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feat(asm): emit RISC-V GOOBJ with the shared emitter

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Assisted-by: DeepSeek V4 Pro
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petrbalvin
2026-08-13 12:07:29 +02:00
parent 31ee8e7941
commit 9b5c878f9e
9 changed files with 358 additions and 383 deletions
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asm/elfriscv.go
+17 -18
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@@ -79,11 +79,10 @@ func (img *Image) ELFRISCVObject() ([]byte, error) {
symIdx[s.name] = i
}
// Build relocations. Each SB reference produces a pair:
// AUIPC rd, 0 → R_RISCV_PCREL_HI20
// ADDI/LD/SD → R_RISCV_PCREL_LO12_I or _S
// For now we record them as individual entries; at link time
// the linker must pair HI20 with its matching LO12.
// Build relocations. Each SB reference is an AUIPC + second-instruction
// pair carrying a single relocation kind; the ELF writer expands it into
// the R_RISCV_PCREL_HI20 + R_RISCV_PCREL_LO12_I/S pair the psABI expects,
// with the same addend on both.
type elfRela struct {
off uint64
typ uint32
@@ -97,22 +96,22 @@ func (img *Image) ELFRISCVObject() ([]byte, error) {
if !ok {
return nil, fmt.Errorf("relocation references unknown symbol %q", r.Name)
}
// Determine relocation type from the relocation kind.
typ := uint32(rRISCVPCRELHI20) // default: AUIPC
switch r.Kind {
case RelPCRelLO12:
typ = rRISCVPCRELLO12I
case RelPCRelLO12S:
typ = rRISCVPCRELLO12S
case RelRISCVPCRELIType:
relas = append(relas,
elfRela{off: uint64(fn.Offset + r.Off), typ: rRISCVPCRELHI20, sym: idx, addend: r.Addend},
elfRela{off: uint64(fn.Offset + r.Off + 4), typ: rRISCVPCRELLO12I, sym: idx, addend: r.Addend},
)
case RelRISCVPCRELSType:
relas = append(relas,
elfRela{off: uint64(fn.Offset + r.Off), typ: rRISCVPCRELHI20, sym: idx, addend: r.Addend},
elfRela{off: uint64(fn.Offset + r.Off + 4), typ: rRISCVPCRELLO12S, sym: idx, addend: r.Addend},
)
case RelPCRelAbs:
typ = rRISCV32
relas = append(relas, elfRela{off: uint64(fn.Offset + r.Off), typ: rRISCV32, sym: idx, addend: r.Addend})
default:
return nil, fmt.Errorf("relocation kind %v unsupported in ELF emission", r.Kind)
}
relas = append(relas, elfRela{
off: uint64(fn.Offset + r.Off),
typ: typ,
sym: idx,
addend: r.Addend - int64(r.After-r.Off),
})
}
}