[Asan] Teach FunctionStackPoisoner to filter out struct type with sclable vector type.

FunctionStackPoisoner does not serve for AllocaInst with scalable vector type,
but it does not filter out struct type with scalable vector introduced
by c8eb535.
Currently, llvm does not allows an element of a struct type with scalable vector
is an element of a struct type vector, so we only need to check the first layer
of the struct type of AllocaInst.

Author: Yeting Kuo

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -1139,8 +1139,16 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
   /// Collect Alloca instructions we want (and can) handle.
   void visitAllocaInst(AllocaInst &AI) {
     // FIXME: Handle scalable vectors instead of ignoring them.
+    auto IsScalableVecTy = [](const Type *Ty) {
+      if (const auto *STy = dyn_cast<StructType>(Ty))
+        return any_of(STy->elements(), [](const Type *ElemTy) {
+          return isa<ScalableVectorType>(ElemTy);
+        });
+      return isa<ScalableVectorType>(Ty);
+    };
+
     if (!ASan.isInterestingAlloca(AI) ||
-        isa<ScalableVectorType>(AI.getAllocatedType())) {
+        IsScalableVecTy(AI.getAllocatedType())) {
       if (AI.isStaticAlloca()) {
         // Skip over allocas that are present *before* the first instrumented
         // alloca, we don't want to move those around.

llvm/test/Instrumentation/AddressSanitizer/asan-struct-scalable.ll

@@ -0,0 +1,11 @@
+; RUN: opt -passes=asan -disable-output -S %s
+; Check not crash.
+
+define void @test() #0 {
+entry:
+  %t0 = alloca { <vscale x 2 x i32>, <vscale x 2 x i32> }, align 4
+  call void null(ptr null, ptr %t0, i64 0)
+  ret void
+}
+
+attributes #0 = { sanitize_address }