[asan] workaround for PR16277: don't instrument AllocaInstr with alignment more than the redzone size

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184928 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 21 insertions, 1 deletions

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 67a8325b0c..417fd76dc1 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -451,7 +451,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
 
     StackAlignment = std::max(StackAlignment, AI.getAlignment());
     AllocaVec.push_back(&AI);
-    uint64_t AlignedSize =  getAlignedAllocaSize(&AI);
+    uint64_t AlignedSize = getAlignedAllocaSize(&AI);
     TotalStackSize += AlignedSize;
   }
 
@@ -488,6 +488,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
   bool isInterestingAlloca(AllocaInst &AI) {
     return (!AI.isArrayAllocation() &&
             AI.isStaticAlloca() &&
+            AI.getAlignment() <= RedzoneSize() &&
             AI.getAllocatedType()->isSized());
   }
 
diff --git a/test/Instrumentation/AddressSanitizer/basic.ll b/test/Instrumentation/AddressSanitizer/basic.ll
index fb32e704af..6002b9e897 100644
--- a/test/Instrumentation/AddressSanitizer/basic.ll
+++ b/test/Instrumentation/AddressSanitizer/basic.ll
@@ -89,6 +89,25 @@ entry:
 ; CHECK-NOT: = alloca
 ; CHECK: ret void
 
+; Check that asan does not touch allocas with alignment > 32.
+define void @alloca_alignment_test() sanitize_address {
+entry:
+  %x = alloca [10 x i8], align 64
+  %y = alloca [10 x i8], align 128
+  %z = alloca [10 x i8], align 256
+  call void @alloca_test_use([10 x i8]* %x)
+  call void @alloca_test_use([10 x i8]* %y)
+  call void @alloca_test_use([10 x i8]* %z)
+  ret void
+}
+
+; CHECK: define void @alloca_alignment_test()
+; CHECK: = alloca{{.*}} align 64
+; CHECK: = alloca{{.*}} align 128
+; CHECK: = alloca{{.*}} align 256
+; CHECK: ret void
+
+
 define void @LongDoubleTest(x86_fp80* nocapture %a) nounwind uwtable sanitize_address {
 entry:
     store x86_fp80 0xK3FFF8000000000000000, x86_fp80* %a, align 16