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daa5b7cb79
A sibling to core:rexcode/isa for the intermediate representations (WASM,
SPIR-V, LLVM bitcode + the LLVM dialects AIR/DXIL). Holds the shared
vocabulary every IR package builds on, implements no specific IR.
Design stance (see docs/ir_design.md): keep the ISA layer's spirit, but
where IRs are structurally MORE uniform than ISAs (SSA + a type system
regularize the operand/module shape), the shared core is richer. ir/ owns:
status.odin Error/Error_Code (shape-identical to isa.Error)
refs.odin Id/Ref/Ref_Space/Symbol_Table (the label analog: structural
id references, not PC-relative byte offsets)
types.odin Type/Type_Ref/Type_Kind (the type table -- no ISA analog)
module.odin Module/Function/Block/Operation/Operand/Result/Dataflow
(the structured model; Operation = isa.Instruction + an
optional typed Result, opcode a u16 like Mnemonic)
print.odin token kinds + options + num-fmt (parallels isa.print)
Three honest concessions vs the ISA API, made explicit not inert: a
structured Module replaces the flat []Instruction; a first-class type
system; id-based entity refs replace labels. The encode/decode verbs take
a Module and drop label_defs/resolve/base_address. Dataflow hosts both the
WASM value stack and SSA; the codec is pluggable (table for WASM/SPIR-V,
bitstream for the LLVM family -- AIR/DXIL are LLVM dialects, not peers).
Package compiles; a hand-built SSA module round-trips through the types.
100 lines
3.7 KiB
Odin
100 lines
3.7 KiB
Odin
// rexcode · Brendan Punsky (dotbmp@github), original author
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package rexcode_ir
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// =============================================================================
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// REFERENCES (the IR analog of isa.labels)
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// =============================================================================
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//
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// This is the first place the IR API genuinely diverges from the ISA API.
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//
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// An ISA resolves control flow as *PC-relative labels*: `Label_Definition`
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// maps a label id to an instruction index and `encode()` rewrites it to a byte
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// offset (isa.labels.rewrite_label_defs_to_offsets). That model is wrong for an
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// IR: IR operands reference *entities by id* -- SSA results, blocks, functions,
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// globals, types -- which are stable indices into the module's entity tables,
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// not byte offsets, and resolve *structurally* (no PC-relative pass).
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//
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// So the label machinery is replaced, not re-exported. What survives in spirit:
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// * a small distinct-u32 id type with an "undefined" sentinel (forward refs),
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// * a name<->id table for the externally-visible symbols (the Label_Map analog).
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//
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// Object-file *symbol* fixups (a linker patching a function/global index) are
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// still real and still produce Relocations -- but that is a codec concern,
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// defined per-IR (parallel to each arch's reloc.odin), not here.
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// A stable id into one of the module's entity spaces (see Ref_Space).
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Id :: distinct u32
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ID_NONE :: Id(0xFFFFFFFF)
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// Which id space a reference addresses. Drives validation, printer annotation,
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// and (for EXTERNAL) relocation-type selection. This is the union of the spaces
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// the modelled IRs use; a concrete IR uses only the subset it needs -- a stack
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// IR (WASM) never produces a VALUE ref, an untyped IR never produces a TYPE ref.
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Ref_Space :: enum u8 {
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NONE,
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VALUE, // an SSA result (or a local/stack slot)
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BLOCK, // a basic block / structured-control label (branch target)
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FUNCTION,
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GLOBAL,
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TYPE,
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CONSTANT, // a constant-pool entry
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MEMORY, // a linear memory / address space
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METADATA, // a metadata/debug node
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EXTERNAL, // an imported/exported symbol -- relocatable across object files
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}
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// A typed reference: which space, plus the id within it. Carried by REF operands
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// and by branch targets. 8 bytes, like isa.Label_Definition is u32-cheap.
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Ref :: struct #packed {
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id: Id,
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space: Ref_Space,
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_: [3]u8,
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}
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#assert(size_of(Ref) == 8)
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@(require_results)
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ref :: #force_inline proc "contextless" (space: Ref_Space, id: Id) -> Ref {
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return Ref{id = id, space = space}
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}
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// -----------------------------------------------------------------------------
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// Symbol table (the IR analog of isa.Label_Map: name <-> id for visible names)
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// -----------------------------------------------------------------------------
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Symbol_Table :: struct {
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names: map[string]Id,
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space: Ref_Space, // what these names address (usually FUNCTION/GLOBAL)
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}
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symbol_table_init :: #force_inline proc(st: ^Symbol_Table, space := Ref_Space.EXTERNAL, allocator := context.allocator) {
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st.names = make(map[string]Id, allocator = allocator)
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st.space = space
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}
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symbol_table_destroy :: #force_inline proc(st: ^Symbol_Table) {
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delete(st.names)
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}
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// Bind a name to an id (e.g. when a definition is emitted).
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symbol_define :: #force_inline proc(st: ^Symbol_Table, name: string, id: Id) {
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st.names[name] = id
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}
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// Reserve a name for a forward reference; resolve later with symbol_define.
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@(require_results)
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symbol_reserve :: #force_inline proc(st: ^Symbol_Table, name: string) -> Id {
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if existing, ok := st.names[name]; ok {
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return existing
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}
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st.names[name] = ID_NONE
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return ID_NONE
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}
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@(require_results)
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symbol_lookup :: #force_inline proc(st: ^Symbol_Table, name: string) -> (id: Id, ok: bool) {
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id, ok = st.names[name]
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return
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}
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