clang/test/CodeGenCXX/stack-reuse-miscompile.cpp

   1 // RUN: %clang_cc1 -triple armv7l-unknown-linux-gnueabihf -emit-llvm -O1 -disable-llvm-passes -std=c++03 %s -o - | FileCheck %s --implicit-check-not=llvm.lifetime
   2
   3 class S {
   4   char *ptr;
   5   unsigned int len;
   6 };
   7
   8 class T {
   9   S left;
  10   S right;
  11
  12 public:
  13   T(const char s[]);
  14   T(S);
  15
  16   T concat(const T &Suffix) const;
  17   const char * str() const;
  18 };
  19
  20 const char * f(S s)
  21 {
  22 // It's essential that the lifetimes of all three T temporaries here are
  23 // overlapping. They must all remain alive through the call to str().
  24 //
  25 // CHECK: [[T1:%.*]] = alloca %class.T, align 4
  26 // CHECK: [[T2:%.*]] = alloca %class.T, align 4
  27 // CHECK: [[T3:%.*]] = alloca %class.T, align 4
  28 //
  29 // FIXME: We could defer starting the lifetime of the return object of concat
  30 // until the call.
  31 // CHECK: call void @llvm.lifetime.start.p0(i64 16, ptr [[T1]])
  32 //
  33 // CHECK: call void @llvm.lifetime.start.p0(i64 16, ptr [[T2]])
  34 // CHECK: [[T4:%.*]] = call noundef ptr @_ZN1TC1EPKc(ptr {{[^,]*}} [[T2]], ptr noundef @.str)
  35 //
  36 // CHECK: call void @llvm.lifetime.start.p0(i64 16, ptr [[T3]])
  37 // CHECK: [[T5:%.*]] = call noundef ptr @_ZN1TC1E1S(ptr {{[^,]*}} [[T3]], [2 x i32] %{{.*}})
  38 //
  39 // CHECK: call void @_ZNK1T6concatERKS_(ptr sret(%class.T) align 4 [[T1]], ptr {{[^,]*}} [[T2]], ptr noundef nonnull align 4 dereferenceable(16) [[T3]])
  40 // CHECK: [[T6:%.*]] = call noundef ptr @_ZNK1T3strEv(ptr {{[^,]*}} [[T1]])
  41 //
  42 // CHECK: call void @llvm.lifetime.end.p0(
  43 // CHECK: call void @llvm.lifetime.end.p0(
  44 // CHECK: call void @llvm.lifetime.end.p0(
  45 // CHECK: ret ptr [[T6]]
  46
  47   return T("[").concat(T(s)).str();
  48 }
  49
  50 // CHECK: declare {{.*}}llvm.lifetime.start
  51 // CHECK: declare {{.*}}llvm.lifetime.end