[runtimes] Remove support for GCC-style 32 bit multilib builds
This patch removes the ability to build the runtimes in the 32 bit
multilib configuration, i.e. using -m32. Instead of doing this, one
should cross-compile the runtimes for the appropriate target triple,
like we do for all other triples.
As it stands, -m32 has several issues, which all seem to be related to
the fact that it's not well supported by the operating systems that
libc++ support. The simplest path towards fixing this is to remove
support for the configuration, which is also the best course of action
if there is little interest for keeping that configuration. If there
is a desire to keep this configuration around, we'll need to do some
work to figure out the underlying issues and fix them.
Differential Revision: https://reviews.llvm.org/D114473
NOKEYCHECK=True
GitOrigin-RevId: fa1c077b41ae1335332d65399802f2c68e82ca7b
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index d3b9d98..2484ecf 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -148,3 +148,12 @@
.. code-block:: bash
$ cmake -S <monorepo>/runtimes -B build -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" <LIBCXX-OPTIONS> <LIBCXXABI-OPTIONS>
+
+ - Support for building the runtimes using the GCC 32 bit multilib flag (``-m32``) has been removed. Support
+ for this had been flaky for a while, and we didn't know of anyone depending on this. Instead, please perform
+ a normal cross-compilation of the runtimes using the appropriate target, such as passing the following to
+ your bootstrapping build:
+
+ .. code-block:: bash
+
+ -DLLVM_RUNTIME_TARGETS=i386-unknown-linux