feat(asm): integrate DWARF5 sections into all ELF emitters

Assisted-by: MiMo V2.5 Pro

asm/elf.go

@@ -48,6 +48,7 @@ const (
 	shnUndef = 0
 
 	rX8664PC32 = 2
+	rX8664_64  = 1 // R_X86_64_64 (absolute 64-bit)
 )
 
 // elfSym is one symbol-table entry in construction.
@@ -160,6 +161,9 @@ func (img *Image) ELFObject() ([]byte, error) {
 	for _, n := range []string{".text", ".data", ".symtab", ".strtab", ".rela.text", ".shstrtab"} {
 		stSections.add(n)
 	}
+	for _, n := range dwarfSectionNames {
+		stSections.add(n)
+	}
 
 	// Section presence: .rela.text only when there are relocations.
 	hasRela := len(relas) > 0
@@ -220,6 +224,17 @@ func (img *Image) ELFObject() ([]byte, error) {
 	shstrOff := len(out)
 	out = append(out, stSections.bytes()...)
 
+	// DWARF debug sections (no relocations — the linker resolves DWARF fixups).
+	dwAlign := func(n int) {
+		for len(out)%n != 0 {
+			out = append(out, 0)
+		}
+	}
+	dw := appendDWARFSections(&out, img, "gasm.s", symIdx, dwAlign)
+	if dw != nil {
+		nSections += 4 // .debug_abbrev, .debug_info, .debug_line, .debug_line_str
+	}
+
 	align(8)
 	shoff := len(out)
 
@@ -248,6 +263,14 @@ func (img *Image) ELFObject() ([]byte, error) {
 	}
 	putSh(".shstrtab", shtStrtab, 0, shstrOff, len(stSections.bytes()), 0, 0, 1, 0)
 
+	// DWARF section headers.
+	if dw != nil {
+		putSh(".debug_abbrev", shtProgbits, 0, dw.abbrevOff, dw.abbrevSize, 0, 0, 1, 0)
+		putSh(".debug_info", shtProgbits, 0, dw.infoOff, dw.infoSize, 0, 0, 1, 0)
+		putSh(".debug_line", shtProgbits, 0, dw.lineOff, dw.lineSize, 0, 0, 1, 0)
+		putSh(".debug_line_str", shtProgbits, 0, dw.lineStrOff, dw.lineStrSize, 0, 0, 1, 0)
+	}
+
 	// The ELF header.
 	hdr := out[:64]
 	copy(hdr[0:], []byte{0x7f, 'E', 'L', 'F', elfClass64, elfDataLSB, elfVersion, 0})