From b32077e24586813267bc201068bfecf79666792e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cyryl=20P=C5=82otnicki?= <cyplo@cyplo.net>
Date: Sat, 30 Jan 2021 15:56:36 +0000
Subject: [PATCH] better gdb dashboard setup

---
 .gdbinit                     | 43 +++++++++++++++++++++++-------------
 nixos/home-manager/links.nix |  4 ++++
 2 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/.gdbinit b/.gdbinit
index 993a3f6d..defb8da2 100644
--- a/.gdbinit
+++ b/.gdbinit
@@ -412,7 +412,9 @@ class Dashboard(gdb.Command):
     def on_continue(self, _):
         # try to contain the GDB messages in a specified area unless the
         # dashboard is printed to a separate file (dashboard -output ...)
-        if self.is_running() and not self.output:
+        # or there are no modules to display in the main terminal
+        enabled_modules = list(filter(lambda m: not m.output and m.enabled, self.modules))
+        if self.is_running() and not self.output and len(enabled_modules) > 0:
             width, _ = Dashboard.get_term_size()
             gdb.write(Dashboard.clear_screen())
             gdb.write(divider(width, 'Output/messages', True))
@@ -514,6 +516,9 @@ class Dashboard(gdb.Command):
                     buf += Dashboard.clear_screen()
                 # show message if all the modules in this output are disabled
                 if not any(instances):
+                    # skip the main terminal
+                    if fs is gdb:
+                        continue
                     # write the error message
                     buf += divider(width, 'Warning', True)
                     buf += '\n'
@@ -521,11 +526,7 @@ class Dashboard(gdb.Command):
                         buf += 'No module to display (see `dashboard -layout`)'
                     else:
                         buf += 'No module loaded'
-                    # write the terminator only in the main terminal
                     buf += '\n'
-                    if fs is gdb:
-                        buf += divider(width, primary=True)
-                        buf += '\n'
                     fs.write(buf)
                     continue
                 # process all the modules for that output
@@ -1306,16 +1307,8 @@ The instructions constituting the current statement are marked, if available.'''
         frame = gdb.selected_frame()  # PC is here
         height = self.height or (term_height - 1)
         try:
-            # disassemble the current block (if function information is
-            # available then try to obtain the boundaries by looking at the
-            # superblocks)
-            block = frame.block()
-            if frame.function():
-                while block and (not block.function or block.function.name != frame.function().name):
-                    block = block.superblock
-                block = block or frame.block()
-            asm_start = block.start
-            asm_end = block.end - 1
+            # disassemble the current block
+            asm_start, asm_end = self.fetch_function_boundaries()
             asm = self.fetch_asm(asm_start, asm_end, False, highlighter)
             # find the location of the PC
             pc_index = next(index for index, instr in enumerate(asm)
@@ -1471,6 +1464,26 @@ A value of 0 uses the whole height.''',
         else:
             self.offset = 0
 
+    def fetch_function_boundaries(self):
+        frame = gdb.selected_frame()
+        # parse the output of the disassemble GDB command to find the function
+        # boundaries, this should handle cases in which a function spans
+        # multiple discontinuous blocks
+        disassemble = run('disassemble')
+        for block_start, block_end in re.findall(r'Address range 0x([0-9a-f]+) to 0x([0-9a-f]+):', disassemble):
+            block_start = int(block_start, 16)
+            block_end = int(block_end, 16)
+            if block_start <= frame.pc() < block_end:
+                return block_start, block_end - 1 # need to be inclusive
+        # if function information is available then try to obtain the
+        # boundaries by looking at the superblocks
+        block = frame.block()
+        if frame.function():
+            while block and (not block.function or block.function.name != frame.function().name):
+                block = block.superblock
+            block = block or frame.block()
+        return block.start, block.end - 1
+
     def fetch_asm(self, start, end_or_count, relative, highlighter):
         # fetch asm from cache or disassemble
         if self.cache_key == (start, end_or_count):
diff --git a/nixos/home-manager/links.nix b/nixos/home-manager/links.nix
index 1e72463b..5a0d3907 100644
--- a/nixos/home-manager/links.nix
+++ b/nixos/home-manager/links.nix
@@ -8,4 +8,8 @@
     set auto-load safe-path /
     source /home/cyryl/dev/dotfiles/.gdbinit
   '';
+  home.file.".gdbinit.d/dashboard".text = ''
+    dashboard -layout breakpoints source expressions stack threads variables
+    dashboard variables -style compact 0
+  '';
 }