feat(asm): add LoongArch encoder with ELF and GOOBJ emission

Assisted-by: DeepSeek V4 Pro

asm/link.go

@@ -89,11 +89,13 @@ func (fl *FuncLayout) LineAt(offset int) int {
 type RelocKind int
 
 const (
-	RelPCRel32    RelocKind = iota // 32-bit PC-relative (amd64)
-	RelPCRelHI20                   // R_RISCV_PCREL_HI20 (AUIPC)
-	RelPCRelLO12                   // R_RISCV_PCREL_LO12_I (ADDI, LD)
-	RelPCRelLO12S                  // R_RISCV_PCREL_LO12_S (SD)
-	RelPCRelAbs                    // 32-bit absolute (R_RISCV_32)
+	RelPCRel32       RelocKind = iota // 32-bit PC-relative (amd64)
+	RelPCRelHI20                      // R_RISCV_PCREL_HI20 (AUIPC)
+	RelPCRelLO12                      // R_RISCV_PCREL_LO12_I (ADDI, LD)
+	RelPCRelLO12S                     // R_RISCV_PCREL_LO12_S (SD)
+	RelPCRelAbs                       // 32-bit absolute (R_RISCV_32)
+	RelLoong64AddrHi                  // R_LOONG64_ADDR_HI (pcalau12i)
+	RelLoong64AddrLo                  // R_LOONG64_ADDR_LO (addi.d/ld/st)
 )
 
 type Reloc struct {
@@ -289,7 +291,78 @@ func AssembleFileRISCV(f *ast.File) (*Image, error) {
 		img.DataSyms = append(img.DataSyms, DataSymbol{
 			Name:   d.name,
 			Pkg:    d.pkg,
-			Offset: pos,
+			Offset: len(img.Data) - len(d.buf), // relative to the data section
+			Size:   d.size,
+			Static: d.static,
+			Rodata: d.rodata,
+			Dupok:  d.dupok,
+		})
+	}
+
+	return img, nil
+}
+
+// AssembleFileLOONG64 assembles every TEXT function of a parsed loong64 file
+// and lays out its static symbols (GLOBL/DATA) in a data section behind the
+// code.  SB references in the code are encoded as pcalau12i pairs with zero
+// immediates; the object-file emitters record R_LOONG64_ADDR_HI/LO
+// relocations for the linker.
+func AssembleFileLOONG64(f *ast.File) (*Image, error) {
+	dataSyms, err := collectData(f)
+	if err != nil {
+		return nil, err
+	}
+
+	img := &Image{Symbols: map[string]int{}}
+	for _, d := range f.Decls {
+		t, ok := d.(*ast.Text)
+		if !ok {
+			continue
+		}
+		code, labels, relocs, lines, spadj, err := assembleLOONG64(t)
+		if err != nil {
+			return nil, fmt.Errorf("%s: %w", t.Name.Name, err)
+		}
+		fl := FuncLayout{
+			Name:   t.Name.Name,
+			Pkg:    t.Name.Pkg,
+			Static: t.Name.Static,
+			Offset: len(img.Code),
+			Size:   len(code),
+			Frame:  frameSize(t),
+			Args:   argsSize(t),
+			Line:   t.Pos().Line,
+			Labels: labels,
+			Lines:  lines,
+			Spadj:  spadj,
+			Relocs: relocs,
+		}
+		for _, f := range t.Flags {
+			switch f {
+			case "NOSPLIT":
+				fl.NoSplit = true
+			case "SPWRITE":
+				fl.SPWrite = true
+			}
+		}
+		img.Funcs = append(img.Funcs, fl)
+		img.Code = append(img.Code, code...)
+	}
+
+	// Lay out the data section behind the code, 16-aligned.
+	dataStart := len(img.Code)
+	for _, d := range dataSyms {
+		pos := dataStart + len(img.Data)
+		for pos%16 != 0 {
+			img.Data = append(img.Data, 0)
+			pos++
+		}
+		img.Symbols[d.name] = pos
+		img.Data = append(img.Data, d.buf...)
+		img.DataSyms = append(img.DataSyms, DataSymbol{
+			Name:   d.name,
+			Pkg:    d.pkg,
+			Offset: len(img.Data) - len(d.buf), // relative to the data section
 			Size:   d.size,
 			Static: d.static,
 			Rodata: d.rodata,