[ELF] Fix Initial-Exec TLS variables

Previously, GOTTPOFF relocations against Initial-Exec TLS variables
got wrong value.

Fixes #197

elf/output-chunks.cc

@@ -819,7 +819,7 @@ i64 GotSection<E>::get_reldyn_size(Context<E> &ctx) const {
   n += tlsdesc_syms.size();
 
   for (Symbol<E> *sym : gottp_syms)
-    if (sym->is_imported)
+    if (sym->is_imported || ctx.arg.shared)
       n++;
 
   if (tlsld_idx != -1)
@@ -869,6 +869,9 @@ void GotSection<E>::copy_buf(Context<E> &ctx) {
     if (sym->is_imported) {
       *rel++ = reloc<E>(sym->get_gottp_addr(ctx), E::R_TPOFF,
                         sym->get_dynsym_idx(ctx));
+    } else if (ctx.arg.shared) {
+      *rel++ = reloc<E>(sym->get_gottp_addr(ctx), E::R_TPOFF, 0,
+                        sym->get_addr(ctx) - ctx.tls_begin);
     } else if (E::e_machine == EM_386 || E::e_machine == EM_X86_64) {
       buf[sym->get_gottp_idx(ctx)] = sym->get_addr(ctx) - ctx.tls_end;
     } else {

test/elf/tls-ie.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+export LANG=
+set -e
+cd $(dirname $0)
+mold=`pwd`/../../mold
+echo -n "Testing $(basename -s .sh $0) ... "
+t=$(pwd)/../../out/test/elf/$(basename -s .sh $0)
+mkdir -p $t
+
+if [ $(uname -m) = x86_64 ]; then
+  dialect=gnu
+elif [ $(uname -m) = aarch64 ]; then
+  dialect=trad
+else
+  echo skipped
+  exit 0
+fi
+
+cat <<EOF | gcc -ftls-model=initial-exec -mtls-dialect=$dialect -fPIC -c -o $t/a.o -xc -
+#include <stdio.h>
+
+static _Thread_local int foo;
+static _Thread_local int bar;
+
+void set() {
+  foo = 3;
+  bar = 5;
+}
+
+void print() {
+  printf("%d %d ", foo, bar);
+}
+EOF
+
+clang -fuse-ld=$mold -shared -o $t/b.so $t/a.o
+
+cat <<EOF | gcc -c -o $t/c.o -xc -
+#include <stdio.h>
+
+_Thread_local int baz;
+
+void set();
+void print();
+
+int main() {
+  baz = 7;
+  print();
+  set();
+  print();
+  printf("%d\n", baz);
+}
+EOF
+
+clang -fuse-ld=$mold -o $t/exe $t/b.so $t/c.o
+$t/exe | grep -q '^0 0 3 5 7$'
+
+clang -fuse-ld=$mold -o $t/exe $t/b.so $t/c.o -Wl,-no-relax
+$t/exe | grep -q '^0 0 3 5 7$'
+
+echo OK