontend (see r213291). This fixes PR20085.

Reviewed in http://reviews.llvm.org/D4544.

llvm-svn: 213292
---
 .../Instrumentation/AddressSanitizer.cpp           |  3 ++
 .../test/Instrumentation/AddressSanitizer/ubsan.ll | 52 ++++++++++++++++++++++
 2 files changed, 55 insertions(+)
 create mode 100644 llvm/test/Instrumentation/AddressSanitizer/ubsan.ll

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index e42839c..124ffe2 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -655,6 +655,9 @@ void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
 // and set IsWrite/Alignment. Otherwise return NULL.
 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
                                         unsigned *Alignment) {
+  // Skip memory accesses inserted by another instrumentation.
+  if (I->getMetadata("nosanitize"))
+    return nullptr;
   if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
     if (!ClInstrumentReads) return nullptr;
     *IsWrite = false;
diff --git a/llvm/test/Instrumentation/AddressSanitizer/ubsan.ll b/llvm/test/Instrumentation/AddressSanitizer/ubsan.ll
new file mode 100644
index 0000000..22e4172
--- /dev/null
+++ b/llvm/test/Instrumentation/AddressSanitizer/ubsan.ll
@@ -0,0 +1,52 @@
+; ASan shouldn't instrument code added by UBSan.
+
+; RUN: opt < %s -asan -asan-module -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.A = type { i32 (...)** }
+declare void @__ubsan_handle_dynamic_type_cache_miss(i8*, i64, i64) uwtable
+@__ubsan_vptr_type_cache = external global [128 x i64]
+@.src = private unnamed_addr constant [19 x i8] c"tmp/ubsan/vptr.cpp\00", align 1
+@0 = private unnamed_addr constant { i16, i16, [4 x i8] } { i16 -1, i16 0, [4 x i8] c"'A'\00" }
+@_ZTI1A = external constant i8*
+@1 = private unnamed_addr global { { [19 x i8]*, i32, i32 }, { i16, i16, [4 x i8] }*, i8*, i8 } { { [19 x i8]*, i32, i32 } { [19 x i8]* @.src, i32 2, i32 18 }, { i16, i16, [4 x i8] }* @0, i8* bitcast (i8** @_ZTI1A to i8*), i8 4 }
+
+define void @_Z3BarP1A(%struct.A* %a) uwtable sanitize_address {
+; CHECK-LABEL: define void @_Z3BarP1A
+entry:
+  %0 = bitcast %struct.A* %a to void (%struct.A*)***
+  %vtable = load void (%struct.A*)*** %0, align 8
+; CHECK: __asan_report_load8
+  %1 = load void (%struct.A*)** %vtable, align 8
+; CHECK: __asan_report_load8
+  %2 = ptrtoint void (%struct.A*)** %vtable to i64
+  %3 = xor i64 %2, -303164226014115343, !nosanitize !0
+  %4 = mul i64 %3, -7070675565921424023, !nosanitize !0
+  %5 = lshr i64 %4, 47, !nosanitize !0
+  %6 = xor i64 %4, %2, !nosanitize !0
+  %7 = xor i64 %6, %5, !nosanitize !0
+  %8 = mul i64 %7, -7070675565921424023, !nosanitize !0
+  %9 = lshr i64 %8, 47, !nosanitize !0
+  %10 = xor i64 %9, %8, !nosanitize !0
+  %11 = mul i64 %10, -7070675565921424023, !nosanitize !0
+  %12 = and i64 %11, 127, !nosanitize !0
+  %13 = getelementptr inbounds [128 x i64]* @__ubsan_vptr_type_cache, i64 0, i64 %12, !nosanitize !0
+; CHECK-NOT: __asan_report_load8
+  %14 = load i64* %13, align 8, !nosanitize !0
+  %15 = icmp eq i64 %14, %11, !nosanitize !0
+  br i1 %15, label %cont, label %handler.dynamic_type_cache_miss, !nosanitize !0
+
+handler.dynamic_type_cache_miss:                  ; preds = %entry
+  %16 = ptrtoint %struct.A* %a to i64, !nosanitize !0
+  tail call void @__ubsan_handle_dynamic_type_cache_miss(i8* bitcast ({ { [19 x i8]*, i32, i32 }, { i16, i16, [4 x i8] }*, i8*, i8 }* @1 to i8*), i64 %16, i64 %11) #2, !nosanitize !0
+  br label %cont, !nosanitize !0
+
+cont:                                             ; preds = %handler.dynamic_type_cache_miss, %entry
+  tail call void %1(%struct.A* %a)
+; CHECK: ret void
+  ret void
+}
+
+!0 = metadata !{}
-- 
2.7.4