JIT graph

Overview

JITGraph is the recorded representation of an XAD expression DAG in JIT-enabled builds.

It consists of:

• JITOpCode: operation codes (add, mul, sin, comparisons, If, …)
• JITNode: one recorded node (opcode + operands + immediate + flags)
• JITGraph: the full node list plus constant/input/output metadata

JITOpCode

enum class JITOpCode : std::uint16_t

Defines the opcode values used by JIT backends.

JITNode

struct JITNode

Each node contains:

• op: opcode (JITOpCode, stored as uint16_t)
• a, b, c: operand node IDs (stored as uint32_t)
• imm: immediate value, a double (used for op-specific data, e.g. constant pool index or integer exponent)
• flags: node flags (e.g. “active”)

JITGraph

struct JITGraph

Node storage

Nodes are stored in a chunked container (ChunkContainer<JITNode, 262144>, 8 MiB chunks) to avoid large reallocation/copy spikes when building very large graphs, without reserving much memory for small ones.

Constant pool

const_pool stores unique constants. addConstant(value) deduplicates by value and records a Constant node that references the pool via imm.

Inputs/outputs

• input_ids: node IDs that correspond to inputs
• output_ids: node IDs marked as outputs

Construction helpers

JITGraph provides convenience methods:

• addInput()
• addConstant(double value)
• addUnary(...), addBinary(...), addTernary(...)
• markOutput(nodeId)