Commit 01d8e09f authored by Senran Zhang's avatar Senran Zhang Committed by Fangrui Song
Browse files

[clang][CodeGen] Fix wrong memcpy size of no_unique_address in FieldMemcpyizer 

When generating ctor, FieldMemcpyizer wrongly treated zero-sized class members
as what should be copied, and generated wrong memcpy size under some special
circumstances. This patch tries to fix it.

Reviewed By: MaskRay, rjmccall

Differential Revision: https://reviews.llvm.org/D70671
parent 6f773205

clang/lib/CodeGen/CGClass.cpp

+2 −0
Original line number Diff line number Diff line
@@ -914,6 +914,8 @@ namespace { 
    }



    void addMemcpyableField(FieldDecl *F) {

      if (F->isZeroSize(CGF.getContext()))

        return;

      if (!FirstField)

        addInitialField(F);

      else

clang/test/CodeGenCXX/no-unique-address-2.cpp

0 → 100644
+25 −0
Original line number Diff line number Diff line 
// RUN: %clang_cc1 -std=c++2a %s -emit-llvm -o - -triple x86_64-linux-gnu | FileCheck %s



struct TriviallyCopyable {};



struct NonTriviallyCopyable {

  NonTriviallyCopyable() = default;

  NonTriviallyCopyable(const NonTriviallyCopyable&) = default;

  NonTriviallyCopyable(NonTriviallyCopyable &&) {}

};



struct Foo {

  int i;

  [[no_unique_address]] TriviallyCopyable m;

  [[no_unique_address]] NonTriviallyCopyable n;

};



void call() {

  Foo foo;

  Foo foo2(static_cast<Foo&&>(foo));

}



// The memcpy call should copy exact 4 bytes for member 'int i'

// CHECK: define {{.*}} void @_ZN3FooC2EOS_

// CHECK:  call void @llvm.memcpy.p0i8.p0i8.i64(i8* {{.+}}, i8* {{.+}}, i64 4, i1 false)

// CHECK:  call void @_ZN20NonTriviallyCopyableC2EOS_