varasm: Handle private COMDAT function symbol reference in readonly data section [PR113617]

If default_elf_select_rtx_section is called to put a reference to some
local symbol defined in a comdat section into memory, which happens more often
since the r14-4944 RA change, linking might fail.
default_elf_select_rtx_section puts such constants into .data.rel.ro.local
etc. sections and if linker chooses comdat sections from some other TU
and discards the one to which a relocation in .data.rel.ro.local remains,
linker diagnoses error.  References to private comdat symbols can only appear
from functions or data objects in the same comdat group, so the following
patch arranges using .data.rel.ro.local.pool.<comdat_name> and similar sections.

2024-02-26  Jakub Jelinek  <jakub@redhat.com>
	    H.J. Lu  <hjl.tools@gmail.com>

	PR rtl-optimization/113617
	* varasm.cc (default_elf_select_rtx_section): For
	references to private symbols in comdat sections
	use .data.relro.local.pool.<comdat>, .data.relro.pool.<comdat>
	or .rodata.<comdat> comdat sections.

	* g++.dg/other/pr113617.C: New test.
	* g++.dg/other/pr113617.h: New test.
	* g++.dg/other/pr113617-aux.cc: New test.

4 files changed, 215 insertions, 1 deletions

diff --git a/gcc/testsuite/g++.dg/other/pr113617-aux.cc b/gcc/testsuite/g++.dg/other/pr113617-aux.cc
new file mode 100644
index 0000000..e6900e0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/other/pr113617-aux.cc
@@ -0,0 +1,9 @@
+// PR rtl-optimization/113617
+// { dg-do link { target { c++17 && c++14_down } } }
+
+#include "pr113617.h"
+
+void qux() {
+  A<long long> a;
+  a.foo(0, 0);
+}
diff --git a/gcc/testsuite/g++.dg/other/pr113617.C b/gcc/testsuite/g++.dg/other/pr113617.C
new file mode 100644
index 0000000..a02dda1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/other/pr113617.C
@@ -0,0 +1,27 @@
+// PR rtl-optimization/113617
+// { dg-do link { target c++11 } }
+// { dg-options "-O2" }
+// { dg-additional-options "-fPIC" { target fpic } } */
+// { dg-additional-options "-shared" { target shared } } */
+// { dg-additional-sources pr113617-aux.cc }
+
+#include "pr113617.h"
+
+int z;
+long xx1;
+void corge() {
+  A<long long> a;
+  a.foo(xx1, 0);
+}
+
+typedef unsigned long int VV __attribute__((vector_size (2 * sizeof (long))));
+VV vv;
+__attribute__((noipa)) static void fn1 (void) {}
+__attribute__((noipa)) static void fn2 (void) {}
+
+void
+fn3 ()
+{
+  VV a = { (unsigned long) &fn1, (unsigned long) &fn2 };
+  vv = a;
+}
diff --git a/gcc/testsuite/g++.dg/other/pr113617.h b/gcc/testsuite/g++.dg/other/pr113617.h
new file mode 100644
index 0000000..4d30edd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/other/pr113617.h
@@ -0,0 +1,132 @@
+namespace {
+template <int V> struct J { static constexpr int value = V; };
+template <bool V> using K = J<V>;
+using M = K<true>;
+template <int> struct L { template <typename _Tp, typename> using type = _Tp; };
+template <bool _Cond, typename _If, typename _Else> using N = typename L<_Cond>::type<_If, _Else>;
+M k;
+template <typename _Tp> struct O { using type = _Tp; };
+template <typename _Up>
+struct P : N<M ::value, O<_Up>, _Up> {};
+template <typename _Tp> struct Q { using type = typename P<_Tp>::type; };
+}
+namespace R {
+struct H;
+enum G {};
+template <typename> class S;
+struct T { using U = bool (*) (H &, const H &, G); U F; };
+template <typename, typename> class B;
+template <typename _R, typename _F, typename... _A>
+struct B<_R(_A...), _F> {
+  static bool F(H &, const H &, G) { return false; }
+  __attribute__((noipa)) static _R bar(const H &) {}
+};
+template <typename _R, typename... _A>
+struct S<_R(_A...)> : T {
+  template <typename _F> using AH = B<_R(), _F>;
+  template <typename _F> S(_F) {
+    using AG = AH<_F>;
+    barr = AG::bar;
+    F = AG::F;
+  }
+  using AF = _R (*)(const H &);
+  AF barr;
+};
+template <typename> class I;
+template <typename _F, typename... _B>
+struct I<_F(_B...)> {};
+template <typename> using W = decltype(k);
+template <int, typename _F, typename... _B> struct V {
+  typedef I<typename Q<_F>::type(typename Q<_B>::type...)> type;
+};
+template <typename _F, typename... _B>
+__attribute__((noipa)) typename V<W<_F>::value, _F, _B...>::type
+baz(_F, _B...) { return typename V<W<_F>::value, _F, _B...>::type (); }
+template <typename _Tp> struct AJ {
+  template <typename _Up> struct _Ptr { using type = _Up *; };
+  using AI = typename _Ptr<_Tp>::type;
+};
+template <typename _Tp> struct Y {
+  using AI = typename AJ<_Tp>::AI;
+  AI operator->();
+};
+}
+extern int z;
+namespace N1 {
+namespace N2 {
+namespace N3 {
+enum Z { Z1, Z2 };
+template <int> struct X {
+  template <typename _F>
+  __attribute__((noipa)) void boo(long long, long long, long long, _F &) {}
+};
+struct AC {
+  AC(int);
+  void m1(R::S<void()>);
+};
+template <typename>
+__attribute__((noipa)) void garply(void *, long long, long long, long long) {}
+template <>
+template <typename _F>
+void X<Z2>::boo(long long, long long x, long long y, _F &fi) {
+  AC pool(z);
+  for (;;) {
+    auto job = R::baz(garply<_F>, &fi, y, y, x);
+    pool.m1(job);
+  }
+}
+struct AB {
+  static AB &bleh();
+  template <typename _F>
+  void boo(long first, long x, long y, _F fi) {
+    switch (ab1) {
+    case Z1:
+      ab2->boo(first, x, y, fi);
+    case Z2:
+      ab3->boo(first, x, y, fi);
+    }
+  }
+  Z ab1;
+  R::Y<X<Z1>> ab2;
+  R::Y<X<Z2>> ab3;
+};
+template <typename, bool> struct C;
+template <typename _F> struct C<_F, false> {
+  __attribute__((noipa)) C(_F) {}
+  void boo(long first, long x, long y) {
+    auto u = AB::bleh();
+    u.boo(first, x, y, *this);
+  }
+};
+template <typename _F> struct AA { typedef C<_F, 0> type; };
+}
+}
+}
+struct AD {
+  template <typename _F>
+  static void boo(long first, long x, long y, _F f) {
+    typename N1::N2::N3::AA<_F>::type fi(f);
+    fi.boo(first, x, y);
+  }
+  template <typename _F>
+  static void boo(long first, long x, _F f) {
+    boo(first, x, 0, f);
+  }
+};
+template <typename> struct A {
+  void foo(long long, long long);
+  int *c;
+};
+namespace {
+template <typename> struct D { __attribute__((noipa)) D(int *) {} };
+}
+template <typename T>
+void A<T>::foo(long long x, long long y)
+{
+  int e;
+  D<T> d(&e);
+  AD::boo(0, y, d);
+  long p;
+  for (p = 0; p < x; p++)
+    c[p] = c[p - 1];
+}
diff --git a/gcc/varasm.cc b/gcc/varasm.cc
index 008d9b1..747f74b 100644
--- a/gcc/varasm.cc
+++ b/gcc/varasm.cc
@@ -7458,17 +7458,63 @@ default_elf_select_rtx_section (machine_mode mode, rtx x,
 				unsigned HOST_WIDE_INT align)
 {
   int reloc = compute_reloc_for_rtx (x);
+  tree decl = nullptr;
+  const char *prefix = nullptr;
+  int flags = 0;
+
+  /* If it is a private COMDAT function symbol reference, call
+     function_rodata_section for the read-only or relocated read-only
+     data section associated with function DECL so that the COMDAT
+     section will be used for the private COMDAT function symbol.  */
+  if (HAVE_COMDAT_GROUP)
+    {
+      if (GET_CODE (x) == CONST
+	 && GET_CODE (XEXP (x, 0)) == PLUS
+	 && CONST_INT_P (XEXP (XEXP (x, 0), 1)))
+       x = XEXP (XEXP (x, 0), 0);
+
+      if (GET_CODE (x) == SYMBOL_REF)
+       {
+	 decl = SYMBOL_REF_DECL (x);
+	 if (decl
+	     && (TREE_CODE (decl) != FUNCTION_DECL
+		 || !DECL_COMDAT_GROUP (decl)
+		 || TREE_PUBLIC (decl)))
+	   decl = nullptr;
+       }
+    }
 
   /* ??? Handle small data here somehow.  */
 
   if (reloc & targetm.asm_out.reloc_rw_mask ())
     {
-      if (reloc == 1)
+      if (decl)
+	{
+	  prefix = reloc == 1 ? ".data.rel.ro.local" : ".data.rel.ro";
+	  flags = SECTION_WRITE | SECTION_RELRO;
+	}
+      else if (reloc == 1)
 	return get_named_section (NULL, ".data.rel.ro.local", 1);
       else
 	return get_named_section (NULL, ".data.rel.ro", 3);
     }
 
+  if (decl)
+    {
+      const char *comdat = IDENTIFIER_POINTER (DECL_COMDAT_GROUP (decl));
+      if (!prefix)
+	prefix = ".rodata";
+      size_t prefix_len = strlen (prefix);
+      size_t comdat_len = strlen (comdat);
+      size_t len = prefix_len + sizeof (".pool.") + comdat_len;
+      char *name = XALLOCAVEC (char, len);
+      memcpy (name, prefix, prefix_len);
+      memcpy (name + prefix_len, ".pool.", sizeof (".pool.") - 1);
+      memcpy (name + prefix_len + sizeof (".pool.") - 1, comdat,
+	      comdat_len + 1);
+      return get_section (name, flags | SECTION_LINKONCE, decl);
+    }
+
   return mergeable_constant_section (mode, align, 0);
 }