Refactor: unify scalar reads across host_build_graph and TaskArgsTpl - #2197
Refactor: unify scalar reads across host_build_graph and TaskArgsTpl#2197poursoul wants to merge 1 commit into
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📝 WalkthroughWalkthroughThe change replaces deprecated scalar conversions with typed accessors, adds native Python scalar encoding, updates scalar argument bindings, and migrates examples, orchestration code, documentation, and tests. ChangesScalar API migration
Priority: ➖ Normal Estimated code review effort: 3 (Moderate) | ~25 minutes Change: Refactor Merge Risk: 🟡 Moderate · up to Documentation currently instructs users to use removed scalar conversions, and scalar encoding can fail unsafely for indexable objects whose index raises. These should be corrected before merge. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 50 functions across 29 files. (2 skipped: 1 unsupported, 1 too large.)
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In `@python/bindings/task_interface.cpp`:
- Line 1743: Check the result of PyNumber_Index in the scalar conversion path
before wrapping it with nb::steal and passing it to PyLong_AsLongLong; propagate
the pending exception when __index__ fails. Add a regression test verifying
scalar_to_uint64(BrokenIndex()) raises the original RuntimeError.
In `@src/common/host_build_graph/types.h`:
- Line 211: Update the removed-conversion documentation in GRAPH_EXECUTION.md to
remove or revise the paragraph describing uint64_t assignment and
static_cast<int32_t> as deprecated conversions; state that these expressions now
fail to compile rather than offering a warning-based migration path.
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📒 Files selected for processing (31)
examples/a2a3/host_build_graph/deepseek_v4_flash_decode/kernels/orchestration/decode_fwd_graph.cppexamples/a2a3/host_build_graph/paged_attention_unroll_manual_scope/kernels/orchestration/paged_attention_orch.cppexamples/a5/host_build_graph/benchmark_bgemm/kernels/orchestration/bgemm_orch.cppexamples/a5/host_build_graph/paged_attention_unroll_manual_scope/kernels/orchestration/paged_attention_orch.cppexamples/workers/l3/worker_chip_orch_comm_stream/test_worker_chip_orch_comm_stream.pypython/bindings/task_interface.cpppython/simpler/task_interface.pysimpler_setup/scene_test.pysrc/common/host_build_graph/docs/GRAPH_EXECUTION.mdsrc/common/host_build_graph/types.hsrc/common/task_interface/task_args.htests/st/a2a3/host_build_graph/alternating_matmul_add/kernels/orchestration/alternating_orch.cpptests/st/a2a3/host_build_graph/batch_paged_attention/kernels/orchestration/paged_attention_orch.cpptests/st/a2a3/host_build_graph/paged_attention/kernels/orchestration/paged_attention_orch.cpptests/st/a2a3/host_build_graph/paged_attention_unroll/kernels/orchestration/paged_attention_orch.cpptests/st/a2a3/host_build_graph/predicated_dispatch/kernels/orchestration/predicated_dispatch_orch.cpptests/st/a2a3/host_build_graph/spmd_paged_attention/kernels/orchestration/spmd_paged_attention_orch.cpptests/st/a2a3/host_build_graph/worker_async_fifo/kernels/orchestration/pipelined_vector_orch.cpptests/st/a2a3/host_build_graph/worker_async_fifo/test_worker_async_fifo.pytests/st/a5/host_build_graph/alternating_matmul_add/kernels/orchestration/alternating_orch.cpptests/st/a5/host_build_graph/batch_paged_attention/kernels/orchestration/paged_attention_orch.cpptests/st/a5/host_build_graph/multi_core_dag/kernels/orchestration/multi_core_dag_orch.cpptests/st/a5/host_build_graph/paged_attention/kernels/orchestration/paged_attention_orch.cpptests/st/a5/host_build_graph/paged_attention_unroll/kernels/orchestration/paged_attention_orch.cpptests/st/a5/host_build_graph/predicated_dispatch/kernels/orchestration/predicated_dispatch_orch.cpptests/st/a5/host_build_graph/single_core_dag/kernels/orchestration/single_core_dag_orch.cpptests/st/a5/host_build_graph/spmd_paged_attention/kernels/orchestration/spmd_paged_attention_orch.cpptests/st/host_build_graph_validation/kernels/orchestration/validation_orch.cpptests/st/worker/comm_region/recursive_single_owner/_helpers.pytests/ut/cpp/common/test_hbg_graph_async_submit.cpptests/ut/cpp/common/test_hbg_graph_cache.cpp
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Two scalar-encoding corner cases need handling before merge.
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Re-reviewed at 198c3f9f. Both scalar-encoding findings are addressed: finite Python floats that overflow float32 are rejected while existing infinities/NaNs retain their prior behavior, and ctypes admission now validates numeric format plus native byte order before copying. The added regression tests cover overflow boundaries, non-finite values, foreign/native byte-order variants, non-numeric ctypes values, and admitted subclasses. I found no additional blocking issues in the updated diff. A few CI jobs are still running at review time.
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Not blocking — the encoder work looks settled after
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| TMR (unchanged) | host_build_graph twin (migrated) |
|---|---|
examples/a2a3/tensormap_and_ringbuffer/deepseek_v4_flash_decode/kernels/orchestration/decode_fwd.cpp:136int32_t my_rank = from_u64<int32_t>(orch_args.scalar(0)); |
examples/a2a3/host_build_graph/deepseek_v4_flash_decode/kernels/orchestration/decode_fwd_graph.cppargs.scalar<int32_t>(...) |
examples/{a2a3,a5}/tensormap_and_ringbuffer/paged_attention*/kernels/orchestration/paged_attention_orch.cppuint64_t scale_value = orch_args.scalar(0); |
migrated |
examples/a5/tensormap_and_ringbuffer/benchmark_bgemm/kernels/orchestration/bgemm_orch.cpp:42-43int tile_size = static_cast<int>(orch_args.scalar(0)); |
migrated |
Two ways to close this, with different strength:
- Migrate one TMR call site. Instantiates the branch, and demonstrates
in-repo the claim the PR rests on — that one spelling works against either
runtime — and removes the twin-file disagreement above. Percodestyle.md
rule 10 the a2a3/a5 siblings move in the same commit. - Add a C++ UT that instantiates
scalar<T>. Instantiates the branch and
nothing else.
The first seems worth the few extra lines.
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host_build_graph's Arg::scalar(i) returned InheritableScalar
unconditionally and exposed the raw uint64_t only through a deprecated
implicit conversion, kept for callers that had not yet moved to
args.scalar(i).to<T>(). TaskArgsTpl::scalar(i) (TMR and every other Arg
built directly on it) returned S itself with no template parameter at
all. The two spellings disagreed on what a caller writes for a static
read even though both slots are the same uint64_t.
scalar(i) is now a template on both sides, its parameter spelled
ScalarT in both -- TaskArgsTpl's T is its tensor type. host_build_graph
defaults it to InheritableScalar, so a bare scalar(i) still forwards
with its origin; TaskArgsTpl defaults it to S (uint64_t), so a bare
scalar(i) there is unchanged. Either side accepts an explicit type for
a static value read (args.scalar<T>(i)), and TaskArgsTpl bounds that
read by sizeof(S) -- the slot the value has to fit in -- rather than by
a hardcoded 8. task_args.h includes data_type.h for the from_u64 that
read applies, rather than reaching it through tensor.h.
The deprecated operator uint64_t() is removed, which is stronger than
the deprecation it replaces: with no conversion left to suppress, a
value read is a compile error rather than a warning. That closes the
blind spot the deprecation had, where a read instantiated inside a
system header -- EXPECT_EQ(args.scalar(i), v) -- was silently exempt.
InheritableScalar::to<T>() stays: it is the only way to read a handle
that was passed on as a function argument, where Arg::scalar<T>(i) is
unavailable because the Arg is not in hand.
Every call site that triggered the deprecation warning (98 across 20
orchestration files) moves to the explicit-T spelling. All of them were
already value reads, so no call site changes meaning; which of them
ought to forward instead is a question about each example's semantics
and is tracked separately.
The tensormap_and_ringbuffer orchestrations that read a slot as some
type other than the slot's own move with them, so both runtimes spell
that read the same way and the non-S branch of TaskArgsTpl::scalar has
in-tree instantiations -- a template body is only checked when it is
instantiated, and until now every scalar<T> call site was
host_build_graph, whose Arg hides the base's scalar with its own. A
bare uint64_t read is left alone: that is what scalar(i) already
answers, so naming the type would add nothing.
Python's add_scalar took a pre-encoded uint64_t, pushing
scalar_to_uint64(value) onto every caller. It now takes the value
directly -- int, float, bool, or a ctypes scalar -- and encodes it
natively (encode_scalar in the bindings, exposed to Python as
scalar_to_uint64 for callers that still want the raw bits).
scene_test.py's three add_scalar call sites drop their
scalar_to_uint64 wrapping accordingly.
That encoder matches C++ to_u64() bit for bit, which the previous
Python implementation did not: it read a ctypes scalar through its
`.value`, which ctypes has already sign-extended for a signed type, so
c_int8(-1) produced 0xFFFF'FFFF'FFFF'FFFF where to_u64(int8_t{-1}) is
0xFF. A ctypes scalar is now read through the buffer protocol at its
own width and zero-extended, which is what to_u64's union does.
Reading raw bytes makes the scalar's byte order load-bearing, and its
buffer format is where that order is stated. ctypes admits
byte-order-qualified variants -- c_uint32.__ctype_be__ carries the same
_type_ as c_uint32 and differs only in the format prefix -- whose bytes
for the value 1 are 00 00 00 01, which a raw copy would store as
0x01000000. A reversed-order scalar has no native C++ counterpart to
agree with, so the format decides admission: host byte order plus one
of the integer widths, f, d or ?. The pointer and character types (P,
z, Z, c, u) and long double are refused with it; c_void_p and c_char_p
would otherwise encode a host pointer into a device-bound slot. A
subclass inherits its base's format and so is admitted with the base,
which dispatching on the type's __name__ would not do.
A native Python float still narrows to IEEE-754 single precision, and a
finite value out of that range now raises where a narrowing conversion
would produce an infinity -- struct.pack("<f", 1e100) raised too, and
storing that infinity would silently be a different number. inf and NaN
pass through as themselves. This is the one encoding that cannot align
with its C++ counterpart, because a Python float carries no width where
to_u64(1.5) is a double; ctypes.c_double is the spelling for full
precision.
Two Python C API returns that signal failure are checked rather than
used: PyObject_IsInstance answers -1, which is truthy, and
PyNumber_Index answers nullptr with the caller's own exception pending.
The common Python-int case is tested first, so the hot path costs one
PyLong_CheckExact and no attribute lookup.
test_task_interface.py pins every encoding across scalar_to_uint64,
TaskArgs.add_scalar and ChipStorageTaskArgs.add_scalar, including the
zero-extension widths, a c_double subclass, both byte-order qualifiers,
the single-precision range boundary against struct.pack's own verdict,
out-of-range integers, and an __index__ that raises.
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Thanks — this is the sharpest finding on the PR, and every fact in it checked out. Addressed in Confirmed, including the part that makes it load-bearingAll 22 I did force an instantiation by hand to find out, and it does compile ( Took option 1One detail that decides whether option 1 actually works, which is worth recording for the next person: most TMR call sites cannot instantiate that branch. TMR's So the migration is scoped by that: 15 files, 28 sites, every TMR read that went through Your table's three rows are covered: One semantic check before migrating And the includeFixed — VerificationThe sim platforms reach only 4 of the migrated TMR files, so the rest went through hardware and the compiler directly:
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Summary
Arg::scalar(i)on host_build_graph andTaskArgsTpl::scalar(i)(TMR and every otherArgbuilt on it) disagreed on what a caller writes for a static read, even though both slots are the sameuint64_t.scalar(i)is now a template on both sides, with the parameter spelledScalarTin both (TaskArgsTpl'sTis its tensor type): host_build_graph defaults it toInheritableScalar(a barescalar(i)still forwards with its origin),TaskArgsTpldefaults it toS/uint64_t(unchanged), and either side accepts an explicit type for a static value read (args.scalar<T>(i)).TaskArgsTplbounds that read bysizeof(S)— the slot it has to fit in — rather than by a hardcoded 8.Removes the deprecated
InheritableScalar::operator uint64_t(). This is strictly stronger than the deprecation it replaces: with no conversion left to suppress, a value read is a compile error rather than a warning, which closes Migrate boundary-scalar value reads off the deprecated InheritableScalar conversion #2170's "known blind spot" — a read inside third-party template code (EXPECT_EQ(args.scalar(i), v)) no longer slips past GCC's system-header suppression.Migrates all 98 call sites (20 orchestration files) that were hitting the deprecation warning to the explicit-
Tspelling. Every one of them was already a value read (uint64_t v = args.scalar(i),static_cast<T>(...),from_u64<T>(...),.to<T>()); no forwarding site is touched, so no call site changes meaning. Deciding which of these should become forwards is a separate change against the individual examples — see Migrate boundary-scalar value reads off the deprecated InheritableScalar conversion #2170.InheritableScalar::to<T>()stays. Removing it is what forced every value read to name its type while the call sites were migrated; now that they have been, it is the only way to read a handle that was passed on as a function argument, whereArg::scalar<T>(i)is unavailable because theArgis not in hand.Python's
add_scalartook a pre-encodeduint64_t; it now takes the value directly (int, float, bool, or a ctypes scalar) and encodes it natively in the bindings (encode_scalar, exposed to Python asscalar_to_uint64).scene_test.py's three call sites drop theirscalar_to_uint64wrapping accordingly. The encoder matches C++to_u64()bit for bit (see Behavior changes) and reads a ctypes scalar through the buffer protocol, so it needs no per-type dispatch and handles subclasses correctly.The
tensormap_and_ringbufferorchestrations that read a slot as some type other than the slot's own move with them (15 files, 28 sites). Two reasons beyond consistency: it puts the same spelling in front of both runtimes in-tree, which is the claim this PR is named after, and it givesTaskArgsTpl::scalar's non-Sbranch its first instantiations — a template body is only checked when instantiated, and until now everyscalar<T>call site washost_build_graph, whoseArghides the base'sscalarwith its own. A bareuint64_tread is deliberately left asscalar(i): that is already what it answers, so naming the type would add nothing.Progress on #2170 — this PR migrates the
simpler-repo side only (the 98 sites above). #2170 also scopes apypto-side change (the codegen templates that emit these value reads) that is not part of this PR; see the issue for the remaining work. Not closing the issue yet.Behavior changes
Five, all on the Python scalar-encoding boundary (
scalar_to_uint64andadd_scalar). The first three make the encoding agree with C++to_u64(); the last two replace a silent wrong answer with an error:c_int8(-1)now encodes to0xFF, matchingto_u64(int8_t{-1}); it was0xFFFF_FFFF_FFFF_FFFF. Same forc_int16/c_int32. Reading the slot back at the matching width (scalar<int8_t>) yields-1either way, so this is only observable by reading a narrow-signed slot asscalar<int64_t>, which is already a width mismatch. This makes a slot written from Python and one written from orchestration identical for the same value.scalar_to_uint64no longer accepts an object that only implements__int__(e.g.numpy.float32,Decimal). The old fallback wasint(value) & 0xFFFF…, which silently truncated.bool,IntEnummembers and numpy integer scalars are still accepted, via__index__.floatoutside IEEE-754 single-precision range raises (1e100) instead of being stored as an infinity. This matches the oldstruct.pack("<f", ...), which raisedOverflowErrorfor the same set; the tests assert againststruct.pack's own verdict rather than hardcoding a range.infandNaNpass through as themselves.c_uint32.__ctype_be__on a little-endian host, and__ctype_le__on a big-endian one. The old.valuepath read the number and so was order-blind; reading raw bytes is not. A refusal, rather than a byte swap, becauseto_u64has no reversed-order form for such a value to agree with. Pointer and character types (c_void_p,c_char_p,c_char,c_wchar) andc_longdoubleare refused for the same "no number a slot can carry" reason;c_char_palready raised.A native Python
floatstill narrows to IEEE-754 single precision. It is the one encoding that cannot align with its C++ counterpart — a Python float carries no width, whereto_u64(1.5)in orchestration is a double. Passctypes.c_doublefor full precision.Test plan
pip install --no-build-isolation -e .— full rebuild across all 4host_build_graphvariants (a2a3/a5 × onboard/sim), no compile errors or warnings.test_task_interface.pypinning every encoding acrossscalar_to_uint64,TaskArgs.add_scalarandChipStorageTaskArgs.add_scalar. Regression anchors, one per behavior above:c_int8(-1)→0xFF, ac_doublesubclass, both byte-order qualifiers (the foreign one refused, the host one accepted), the single-precision boundary checked againststruct.pack's own verdict, out-of-range integers, and an__index__that raises.ctest -LE requires_hardware— 140/140 passed.predicated_dispatch,paged_attention,batch_paged_attention,host_build_graph_validation— 0 failed.task-submit, device 7): the TMR files no sim platform reaches —alternating_matmul_add,fanin_lookup_perf,paged_attention_unroll,dfx/chip_swimlane— 6 passed, 0 failed.sliding_window_deps(a2a3+a5),benchmark_bgemm(a5),dfx— 0 failed.alternating_matmul_add/fanin_lookup_perf/chip_swimlane/sdma/urma, a2a3sdma/decode_fwd) syntax-checked against each arch's owncompile_commands.jsoninclude set — all clean. a5 onboard is not runnable here (host is a2a3 silicon); CI'sst-onboard-a5covers them.predicated_dispatch,single_core_dag,multi_core_dag,paged_attention,alternating_matmul_add,benchmark_bgemm,host_build_graph_validation— 0 failed.pre-commit runon all changed files — all hooks pass.deepseek_v4_flash_decode,spmd_paged_attention(a2a3+a5),worker_async_fifo,alternating_matmul_add(a2a3),paged_attention_unroll(a2a3+a5),paged_attention_unroll_manual_scope(a2a3+a5) — covered by the onboard CI jobs on this PR.