This diff adds initial support for the legacy LC_VERSION_MIN_* load commands.
Test plan: make check-lld-macho
Differential revision: https://reviews.llvm.org/D100523
Previously, we were loading re-exports without checking whether
they were compatible with our target. Prior to {D97209}, it meant that
we were defining dylib symbols that were invalid -- usually a silent
failure unless our binary actually used them. D97209 exposed this as an
explicit error.
Along the way, I've extended our TAPI compatibility check to cover the
platform as well, instead of just checking the arch. To this end, I've
replaced MachO::Architecture with MachO::Target in our Config struct.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D97867
We should have maxprot == initprot for all non-i386 architectures, which
is what ld64 does.
Reviewed By: #lld-macho, compnerd
Differential Revision: https://reviews.llvm.org/D89420
Summary:
There were a few issues with the previous setup:
1. The section sorting comparator used a declarative map of section names to
determine the correct order, but it turns out we need to match on more than
just names -- in particular, an upcoming diff will sort based on whether the
S_ZERO_FILL flag is set. This diff changes the sorter to a more imperative but
flexible form.
2. We were sorting OutputSections stored in a MapVector, which left the
MapVector in an inconsistent state -- the wrong keys map to the wrong values!
In practice, we weren't doing key lookups (only container iteration) after the
sort, so this was fine, but it was still a dubious state of affairs. This diff
copies the OutputSections to a vector before sorting them.
3. We were adding unneeded OutputSections to OutputSegments and then filtering
them out later, which meant that we had to remember whether an OutputSegment
was in a pre- or post-filtered state. This diff only adds the sections to the
segments if they are needed.
In addition to those major changes, two minor ones worth noting:
1. I renamed all OutputSection variable names to `osec`, to parallel `isec`.
Previously we were using some inconsistent combination of `osec`, `os`, and
`section`.
2. I added a check (and a test) for InputSections with names that clashed with
those of our synthetic OutputSections.
Reviewers: #lld-macho
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D81887
The order file indicates how input sections should be sorted within each
output section, based on the symbols contained within those sections.
This diff sets the stage for implementing and testing
`.subsections_via_symbols`, where we will break up InputSections by each
symbol and sort them more granularly.
Reviewed By: smeenai
Differential Revision: https://reviews.llvm.org/D79668
Summary:
1. Don't have isHidden() depend on isNeeded(). Whether a section is
hidden is orthogonal from whether it is needed: hidden sections will
never have a header regardless of whether they have a body. (I know we
override this method with return false for synthetic sections, but
regardless I think it's confusing to write it this way for non-synthetic
sections.)
2. Don't call writeTo() on unneeded sections. D78270 assumes that this
is true when implementing the stub helper section.
3. Filter out the unneeded sections early on to avoid having to deal
with them in multiple places.
4. Remove assumption in test that the referenced file has no other symbols.
(We should create separate input files for future tests to avoid such
issues.)
Reviewers: ruiu, pcc, MaskRay, smeenai, alexshap, gkm, Ktwu, christylee
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D79460
Summary: Similar to other formats, input sections in the MachO
implementation are now grouped under output sections. This is primarily
a refactor, although there's some new logic (like resolving the output
section's flags based on its inputs).
Differential Revision: https://reviews.llvm.org/D77893
Previously, the special segments `__PAGEZERO` and `__LINKEDIT` were
implemented as special LoadCommands. This diff implements them using
special sections instead which have an `isHidden()` attribute. We do not
emit section headers for hidden sections, but we use their addresses and
file offsets to determine that of their containing segments. In addition
to allowing us to share more segment-related code, this refactor is also
important for the next step of emitting dylibs:
1) dylibs don't have segments like __PAGEZERO, so we need an easy way of
omitting them w/o messing up segment indices
2) Unlike the kernel, which is happy to run an executable with
out-of-order segments, dyld requires dylibs to have their segment
load commands arranged in increasing address order. The refactor
makes it easier to implement sorting of sections and segments.
Differential Revision: https://reviews.llvm.org/D76839
Summary:
This is the first commit for the new Mach-O backend, designed to roughly
follow the architecture of the existing ELF and COFF backends, and
building off work that @ruiu and @pcc did in a branch a while back. Note
that this is a very stripped-down commit with the bare minimum of
functionality for ease of review. We'll be following up with more diffs
soon.
Currently, we're able to generate a simple "Hello World!" executable
that runs on OS X Catalina (and possibly on earlier OS X versions; I
haven't tested them). (This executable can be obtained by compiling
`test/MachO/relocations.s`.) We're mocking out a few load commands to
achieve this -- for example, we can't load dynamic libraries, but
Catalina requires binaries to be linked against `dyld`, so we hardcode
the emission of a `LC_LOAD_DYLIB` command. Other mocked out load
commands include LC_SYMTAB and LC_DYSYMTAB.
Differential Revision: https://reviews.llvm.org/D75382
Jez Ng