[llvm] r250259 - [asan] Disabling speculative loads under asan. Patch by Mike Aizatsky

[Kostya Serebryany via llvm-commits]

Author: kcc
Date: Tue Oct 13 19:21:05 2015
New Revision: 250259

URL: http://llvm.org/viewvc/llvm-project?rev=250259&view=rev
Log:
[asan] Disabling speculative loads under asan. Patch by Mike Aizatsky

Added:
    llvm/trunk/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll
Modified:
    llvm/trunk/lib/Analysis/ValueTracking.cpp

Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=250259&r1=250258&r2=250259&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Tue Oct 13 19:21:05 2015
@@ -3187,7 +3187,11 @@ bool llvm::isSafeToSpeculativelyExecute(
     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(

Added: llvm/trunk/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll?rev=250259&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll (added)
+++ llvm/trunk/test/Transforms/SimplifyCFG/no_speculative_loads_with_asan.ll Tue Oct 13 19:21:05 2015
@@ -0,0 +1,40 @@
+; RUN: opt -simplifycfg -S %s | FileCheck %s
+; Make sure we don't speculate loads under AddressSanitizer.
+ at 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
+}