[Frontend] Remap -O to -cc commandline flag #29557

gmagogsfm · 2025-11-27T00:03:06Z

Users can now:

Continue using -O{1,2,3}, which now means optimization level, not compilation mode any more.
Continue using -O.xxx (deprecation warning until later time when we remove the support)
Start using -cc (no warning, preferred)
Use --compilation-config (no change)

Warning message: "The -O flag for --compilation-config is deprecated and will be removed in a later release. Please use -cc instead. Example: -cc.mode=0 instead of -O.mode=0"

Fixes #27832

mergify · 2025-11-27T00:03:51Z

Documentation preview: https://vllm--29557.org.readthedocs.build/en/29557/

gemini-code-assist

Code Review

This pull request remaps the -O command-line flag to -cc for compilation configuration, deprecating the former. The changes span documentation, tests, and argument parsing logic. While the updates to documentation and tests are correct, I've found a critical issue with the implementation of the deprecation warning for the -O flag. The current approach will not trigger the warning due to how arguments are pre-processed. I have provided detailed comments and suggestions to fix this issue by relocating the warning logic. Once addressed, the PR will correctly implement the intended functionality.

vllm/engine/arg_utils.py

gemini-code-assist · 2025-11-27T00:06:29Z

vllm/engine/arg_utils.py

+            "--compilation-config",
+            "-cc",
+            "-O",
+            action=CompilationConfigAction,


Following my other comment, this action should be removed as CompilationConfigAction is ineffective and should be removed.

vllm/utils/argparse_utils.py

ProExpertProg

Thanks for implementing this! We should wait for #26847 to merge first. Can you make the deprecation comments and warnings mention the functionality will be removed in v0.13.0?

ProExpertProg · 2025-11-27T00:08:27Z

tests/utils_/test_argparse_utils.py

+    args = parser.parse_args(["-O.mode", "0"])
+    assert args.compilation_config == {"mode": 0}
+
+    args = parser.parse_args(["-O.mode=NONE"])
+    assert args.compilation_config == {"mode": "NONE"}


Add a comment that we're planning to deprecate these in v0.13.0?

ProExpertProg · 2025-11-27T00:10:10Z

vllm/config/vllm.py

+    As a shorthand, one can append compilation arguments via
+    -cc.parameter=argument such as `-cc.mode=3` (same as `-cc='{"mode":3}'`).
+    Optimization level shortcuts like `-O3` are also supported (equivalent to
+    -cc.mode=3).


This will no longer be true after #26247; -O<n> will map to optimization level.

OK, I will wait for #26847 to land and fix up the logic.

ProExpertProg · 2025-11-27T00:14:18Z

vllm/engine/arg_utils.py

-            "--compilation-config", "-O", **vllm_kwargs["compilation_config"]
+            "--compilation-config",
+            "-cc",
+            "-O",


Yeah let's remove the -O here completely and just remap any use of -O.<...>/-O {...} to -cc in argparse_utils

mergify · 2025-11-28T06:44:52Z

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @gmagogsfm.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

Migrate compilation configuration from -O to -cc flags while preserving the new optimization level functionality that uses -O flags. Changes: - Update argparse_utils.py to handle -O flag disambiguation - Add deprecation warnings for -O.* dotted syntax for compilation config - Convert -O.backend, -O.mode, etc. to -cc.backend, -cc.mode with warnings - Update CLI argument parsing to use -cc instead of -O for compilation config - Update tests to use new -cc syntax for compilation config - Maintain backward compatibility with proper deprecation messages 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> Signed-off-by: Yanan Cao <gmagogsfm@gmail.com>

Replace all remaining references to deprecated -O.* compilation config syntax with the new -cc.* syntax throughout the codebase: - Documentation: Update debug guide and torch_compile.md examples - Tests: Update compilation tests to use -cc.* syntax - CI scripts: Update buildkite XPU test script - Config docs: Update VllmConfig docstring examples This ensures consistency across the codebase and removes deprecated usage examples that might confuse users. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> Signed-off-by: Yanan Cao <gmagogsfm@gmail.com>

mergify · 2025-11-28T08:55:05Z

Documentation preview: https://vllm--29557.org.readthedocs.build/en/29557/

tests/utils_/test_argparse_utils.py

hmellor · 2025-11-28T13:22:04Z

vllm/utils/argparse_utils.py

            ):
                # Convert -O <n> to --optimization-level <n>
                processed_args.append("--optimization-level")
+            elif arg.startswith("-O") and arg[2] == ".":


Suggested change

elif arg.startswith("-O") and arg[2] == ".":

elif arg.startswith("-O."):

hmellor · 2025-11-28T13:24:24Z

vllm/utils/argparse_utils.py

+                if any(
+                    cc_option in arg
+                    for cc_option in [
+                        ".mode",
+                        ".backend",
+                        ".custom_option",
+                        ".enable_fusion",
+                        ".disable_custom_fusion",
+                    ]


This list is not exhaustive and it shouldn't need to exist. Any use of -O. is deprecated

- Handle all -O.* dotted syntax as deprecated, not just specific options - Emit warning and convert -O.* to -cc.* syntax automatically - Update codebase references from -O.* to -cc.* syntax - Add comprehensive test for deprecation warning - Simplify condition checking and remove unnecessary scope parameter The -O.* dotted syntax is deprecated and will be removed in v0.13.0 or v1.0.0, whichever is earlier. Users should use -cc.* instead. Example: -cc.backend=eager instead of -O.backend=eager. Signed-off-by: Yanan Cao <gmagogsfm@gmail.com>

hmellor

LGTM, thanks!

gmagogsfm requested review from ProExpertProg, WoosukKwon, hmellor, houseroad, mgoin, robertgshaw2-redhat, tlrmchlsmth, yewentao256 and youkaichao as code owners November 27, 2025 00:03

mergify bot added documentation Improvements or additions to documentation ci/build labels Nov 27, 2025

gemini-code-assist bot reviewed Nov 27, 2025

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gmagogsfm mentioned this pull request Nov 27, 2025

[RFC]: Remap CompilationConfig from -O to -cc in CLI #27832

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ProExpertProg reviewed Nov 27, 2025

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gmagogsfm force-pushed the o_cc branch from 69c34c4 to d07ec09 Compare November 27, 2025 01:35

mergify bot added the needs-rebase label Nov 28, 2025

gmagogsfm force-pushed the o_cc branch 2 times, most recently from 3149903 to c556b06 Compare November 28, 2025 07:54

mergify bot removed the needs-rebase label Nov 28, 2025

gmagogsfm force-pushed the o_cc branch from c556b06 to 4df4cae Compare November 28, 2025 08:01

gmagogsfm requested a review from ProExpertProg November 28, 2025 08:03

hmellor requested changes Nov 28, 2025

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gmagogsfm force-pushed the o_cc branch from caedd05 to 6914b23 Compare November 28, 2025 16:37

gmagogsfm force-pushed the o_cc branch from 6914b23 to 58d6f87 Compare November 28, 2025 16:43

hmellor approved these changes Nov 28, 2025

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hmellor enabled auto-merge (squash) November 28, 2025 19:44

github-actions bot added the ready ONLY add when PR is ready to merge/full CI is needed label Nov 28, 2025

hmellor merged commit 3461e7e into vllm-project:main Nov 28, 2025
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ProExpertProg mentioned this pull request Nov 29, 2025

[Core] Rename PassConfig flags as per RFC #27995 #29646

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	elif arg.startswith("-O") and arg[2] == ".":
	elif arg.startswith("-O."):

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[Frontend] Remap -O to -cc commandline flag #29557

[Frontend] Remap -O to -cc commandline flag #29557

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gmagogsfm commented Nov 27, 2025 •

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