vitalybuka marked an inline comment as done.
vitalybuka added inline comments.
================
Comment at: clang/test/CodeGen/init.c:197
// CHECK-LABEL: @nonzeroPaddedUnionMemset(
- // CHECK-NOT: store
- // CHECK-NOT: memcpy
- // CHECK: call void @llvm.memset.p0i8.i32(i8* {{.*}}, i8 -16, i32 36, i1
false)
+ // CHECK: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 {{.*}}, i8* align
4 {{.*}} [[INIT_PADDEDUNION]], {{.*}}, i32 36, i1 false)
}
----------------
vitalybuka wrote:
> hubert.reinterpretcast wrote:
> > This is C++ aggregate initialization and not value-initialization. The
> > wording you quoted from the C++ standard is for zero-initialization, which
> > might be part of value initialization, but you have not shown that
> > aggregate initialization of a union involves zero-initialization of that
> > union.
> reading this more I don't see any evidence that either C++ or C requires
> padding initialization.
> Reading this I expect that all function here should be equivalent
> https://godbolt.org/z/1O_9-e
> But they are not. Clang and GCC initialized padding after the first member.
So if go trough "aggregates" then nothing is said about padding in union.
If we go trough "list-initialization" then value initialization should be
applied, part of which is zero initialization.
If so union padding should be initialized.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D68115/new/
https://reviews.llvm.org/D68115
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