Author: kristina Date: Sun Nov 11 17:19:16 2018 New Revision: 346628 URL: http://llvm.org/viewvc/llvm-project?rev=346628&view=rev Log: [CodeGen][CXX]: Fix no_destroy CG bug under specific circumstances
Summary: Class with no user-defined destructor that has an inherited member that has a non-trivial destructor and a non-default constructor will attempt to emit a destructor despite being marked as __attribute((no_destroy)) in which case it would trigger an assertion due to an incorrect assumption. In addition this adds missing test coverage for IR generation for no_destroy. (Note that here use of no_destroy is synonymous with its global flag counterpart `-fno-c++-static-destructors` being enabled) Differential Revision: https://reviews.llvm.org/D54344 Added: cfe/trunk/test/CodeGenCXX/attr-no-destroy-d54344.cpp Modified: cfe/trunk/lib/CodeGen/CGDeclCXX.cpp Modified: cfe/trunk/lib/CodeGen/CGDeclCXX.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDeclCXX.cpp?rev=346628&r1=346627&r2=346628&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CGDeclCXX.cpp (original) +++ cfe/trunk/lib/CodeGen/CGDeclCXX.cpp Sun Nov 11 17:19:16 2018 @@ -64,6 +64,15 @@ static void EmitDeclInit(CodeGenFunction /// static storage duration. static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D, ConstantAddress Addr) { + // Honor __attribute__((no_destroy)) and bail instead of attempting + // to emit a reference to a possibly nonexistent destructor, which + // in turn can cause a crash. This will result in a global constructor + // that isn't balanced out by a destructor call as intended by the + // attribute. This also checks for -fno-c++-static-destructors and + // bails even if the attribute is not present. + if (D.isNoDestroy(CGF.getContext())) + return; + CodeGenModule &CGM = CGF.CGM; // FIXME: __attribute__((cleanup)) ? Added: cfe/trunk/test/CodeGenCXX/attr-no-destroy-d54344.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/attr-no-destroy-d54344.cpp?rev=346628&view=auto ============================================================================== --- cfe/trunk/test/CodeGenCXX/attr-no-destroy-d54344.cpp (added) +++ cfe/trunk/test/CodeGenCXX/attr-no-destroy-d54344.cpp Sun Nov 11 17:19:16 2018 @@ -0,0 +1,42 @@ +// RUN: %clang_cc1 -std=c++2a -emit-llvm -O0 -triple x86_64-unknown-linux-gnu -DNOATTR %s -o - | FileCheck %s +// RUN: %clang_cc1 -std=c++2a -emit-llvm -O0 -triple x86_64-unknown-linux-gnu %s -o - | FileCheck %s --check-prefix=CHECK-ATTR +// RUN: %clang_cc1 -std=c++2a -emit-llvm -O0 -triple x86_64-unknown-linux-gnu -DNOATTR -fno-c++-static-destructors %s -o - | FileCheck %s --check-prefix=CHECK-FLAG + +// Regression test for D54344. Class with no user-defined destructor +// that has an inherited member that has a non-trivial destructor +// and a non-default constructor will attempt to emit a destructor +// despite being marked as __attribute((no_destroy)) in which case +// it would trigger an assertion due to an incorrect assumption. + +// This test is more reliable with asserts to work as without +// the crash may (unlikely) could generate working but semantically +// incorrect code. + +class a { +public: + ~a(); +}; +class logger_base { + a d; +}; +class e : logger_base {}; +#ifndef NOATTR +__attribute((no_destroy)) +#endif +e g; + +// In the absence of the attribute and flag, both ctor and dtor should +// be emitted, check for that. +// CHECK: @__cxx_global_var_init +// CHECK: @__cxa_atexit + +// When attribute is enabled, the constructor should not be balanced +// by a destructor. Make sure we have the ctor but not the dtor +// registration. +// CHECK-ATTR: @__cxx_global_var_init +// CHECK-ATTR-NOT: @__cxa_atexit + +// Same scenario except with global flag (-fno-c++-static-destructors) +// supressing it instead of the attribute. +// CHECK-FLAG: @__cxx_global_var_init +// CHECK-FLAG-NOT: @__cxa_atexit _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
