Revision history for hhlo

0.1.0.0 -- 2026-04-22

• Initial release.
• Type-safe EDSL for StableHLO with 50+ ops.
• CPU execution via PJRT CPU plugin.
• GPU execution via PJRT CUDA plugin with device enumeration and selection.
• Multi-GPU concurrent inference scaling via executeReplicas.
• 115 CPU tests + 6 GPU integration tests.
• 29 executable examples including ResNet-18, AlexNet, Transformer, and UNet.

0.2.0.0 -- 2026-04-22

BREAKING: Operation AST changed from single-result to multi-result. Any code using opResult / opResultType or pattern-matching on the Operation constructor must update to opResults / opResultTypes.

• Multi-result Operation AST — Operation now supports opResults :: [ValueId] and opResultTypes :: [TensorType], enabling ops with multiple outputs such as stablehlo.rng_bit_generator.
• Multi-value control flow — added whileLoop2, conditional2, whileLoopN, and conditionalN for carrying multiple typed tensors through loops and conditionals without manual packing.
• Random number generation — added rngUniform, rngNormal, and rngBitGenerator to the EDSL, wrapping stablehlo.rng and stablehlo.rng_bit_generator.
• PJRT CPU v1.16.0 parser compatibility fixes:
  • stablehlo.compare now emits generic form with enum attributes (#stablehlo<comparison_direction LT>) instead of custom form.
  • stablehlo.rng and stablehlo.rng_bit_generator emit generic form.
  • func.return for multi-result functions no longer wraps types in parentheses.
• New examples: 30-rng-uniform, 31-rng-normal, 32-rng-bit-generator, 33-multi-value-loop.
• Updated example 12-while from print-only to fully executable.
• Test count: 124 CPU tests + 6 GPU integration tests.

0.3.0.0 -- 2026-04-25

BREAKING: compare and lessThan now return shape-preserving Tensor s 'Bool instead of scalar Tensor '[] 'Bool. New exports sqrt, sin, cos, tan, floor, ceil may conflict with Prelude.

• New primitive ops: sqrt, rsqrt, sin, cos, tan, pow, log1p, floor, ceil.
• New composite / convenience ops: sigmoid, sumAll, pack2, pack3, slice1.
• Fixed compare to return shape-preserving Tensor s 'Bool per StableHLO spec.
• New comparison wrappers: equal, notEqual, greaterThan, lessThanOrEqual, greaterThanOrEqual.
• Test count: 141 CPU tests + 6 GPU integration tests.

0.4.0.0 -- 2026-04-26

BREAKING: HostType 'Bool changed from Bool to Word8 to match PJRT's PRED buffer transfer semantics.

• Convenience layer — two new modules that eliminate boilerplate for the common compile-and-run workflow:
  • HHLO.ModuleBuilder provides buildModule @nIn @nOut, a polymorphic entry point (via TypeApplications) that auto-generates FuncArg declarations and wires up arg calls. No more natVal or FuncArg boilerplate.
  • HHLO.Session provides withCPU, withGPU, withGPUDevice, compile, run, runAsync, and typed HostTensor host-device transfers. No more manual render, toDeviceF32, fromDeviceF32, or shape lists.
• whileLoop3–whileLoop8 and conditional3–conditional8 for carrying 3–8 heterogeneous tensors through control flow.
• Boolean logic ops: logicalAnd, logicalOr, logicalNot.
• New dependency: directory (for plugin-path discovery in withCPU/withGPU).
• Test count: 155 CPU tests + 6 GPU integration tests.

0.5.0.0 -- 2026-04-27

• Autograd — reverse-mode automatic differentiation is now part of HHLO. New module HHLO.Autograd provides grad and vjp combinators that transform HHLO computation graphs into their gradients, producing new StableHLO modules that compile via PJRT. VJP rules cover ~25 ops including element-wise arithmetic, matmul, transpose, reshape, broadcast, reduce, slice, pad, concatenate, select, and more.
• New convenience ops:
  • einsum — Einstein summation via subscript strings (e.g. "ij,jk->ik"). Parses labels, computes batch/contracting dims, and emits the correct stablehlo.dot_general + optional stablehlo.transpose.
  • split — split a tensor into N equal parts along a dimension.
  • stack — stack N tensors along a new axis.
  • productAll, productDim — product reductions (mirrors sumAll/reduceSumDim).
  • topK — return top-K values along a dimension via sort + slice.
• Bug fix: stablehlo.sort now wraps its region in parentheses for PJRT v1.16.0 parser compatibility.
• Test count: 181 CPU tests + 6 GPU integration tests.