Fix -Wunused-variable

Fixes https://github.com/rui314/mold/issues/1063

common/tar.cc

@@ -50,6 +50,8 @@ struct UstarHeader {
   char pad[12];
 };
 
+static_assert(sizeof(UstarHeader) == 512);
+
 static std::string encode_path(std::string basedir, std::string path) {
   path = path_clean(basedir + "/" + path);
 
@@ -81,6 +83,7 @@ void TarWriter::append(std::string path, std::string_view data) {
 
   std::string attr = encode_path(basedir, path);
   snprintf(pax.size, sizeof(pax.size), "%011zo", attr.size());
+  pax.name[0] = '/';
   pax.typeflag[0] = 'x';
   pax.finalize();
   fwrite(&pax, sizeof(pax), 1, out);

elf/arch-arm32.cc

@@ -638,13 +638,13 @@ void RangeExtensionThunk<E>::copy_buf(Context<E> &ctx) {
   // It has two entry points: +0 for Thumb and +4 for ARM.
   const u8 entry[] = {
     // .thumb
-    0xfc, 0x46,             //    mov  ip, pc
-    0x60, 0x47,             //    bx   ip  # jumps to the following `ldr` insn
+    0x78, 0x47,             //    bx   pc  # jumps to 1f
+    0xc0, 0x46,             //    nop
     // .arm
-    0x04, 0xc0, 0x9f, 0xe5, //    ldr  ip, 2f
-    0x0f, 0xc0, 0x8c, 0xe0, // 1: add  ip, ip, pc
+    0x04, 0xc0, 0x9f, 0xe5, // 1: ldr  ip, 3f
+    0x0f, 0xc0, 0x8c, 0xe0, // 2: add  ip, ip, pc
     0x1c, 0xff, 0x2f, 0xe1, //    bx   ip
-    0x00, 0x00, 0x00, 0x00, // 2: .word sym - 1b
+    0x00, 0x00, 0x00, 0x00, // 3: .word sym - 2b
   };
 
   static_assert(E::thunk_hdr_size == sizeof(hdr));

elf/arch-mips64.cc

@@ -44,7 +44,7 @@ template <typename E>
 void InputSection<E>::apply_reloc_alloc(Context<E> &ctx, u8 *base) {
   std::span<const ElfRel<E>> rels = get_rels(ctx);
 
-  ElfRel<E> *dynrel = nullptr;
+  [[maybe_unused]] ElfRel<E> *dynrel = nullptr;
   if (ctx.reldyn)
     dynrel = (ElfRel<E> *)(ctx.buf + ctx.reldyn->shdr.sh_offset +
                            file.reldyn_offset + this->reldyn_offset);
@@ -60,7 +60,7 @@ void InputSection<E>::apply_reloc_alloc(Context<E> &ctx, u8 *base) {
     Symbol<E> &sym = *file.symbols[rel.r_sym];
     u8 *loc = base + rel.r_offset;
 
-    auto check = [&](i64 val, i64 lo, i64 hi) {
+    [[maybe_unused]] auto check = [&](i64 val, i64 lo, i64 hi) {
       if (val < lo || hi <= val)
         Error(ctx) << *this << ": relocation " << rel << " against "
                    << sym << " out of range: " << val << " is not in ["
@@ -105,7 +105,6 @@ void InputSection<E>::apply_reloc_alloc(Context<E> &ctx, u8 *base) {
 
     u64 S = sym.get_addr(ctx);
     u64 A = rel.r_addend;
-    u64 P = get_addr() + rel.r_offset;
 
     switch (rel.r_type) {
     case R_MIPS_64:

elf/cmdline.cc

@@ -1,6 +1,7 @@
 #include "mold.h"
 #include "../common/cmdline.h"
 
+#include <random>
 #include <regex>
 #include <sstream>
 #include <sys/stat.h>
@@ -406,6 +407,7 @@ std::vector<std::string> parse_nonpositional_args(Context<E> &ctx) {
   bool warn_shared_textrel = false;
   std::optional<SeparateCodeKind> z_separate_code;
   std::optional<bool> z_relro;
+  std::optional<u64> shuffle_sections_seed;
   std::unordered_set<std::string_view> rpaths;
 
   auto add_rpath = [&](std::string_view arg) {
@@ -635,7 +637,7 @@ std::vector<std::string> parse_nonpositional_args(Context<E> &ctx) {
       ctx.arg.shuffle_sections = SHUFFLE_SECTIONS_SHUFFLE;
     } else if (read_eq("shuffle-sections")) {
       ctx.arg.shuffle_sections = SHUFFLE_SECTIONS_SHUFFLE;
-      ctx.arg.shuffle_sections_seed = parse_number(ctx, "shuffle-sections", arg);
+      shuffle_sections_seed = parse_number(ctx, "shuffle-sections", arg);
     } else if (read_flag("reverse-sections")) {
       ctx.arg.shuffle_sections = SHUFFLE_SECTIONS_REVERSE;
     } else if (read_flag("rosegment")) {
@@ -1181,6 +1183,14 @@ std::vector<std::string> parse_nonpositional_args(Context<E> &ctx) {
   if (ctx.arg.relocatable)
     ctx.arg.is_static = true;
 
+  if (ctx.arg.shuffle_sections == SHUFFLE_SECTIONS_SHUFFLE) {
+    if (shuffle_sections_seed)
+      ctx.arg.shuffle_sections_seed = *shuffle_sections_seed;
+    else
+      ctx.arg.shuffle_sections_seed =
+        ((u64)std::random_device()() << 32) | std::random_device()();
+  }
+
   // --section-order implies `-z separate-loadable-segments`
   if (z_separate_code)
     ctx.arg.z_separate_code = *z_separate_code;

elf/input-files.cc

@@ -1396,7 +1396,8 @@ SharedFile<E>::mark_live_objects(Context<E> &ctx,
     if (sym.is_traced)
       print_trace_symbol(ctx, *this, esym, sym);
 
-    if (esym.is_undef() && sym.file && !sym.file->is_alive.test_and_set()) {
+    if (esym.is_undef() && !esym.is_weak() && sym.file &&
+        !sym.file->is_alive.test_and_set()) {
       feeder(sym.file);
 
       if (sym.is_traced)

elf/mold.h

@@ -1766,10 +1766,10 @@ struct Context {
     i64 spare_dynamic_tags = 5;
     i64 thread_count = 0;
     i64 z_stack_size = 0;
+    u64 shuffle_sections_seed;
     std::string_view emulation;
     std::optional<Glob> unique;
     std::optional<u64> physical_image_base;
-    std::optional<u64> shuffle_sections_seed;
     std::string Map;
     std::string chroot;
     std::string dependency_file;

elf/passes.cc

@@ -4,7 +4,6 @@
 #include <functional>
 #include <map>
 #include <optional>
-#include <random>
 #include <regex>
 #include <shared_mutex>
 #include <tbb/parallel_for_each.h>
@@ -1109,37 +1108,35 @@ template <typename E>
 void shuffle_sections(Context<E> &ctx) {
   Timer t(ctx, "shuffle_sections");
 
-  auto is_eligible = [](OutputSection<E> &osec) {
-    return osec.name != ".init" && osec.name != ".fini" &&
-           osec.name != ".ctors" && osec.name != ".dtors" &&
-           osec.name != ".init_array" && osec.name != ".preinit_array" &&
-           osec.name != ".fini_array";
+  auto is_eligible = [](OutputSection<E> *osec) {
+    if (osec) {
+      std::string_view name = osec->name;
+      return name != ".init" && name != ".fini" &&
+             name != ".ctors" && name != ".dtors" &&
+             name != ".init_array" && name != ".preinit_array" &&
+             name != ".fini_array";
+    }
+    return false;
   };
 
   switch (ctx.arg.shuffle_sections) {
-  case SHUFFLE_SECTIONS_NONE:
-    unreachable();
   case SHUFFLE_SECTIONS_SHUFFLE: {
-    u64 seed;
-    if (ctx.arg.shuffle_sections_seed)
-      seed = *ctx.arg.shuffle_sections_seed;
-    else
-      seed = ((u64)std::random_device()() << 32) | std::random_device()();
-
     tbb::parallel_for_each(ctx.chunks, [&](Chunk<E> *chunk) {
-      if (OutputSection<E> *osec = chunk->to_osec())
-        if (is_eligible(*osec))
-          shuffle(osec->members, seed + hash_string(osec->name));
+      if (OutputSection<E> *osec = chunk->to_osec(); is_eligible(osec)) {
+        u64 seed = ctx.arg.shuffle_sections_seed + hash_string(osec->name);
+        shuffle(osec->members, seed);
+      }
     });
     break;
   }
   case SHUFFLE_SECTIONS_REVERSE:
     tbb::parallel_for_each(ctx.chunks, [&](Chunk<E> *chunk) {
-      if (OutputSection<E> *osec = chunk->to_osec())
-        if (is_eligible(*osec))
-          std::reverse(osec->members.begin(), osec->members.end());
+      if (OutputSection<E> *osec = chunk->to_osec(); is_eligible(osec))
+        std::reverse(osec->members.begin(), osec->members.end());
     });
     break;
+  default:
+    unreachable();
   }
 }
 

install-build-deps.sh

@@ -45,6 +45,10 @@ void-*)
   xbps-install -Sy bash make cmake openssl-devel zlib-devel gcc
   xbps-install -Sy tar diffutils util-linux
   ;;
+alpine-*)
+  apk update
+  apk add bash make openssl-dev linux-headers cmake zlib-dev gcc g++
+  ;;
 *)
   echo "Error: don't know anything about build dependencies on $ID-$VERSION_ID"
   exit 1

test/elf/arm_range-extension-thunk-disassembly.sh

@@ -22,6 +22,5 @@ $CC -B. -o $t/exe $t/a.o \
 
 $OBJDUMP -dr $t/exe | grep -F -A7 '<fn1$thunk>:' > $t/log
 
-grep -Eq 'mov\s+ip, pc' $t/log
-grep -Eq 'bx\s+ip' $t/log
+grep -Eq 'bx\s+pc' $t/log
 grep -Eq 'add\s+ip, ip, pc' $t/log

test/elf/as-needed-dso2.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+. $(dirname $0)/common.inc
+
+cat <<EOF | $CC -c -fPIC -o $t/a.o -xc -
+int foo() {
+  return 0;
+}
+EOF
+
+cat <<EOF | $CC -c -fPIC -o $t/b.o -xc -
+__attribute__((weak)) int foo();
+
+int bar() {
+  if (foo) return foo();
+  return 0;
+}
+EOF
+
+cat <<EOF | $CC -xc -c -o $t/c.o -
+int bar();
+
+int main() {
+  return bar();
+}
+EOF
+
+$CC -B. -shared -o $t/libfoo.so $t/a.o
+$CC -B. -shared -o $t/libbar.so $t/b.o
+$CC -B. -o $t/exe $t/c.o -L$t -Wl,--as-needed -lfoo -lbar
+
+readelf --dynamic $t/exe > $t/log
+! grep libfoo.so $t/log || false
+grep -q libbar.so $t/log

test/elf/physical-image-base.sh

@@ -3,6 +3,9 @@
 
 [ $MACHINE = ppc64 ] && skip
 
+# BusyBox's grep can't handle capture groups (e.g. \1, \2 ...)
+grep --version 2>&1 | grep BusyBox && skip
+
 cat <<EOF | $CC -o $t/a.o -c -xc -
 #include <stdio.h>