[PR63238] output alignment debug information

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index f40f759..f3928e0 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -3342,6 +3342,7 @@  static void add_bound_info (dw_die_ref, enum dwarf_attribute, tree,
 			    const struct loc_descr_context *);
 static void add_subscript_info (dw_die_ref, tree, bool);
 static void add_byte_size_attribute (dw_die_ref, tree);
+static void add_alignment_attribute (dw_die_ref, tree);
 static inline void add_bit_offset_attribute (dw_die_ref, tree,
 					     struct vlr_context *);
 static void add_bit_size_attribute (dw_die_ref, tree);
@@ -7415,6 +7416,7 @@  clone_as_declaration (dw_die_ref die)
           add_dwarf_attr (clone, a);
           break;
         case DW_AT_byte_size:
+	case DW_AT_alignment:
         default:
           break;
         }
@@ -10941,6 +10943,8 @@  base_type_die (tree type, bool reverse)
     add_AT_unsigned (base_type_result, DW_AT_endianity,
 		     BYTES_BIG_ENDIAN ? DW_END_little : DW_END_big);
 
+  add_alignment_attribute (base_type_result, type);
+
   if (fpt_used)
     {
       switch (fpt_info.scale_factor_kind)
@@ -11104,6 +11108,8 @@  subrange_type_die (tree type, tree low, tree high, tree bias,
       add_AT_unsigned (subrange_die, DW_AT_byte_size, size_in_bytes);
     }
 
+  add_alignment_attribute (subrange_die, type);
+
   if (low)
     add_bound_info (subrange_die, DW_AT_lower_bound, low, NULL);
   if (high)
@@ -11421,6 +11427,7 @@  modified_type_die (tree type, int cv_quals, bool reverse,
 
       add_AT_unsigned (mod_type_die, DW_AT_byte_size,
 		       simple_type_size_in_bits (type) / BITS_PER_UNIT);
+      add_alignment_attribute (mod_type_die, type);
       item_type = TREE_TYPE (type);
 
       addr_space_t as = TYPE_ADDR_SPACE (item_type);
@@ -18600,6 +18607,37 @@  add_byte_size_attribute (dw_die_ref die, tree tree_node)
     add_AT_unsigned (die, DW_AT_byte_size, size);
 }
 
+/* Add a DW_AT_alignment attribute to DIE with TREE_NODE's non-default
+   alignment.  */
+
+static void
+add_alignment_attribute (dw_die_ref die, tree tree_node)
+{
+  if (dwarf_version < 5 && dwarf_strict)
+    return;
+
+  unsigned align;
+
+  if (DECL_P (tree_node))
+    {
+      if (!DECL_USER_ALIGN (tree_node))
+	return;
+
+      align = DECL_ALIGN_UNIT (tree_node);
+    }
+  else if (TYPE_P (tree_node))
+    {
+      if (!TYPE_USER_ALIGN (tree_node))
+	return;
+
+      align = TYPE_ALIGN_UNIT (tree_node);
+    }
+  else
+    gcc_unreachable ();
+
+  add_AT_unsigned (die, DW_AT_alignment, align);
+}
+
 /* For a FIELD_DECL node which represents a bit-field, output an attribute
    which specifies the distance in bits from the highest order bit of the
    "containing object" for the bit-field to the highest order bit of the
@@ -19363,6 +19401,8 @@  gen_array_type_die (tree type, dw_die_ref context_die)
 
   if (get_AT (array_die, DW_AT_name))
     add_pubtype (type, array_die);
+
+  add_alignment_attribute (array_die, type);
 }
 
 /* This routine generates DIE for array with hidden descriptor, details
@@ -19457,6 +19497,8 @@  gen_descr_array_type_die (tree type, struct array_descr_info *info,
 
   if (get_AT (array_die, DW_AT_name))
     add_pubtype (type, array_die);
+
+  add_alignment_attribute (array_die, type);
 }
 
 #if 0
@@ -19561,6 +19603,7 @@  gen_enumeration_type_die (tree type, dw_die_ref context_die)
 
       TREE_ASM_WRITTEN (type) = 1;
       add_byte_size_attribute (type_die, type);
+      add_alignment_attribute (type_die, type);
       if (dwarf_version >= 3 || !dwarf_strict)
 	{
 	  tree underlying = lang_hooks.types.enum_underlying_base_type (type);
@@ -19619,6 +19662,8 @@  gen_enumeration_type_die (tree type, dw_die_ref context_die)
   else
     add_AT_flag (type_die, DW_AT_declaration, 1);
 
+  add_alignment_attribute (type_die, type);
+
   add_pubtype (type, type_die);
 
   return type_die;
@@ -20521,6 +20566,8 @@  gen_subprogram_die (tree decl, dw_die_ref context_die)
       if (TREE_THIS_VOLATILE (decl) && (dwarf_version >= 5 || !dwarf_strict))
 	add_AT_flag (subr_die, DW_AT_noreturn, 1);
 
+      add_alignment_attribute (subr_die, decl);
+
       add_accessibility_attribute (subr_die, decl);
     }
 
@@ -21227,6 +21274,7 @@  gen_variable_die (tree decl, tree origin, dw_die_ref context_die)
       add_type_attribute (var_die, TREE_TYPE (decl_or_origin),
 			  decl_quals (decl_or_origin), false,
 			  context_die);
+      add_alignment_attribute (var_die, decl);
       add_AT_flag (var_die, DW_AT_external, 1);
       if (loc)
 	{
@@ -21354,6 +21402,8 @@  gen_variable_die (tree decl, tree origin, dw_die_ref context_die)
       if (DECL_ARTIFICIAL (decl))
 	add_AT_flag (var_die, DW_AT_artificial, 1);
 
+      add_alignment_attribute (var_die, decl);
+
       add_accessibility_attribute (var_die, decl);
     }
 
@@ -21703,6 +21753,8 @@  gen_field_die (tree decl, struct vlr_context *ctx, dw_die_ref context_die)
       add_bit_offset_attribute (decl_die, decl, ctx);
     }
 
+  add_alignment_attribute (decl_die, decl);
+
   /* If we have a variant part offset, then we are supposed to process a member
      of a QUAL_UNION_TYPE, which is how we represent variant parts in
      trees.  */
@@ -21777,6 +21829,7 @@  gen_ptr_to_mbr_type_die (tree type, dw_die_ref context_die,
 		  lookup_type_die (class_type));
   add_type_attribute (ptr_die, member_type, TYPE_UNQUALIFIED, false,
 		      context_die);
+  add_alignment_attribute (ptr_die, type);
 
   if (TREE_CODE (type) == OFFSET_TYPE)
     {
@@ -22629,6 +22682,7 @@  gen_struct_or_union_type_die (tree type, dw_die_ref context_die,
 	 this type is expressed in terms of this type itself.  */
       TREE_ASM_WRITTEN (type) = 1;
       add_byte_size_attribute (type_die, type);
+      add_alignment_attribute (type_die, type);
       if (TYPE_STUB_DECL (type) != NULL_TREE)
 	{
 	  add_src_coords_attributes (type_die, TYPE_STUB_DECL (type));
@@ -22686,6 +22740,7 @@  gen_subroutine_type_die (tree type, dw_die_ref context_die)
   add_prototyped_attribute (subr_die, type);
   add_type_attribute (subr_die, return_type, TYPE_UNQUALIFIED, false,
 		      context_die);
+  add_alignment_attribute (subr_die, type);
   gen_formal_types_die (type, subr_die);
 
   if (get_AT (subr_die, DW_AT_name))
@@ -22733,7 +22788,10 @@  gen_typedef_die (tree decl, dw_die_ref context_die)
     add_abstract_origin_attribute (type_die, origin);
   else
     {
-      tree type;
+      tree type = TREE_TYPE (decl);
+
+      if (type == error_mark_node)
+	return;
 
       add_name_and_src_coords_attributes (type_die, decl);
       if (DECL_ORIGINAL_TYPE (decl))
@@ -22748,11 +22806,6 @@  gen_typedef_die (tree decl, dw_die_ref context_die)
 	}
       else
 	{
-	  type = TREE_TYPE (decl);
-
-	  if (type == error_mark_node)
-	    return;
-
 	  if (is_naming_typedef_decl (TYPE_NAME (type)))
 	    {
 	      /* Here, we are in the case of decl being a typedef naming
@@ -22791,6 +22844,10 @@  gen_typedef_die (tree decl, dw_die_ref context_die)
 	   created.  */
 	equate_type_number_to_die (type, type_die);
 
+      type = TREE_TYPE (decl);
+
+      add_alignment_attribute (type_die, type);
+
       add_accessibility_attribute (type_die, decl);
     }
 
@@ -26369,6 +26426,7 @@  base_type_cmp (const void *x, const void *y)
   dw_die_ref dy = *(const dw_die_ref *) y;
   unsigned int byte_size1, byte_size2;
   unsigned int encoding1, encoding2;
+  unsigned int align1, align2;
   if (dx->die_mark > dy->die_mark)
     return -1;
   if (dx->die_mark < dy->die_mark)
@@ -26385,6 +26443,12 @@  base_type_cmp (const void *x, const void *y)
     return 1;
   if (encoding1 > encoding2)
     return -1;
+  align1 = get_AT_unsigned (dx, DW_AT_alignment);
+  align2 = get_AT_unsigned (dy, DW_AT_alignment);
+  if (align1 < align2)
+    return 1;
+  if (align1 > align2)
+    return -1;
   return 0;
 }
 
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/align-1.C b/gcc/testsuite/g++.dg/debug/dwarf2/align-1.C
new file mode 100644
index 0000000..58b7731
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/align-1.C
@@ -0,0 +1,5 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+int __attribute__((__aligned__(64))) i;
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/align-2.C b/gcc/testsuite/g++.dg/debug/dwarf2/align-2.C
new file mode 100644
index 0000000..31eed4a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/align-2.C
@@ -0,0 +1,6 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+typedef int __attribute__((__aligned__(64))) i_t;
+i_t i;
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/align-3.C b/gcc/testsuite/g++.dg/debug/dwarf2/align-3.C
new file mode 100644
index 0000000..328ea0d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/align-3.C
@@ -0,0 +1,7 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+typedef int int_t;
+typedef int_t __attribute__((__aligned__(64))) i_t;
+i_t i;
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/align-4.C b/gcc/testsuite/g++.dg/debug/dwarf2/align-4.C
new file mode 100644
index 0000000..31e9e81
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/align-4.C
@@ -0,0 +1,7 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 2 { xfail { powerpc-ibm-aix* } } } }
+
+struct tt {
+  int __attribute__((__aligned__(64))) i;
+} t;
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/align-5.C b/gcc/testsuite/g++.dg/debug/dwarf2/align-5.C
new file mode 100644
index 0000000..2116646
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/align-5.C
@@ -0,0 +1,7 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+struct tt {
+  int i;
+} __attribute__((__aligned__(64))) t;
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/align-6.C b/gcc/testsuite/g++.dg/debug/dwarf2/align-6.C
new file mode 100644
index 0000000..e8fc43f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/align-6.C
@@ -0,0 +1,9 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+struct tt {
+  int i;
+};
+
+struct tt __attribute__((__aligned__(64))) t;
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/align-1.c b/gcc/testsuite/gcc.dg/debug/dwarf2/align-1.c
new file mode 100644
index 0000000..58b7731
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/align-1.c
@@ -0,0 +1,5 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+int __attribute__((__aligned__(64))) i;
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/align-2.c b/gcc/testsuite/gcc.dg/debug/dwarf2/align-2.c
new file mode 100644
index 0000000..31eed4a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/align-2.c
@@ -0,0 +1,6 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+typedef int __attribute__((__aligned__(64))) i_t;
+i_t i;
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/align-3.c b/gcc/testsuite/gcc.dg/debug/dwarf2/align-3.c
new file mode 100644
index 0000000..328ea0d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/align-3.c
@@ -0,0 +1,7 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+typedef int int_t;
+typedef int_t __attribute__((__aligned__(64))) i_t;
+i_t i;
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/align-4.c b/gcc/testsuite/gcc.dg/debug/dwarf2/align-4.c
new file mode 100644
index 0000000..31e9e81
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/align-4.c
@@ -0,0 +1,7 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 2 { xfail { powerpc-ibm-aix* } } } }
+
+struct tt {
+  int __attribute__((__aligned__(64))) i;
+} t;
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/align-5.c b/gcc/testsuite/gcc.dg/debug/dwarf2/align-5.c
new file mode 100644
index 0000000..2116646
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/align-5.c
@@ -0,0 +1,7 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+struct tt {
+  int i;
+} __attribute__((__aligned__(64))) t;
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/align-6.c b/gcc/testsuite/gcc.dg/debug/dwarf2/align-6.c
new file mode 100644
index 0000000..e8fc43f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/align-6.c
@@ -0,0 +1,9 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+struct tt {
+  int i;
+};
+
+struct tt __attribute__((__aligned__(64))) t;
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/align-as-1.c b/gcc/testsuite/gcc.dg/debug/dwarf2/align-as-1.c
new file mode 100644
index 0000000..6923257
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/align-as-1.c
@@ -0,0 +1,5 @@ 
+// { dg-do compile }
+// { dg-options "-O -g -dA" }
+// { dg-final { scan-assembler-times " DW_AT_alignment" 1 { xfail { powerpc-ibm-aix* } } } }
+
+int _Alignas(64) i;
diff --git a/include/dwarf2.def b/include/dwarf2.def
index 8546f7e..9268497 100644
--- a/include/dwarf2.def
+++ b/include/dwarf2.def
@@ -312,6 +312,7 @@  DW_AT (DW_AT_linkage_name, 0x6e)
 DW_AT (DW_AT_reference, 0x77)
 DW_AT (DW_AT_rvalue_reference, 0x78)
 DW_AT (DW_AT_noreturn, 0x87)
+DW_AT (DW_AT_alignment, 0x88)
 DW_AT (DW_AT_deleted, 0x8a)
 DW_AT (DW_AT_defaulted, 0x8b)