[RFQ] build: add bazel-orfs beta test for design builds

[oharboe]

bazel-orfs Beta Test

This is an early integration of bazel-orfs
into OpenROAD-flow-scripts. It lets you build ORFS designs with Bazel
using the same config.mk files you already have.

Status: beta -- 46 designs across 6 public PDK platforms build and
pass QoR tests. Platforms without public PDK files (gf12, gf55,
rapidus2hp) are not wired up.

Quick Start

# Install bazelisk (one-time) -- see https://github.com/bazelbuild/bazelisk
# Then, from the ORFS root:

# Synthesize gcd on asap7 (downloads Docker image on first run)
bazelisk build //flow/designs/asap7/gcd:gcd_synth

# Run through floorplan
bazelisk build //flow/designs/asap7/gcd:gcd_floorplan

# Full flow through final
bazelisk build //flow/designs/asap7/gcd:gcd_final

# Run the test (includes QoR regression check)
bazelisk test //flow/designs/asap7/gcd:gcd_test

# List all targets for a design
bazelisk query //flow/designs/asap7/gcd:all

Available Targets Per Design

Each enabled design gets these targets automatically from its config.mk:

Target suffix	What it does
_synth	Yosys synthesis
_floorplan	Floorplan + I/O placement
_place	Global + detailed placement
_cts	Clock tree synthesis
_grt	Global routing
_route	Detailed routing
_final	Final optimization + fill
_generate_abstract	LEF/LIB abstract for hierarchical use
_generate_metadata	Flow metadata (logs, reports)
_test	Full flow + QoR regression check

Each stage depends on the previous one, so building _final runs the
entire flow.

Working Designs (46 passing tests)

All designs below have orfs_design() enabled and pass
bazelisk test with QoR regression checks.

asap7 (16 designs)

Design	DESIGN_NAME	Notes
gcd	gcd	smoketest, ~1 min
gcd-ccs	gcd	CCS lib model
aes	aes_cipher_top	medium
aes-block	aes_cipher_top	block variant
aes-mbff	aes_cipher_top	MBFF
aes_lvt	aes_cipher_top	LVT cells
ethmac	ethmac	Ethernet MAC
ethmac_lvt	ethmac	LVT cells
ibex	ibex_core	RISC-V core (slang)
jpeg	jpeg_encoder	JPEG encoder
jpeg_lvt	jpeg_encoder	LVT cells
uart	uart	UART
riscv32i	riscv_top	RISC-V RV32I
mock-cpu	mock_cpu	mock CPU with FIFO
swerv_wrapper	swerv_wrapper	SweRV EH1
cva6	cva6	CVA6 RISC-V (~63 min)

sky130hd (7 designs)

Design	DESIGN_NAME	Notes
gcd	gcd	smoketest
aes	aes_cipher_top	medium
ibex	ibex_core	RISC-V core
jpeg	jpeg_encoder	JPEG encoder
riscv32i	riscv	RISC-V RV32I
chameleon	soc_core	SoC with macros
microwatt	microwatt	POWER ISA core

nangate45 (7 designs)

Design	DESIGN_NAME	Notes
gcd	gcd	smoketest
aes	aes_cipher_top	medium
ibex	ibex_core	RISC-V core
jpeg	jpeg_encoder	JPEG encoder
dynamic_node	dynamic_node_top_wrap	NoC router
swerv	swerv	SweRV EH1
tinyRocket	RocketTile	RISC-V Rocket

gf180 (5 designs)

Design	DESIGN_NAME	Notes
aes	aes_cipher_top	medium
aes-hybrid	aes_cipher_top	hybrid variant
ibex	ibex_core	RISC-V core
jpeg	jpeg_encoder	JPEG encoder
riscv32i	riscv	RISC-V RV32I

ihp-sg13g2 (6 designs)

Design	DESIGN_NAME	Notes
gcd	gcd	smoketest
aes	aes_cipher_top	medium
ibex	ibex_core	RISC-V core
jpeg	jpeg_encoder	JPEG encoder
riscv32i	riscv	RISC-V RV32I
spi	spi	SPI controller

sky130hs (5 designs)

Design	DESIGN_NAME	Notes
gcd	gcd	smoketest
aes	aes_cipher_top	medium
ibex	ibex_core	RISC-V core
jpeg	jpeg_encoder	JPEG encoder
riscv32i	riscv	RISC-V RV32I

Designs Blocked on bazel-orfs Changes

These designs have BUILD.bazel with a commented-out orfs_design()
and a TODO(bazel-orfs) note. They need changes in bazel-orfs before
they can be enabled.

Hierarchical sub-design targets (riscv32i-mock-sram)

asap7/riscv32i-mock-sram uses include designs/asap7/riscv32i/config.mk
in its config.mk and has a fakeram7_256x32/ sub-design directory.
The orfs_designs rule generates spurious riscv_top_* targets in
the sub-design package from the parent config. This causes a build
failure because the sub-design lacks the parent's rules-base.json.

Fix: orfs_designs should only generate targets from config.mk
files that are directly in the scanned directory, not from included
configs resolved at Make-time.

Specific file references in VERILOG_FILES

Several designs list individual files in VERILOG_FILES from directories
other than the design's own src/ tree (e.g. $(DESIGN_HOME)/src/ariane133/ariane.sv2v.v
or $(DESIGN_HOME)/src/$(DESIGN_NAME)/pickled.v). The orfs_designs
rule resolves $(wildcard ...) patterns but does not handle explicit
file paths that use $(DESIGN_NAME) or $(DESIGN_NICKNAME).

Affected: nangate45: ariane133, ariane136, black_parrot, bp_be_top,
bp_fe_top, bp_multi_top, bp_quad, mempool_group, swerv_wrapper.

Fix: Extend the orfs_designs config.mk parser to resolve
$(DESIGN_NAME) and $(DESIGN_NICKNAME) variable references in
explicit file paths, not just in $(wildcard ...) patterns.

VERILOG_FILES from non-matching src directory

gf180/uart-blocks references src/uart-no-param/*.v -- a different
src directory than its own name.

Fix: The parser already handles $(DESIGN_NICKNAME) in wildcard
patterns; verify it also resolves when the source directory name
differs from the design directory name.

Platform-local verilog in VERILOG_FILES

ihp-sg13g2/i2c-gpio-expander adds $(PLATFORM_DIR)/verilog/sg13g2_io.v
to VERILOG_FILES and also references verilog from its own platform
design directory ($(DESIGN_HOME)/$(PLATFORM)/$(DESIGN_NICKNAME)/*.v).

Fix: Support $(PLATFORM_DIR)/... file references in VERILOG_FILES
by resolving them against the PDK target.

Generated verilog (mock-alu)

asap7/mock-alu generates its verilog via src/mock-alu/generate_*.py
scripts. Needs a Bazel genrule to run the Python generator before
synthesis.

No VERILOG_FILES (minimal)

asap7/minimal is a test design with no VERILOG_FILES in config.mk
(empty SDC). Not expected to work with orfs_designs.

Platforms without public PDK

gf12, gf55, and rapidus2hp have design directories but no platform
files in the open-source repo. These are skipped entirely.

How to Add More Designs

1. Create flow/designs/<platform>/<design>/BUILD.bazel:

load("@bazel-orfs//:openroad.bzl", "orfs_design")
load("@orfs_designs//:designs.bzl", "DESIGNS")

exports_files(glob(["*"]))

orfs_design(designs = DESIGNS)

2. If flow/designs/src/<name>/BUILD.bazel doesn't exist, create it:

exports_files(
    glob(["*.v", "*.sv"], allow_empty = True),
    visibility = ["//visibility:public"],
)

filegroup(
    name = "verilog",
    srcs = glob(include = ["*.v", "*.sv"], allow_empty = True),
    visibility = ["//visibility:public"],
)

3. Run bazelisk query //flow/designs/<platform>/<design>:all to verify.

Using a Local bazel-orfs Checkout

To iterate on bazel-orfs rules locally, replace the git_override in
MODULE.bazel:

# Comment out the git_override block, then add:
local_path_override(
    module_name = "bazel-orfs",
    path = "/path/to/your/bazel-orfs",
)

Also update the bazel-orfs-verilog override:

local_path_override(
    module_name = "bazel-orfs-verilog",
    path = "/path/to/your/bazel-orfs/verilog",
)

Key Differences from Make

• Incremental: Bazel caches every stage. Changing PLACE_DENSITY
  in config.mk rebuilds only floorplan onward -- synthesis is cached.
• Hermetic: Tools come from a Docker image (extracted automatically).
  No make install or PATH setup needed.
• Parallel: Independent designs build in parallel automatically.
• Reproducible: Same inputs always produce the same outputs.

Performance Notes

Each OpenROAD invocation uses -threads <nproc> (all available cores).
When Bazel runs many designs in parallel, the machine becomes heavily
overcommitted. On a 48-core machine, 50+ OpenROAD instances may run
simultaneously during a full bazelisk test ..., each requesting 48
threads.

To limit parallelism:

# Limit to 4 concurrent OpenROAD invocations
bazelisk test --jobs=4 ...

A full test suite run (46 designs, 6 platforms) takes roughly 3-4 hours
on a 48-core machine with default parallelism (overcommitted). Individual
design times vary from ~1 minute (gcd) to ~63 minutes (cva6 on asap7).

Updating Metric Thresholds

When OpenROAD or flow scripts change, metric thresholds in
rules-base.json may go stale. To update them for a specific design:

# Rebuilds the design and writes updated thresholds back to source
bazelisk run //flow/designs/asap7/aes-block:aes_cipher_top_update

The target name follows the pattern <design_name>_update where
<design_name> comes from DESIGN_NAME in config.mk.

Equivalence Checking (eqy)

Some designs (e.g. aes) set EQUIVALENCE_CHECK=1 in their
config.mk to enable equivalence checking of repair_timing. The
actual eqy tool invocation is gated by a separate RUN_EQY
variable (default 0), so builds don't fail when eqy is not installed.
CI sets RUN_EQY=1 when eqy is available.

Workflow: Unmerged Commits

This PR serves as a working branch against master. Commits here are
spun off as separate, focused PRs for review. Once a PR merges, this
branch is rebased on master to drop the merged commit. The branch is
force-pushed after each rebase so the PR commit list is always the
source of truth for what's pending.

Filing of PRs is throttled to avoid overwhelming maintainers --
submitting too many at once just causes "maintainer packet dropping"
where reviews stall.

Known Limitations

• The Docker image is pinned; updating it requires changing
  MODULE.bazel.
• Platforms without public PDK files (gf12, gf55, rapidus2hp) are not
  supported.
• Some designs are blocked on bazel-orfs parser improvements (see above).
• riscv32i-mock-sram hierarchical flow does not work yet.
• This is a beta -- expect rough edges. File issues at
  https://github.com/The-OpenROAD-Project/bazel-orfs/issues

[oharboe]

@jhkim-pii Would you take it for a spin and comment?

[oharboe]

@hzeller Thoughts?

[jhkim-pii]

ORFS bazel works.
But there are many BUILD.bazel files. Is there a way to reduce the number of files?

/workspace/ws6/OpenROAD-flow-scripts/flow/designs/src/cva6 $ find . -name BUILD.bazel
./BUILD.bazel
./common/BUILD.bazel
./common/local/BUILD.bazel
./common/local/util/BUILD.bazel
./vendor/BUILD.bazel
./vendor/pulp-platform/BUILD.bazel
./vendor/pulp-platform/tech_cells_generic/BUILD.bazel
./vendor/pulp-platform/tech_cells_generic/src/rtl/BUILD.bazel
./vendor/pulp-platform/tech_cells_generic/src/BUILD.bazel
./vendor/pulp-platform/common_cells/BUILD.bazel
./vendor/pulp-platform/common_cells/src/BUILD.bazel
./vendor/pulp-platform/axi/BUILD.bazel
./vendor/pulp-platform/axi/src/BUILD.bazel
./core/BUILD.bazel
./core/include/BUILD.bazel
./core/pmp/BUILD.bazel
./core/pmp/src/BUILD.bazel
./core/frontend/BUILD.bazel
./core/cvxif_example/BUILD.bazel
./core/cvxif_example/include/BUILD.bazel
./core/cvfpu/BUILD.bazel
./core/cvfpu/src/BUILD.bazel
./core/cvfpu/src/fpu_div_sqrt_mvp/BUILD.bazel
./core/cvfpu/src/fpu_div_sqrt_mvp/hdl/BUILD.bazel
./core/cvfpu/src/common_cells/BUILD.bazel
./core/cvfpu/src/common_cells/include/BUILD.bazel
./core/cvfpu/src/common_cells/include/common_cells/BUILD.bazel
./core/cva6_mmu/BUILD.bazel
./core/cache_subsystem/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/include/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/src/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/src/common/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/src/common/macros/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/src/common/macros/blackbox/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/src/utils/BUILD.bazel
./core/cache_subsystem/hpdcache/rtl/src/hwpf_stride/BUILD.bazel
./core/cache_subsystem/hpdcache/BUILD.bazel

[oharboe]

ORFS bazel works. But there are many BUILD.bazel files. Is there a way to reduce the number of files?

Not without making the use-case worse, you'd have to write something like bazelisk build @orfs//:..../designs/asap7/....

I think on the balance we're better off with having these copy and paste BUILD files. Over time, they will grow extra features I believe so they won't just be copy and paste.

Yes they pollute a bit, but the cognitive load should be small otherwise...

🤞

[oharboe]

@MrAMS Thoughts?