glider marked 3 inline comments as done.
glider added inline comments.
================
Comment at: clang/test/CodeGen/PR42672.c:50
+ struct {
+ long long int v1, v2, v3, v4;
+ } str;
----------------
efriedma wrote:
> glider wrote:
> > The acceptable size actually depends on the target platform. Not sure we
> > can test for all of them, and we'll probably need to restrict this test to
> > e.g. x86
> The interesting case for a 32-byte struct would actually be something like
> `"=x"(str)`... which currently passes the clang frontend, since 32 is a legal
> size for that constraint (although it eventually fails in the backend).
Changing "=r" to "=X" indeed makes this particular test pass (there's nothing
to fail in the backend, as we don't actually generate instructions that write
to memory)
I'm however unsure adding a test for "=X" makes any difference, as our patch is
irrelevant to this constraint.
================
Comment at: clang/test/CodeGen/PR42672.c:40
+ unsigned short first;
+ unsigned char second;
+ } str;
----------------
efriedma wrote:
> This isn't a three-byte struct; it's a four-byte struct where one of the
> bytes is only used for padding.
You're right. Making this structure packed yields an error, which conforms to
GCC behavior.
I've added a test for that as well.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D65234/new/
https://reviews.llvm.org/D65234
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