Set a correct value to __iplt_start for statically-linked binaries

Fixes #930

elf/input-sections.cc

@@ -197,14 +197,17 @@ static void scan_rel(Context<E> &ctx, InputSection<E> &isec, Symbol<E> &sym,
       sym.flags |= NEEDS_CPLT;
     break;
   case DYNREL:
-  case IFUNC:
     dynrel();
     break;
   case BASEREL:
     check_textrel();
     if (!isec.is_relr_reloc(ctx, rel))
       isec.file.num_dynrel++;
     break;
+  case IFUNC:
+    dynrel();
+    ctx.num_ifunc_dynrels.fetch_add(1, std::memory_order_relaxed);
+    break;
   default:
     unreachable();
   }

elf/mold.h

@@ -1792,6 +1792,7 @@ struct Context {
   std::atomic_bool needs_tlsld = false;
   std::atomic_bool has_gottp_rel = false;
   std::atomic_bool has_textrel = false;
+  std::atomic_uint32_t num_ifunc_dynrels = 0;
 
   tbb::concurrent_hash_map<std::string_view, std::vector<std::string>> undef_errors;
 

elf/passes.cc

@@ -2160,9 +2160,9 @@ i64 set_osec_offsets(Context<E> &ctx) {
 
 template <typename E>
 static i64 get_num_irelative_relocs(Context<E> &ctx) {
-  return std::count_if(
-    ctx.got->got_syms.begin(), ctx.got->got_syms.end(),
-    [](Symbol<E> *sym) { return sym->is_ifunc(); });
+  i64 n = std::count_if(ctx.got->got_syms.begin(), ctx.got->got_syms.end(),
+                        [](Symbol<E> *sym) { return sym->is_ifunc(); });
+  return n + ctx.num_ifunc_dynrels;
 }
 
 template <typename E>

test/elf/x86_64_ifunc-alias.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+. $(dirname $0)/common.inc
+
+cat <<EOF | $CXX -o $t/a.o -c -xc++ - -fno-PIE
+#include <assert.h>
+#include <stdio.h>
+
+__attribute__((target("default")))
+int foo() {
+  return 0;
+}
+
+__attribute__((target("ssse3,avx2")))
+int foo() {
+  return 1;
+}
+
+int (*p)() = foo;
+
+int main() {
+  int val = foo();
+  assert(val == p());
+}
+EOF
+
+$CXX -B. -o $t/exe $t/a.o -static
+$QEMU $t/exe