From: Kostya Serebryany <kcc@google.com>
Date: Wed, 14 Oct 2015 00:21:05 +0000 (+0000)
Subject: [asan] Disabling speculative loads under asan. Patch by Mike Aizatsky
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9253eff13e3eb1c4ae66ae2b660c702f285c229d;p=oota-llvm.git

[asan] Disabling speculative loads under asan. Patch by Mike Aizatsky

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@250259 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 2a93e0d64d6..5caffee8fe7 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -3187,7 +3187,11 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V,
     const LoadInst *LI = cast<LoadInst>(Inst);
     if (!LI->isUnordered() ||
         // Speculative load may create a race that did not exist in the source.
-        LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread))
+        LI->getParent()->getParent()->hasFnAttribute(
+            Attribute::SanitizeThread) ||
+        // Speculative load may load data from dirty regions.
+        LI->getParent()->getParent()->hasFnAttribute(
+            Attribute::SanitizeAddress))
       return false;
     const DataLayout &DL = LI->getModule()->getDataLayout();
     return isDereferenceableAndAlignedPointer(
diff --git a/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll b/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll
new file mode 100644
index 00000000000..063bde83f7b
--- /dev/null
+++ b/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll
@@ -0,0 +1,40 @@
+; RUN: opt -simplifycfg -S %s | FileCheck %s
+; Make sure we don't speculate loads under AddressSanitizer.
+@g = global i32 0, align 4
+
+define i32 @TestNoAsan(i32 %cond) nounwind readonly uwtable {
+entry:
+  %tobool = icmp eq i32 %cond, 0
+  br i1 %tobool, label %return, label %if.then
+
+if.then:                                          ; preds = %entry
+  %0 = load i32, i32* @g, align 4
+  br label %return
+
+return:                                           ; preds = %entry, %if.then
+  %retval = phi i32 [ %0, %if.then ], [ 0, %entry ]
+  ret i32 %retval
+; CHECK-LABEL: @TestNoAsan
+; CHECK: %[[LOAD:[^ ]*]] = load
+; CHECK: select{{.*}}[[LOAD]]
+; CHECK: ret i32
+}
+
+define i32 @TestAsan(i32 %cond) nounwind readonly uwtable sanitize_address {
+entry:
+  %tobool = icmp eq i32 %cond, 0
+  br i1 %tobool, label %return, label %if.then
+
+if.then:                                          ; preds = %entry
+  %0 = load i32, i32* @g, align 4
+  br label %return
+
+return:                                           ; preds = %entry, %if.then
+  %retval = phi i32 [ %0, %if.then ], [ 0, %entry ]
+  ret i32 %retval
+; CHECK-LABEL: @TestAsan
+; CHECK: br i1
+; CHECK: load i32, i32* @g
+; CHECK: br label
+; CHECK: ret i32
+}