kit

05-addr2line-linked.sh (1877B)

---

 # Golden: debug-info retention through the linker (IMAGE_INSPECT phase 5).
 # Links two `-g` objects into a static aarch64 ELF executable, then asserts
 # `kit addr2line` resolves file:line for a function from *each* input —
 # exercising multi-input .debug_* concatenation, per-input SK_SECTION
 # rebasing, and the .debug_aranges debug_info_offset reloc. Also confirms
 # the merged image carries a single .debug_info/.debug_line and that
 # `ld -S` drops debug entirely. Built fresh (not a committed binary) so the
 # file:line mapping tracks the C front-end + debug emitter.
 set -e
 CC="cc -g -c -target aarch64-linux"
 
 cat > a.c <<'EOF'
 extern int compute(int);
 int helper(int x) { return x * 3; }
 void _start(void) { compute(5); }
 EOF
 cat > b.c <<'EOF'
 extern int helper(int);
 int compute(int n) {
   int acc = 0;
   for (int i = 0; i < n; i++) acc += helper(i);
   return acc;
 }
 int main(void) { return compute(5); }
 EOF
 
 $KIT $CC -o a.o a.c
 $KIT $CC -o b.o b.c
 $KIT ld -o prog.elf a.o b.o -e _start
 
 # Merged debug sections: one .debug_info / .debug_line spanning both inputs.
 echo "merged debug sections:"
 $KIT objdump -h prog.elf | awk '$2 ~ /^\.debug_(info|line)$/ {print "  " $2}' | sort
 
 # addr2line resolves a function defined in each input (helper/_start from
 # a.c, compute/main from b.c) — wrong rebasing would map them all to one CU.
 echo "addr2line:"
 for fn in _start helper compute main; do
   addr=$($KIT nm prog.elf | awk -v f=" $fn\$" '$0 ~ f {print $1}')
   printf '  %-8s %s\n' "$fn" "$($KIT addr2line -e prog.elf "0x$addr")"
 done
 
 # -S strips debug: no .debug_* shdrs, addr2line reports no info.
 $KIT ld -S -o stripped.elf a.o b.o -e _start
 echo "stripped debug shdrs: $($KIT objdump -h stripped.elf | grep -c '\.debug_')"
 caddr=$($KIT nm stripped.elf | awk '/ compute$/{print $1}')
 echo "stripped addr2line: $($KIT addr2line -e stripped.elf "0x$caddr" 2>&1)"