Introduce placement pass by yenjames · Pull Request #2900 · Xilinx/mlir-aie

yenjames · 2026-02-26T22:41:04Z

Summary

This PR implements the --aie-place-tiles pass with sequential placer algorithm, ~~completing logical-to-physical tile mapping~~.

Changes

New pass definition that can be extended with other placer algorithm.
Follows structure similar to AIEPathfinder pass.
Not registered to aiecc for now.
Removed "Pure" class from aie.logical_tile, noticed canonicalization pass was removing logical_tiles because they appear identical in mlir.

Future PR

Enhance placer to handle ShimPL tiles.
Consolidate with ObjectFifo refactor plans.

Update (2026-03-18): Change plans to merge this PR first as it's self isolated. Will introduce this pass without registering to aiecc.cpp and part of lowering pipeline. This pass has been verified with local tests.

Update (2026-03-24):
Review Changes:

Placer as a typed enum option.
Support partially constrained tiles with sequential placer. These are provided a "filtered" list of candidate tiles for them to map to.
Additional tests: mem/shim/compute tile exhaustion, cores-per-col exceeding device capacity, exact capacity fitting.
Added checks to tests to ensure tiles are actually merged (by checking next tile in coordinate system wasn't created).

github-actions · 2026-02-27T22:43:24Z

Coverage Report

Created: 2026-03-27 17:59

Click here for information about interpreting this report.

Filename	Function Coverage	Line Coverage	Region Coverage	Branch Coverage
include/aie/Dialect/AIE/Transforms/AIEPasses.h	100.00%	100.00%	100.00%	-
include/aie/Dialect/AIE/Transforms/AIEPlacer.h	80.00%	80.00%	77.78%	50.00%
lib/Dialect/AIE/Transforms/AIEPlaceTiles.cpp	100.00%	92.50%	90.48%	71.43%
lib/Dialect/AIE/Transforms/AIEPlacer.cpp	100.00%	95.90%	94.96%	85.59%
Totals	95.83%	95.31%	94.12%	84.52%

Generated by llvm-cov -- llvm version 18.1.3

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

… are placed correctly. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…nnected by objectfifo.link together. - The common column function was incorrectly obtaining a global best column when it should be by fifo or fifoGroup if linked. - Reformatted the placement code structure; PlacementAnalysis is kept thin, considered removal but this allows re-calling placer or even a set of placers if future implementation is iterative placement. - Each placer will obtain its own necessary mlir ops. - Canonicalization was accidentally removing logical tiles because they appear the same in syntax; removed Pure trait. TODO: - Trace support is not added for IRON and mlir itself; trace operations aren't mapped to use aie.logical_tile. - cores_per_column that limits sequentialplacer's row usage feature not implemented yet.

- Add GEN_PASS_DEF_AIEPLACETILES to properly generate pass base class - Use fully qualified xilinx::AIE::impl::AIEPlaceTilesBase for CRTP - Add -split-input-file flag to cores_per_col test for multi-module files - Revert example changes (pass not yet registered to aiecc pipeline) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Add MemTile DMA exhaustion test (single-column device) - Add allocation_scheme attribute copy test - Add unknown placer error test Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Copilot

Pull request overview

This PR introduces a new --aie-place-tiles MLIR pass that performs logical-to-physical tile placement using a C++ sequential placer, then rewrites aie.logical_tile ops into concrete aie.tile ops.

Changes:

Add AIEPlaceTiles pass + options (placer, cores-per-col) and wire it into the AIE transforms library build.
Implement a C++ Placer interface with an initial SequentialPlacer + PlacementAnalysis.
Add a focused lit test suite for sequential placement behavior and error cases; adjust aie.logical_tile traits to avoid incorrect IR canonicalization/CSE.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
test/place-tiles/unknown_placer.mlir	Verifies unknown placer option produces an error.
test/place-tiles/sequential_placer/test_objectfifo_link.mlir	Tests placement behavior around `aie.objectfifo.link` grouping/column choice.
test/place-tiles/sequential_placer/place_tiles_simple.mlir	Tests basic core placement and attribute propagation (`allocation_scheme`).
test/place-tiles/sequential_placer/place_tiles_objectfifo.mlir	Tests mem/shim/core placement interactions across multiple ObjectFifos/consumers.
test/place-tiles/sequential_placer/place_tiles_constrained.mlir	Tests fully constrained and mixed constrained/unconstrained placement cases.
test/place-tiles/sequential_placer/partial_constraints_ignored.mlir	Documents current behavior: partial constraints are ignored.
test/place-tiles/sequential_placer/edge_detect.mlir	End-to-end style test matching expected placement for an edge-detect pattern.
test/place-tiles/sequential_placer/cores_per_col.mlir	Tests `cores-per-col` option spreads cores across columns.
test/place-tiles/sequential_placer/channel_capacity_bad.mlir	Negative tests for DMA channel capacity validation / exhaustion.
lib/Dialect/AIE/Transforms/CMakeLists.txt	Adds new placer + placement pass sources to the transforms library.
lib/Dialect/AIE/Transforms/AIEPlaceTiles.cpp	Implements the `--aie-place-tiles` pass and logical→physical tile rewrite.
lib/Dialect/AIE/Transforms/AIEPlacer.cpp	Implements the sequential placement algorithm + channel accounting and grouping.
include/aie/Dialect/AIE/Transforms/AIEPlacer.h	Declares placer interface and sequential placer/analysis types.
include/aie/Dialect/AIE/Transforms/AIEPasses.td	Declares the new `aie-place-tiles` pass and CLI options.
include/aie/Dialect/AIE/Transforms/AIEPasses.h	Exposes `createAIEPlaceTilesPass()` factory.
include/aie/Dialect/AIE/IR/AIEOps.td	Removes `Pure` from `aie.logical_tile` to prevent incorrect CSE/canonicalization.

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- Add ShimPLTile error diagnostic for unsupported unplaced ShimPLTiles - Add fallback placement for non-core tiles not in ObjectFifos - Fix comment: row-major -> column-major placement - Reduce over-commenting in AIEPlacer.cpp - Reorganize tests: consolidate 8 files into 5 with split-input-file Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…ed consider adding back.

hunhoffe

Overall, this looks very good! I'd prefer a bit more testing (although the current Placer isn't that well tested).

hunhoffe · 2026-03-21T17:34:53Z

+//
+//===----------------------------------------------------------------------===//
+
+// RUN: not aie-opt --split-input-file --aie-place-tiles %s 2>&1 | FileCheck %s


Are there any other error cases you need to check?

hunhoffe · 2026-03-21T17:35:53Z

+}
+
+// -----
+


I think there need to be a few more tests about column grouping, exceeding channels (so place near column group)

hunhoffe · 2026-03-21T17:36:25Z

@@ -0,0 +1,155 @@
+//===- test_place_basic.mlir -----------------------------------*- MLIR -*-===//
+//


There might need to be a test for "exactly fills capacity" in various ways. It's good to double check the edge cases.

…roved tests - Convert placer pass option from string to enum (PlacerType) - Fix partial constraint support for CoreTile, MemTile, and ShimTile - Add cores-per-col validation against device capacity Test improvements: - Use separate logical tiles per fifo to properly test merging behavior - Add CHECK-NOT patterns to verify no extra tiles created during merging - Add exact capacity tests (core, shim, memtile channel limits) - Add overflow tests (partial capacity remaining triggers new tile) - Add error tests: ShimNOC/MemTile exhaustion, compute tile exhaustion

hunhoffe

Looks good! Thanks for the changes/tests

yenjames force-pushed the sequential-placer-pass branch from 1997911 to 388a061 Compare February 26, 2026 22:47

yenjames mentioned this pull request Feb 26, 2026

Port placement to MLIR and placer enhancement #2864

Open

10 tasks

yenjames force-pushed the sequential-placer-pass branch 2 times, most recently from 05ef19a to 077a736 Compare February 27, 2026 22:19

yenjames and others added 5 commits March 18, 2026 15:03

Implement sequential placer pass, set up placement pass infrastructure.

11d2980

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add tile type filtering to sequential placer to ensure mem/shim tiles…

b46ba7b

… are placed correctly. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Fix clang format. Check if tests fixed for #2899.

2217fcc

Added cores_per_column feature to sequential placer.

7b6d1b0

yenjames force-pushed the sequential-placer-pass branch from 077a736 to 1ea63ec Compare March 18, 2026 21:16

yenjames changed the base branch from logical-tile-iron to main March 18, 2026 21:18

yenjames force-pushed the sequential-placer-pass branch from 1ea63ec to 5d4d200 Compare March 18, 2026 21:25

Add test coverage for sequential placer.

4c19e1a

- Add MemTile DMA exhaustion test (single-column device) - Add allocation_scheme attribute copy test - Add unknown placer error test Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

yenjames marked this pull request as ready for review March 19, 2026 21:18

yenjames requested review from abisca, erwei-xilinx, fifield, hunhoffe, jackl-xilinx, jgmelber and stephenneuendorffer as code owners March 19, 2026 21:18

Copilot AI review requested due to automatic review settings March 19, 2026 21:18

Copilot started reviewing on behalf of yenjames March 19, 2026 21:20 View session

Copilot AI reviewed Mar 19, 2026

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yenjames commented Mar 19, 2026

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Comment thread test/place-tiles/unknown_placer.mlir Outdated

Removed PlacementAnalysis wrapper class, if more placers are introduc…

681e4df

…ed consider adding back.

hunhoffe requested changes Mar 21, 2026

View reviewed changes

hunhoffe approved these changes Mar 27, 2026

View reviewed changes

Merge branch 'main' into sequential-placer-pass

31b79ac

yenjames enabled auto-merge March 27, 2026 17:41

yenjames added this pull request to the merge queue Mar 27, 2026

github-merge-queue bot removed this pull request from the merge queue due to no response for status checks Mar 28, 2026

yenjames added this pull request to the merge queue Mar 30, 2026

Merged via the queue into main with commit c7741f2 Mar 30, 2026
71 checks passed

yenjames deleted the sequential-placer-pass branch March 30, 2026 15:52

		@@ -0,0 +1,155 @@
		//===- test_place_basic.mlir ------------------------------------ MLIR --===//
		//

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Coverage Report

Created: 2026-03-27 17:59

Generated by llvm-cov -- llvm version 18.1.3

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yenjames commented Feb 26, 2026 •

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