Sometimes a collection of multilibs has a gap in it, where a set of
driver command-line options can't work with any of the available
libraries.
For example, the Arm MVE extension requires special startup code (you
need to initialize FPSCR.LTPSIZE), and also benefits greatly from
-mfloat-abi=hard. So a multilib provider might build a library for
systems without MVE, and another for MVE with -mfloat-abi=hard,
anticipating that that's what most MVE users would want. But then if a
user compiles for MVE _without_ -mfloat-abi=hard, thhey can't use either
of those libraries – one has an ABI mismatch, and the other will fail to
set up LTPSIZE.
In that situation, it's useful to include a multilib.yaml entry for the
unworkable intermediate situation, and have it map to a fatal error
message rather than a set of actual libraries. Then the user gets a
build failure with a sensible explanation, instead of selecting an
unworkable library and silently generating bad output. The new
regression test demonstrates this case.
This patch introduces extra syntax into multilib.yaml, so that a record
in the `Variants` list can omit the `Dir` key, and in its place, provide
a `FatalError` key. Then, if that variant is selected, the error message
is emitted as a clang diagnostic, and multilib selection fails.
In order to emit the error message in `MultilibSet::select`, I had to
pass a `Driver &` to that function, which involved plumbing one through
to every call site, and in the unit tests, constructing one specially.
This will enable layering multilibs on top of each other.
For example a multilib containing only a no-exceptions libc++ could be
layered on top of a multilib containing C libs. This avoids the need
to duplicate the C library for every libc++ variant.
This change doesn't expose the functionality externally, it only opens
the functionality up to be potentially used by ToolChain classes.
Differential Revision: https://reviews.llvm.org/D143059
The format includes a ClangMinimumVersion entry to avoid a potential
source of subtle errors if an older version of Clang were to be used
with a multilib.yaml that requires a newer Clang to work correctly.
This feature is comparable to CMake's cmake_minimum_required.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D142932
The new algorithm is:
1. Find all multilibs with flags that are a subset of the requested
flags.
2. If more than one multilib matches, choose the last.
In addition a new selection mechanism is permitted via an overload of
MultilibSet::select() for which multiple multilibs are returned.
This allows layering multilibs on top of each other.
Since multilibs are now ordered within a list, they no longer need a
Priority field.
The new algorithm is different to the old algorithm, but in practise
the old algorithm was always used in such a way that the effect is the
same.
The old algorithm was to find the set intersection of the requested
flags (with the first character of each removed) with each multilib's
flags (ditto), and for that intersection check whether the first
character matched. However, ignoring the first characters, the
requested flags were always a superset of all the multilibs flags.
Therefore the new algorithm can be used as a drop-in replacement.
The exception is Fuchsia, which needs adjusting slightly to set both
fexceptions and fno-exceptions flags.
Differential Revision: https://reviews.llvm.org/D142905
The functionality in MultilibSet for creating it is tied to its current
implementation. Putting that code in a separate class is an enabler for
changing the MultilibSet implementation.
Differential Revision: https://reviews.llvm.org/D142893
When more than one multilib flag matches, try to select the best
possible match based on priority. When two different multilibs with
the same same priority match, we still throw an error matching the
existing behavior.
Differential Revision: https://reviews.llvm.org/D60990
llvm-svn: 359359
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
a missing include from CLog.h.
CLog.h referenced most of the core libclang types but never directly
included Index.h that provides them. Previously it got lucky and other
headers were always included first but with the sorting it ended up
first in one case and stopped compiling. Adding the Index.h include
fixes it right up.
llvm-svn: 202810
This patch improves the support for picking Multilibs from gcc installations.
It also provides a better approximation for the flags '-print-multi-directory'
and '-print-multi-lib'.
This reverts r201203 (i.e. re-applying r201202 with small fixes in
unittests/CMakeLists.txtto make the build bots happy).
review: http://llvm-reviews.chandlerc.com/D2538
llvm-svn: 201205
This patch improves the support for picking Multilibs from gcc installations.
It also provides a better approximation for the flags '-print-multi-directory'
and '-print-multi-lib'.
review: http://llvm-reviews.chandlerc.com/D2538
llvm-svn: 201202
