From 54225a9153715dfd9a14f226bdb734476cf11759 Mon Sep 17 00:00:00 2001
From: Mike Aizatsky <aizatsky@chromium.org>
Date: Wed, 18 Nov 2015 20:43:00 +0000
Subject: [PATCH] Disable gvn non-local speculative loads under asan.

Summary: Fix for https://llvm.org/bugs/show_bug.cgi?id=25550

Differential Revision: http://reviews.llvm.org/D14763

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253498 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/GVN.cpp                 |  4 ++
 .../GVN/no_speculative_loads_with_asan.ll     | 57 +++++++++++++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 test/Transforms/GVN/no_speculative_loads_with_asan.ll

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index 06faa2d76b6..d261b2acae9 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -1701,6 +1701,10 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
 /// Attempt to eliminate a load whose dependencies are
 /// non-local by performing PHI construction.
 bool GVN::processNonLocalLoad(LoadInst *LI) {
+  // non-local speculations are not allowed under asan.
+  if (LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeAddress))
+    return false;
+
   // Step 1: Find the non-local dependencies of the load.
   LoadDepVect Deps;
   MD->getNonLocalPointerDependency(LI, Deps);
diff --git a/test/Transforms/GVN/no_speculative_loads_with_asan.ll b/test/Transforms/GVN/no_speculative_loads_with_asan.ll
new file mode 100644
index 00000000000..2e790db1b2a
--- /dev/null
+++ b/test/Transforms/GVN/no_speculative_loads_with_asan.ll
@@ -0,0 +1,57 @@
+; RUN: opt -O3 -S %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+declare noalias i8* @_Znam(i64) #1
+
+define i32 @TestNoAsan() {
+  %1 = tail call noalias i8* @_Znam(i64 2)
+  %2 = getelementptr inbounds i8, i8* %1, i64 1
+  store i8 0, i8* %2, align 1
+  store i8 0, i8* %1, align 1
+  %3 = bitcast i8* %1 to i16*
+  %4 = load i16, i16* %3, align 4
+  %5 = icmp eq i16 %4, 0
+  br i1 %5, label %11, label %6
+
+; <label>:6                                       ; preds = %0
+  %7 = getelementptr inbounds i8, i8* %1, i64 2
+  %8 = bitcast i8* %7 to i16*
+  %9 = load i16, i16* %8, align 2
+  %10 = sext i16 %9 to i32
+  br label %11
+
+; <label>:11                                      ; preds = %0, %6
+  %12 = phi i32 [ %10, %6 ], [ 0, %0 ]
+  ret i32 %12
+}
+
+; CHECK-LABEL: @TestNoAsan
+; CHECK: %[[LOAD:[^ ]+]] = load i32
+; CHECK: {{.*}} = ashr i32 %[[LOAD]]
+; CHECK-NOT: {{.*}} = phi
+
+define i32 @TestAsan() sanitize_address {
+  %1 = tail call noalias i8* @_Znam(i64 2)
+  %2 = getelementptr inbounds i8, i8* %1, i64 1
+  store i8 0, i8* %2, align 1
+  store i8 0, i8* %1, align 1
+  %3 = bitcast i8* %1 to i16*
+  %4 = load i16, i16* %3, align 4
+  %5 = icmp eq i16 %4, 0
+  br i1 %5, label %11, label %6
+
+; <label>:6                                       ; preds = %0
+  %7 = getelementptr inbounds i8, i8* %1, i64 2
+  %8 = bitcast i8* %7 to i16*
+  %9 = load i16, i16* %8, align 2
+  %10 = sext i16 %9 to i32
+  br label %11
+
+; <label>:11                                      ; preds = %0, %6
+  %12 = phi i32 [ %10, %6 ], [ 0, %0 ]
+  ret i32 %12
+}
+
+; CHECK-LABEL: @TestAsan
+; CHECK-NOT: %[[LOAD:[^ ]+]] = load i32
+; CHECK: {{.*}} = phi
+
-- 
2.34.1