[MSAN] Allow emitting checks for struct types

Differential Revision: https://reviews.llvm.org/D82680

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

@@ -1149,11 +1149,11 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     const DataLayout &DL = F.getParent()->getDataLayout();
     const Align OriginAlignment = std::max(kMinOriginAlignment, Alignment);
     unsigned StoreSize = DL.getTypeStoreSize(Shadow->getType());
-    if (Shadow->getType()->isAggregateType()) {
+    if (Shadow->getType()->isArrayTy()) {
       paintOrigin(IRB, updateOrigin(Origin, IRB), OriginPtr, StoreSize,
                   OriginAlignment);
     } else {
-      Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB);
+      Value *ConvertedShadow = convertShadowToScalar(Shadow, IRB);
       if (auto *ConstantShadow = dyn_cast<Constant>(ConvertedShadow)) {
         if (ClCheckConstantShadow && !ConstantShadow->isZeroValue())
           paintOrigin(IRB, updateOrigin(Origin, IRB), OriginPtr, StoreSize,
@@ -1172,8 +1172,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
                             IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
                             Origin});
       } else {
-        Value *Cmp = IRB.CreateICmpNE(
-            ConvertedShadow, getCleanShadow(ConvertedShadow), "_mscmp");
+        Value *Cmp = convertToBool(ConvertedShadow, IRB, "_mscmp");
         Instruction *CheckTerm = SplitBlockAndInsertIfThen(
             Cmp, &*IRB.GetInsertPoint(), false, MS.OriginStoreWeights);
         IRBuilder<> IRBNew(CheckTerm);
@@ -1224,7 +1223,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
                            bool AsCall) {
     IRBuilder<> IRB(OrigIns);
     LLVM_DEBUG(dbgs() << "  SHAD0 : " << *Shadow << "\n");
-    Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB);
+    Value *ConvertedShadow = convertShadowToScalar(Shadow, IRB);
     LLVM_DEBUG(dbgs() << "  SHAD1 : " << *ConvertedShadow << "\n");
 
     if (auto *ConstantShadow = dyn_cast<Constant>(ConvertedShadow)) {
@@ -1246,8 +1245,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
                                                 ? Origin
                                                 : (Value *)IRB.getInt32(0)});
     } else {
-      Value *Cmp = IRB.CreateICmpNE(ConvertedShadow,
-                                    getCleanShadow(ConvertedShadow), "_mscmp");
+      Value *Cmp = convertToBool(ConvertedShadow, IRB, "_mscmp");
       Instruction *CheckTerm = SplitBlockAndInsertIfThen(
           Cmp, OrigIns,
           /* Unreachable */ !MS.Recover, MS.ColdCallWeights);
@@ -1391,14 +1389,49 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     return ty;
   }
 
-  /// Convert a shadow value to it's flattened variant.
-  Value *convertToShadowTyNoVec(Value *V, IRBuilder<> &IRB) {
+  /// Extract combined shadow of struct elements as a bool
+  Value *collapseStructShadow(StructType *Struct, Value *Shadow,
+                              IRBuilder<> &IRB) {
+    Value *FalseVal = IRB.getIntN(/* width */ 1, /* value */ 0);
+    Value *Aggregator = FalseVal;
+
+    for (unsigned Idx = 0; Idx < Struct->getNumElements(); Idx++) {
+      // Combine by ORing together each element's bool shadow
+      Value *ShadowItem = IRB.CreateExtractValue(Shadow, Idx);
+      Value *ShadowInner = convertShadowToScalar(ShadowItem, IRB);
+      Value *ShadowBool = convertToBool(ShadowInner, IRB);
+
+      if (Aggregator != FalseVal)
+        Aggregator = IRB.CreateOr(Aggregator, ShadowBool);
+      else
+        Aggregator = ShadowBool;
+    }
+
+    return Aggregator;
+  }
+
+  /// Convert a shadow value to it's flattened variant. The resulting
+  /// shadow may not necessarily have the same bit width as the input
+  /// value, but it will always be comparable to zero.
+  Value *convertShadowToScalar(Value *V, IRBuilder<> &IRB) {
+    if (StructType *Struct = dyn_cast<StructType>(V->getType()))
+      return collapseStructShadow(Struct, V, IRB);
     Type *Ty = V->getType();
     Type *NoVecTy = getShadowTyNoVec(Ty);
     if (Ty == NoVecTy) return V;
     return IRB.CreateBitCast(V, NoVecTy);
   }
 
+  // Convert a scalar value to an i1 by comparing with 0
+  Value *convertToBool(Value *V, IRBuilder<> &IRB, const Twine &name = "") {
+    Type *VTy = V->getType();
+    assert(VTy->isIntegerTy());
+    if (VTy->getIntegerBitWidth() == 1)
+      // Just converting a bool to a bool, so do nothing.
+      return V;
+    return IRB.CreateICmpNE(V, ConstantInt::get(VTy, 0), name);
+  }
+
   /// Compute the integer shadow offset that corresponds to a given
   /// application address.
   ///
@@ -1732,8 +1765,10 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     if (!InsertChecks) return;
 #ifndef NDEBUG
     Type *ShadowTy = Shadow->getType();
-    assert((isa<IntegerType>(ShadowTy) || isa<VectorType>(ShadowTy)) &&
-           "Can only insert checks for integer and vector shadow types");
+    assert(
+        (isa<IntegerType>(ShadowTy) || isa<VectorType>(ShadowTy) ||
+         isa<StructType>(ShadowTy)) &&
+        "Can only insert checks for integer, vector, and struct shadow types");
 #endif
     InstrumentationList.push_back(
         ShadowOriginAndInsertPoint(Shadow, Origin, OrigIns));
@@ -2088,7 +2123,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
           Constant *ConstOrigin = dyn_cast<Constant>(OpOrigin);
           // No point in adding something that might result in 0 origin value.
           if (!ConstOrigin || !ConstOrigin->isNullValue()) {
-            Value *FlatShadow = MSV->convertToShadowTyNoVec(OpShadow, IRB);
+            Value *FlatShadow = MSV->convertShadowToScalar(OpShadow, IRB);
             Value *Cond =
                 IRB.CreateICmpNE(FlatShadow, MSV->getCleanShadow(FlatShadow));
             Origin = IRB.CreateSelect(Cond, OpOrigin, Origin);

llvm/test/Instrumentation/MemorySanitizer/check-struct.ll

@@ -0,0 +1,23 @@
+; RUN: opt < %s -msan-check-access-address=0 -msan-track-origins=1 -S -passes='module(msan-module),function(msan)' 2>&1 | \
+; RUN:   FileCheck -allow-deprecated-dag-overlap -check-prefixes=CHECK,CHECK-ORIGINS %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-LABEL: @main
+define { i32, i8 } @main() sanitize_memory {
+; CHECK: [[P:%.*]] = inttoptr i64 0 to { i32, i8 }*
+  %p = inttoptr i64 0 to { i32, i8 } *
+; CHECK: [[O:%.*]] = load { i32, i8 }, { i32, i8 }* [[P]]
+  %o = load { i32, i8 }, { i32, i8 } *%p
+; CHECK: [[FIELD0:%.+]] = extractvalue { i32, i8 } %_msld, 0
+; CHECK: [[F0_POISONED:%.+]] = icmp ne i32 [[FIELD0]]
+; CHECK: [[FIELD1:%.+]] = extractvalue { i32, i8 } %_msld, 1
+; CHECK: [[F1_POISONED:%.+]] = icmp ne i8 [[FIELD1]]
+; CHECK: [[F1_OR:%.+]] = or i1 [[F0_POISONED]], [[F1_POISONED]]
+; CHECK-NOT: icmp ne i1 {{.*}}, false
+; CHECK: br i1 [[F1_OR]]
+; CHECK: call void @__msan_warning
+; CHECK: ret { i32, i8 } [[O]]
+  ret { i32, i8 } %o
+}

llvm/test/Instrumentation/MemorySanitizer/msan_x86_bts_asm.ll

@@ -92,8 +92,7 @@ if.else:                                          ; preds = %entry
 ; CHECK: [[MSPROP:%.*]] = trunc i8 [[MSLD]] to i1
 
 ; Is the shadow poisoned?
-; CHECK: [[MSCMP:%.*]] = icmp ne i1 [[MSPROP]], false
-; CHECK: br i1 [[MSCMP]], label %[[IFTRUE:.*]], label {{.*}}
+; CHECK: br i1 [[MSPROP]], label %[[IFTRUE:.*]], label {{.*}}
 
 ; If yes, raise a warning.
 ; CHECK: [[IFTRUE]]: