release/21.x: [DTLTO][Clang][Docs] Update for COFF support (#149988) #151670
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@tru What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-clang Author: None (llvmbot) ChangesBackport c129d65 Requested by: @bd1976bris Full diff: https://github.com/llvm/llvm-project/pull/151670.diff 1 Files Affected:
diff --git a/clang/docs/ThinLTO.rst b/clang/docs/ThinLTO.rst
index 569405ff5b2b7..8cb3e0b2b0d11 100644
--- a/clang/docs/ThinLTO.rst
+++ b/clang/docs/ThinLTO.rst
@@ -249,6 +249,9 @@ during the traditional link step.
The implementation is documented here: https://llvm.org/docs/DTLTO.html.
+Command-Line Options
+^^^^^^^^^^^^^^^^^^^^
+
DTLTO requires the LLD linker (``-fuse-ld=lld``).
``-fthinlto-distributor=<path>``
@@ -260,17 +263,29 @@ DTLTO requires the LLD linker (``-fuse-ld=lld``).
- Can be specified multiple times to pass multiple options.
- Multiple options can also be specified by separating them with commas.
-Examples:
- - ``clang -flto=thin -fthinlto-distributor=incredibuild.exe -Xthinlto-distributor=--verbose,--j10 -fuse-ld=lld``
- - ``clang -flto=thin -fthinlto-distributor=$(which python) -Xthinlto-distributor=incredibuild.py -fuse-ld=lld``
-
If ``-fthinlto-distributor=`` is specified, Clang supplies the path to a
compiler to be executed remotely to perform the ThinLTO backend
compilations. Currently, this is Clang itself.
+Usage
+^^^^^
+
+Compilation is unchanged from ThinLTO. DTLTO options need to supplied for the link step:
+
+.. code-block:: console
+
+ % clang -flto=thin -fthinlto-distributor=distribute.sh -Xthinlto-distributor=--verbose,--j10 -fuse-ld=lld file1.o file2.o
+ % clang -flto=thin -fthinlto-distributor=$(which python) -Xthinlto-distributor=distribute.py -fuse-ld=lld file1.o file2.o
+
+When using lld-link:
+
+.. code-block:: console
+
+ % lld-link /out:a.exe file1.obj file2.obj /thinlto-distributor:distribute.exe /thinlto-remote-compiler:${LLVM}\bin\clang.exe /thinlto-distributor-arg:--verbose
+
Note that currently, DTLTO is only supported in some LLD flavors. Support can
be added to other LLD flavours in the future.
-See `DTLTO <https://lld.llvm.org/dtlto.html>`_ for more information.
+See `DTLTO <https://lld.llvm.org/DTLTO.html>`_ for more information.
More Information
================
|
tru
approved these changes
Aug 5, 2025
github-project-automation
bot
moved this from Needs Triage
to Needs Merge
in LLVM Release Status
As the COFF linker is usually invoked independently, update the Clang DTLTO section to show an example. This follows what is done earlier in the document. Also some minor fixes and improvements: - Use generic distributor names to avoid implying anything about what an Incredibuild distributor may or should support. - Use subheadings for readability. - Correct a mis-cased hyperlink. (cherry picked from commit c129d65)
github-project-automation
bot
moved this from Needs Merge
to Done
in LLVM Release Status
|
@bd1976bris (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
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Backport c129d65
Requested by: @bd1976bris