[PATCH 3/3] Add symbol, line, and location to DAP disassemble result

[Tom Tromey <tromey@adacore.com>]

The DAP spec allows a number of attributes on the resulting
instructions that gdb currently does not emit.  A user requested some
of these, so this patch adds the 'symbol', 'line', and 'location'
attributes.  While the spec lets the implementation omit 'location' in
some cases, it was simpler in the code to just always emit it, as then
no extra tracking was needed.
---
 gdb/python/lib/gdb/dap/disassemble.py |  64 ++++++++++++++--
 gdb/testsuite/gdb.dap/disassem.c      |  52 +++++++++++++
 gdb/testsuite/gdb.dap/disassem.exp    | 105 ++++++++++++++++++++++++++
 3 files changed, 214 insertions(+), 7 deletions(-)
 create mode 100644 gdb/testsuite/gdb.dap/disassem.c
 create mode 100644 gdb/testsuite/gdb.dap/disassem.exp

diff --git a/gdb/python/lib/gdb/dap/disassemble.py b/gdb/python/lib/gdb/dap/disassemble.py
index 65bf3d4457b..035bc3f9356 100644
--- a/gdb/python/lib/gdb/dap/disassemble.py
+++ b/gdb/python/lib/gdb/dap/disassemble.py
@@ -16,6 +16,55 @@
 import gdb
 
 from .server import capability, request
+from .sources import make_source
+
+
+# This tracks labels associated with a disassembly request and helps
+# with updating individual instructions.
+class _BlockTracker:
+    def __init__(self):
+        # Map from PC to symbol names.  A given PC is assumed to have
+        # just one label -- DAP wouldn't let us return multiple labels
+        # anyway.
+        self.labels = {}
+        # List of blocks that have already been handled.  Note that
+        # blocks aren't hashable so a set is not used.
+        self.blocks = []
+
+    # Add a gdb.Block and its superblocks, stopping before the static
+    # block.
+    def add_block(self, block):
+        if block in self.blocks:
+            return
+        self.blocks.append(block)
+        if block.function is not None:
+            self.labels[block.start] = block.function.name
+        for sym in block:
+            if sym.addr_class == gdb.SYMBOL_LOC_LABEL:
+                self.labels[int(sym.value())] = sym.name
+        sblock = block.superblock
+        if not sblock.is_static:
+            self.add_block(sblock)
+
+    # Add PC to this tracker.  Update RESULT as appropriate with
+    # information about the source and any label.
+    def add_pc(self, pc, result):
+        block = gdb.block_for_pc(pc)
+        if block is None:
+            # Nothing to do.
+            return
+        self.add_block(block)
+        if pc in self.labels:
+            result["symbol"] = self.labels[pc]
+        sal = gdb.find_pc_line(pc)
+        if sal.symtab is not None:
+            if sal.line != 0:
+                result["line"] = str(sal.line)
+            if sal.symtab.filename is not None:
+                # The spec says this can be omitted in some
+                # situations, but it's a little simpler to just always
+                # supply it.
+                result["location"] = make_source(sal.symtab.filename)
 
 
 @request("disassemble")
@@ -35,17 +84,18 @@ def disassemble(
     except gdb.error:
         # Maybe there was no frame.
         arch = inf.architecture()
+    tracker = _BlockTracker()
     result = []
     total_count = instructionOffset + instructionCount
     for elt in arch.disassemble(pc, count=total_count)[instructionOffset:]:
         mem = inf.read_memory(elt["addr"], elt["length"])
-        result.append(
-            {
-                "address": hex(elt["addr"]),
-                "instruction": elt["asm"],
-                "instructionBytes": mem.hex(),
-            }
-        )
+        insn = {
+            "address": hex(elt["addr"]),
+            "instruction": elt["asm"],
+            "instructionBytes": mem.hex(),
+        }
+        tracker.add_pc(elt["addr"], insn)
+        result.append(insn)
     return {
         "instructions": result,
     }
diff --git a/gdb/testsuite/gdb.dap/disassem.c b/gdb/testsuite/gdb.dap/disassem.c
new file mode 100644
index 00000000000..c0f5128c97d
--- /dev/null
+++ b/gdb/testsuite/gdb.dap/disassem.c
@@ -0,0 +1,52 @@
+/* Copyright 2024 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+__attribute__((__noinline__)) static int
+callee (int x)
+{
+  return x * 2;
+}
+
+static inline int __attribute__((__always_inline__))
+compute (int x)
+{
+  return callee (x);
+}
+
+static int
+return_value (int x)
+{
+  int accum = 0;
+
+  for (int i = 0; i < x; ++i)
+    {
+      int value = compute (i);
+      if (value < 0)
+	goto out_label;
+    }
+
+ out_label:
+
+  return accum;
+}
+
+int
+main ()
+{
+  int value = return_value (23);
+  return value > 0 ? 0 : 1;
+}
diff --git a/gdb/testsuite/gdb.dap/disassem.exp b/gdb/testsuite/gdb.dap/disassem.exp
new file mode 100644
index 00000000000..87fb516931a
--- /dev/null
+++ b/gdb/testsuite/gdb.dap/disassem.exp
@@ -0,0 +1,105 @@
+# Copyright 2024 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 DAP disassembly.
+
+require allow_dap_tests
+
+load_lib dap-support.exp
+
+standard_testfile
+
+if {[build_executable ${testfile}.exp $testfile] == -1} {
+    return
+}
+
+if {[dap_initialize] == ""} {
+    return
+}
+
+set obj [dap_check_request_and_response "set breakpoint" \
+	     setFunctionBreakpoints \
+	     {o breakpoints [a [o name [s main]]]}]
+set fn_bpno [dap_get_breakpoint_number $obj]
+
+dap_check_request_and_response "configurationDone" configurationDone
+
+if {[dap_launch $testfile] == ""} {
+    return
+}
+dap_wait_for_event_and_check "inferior started" thread "body reason" started
+
+dap_wait_for_event_and_check "stopped at line breakpoint" stopped \
+    "body reason" breakpoint \
+    "body hitBreakpointIds" $fn_bpno
+
+# Find out how many lines of disassembly we should request.  This is
+# kind of lame but DAP doesn't really provide tools to do this, and
+# gdb's DAP implementation doesn't try to figure out what memory might
+# not really be part of a function.
+set obj [dap_check_request_and_response "disassemble using CLI" \
+	     evaluate {o expression [s {disassemble &return_value}] \
+			   context [s repl]}]
+set output [dict get [lindex $obj 0] body result]
+# The result will have literal "\" "n" sequences, turn these into
+# newlines.
+set with_nl [string map [list "\\n" "\n"] $output]
+# The value we want is the number of lines starting with an address.
+set insn_count 0
+foreach line [split $with_nl "\n"] {
+    if {[regexp "^ *0x" $line]} {
+	incr insn_count
+    }
+}
+
+set obj [dap_check_request_and_response "find function address" \
+	     evaluate {o expression [s "&return_value"]}]
+set pc [dict get [lindex $obj 0] body memoryReference]
+
+set obj [dap_check_request_and_response "disassemble the function" \
+	     disassemble \
+	     [format {o memoryReference [s %s] instructionCount [i %d]} \
+		  $pc $insn_count]]
+set response [lindex $obj 0]
+
+set seen_labels(_) _
+set insn_no 1
+foreach insn [dict get $response body instructions] {
+    with_test_prefix $insn_no {
+	gdb_assert {[dict exists $insn line]} \
+	    "line in disassemble output"
+	gdb_assert {[dict exists $insn location]} \
+	    "location in disassemble output"
+	if {[dict exists $insn symbol]} {
+	    set seen_labels([dict get $insn symbol]) 1
+	}
+    }
+    incr insn_no
+}
+
+proc require_label {name} {
+    global seen_labels
+    if {[info exists seen_labels($name)]} {
+	pass "saw label $name"
+    } else {
+	fail "saw label $name"
+    }
+}
+
+require_label return_value
+require_label compute
+require_label out_label
+
+dap_shutdown
-- 
2.44.0