Validate Tt Mlir Against Tt Xla

Validate tt-mlir PR in tt-xla

This skill automates cross-repo validation of tt-mlir PRs against tt-xla CI. The core idea: tt-xla pins a specific tt-mlir commit. To test a PR before it merges, you create a temporary branch that layers the PR's commits on top of that pinned commit, then trigger tt-xla's test workflows against it. The branch is ephemeral — it is deleted once CI completes, and always recreated fresh on each run.

Repos

• tt-mlir: tenstorrent/tt-mlir (the PR lives here)
• tt-xla: tenstorrent/tt-xla (CI runs here)

Workflow

1. Identify the PR

The PR number or URL can be provided as an argument (e.g. /validate-tt-mlir-against-tt-xla 1234). If not provided, detect the PR for the current branch:

gh pr view $(git branch --show-current) --repo tenstorrent/tt-mlir --json number,headRefName,baseRefName,body,commits,state

If no PR is found for the current branch, ask once: PR number or URL:

Extract the PR metadata:

gh pr view <PR> --repo tenstorrent/tt-mlir --json number,headRefName,baseRefName,body,commits,state

If the PR is merged or closed, stop — nothing to do.

2. Resolve tt-xla branch

Determine XLA_BRANCH before anything else — both the uplifted commit and test suite discovery depend on it.

Check if there is a related branch in tt-xla that the user might want to test against. Extract the PR author's GitHub username from the PR metadata, then search for their branches in tt-xla. The tt-xla repo has many branches (100+), so use --paginate:

gh api "repos/tenstorrent/tt-xla/branches" --paginate \
  -q '.[].name' | grep -i "<author-username>"

tt-xla branches follow the convention username/branch-name (e.g. acicovic/rms-test). If any branches match the same author, evaluate whether each candidate branch is semantically related to the tt-mlir PR branch — not just keyword overlap. Strip the username/ prefix from both branches and compare the remaining names. Consider them related only if they clearly refer to the same feature, fix, or work item (e.g. add-permute-reshape-canon and permute-reshape-test are related; fix-reshape and reshape-perf-dashboard are not). When in doubt, treat the branch as unrelated.

If exactly one semantically related branch is found, present a choice via AskUserQuestion:

• question: "Found a related tt-xla branch. Which branch to run CI against?"
• "main (Recommended)"
• "<matched-branch-name>" — with description noting the author match

If multiple related branches are found, list them all as options alongside main. If no related branch is found, silently default to main. The user can also override by specifying a branch as part of their invocation or in conversation. Call the result XLA_BRANCH.

3. Resolve the uplifted tt-mlir commit

Read the version pin from XLA_BRANCH:

gh api "repos/tenstorrent/tt-xla/contents/third_party/CMakeLists.txt?ref=<XLA_BRANCH>" \
  -q .content | base64 -d \
  | grep -oP 'set\(TT_MLIR_VERSION "\K[^"]+'

This returns the SHA that XLA_BRANCH currently builds against. Call it UPLIFTED_SHA.

4. Gather remaining user inputs

Discover available test suites

Fetch the valid test_suite options directly from the workflow file — this is the authoritative source for what values manual-test.yml will actually accept:

gh api "repos/tenstorrent/tt-xla/contents/.github/workflows/manual-test.yml?ref=<XLA_BRANCH>" \
  -q .content | base64 -d \
  | grep -A100 'test_suite:' | grep -oP "'\K[^']+"

Do not truncate this output — capture all options before selecting the default.

If the workflow uses options: under test_suite, parse those. If it uses a free-text input with no enumerated options, fall back to listing JSON files in test-matrix-presets/:

gh api "repos/tenstorrent/tt-xla/git/trees/<XLA_BRANCH>?recursive=1" \
  -q '.tree[] | select(.path | test("test-matrix-presets/.*\\.json$")) | .path | split("/") | last | rtrimstr(".json")'

From the discovered suite names, identify the default suite by finding the one most likely intended for uplift/qualification testing. Look for names containing uplift, qualification, or mlir — in that priority order. If multiple match, prefer the most specific. If none match, present all suites to the user and ask them to designate a default. Never hardcode a suite name — always select from what was actually discovered.

The default suite always runs. From the remaining suites, pick the 3 most relevant to surface as additional options. If discovery fails entirely, fall back to a text prompt.

Ask remaining questions via AskUserQuestion

Use the AskUserQuestion tool with both questions batched together:

Question 1 — header: Extra suites, multiSelect: true

• question: "<default-suite> will always run (discovered dynamically). Select additional suites to run in parallel, if any."
• Options are the 3 most relevant non-default suites discovered above. Do NOT include the default suite as an option — it always runs.
• The auto-added "Type something" option lets the user type any suite name not shown.
• Leave all unselected to run the default suite only.

Question 2 — header: Baseline

• question: "Baseline failure detection? Type a run ID to compare against a previous run."
• "Skip — just report failures (Recommended)"
• "Run baseline in parallel"
• The auto-added "Type something" option lets the user paste a run ID as baseline.

Parse all answers before proceeding. The default suite always runs; selected extra suites run in parallel alongside it.

5. Re-run detection and stale uplift warning

Check if the xla-validate/<pr-number> branch already exists on the remote:

git ls-remote --exit-code origin xla-validate/<pr-number>

If the branch exists, CI from a previous run is likely still in progress. Warn the user:

Note: xla-validate/<pr-number> already exists — a previous CI run may still be in progress. Re-triggering will delete and recreate the branch. Continue?

If they confirm, proceed. If not, stop.

If the branch does not exist but a previous validation block is present in the PR description, this is a re-run after the previous CI completed. Extract the previous UPLIFTED_SHA from the **Base (uplifted):** line in the description. If it differs from the current UPLIFTED_SHA, inform the user:

Note: tt-xla has uplifted to a newer tt-mlir commit since your last validation (<PREV_SHA_SHORT> → <UPLIFTED_SHA_SHORT>). The cherry-pick base has changed.

6. Create the branch

The branch name is always xla-validate/<pr-number>.

If the branch already exists (user confirmed re-trigger above), delete it first:

git push origin --delete xla-validate/<pr-number>

Get the list of commits from the PR:

gh api repos/tenstorrent/tt-mlir/pulls/<pr-number>/commits --paginate -q '.[].sha'

Fetch the PR's head ref to ensure all commit objects are present locally before cherry-picking (the commits may not exist in the local clone if the PR branch was never checked out):

git fetch origin refs/pull/<pr-number>/head

Create the branch fresh by cherry-picking those commits onto UPLIFTED_SHA:

git fetch origin <UPLIFTED_SHA>
git checkout -B xla-validate/<pr-number> <UPLIFTED_SHA>
git cherry-pick <commit1> <commit2> ... <commitN>
git push origin xla-validate/<pr-number>

If cherry-pick has conflicts, stop and tell the user — they need to resolve manually.

Get the HEAD SHA of the pushed branch — this is the MLIR_OVERRIDE_SHA for CI.

7. Trigger tt-xla CI

Dispatch the "Run test" workflow for each selected test suite:

gh workflow run manual-test.yml \
  --repo tenstorrent/tt-xla \
  --ref <XLA_BRANCH> \
  -f test_suite=<suite> \
  -f mlir_override=<MLIR_OVERRIDE_SHA>

If the user chose baseline option 2, also dispatch baseline runs for each suite without mlir_override:

gh workflow run manual-test.yml \
  --repo tenstorrent/tt-xla \
  --ref <XLA_BRANCH> \
  -f test_suite=<suite>

After dispatching, wait ~5 seconds then find the newly created runs. Record the timestamp just before dispatching and use it to filter:

# capture before dispatch
DISPATCH_TIME=$(date -u +%Y-%m-%dT%H:%M:%SZ)

# ... dispatch commands ...

# wait for GitHub to register the run
sleep 5

gh run list --repo tenstorrent/tt-xla --workflow=manual-test.yml --limit 20 \
  --json databaseId,status,name,createdAt,url \
  --jq "[.[] | select(.createdAt >= \"$DISPATCH_TIME\")]"

Match each dispatched suite to exactly one run created at or after DISPATCH_TIME. If multiple candidates appear for the same suite, take the most recent. If no run appears within 15 seconds, retry once — GitHub Actions dispatch is occasionally slow.

Important: Re-triggering failed jobs within an existing run does NOT create a new run ID. The run ID is stable for the lifetime of the workflow run. Only dispatch creates new IDs. Once IDs are recorded here, treat them as final — never update them during polling.

Collect run URLs and IDs. These are the only IDs tracked for the rest of the skill.

8. Update the PR description (initial — in_progress)

Immediately append (or replace) a validation block at the end of the PR description. Use HTML comment markers so the skill can find and replace it on re-runs.

IMPORTANT: Always use the tempfile approach for editing PR descriptions. Writing markdown with backticks, pipes, and special characters into shell variables causes escaping issues that can wipe the PR body. See the "Editing PR descriptions safely" section below for the exact procedure.

Format with no baseline (option 1):

<!-- xla-validate -->
---
### tt-xla Validation

**Base (uplifted):** `<UPLIFTED_SHA_SHORT>`
**tt-xla branch:** `<XLA_BRANCH>` ← omit this line when XLA_BRANCH is `main`

| Test Suite | Run | Status |
|------------|-----|--------|
| <default-suite> | [Run #<id>](<url>) | :hourglass: in_progress |
<!-- /xla-validate -->

Use the actual suite name discovered dynamically — never write a hardcoded name here.

Format with parallel baseline (option 2) — add a Baseline row beneath each PR row, marked with a (baseline) label:

| Test Suite | Run | Status |
|------------|-----|--------|
| <default-suite> | [Run #<id>](<url>) | :hourglass: in_progress |
| <default-suite> (baseline) | [Run #<id>](<url>) | :hourglass: in_progress |

Format with provided baseline (option 3) — same as option 2 but the baseline row links to the user-supplied run and starts as either in_progress or already-resolved depending on that run's current state.

On re-runs, replace everything between <!-- xla-validate --> and <!-- /xla-validate --> with the fresh block.

9. Report to user and start polling

Tell the user:

• CI runs triggered with links
• PR description updated with in_progress status
• That you will monitor the runs and update the PR when they finish

Use the /loop skill (main agent) to poll every 3 minutes so the user can continue other work.

10. Poll for run completion

Each iteration, check the exact run IDs recorded in step 7 — never scan for new runs or add IDs during polling. Re-triggered jobs stay under the same run ID and will be reflected in the existing run's status automatically.

gh run view <run-id> --repo tenstorrent/tt-xla --json status,conclusion,url

A run with re-triggered jobs may cycle through queued or in_progress again after previously being completed — this is normal. Keep polling until the run settles in a terminal state and stays there for one full poll cycle.

Report status in the terminal each iteration (e.g. [12:34] <default-suite>: in_progress, next check in 3min). Keep polling until all tracked runs (PR runs + any baseline runs) reach a terminal state (completed, failure, cancelled, timed_out).

11. Finalize

Once all runs are done:

1. Delete the branch — it is no longer needed:

   git push origin --delete xla-validate/<pr-number>
   

2. Update the PR description with final statuses. Map conclusions to status indicators:

   • success → :white_check_mark: passed
   • failure → :x: failed
   • cancelled → :no_entry_sign: cancelled
   • timed_out → :alarm_clock: timed_out

   If any PR runs failed, run the failure analysis (step 12) first so the failure table is included in the same edit.

3. Notify the user with a summary of results.

12. Analyze failures and report

When a PR run fails, analyze the CI logs to identify which tests failed and why. Then add a compact failure table to the validation block.

Finding failed tests

1. Get the failed jobs:

gh run view <run-id> --repo tenstorrent/tt-xla --json jobs \
  --jq '.jobs[] | select(.conclusion == "failure") | {name, databaseId}'

2. For each failed job, extract test names and errors:

gh api repos/tenstorrent/tt-xla/actions/jobs/<job-id>/logs 2>&1 \
  | grep -E "FAILED|PASSED" | head -30

3. Get error details for each failed test:

gh api repos/tenstorrent/tt-xla/actions/jobs/<job-id>/logs 2>&1 \
  | grep -B5 -A15 "_____ test_all_models_jax\[<test-name>" | head -40

Comparing against baseline (options 2 and 3)

If the user requested a baseline, compare the failed tests against the baseline run's results to classify each failure:

• If the same test failed in the baseline too → (pre-existing)
• If the test passed in the baseline → (regression)
• If the baseline is still in_progress, note that classification is pending

If no baseline was requested (option 1), omit the classification column entirely.

Failure table format

Add this directly below the status table in the validation block:

Without baseline:

#### Failures

| Test | Arch | Error |
|------|------|-------|
| `gpt2/causal_lm/jax-Base-inference` | n150, p150 | `XlaRuntimeError: Error code 13` |

With baseline:

#### Failures

| Test | Arch | Error | Classification |
|------|------|-------|----------------|
| `gpt2/causal_lm/jax-Base-inference` | n150, p150 | `XlaRuntimeError: Error code 13` | regression |
| `t5/summarization/jax-Base-inference` | n150, p150 | `XlaRuntimeError: Error code 13` | pre-existing |

Rules for the failure table:

• Shorten test names: drop single_device and test_all_models_jax[] wrapper
• Combine architectures if the same test fails on multiple (e.g. "n150, p150")
• Error column: just the exception class and code/message
• No graph URLs unless CI actually uploaded graph artifacts (check artifacts list first)

Editing PR descriptions safely

Shell variables containing markdown (backticks, pipes, dollar signs) break when passed through --body. Always use the tempfile + --body-file approach:

Writing the body

1. Use the Write tool (or cat <<'HEREDOC' > /tmp/pr_body_<pr-number>.md) to write the full PR body to a temp file. Using a quoted heredoc (<<'EOF') prevents any shell expansion of the content.

2. Apply the edit:

gh pr edit <PR> --repo tenstorrent/tt-mlir --body-file /tmp/pr_body_<pr-number>.md

3. Clean up:

rm /tmp/pr_body_<pr-number>.md

Verification (required after every edit)

After every gh pr edit, immediately verify the body was applied correctly:

BODY=$(gh pr view <PR> --repo tenstorrent/tt-mlir --json body -q .body)
if [ -z "$BODY" ]; then
  echo "ERROR: PR body is empty after edit!"
elif echo "$BODY" | grep -q "xla-validate"; then
  echo "OK: PR body looks correct"
else
  echo "WARNING: PR body may be corrupted — missing validation block"
fi

If verification fails:

1. Re-read the current PR body to assess damage
2. Reconstruct the full body (original content + validation block) using the Write tool
3. Retry with --body-file
4. Verify again

Constructing updated bodies for re-runs

When replacing an existing validation block, use Python for reliable text manipulation instead of shell tools like awk/sed/perl which struggle with markdown:

python3 -c "
import sys
body = open('/tmp/pr_body_old_<pr-number>.md').read()
new_block = open('/tmp/pr_validation_block_<pr-number>.md').read()
start = body.find('<!-- xla-validate -->')
end = body.find('<!-- /xla-validate -->')
if start >= 0 and end >= 0:
    end = end + len('<!-- /xla-validate -->')
    body = body[:start] + new_block + body[end:]
else:
    body = body + '\n\n' + new_block
open('/tmp/pr_body_<pr-number>.md', 'w').write(body)
"

Error handling

• Cherry-pick conflicts: Stop immediately, show the conflicting commit, and tell the user to resolve manually. Do not force through conflicts.
• Branch push fails: Report clearly and stop.
• Workflow dispatch fails: Delete the xla-validate/<pr-number> branch (it is no longer needed if CI cannot run), then check gh auth and repo permissions. Report the error.
• Test suite discovery fails: Fall back to prompting the user to enter a suite name manually rather than erroring out.
• PR not found: Verify the PR number/URL and repo.
• PR body corrupted: See "Editing PR descriptions safely" — always verify and retry.