fix PR17635: false positive with packed structures

LLVM optimizers may widen accesses to packed structures that overflow the structure itself, but should be in bounds up to the alignment of the object

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193317 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/MemoryBuiltins.h b/include/llvm/Analysis/MemoryBuiltins.h
index c54b7e6dfb5f615065f47b57cc600a2f732cf97b..91224ad94ac2983e3f4008a54b2e33a914b528d3 100644 (file)
--- a/include/llvm/Analysis/MemoryBuiltins.h
+++ b/include/llvm/Analysis/MemoryBuiltins.h
@@ -228,6 +228,7 @@ class ObjectSizeOffsetEvaluator
   Value *Zero;
   CacheMapTy CacheMap;
   PtrSetTy SeenVals;
+  bool RoundToAlign;
 
   SizeOffsetEvalType unknown() {
     return std::make_pair((Value*)0, (Value*)0);
@@ -236,7 +237,7 @@ class ObjectSizeOffsetEvaluator
 
 public:
   ObjectSizeOffsetEvaluator(const DataLayout *DL, const TargetLibraryInfo *TLI,
-                            LLVMContext &Context);
+                            LLVMContext &Context, bool RoundToAlign = false);
   SizeOffsetEvalType compute(Value *V);
 
   bool knownSize(SizeOffsetEvalType SizeOffset) {

diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp
index a2fb544c6575f358328d0ed2a0d3685d37faa7e3..1db0f634c941e4da86a61179fc73ca301cba2eab 100644 (file)
--- a/lib/Analysis/MemoryBuiltins.cpp
+++ b/lib/Analysis/MemoryBuiltins.cpp
@@ -588,8 +588,10 @@ SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
 
 ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const DataLayout *DL,
                                                      const TargetLibraryInfo *TLI,
-                                                     LLVMContext &Context)
-: DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)) {
+                                                     LLVMContext &Context,
+                                                     bool RoundToAlign)
+: DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)),
+  RoundToAlign(RoundToAlign) {
   IntTy = DL->getIntPtrType(Context);
   Zero = ConstantInt::get(IntTy, 0);
 }
@@ -614,7 +616,7 @@ SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
 }
 
 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
-  ObjectSizeOffsetVisitor Visitor(DL, TLI, Context);
+  ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign);
   SizeOffsetType Const = Visitor.compute(V);
   if (Visitor.bothKnown(Const))
     return std::make_pair(ConstantInt::get(Context, Const.first),

diff --git a/lib/Transforms/Instrumentation/BoundsChecking.cpp b/lib/Transforms/Instrumentation/BoundsChecking.cpp
index 4a9e9503675050637980fa122de557a51f0bcf04..7a9f0f69fbdf22e3c2e44f9a4739f972fcbc085c 100644 (file)
--- a/lib/Transforms/Instrumentation/BoundsChecking.cpp
+++ b/lib/Transforms/Instrumentation/BoundsChecking.cpp
@@ -172,7 +172,8 @@ bool BoundsChecking::runOnFunction(Function &F) {
   TrapBB = 0;
   BuilderTy TheBuilder(F.getContext(), TargetFolder(TD));
   Builder = &TheBuilder;
-  ObjectSizeOffsetEvaluator TheObjSizeEval(TD, TLI, F.getContext());
+  ObjectSizeOffsetEvaluator TheObjSizeEval(TD, TLI, F.getContext(),
+                                           /*RoundToAlign=*/true);
   ObjSizeEval = &TheObjSizeEval;
 
   // check HANDLE_MEMORY_INST in include/llvm/Instruction.def for memory

diff --git a/test/Instrumentation/BoundsChecking/simple-32.ll b/test/Instrumentation/BoundsChecking/simple-32.ll
new file mode 100644 (file)
index 0000000..38b210f
--- /dev/null
+++ b/test/Instrumentation/BoundsChecking/simple-32.ll
@@ -0,0 +1,29 @@
+; RUN: opt < %s -bounds-checking -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S128"
+
+%struct.s2_packed = type <{ i64, i32, i32, i32, i16, i8 }>
+
+; CHECK-LABEL: @f
+; CHECK-NOT: trap
+define i16 @f() {
+entry:
+  %packed1 = alloca %struct.s2_packed, align 8
+  %gep = getelementptr inbounds %struct.s2_packed* %packed1, i32 0, i32 4
+  %ptr = bitcast i16* %gep to i32*
+  %val = load i32* %ptr, align 4
+  %valt = trunc i32 %val to i16
+  ret i16 %valt
+}
+
+; CHECK-LABEL: @f
+; CHECK: call void @llvm.trap()
+define i16 @f2() {
+entry:
+  %packed1 = alloca %struct.s2_packed, align 8
+  %gep = getelementptr inbounds %struct.s2_packed* %packed1, i32 0, i32 4
+  %ptr = bitcast i16* %gep to i48*
+  %val = load i48* %ptr, align 4
+  %valt = trunc i48 %val to i16
+  ret i16 %valt
+}