GPU extensions (Metal, oneAPI): unify Float64 → Float32 conversion#280
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sshin23 wants to merge 2 commits into
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GPU extensions (Metal, oneAPI): unify Float64 → Float32 conversion#280sshin23 wants to merge 2 commits into
sshin23 wants to merge 2 commits into
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The Metal and oneAPI backend extensions both need to recursively convert
Float64 host data to Float32 before upload, because
- Metal cannot compile Float64 IR at all,
- oneAPI Arc-class devices reject Float64 allocations outright (Iris Xe /
Data Center GPU Max accept them but the user usually wants fp32 anyway).
Two things were wrong before this change:
1. The Metal extension's `replace_float_64` only handled scalars,
Tuples, and NamedTuples — its catch-all `replace_float_64(x) = x`
silently let plain structs through. So Float64 fields inside structs
like ExaPowerIO's `BusData`/`GenData`/`BranchData` reached the
device, and the JIT either emitted invalid Float64 IR (best case) or
crashed Apple's Metal compiler with an XPC interrupt (typical case for
second-order AD kernels on OPF).
2. The oneAPI extension only defined `convert_array` behind
`if pkgversion(oneAPI) < v\"2.6\"`. On current oneAPI (≥ v2.6) the
branch was skipped, falling back to `adapt(backend, v)` which
preserved Float64 element type. Every fp32 OPF/LV/COPS run on Arc A770
bombed at host-to-device transfer with "Float64 is not supported on
this device".
This commit:
- Hoists `replace_float_64` into `src/templates.jl` (single
implementation, both extensions reuse it).
- Implements the struct recursion with pure multiple dispatch (no
try/catch, no `@generated`). Specialized methods cover Float64,
Tuple, NamedTuple, AbstractArray{Float64}, and AbstractArray; the
generic struct path uses `Val(fieldcount(T))` to keep `ntuple`
type-stable and `ConstructionBase.constructorof(T)` to rebuild the
struct with Float32-typed fields. Adds ConstructionBase as a dep.
- In the Metal extension: removes the bespoke (incomplete)
`replace_float_64` and adds the `MtlArray` identity overload to
`convert_array`. Both extensions now read
`convert_array(v::DeviceArray, ::Backend) = v` and
`convert_array(v, ::Backend) = Backend.Array(ExaModels.replace_float_64.(v))`.
- In the oneAPI extension: drops the `< v2.6` guard from the
`convert_array` definition so the dispatch is unconditional. Keeps
the older `sort!`/`findall` shims inside the version guard since
those remain version-specific.
- Adds a `replace_float_64` test block to UtilsTest covering: scalar
leaf, mixed Tuple/NamedTuple, Vector{Float64} eltype check, mixed-Any
array, parametric struct rebuild, and nested struct with array fields.
Validated manually:
- Apple M1 (Metal, local): OPF case118 polar with T=Float32 — all five
NLPModels callbacks succeed (obj, cons!, grad!, jac_coord!,
hess_coord!). LV.rosenrock with T=Float32 — same.
- Apple M2 Pro (Metal, pro): 231/240-case OPF+LV+COPS benchmark with
T=Float32; remaining 9 failures are rocket/glider Metal-compiler
XPC crashes on hess_coord! and dirichlet/henon/lane_emden which use
a separate PDEProblem struct in ExaModelsPower that needs its own
parameterization on T (out of scope here).
- Intel Arc A770 (oneAPI, shin-compute-002): was 0/240 before this
change; smoke test on case118 polar now PASS. Full 240-case run is
in progress as of this commit.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Contributor
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Your PR requires formatting changes to meet the project's style guidelines. Please run: julia --project=@runic -e 'using Pkg; Pkg.add("Runic")'
julia --project=@runic -e "using Runic; exit(Runic.main(ARGS))" -- --fix <files>(or Note: the full diff is omitted because it can exceed GitHub Actions input limits. |
The convert_array dispatch normalizes host data to Float32 before upload, so the default float type for an oneAPI backend should match. Without this, OracleTest's _atol(backend) helper still picks the Float64 tolerance (1e-10), which is tighter than Float32 machine epsilon (~1e-7), causing 15 false test failures on the oneapi CI runner. This mirrors the existing Metal extension which already declares default_T(::MetalBackend) = Float32.
Contributor
Benchmark Results |
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Two related bugs in the GPU extensions:
replace_float_64's catch-allreplace_float_64(x) = xsilently let plain structs through, soBusData{Float64}arrays reached the device. Result: Float64 IR emitted, Apple's compiler often crashed with an XPC interrupt on second-order AD kernels.convert_array(v, ::oneAPIBackend) = oneArray(v)was gated byif pkgversion(oneAPI) < v"2.6". On ≥ 2.6 the branch was skipped and the defaultadapt(backend, v)preserved Float64, killing all fp32 work on Intel Arc A770 withFloat64 is not supported on this device.Fix
replace_float_64tosrc/templates.jl(single implementation, both extensions reuse it).Float64,Tuple,NamedTuple,AbstractArray{Float64},AbstractArray; generic struct path usesVal(fieldcount(T))for type-stablentuple+ConstructionBase.constructorof(T)for the rebuild. No@generated, no try/catch. AddsConstructionBaseas a dep.convert_array. oneAPI's version guard now wraps only thesort!/findallshims.Testing
New
replace_float_64block intest/UtilsTest/UtilsTest.jlcovers: scalar Float64, scalar passthrough (Float32/Int/Symbol), Tuple/NamedTuple recursion,Vector{Float64}eltype check, mixed-Any vector, parametric struct rebuild, nested struct with array and tuple fields.Stats
6 files, +84/−9.
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