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a4f08f8307
Each ISA's hand-written ENCODING_TABLE (the single source of truth) now lives in a per-arch tablegen/ metaprogram that flattens it and serializes committed binary blobs; the library #loads those into @(rodata) at compile time rather than compiling a table body. No arch keeps encoding_table.odin or decoding_tables.odin -- only a generated tables.odin loader and tables/*.bin. * Two-stage, type-checked pipeline: tablegen Stage A emits human-readable generated Odin, which compiles and serializes the blobs in Stage B. * encode() goes through encoding_forms(m); decoders are unchanged apart from x86's flattened 2-D index. Decode tables are byte-identical to the old ones. * build.lua: a LuaJIT driver for the metaprograms, validations, and tests, with cross-platform gating and a clear report. * Docs refreshed; the obsolete forward-looking plan in cross_arch_design.md trimmed to what was actually built. * Attribution headers added to all rexcode source files; the generators emit them so generated files keep them.
76 lines
2.6 KiB
Odin
76 lines
2.6 KiB
Odin
// rexcode · Brendan Punsky (dotbmp@github), original author
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package rexcode_isa
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// =============================================================================
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// LABEL INFERENCE (decoder helper, architecture-independent)
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// =============================================================================
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//
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// Pass 2 of decode: turn the list of branch targets discovered during
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// instruction decoding into label definitions, reusing label IDs from a
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// caller-supplied relocations array when available (so symbolic names
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// from the encoder survive the round trip).
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// Branch target discovered while decoding. Each branch operand a
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// per-arch decoder produces (RELATIVE-kind operand with a known target
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// offset) becomes one of these for pass 2.
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Branch_Target :: struct {
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inst_idx: u32, // which decoded instruction has the branch
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op_idx: u8, // which operand of that instruction is the target
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target: u32, // absolute byte offset of the branch target
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}
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// Resolve branch targets into label definitions.
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//
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// For each branch target inside the decoded region (target < decoded_end):
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// - if a label is already defined at that offset, do nothing;
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// - else if `relocs` provides a label_id for that offset (named label
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// carried over from the encode side), use that ID;
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// - else create a fresh label ID and append it.
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//
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// label_defs may grow.
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//
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// Parametric over the caller's relocation type `$R`: the body only reads
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// `.offset` and `.label_id`, so any per-arch `Relocation` struct with
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// those fields works. Monomorphizes at the call site with no overhead.
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infer_labels_from_branches :: proc(
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branches: []Branch_Target,
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decoded_end: u32,
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label_defs: ^[dynamic]Label_Definition,
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relocs: []$R,
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) {
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offset_to_label: map[u32]u32
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defer delete(offset_to_label)
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for _, id in label_defs {
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if label_defs[id] != LABEL_UNDEFINED {
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offset_to_label[u32(label_defs[id])] = u32(id)
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}
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}
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relocation_offset_to_label: map[u32]u32
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defer delete(relocation_offset_to_label)
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for relocation in relocs {
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relocation_offset_to_label[relocation.offset] = relocation.label_id
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}
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for branch in branches {
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if branch.target >= decoded_end {
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continue
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}
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if branch.target in offset_to_label {
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continue
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}
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if reloc_id, ok := relocation_offset_to_label[branch.target]; ok {
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for u32(len(label_defs)) <= reloc_id {
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append(label_defs, LABEL_UNDEFINED)
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}
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label_defs[reloc_id] = Label_Definition(branch.target)
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offset_to_label[branch.target] = reloc_id
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} else {
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new_id := u32(len(label_defs))
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append(label_defs, Label_Definition(branch.target))
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offset_to_label[branch.target] = new_id
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}
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}
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}
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