Handle compiler-generated suffixes in Ada names

The compiler may add a suffix to a mangled name.  A typical example
would be splitting a function and creating a ".cold" variant.

This patch changes Ada decoding (aka demangling) to handle these
suffixes.  It also changes the encoding process to handle them as
well.

A symbol like "function.cold" will now be displayed to the user as
"function[cold]".  The "." is not simply preserved because that is
already used in Ada.

3 files changed, 120 insertions, 1 deletions

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index caf8780..6680a4f 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -846,6 +846,21 @@ const struct ada_opname_map ada_opname_table[] = {
   {NULL, NULL}
 };
 
+/* If STR is a decoded version of a compiler-provided suffix (like the
+   "[cold]" in "symbol[cold]"), return true.  Otherwise, return
+   false.  */
+
+static bool
+is_compiler_suffix (const char *str)
+{
+  gdb_assert (*str == '[');
+  ++str;
+  while (*str != '\0' && isalpha (*str))
+    ++str;
+  /* We accept a missing "]" in order to support completion.  */
+  return *str == '\0' || (str[0] == ']' && str[1] == '\0');
+}
+
 /* The "encoded" form of DECODED, according to GNAT conventions.  If
    THROW_ERRORS, throw an error if invalid operator name is found.
    Otherwise, return the empty string in that case.  */
@@ -861,6 +876,13 @@ ada_encode_1 (const char *decoded, bool throw_errors)
     {
       if (*p == '.')
 	encoding_buffer.append ("__");
+      else if (*p == '[' && is_compiler_suffix (p))
+	{
+	  encoding_buffer = encoding_buffer + "." + (p + 1);
+	  if (encoding_buffer.back () == ']')
+	    encoding_buffer.pop_back ();
+	  break;
+	}
       else if (*p == '"')
 	{
 	  const struct ada_opname_map *mapping;
@@ -977,6 +999,24 @@ ada_remove_po_subprogram_suffix (const char *encoded, int *len)
     *len = *len - 1;
 }
 
+/* If ENCODED ends with a compiler-provided suffix (like ".cold"),
+   then update *LEN to remove the suffix and return the offset of the
+   character just past the ".".  Otherwise, return -1.  */
+
+static int
+remove_compiler_suffix (const char *encoded, int *len)
+{
+  int offset = *len - 1;
+  while (offset > 0 && isalpha (encoded[offset]))
+    --offset;
+  if (offset > 0 && encoded[offset] == '.')
+    {
+      *len = offset;
+      return offset + 1;
+    }
+  return -1;
+}
+
 /* See ada-lang.h.  */
 
 std::string
@@ -987,6 +1027,7 @@ ada_decode (const char *encoded, bool wrap)
   const char *p;
   int at_start_name;
   std::string decoded;
+  int suffix = -1;
 
   /* With function descriptors on PPC64, the value of a symbol named
      ".FN", if it exists, is the entry point of the function "FN".  */
@@ -1007,6 +1048,8 @@ ada_decode (const char *encoded, bool wrap)
 
   len0 = strlen (encoded);
 
+  suffix = remove_compiler_suffix (encoded, &len0);
+
   ada_remove_trailing_digits (encoded, &len0);
   ada_remove_po_subprogram_suffix (encoded, &len0);
 
@@ -1212,6 +1255,10 @@ ada_decode (const char *encoded, bool wrap)
     if (isupper (decoded[i]) || decoded[i] == ' ')
       goto Suppress;
 
+  /* If the compiler added a suffix, append it now.  */
+  if (suffix >= 0)
+    decoded = decoded + "[" + &encoded[suffix] + "]";
+
   return decoded;
 
 Suppress:
diff --git a/gdb/testsuite/gdb.ada/complete.exp b/gdb/testsuite/gdb.ada/complete.exp
index facf445..32b58f5 100644
--- a/gdb/testsuite/gdb.ada/complete.exp
+++ b/gdb/testsuite/gdb.ada/complete.exp
@@ -226,7 +226,7 @@ gdb_test_no_output "set max-completions unlimited"
 
 set test "complete break ada"
 gdb_test_multiple "$test" $test {
-    -re "^$test$eol\(break ada\[-a-z0-9._@/\]*$eol\)+$gdb_prompt $" {
+    -re "^$test$eol\(break ada\[\]\[a-z0-9._@/-\]*$eol\)+$gdb_prompt $" {
         pass $test
     }
     -re "\[A-Z\].*$gdb_prompt $" {
diff --git a/gdb/testsuite/gdb.dwarf2/ada-cold-name.exp b/gdb/testsuite/gdb.dwarf2/ada-cold-name.exp
new file mode 100644
index 0000000..2e4441a
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/ada-cold-name.exp
@@ -0,0 +1,72 @@
+# Copyright 2019-2021 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test "cold" suffix handling.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile ada-linkage-name.c -debug.S
+
+# Set up the DWARF for the test.
+
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    global srcdir subdir srcfile
+
+    cu {} {
+	DW_TAG_compile_unit {
+                {DW_AT_language @DW_LANG_Ada95}
+                {DW_AT_name     $srcfile}
+                {DW_AT_comp_dir /tmp}
+        } {
+	    declare_labels b_l
+
+	    b_l: DW_TAG_base_type {
+		{DW_AT_byte_size 1 DW_FORM_sdata}
+		{DW_AT_encoding  @DW_ATE_signed}
+		{DW_AT_name      bool}
+	    }
+
+            DW_TAG_subprogram {
+                {name pck__xtra__function.cold}
+		{MACRO_AT_range {first}}
+                {type :$b_l}
+	    }
+
+            DW_TAG_subprogram {
+                {name pck__xtra__function}
+                {MACRO_AT_range {second}}
+                {type :$b_l}
+	    }
+	}
+    }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+	  [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+gdb_test_no_output "set language ada"
+gdb_breakpoint "pck.xtra.function" message
+gdb_breakpoint "pck.xtra.function\[cold\]" message
+gdb_test "complete break pck.xtra.function\[co" \
+    "break pck.xtra.function\\\[cold\\\]" \
+    "test completion of cold function"