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[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
This commit is contained in:
Senran Zhang 2019-11-26 10:15:14 +08:00 committed by Fangrui Song
parent 6f773205cd
commit 01d8e09fdb
2 changed files with 27 additions and 0 deletions
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2
clang/lib/CodeGen/CGClass.cpp
View File

@ -914,6 +914,8 @@ namespace {
}
void addMemcpyableField(FieldDecl *F) {
if (F->isZeroSize(CGF.getContext()))
return;
if (!FirstField)
addInitialField(F);
else

25
clang/test/CodeGenCXX/no-unique-address-2.cpp Normal file
View File

@ -0,0 +1,25 @@
// 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_