Summary:
This patch fixes several small problems with external layouts support in
`MicrosoftRecordLayoutBuilder`:
- aligns properly the size of a struct that ends with a bit field. It was
aligned on byte before, not on the size of the field, so the struct size was
smaller than it should be;
- adjusts the struct size when injecting a vbptr in the case when there were no
bases or fields allocated after the vbptr. Similarly, without the adjustment
the struct was smaller than it should be;
- the same fix as above for the vfptr.
All these fixes affect the non-virtual size of a struct, so they are tested
through non-virtual inheritance.
Reviewers: rnk, zturner, rsmith
Reviewed By: rnk
Subscribers: jdoerfert, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58544
llvm-svn: 356047
It broke test/PCH/headersearch.cpp because it was using -Wpadding, which
only works for Itanium layout. Before this commit, we would use Itanium
record layout when using PCH, which is crazy. Now that the test uses an
explicit Itanium triple, we can reland.
llvm-svn: 230525
Covered by existing tests in test/CodeGen/override-layout.c and
test/CodeGenCXX/override-layout.cpp. Seriously, they found real bugs in
my code. :)
llvm-svn: 230446
doesn't include padding up to the alignment of the record, take this
as a cue that the alignment of the record should (conservatively) be
set to 1. This is similar to other the other cues we use to determine
that the record has a lower alignment, e.g., that the
externally-supplied layout places fields at lower offsets than we
would. Fixes <rdar://problem/12582052>; test case in LLDB.
llvm-svn: 166824
provide the layout of records, rather than letting Clang compute
the layout itself. LLDB provides the motivation for this feature:
because various layout-altering attributes (packed, aligned, etc.)
don't get reliably get placed into DWARF, the record layouts computed
by LLDB from the reconstructed records differ from the actual layouts,
and badness occurs. This interface lets the DWARF data drive layout,
so we don't need the attributes preserved to get the answer write.
The testing methodology for this change is fun. I've introduced a
variant of -fdump-record-layouts called -fdump-record-layouts-simple
that always has the simple C format and provides size/alignment/field
offsets. There is also a -cc1 option -foverride-record-layout=<file>
to take the output of -fdump-record-layouts-simple and parse it to
produce a set of overridden layouts, which is introduced into the AST
via a testing-only ExternalASTSource (called
LayoutOverrideSource). Each test contains a number of records to lay
out, which use various layout-changing attributes, and then dumps the
layouts. We then run the test again, using the preprocessor to
eliminate the layout-changing attributes entirely (which would give us
different layouts for the records), but supplying the
previously-computed record layouts. Finally, we diff the layouts
produced from the two runs to be sure that they are identical.
Note that this code makes the assumption that we don't *have* to
provide the offsets of bases or virtual bases to get the layout right,
because the alignment attributes don't affect it. I believe this
assumption holds, but if it does not, we can extend
LayoutOverrideSource to also provide base offset information.
Fixes the Clang side of <rdar://problem/10169539>.
llvm-svn: 149055
Aleksandr Urakov