From 98347c251a9c73eba51ffe50519e18334320ac91 Mon Sep 17 00:00:00 2001
From: Takashi Kokubun <takashikkbn@gmail.com>
Date: Fri, 31 Mar 2023 02:54:24 -0700
Subject: gdb: Dump env data in cfp command

---
 misc/gdb.py | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 72 insertions(+), 3 deletions(-)

diff --git a/misc/gdb.py b/misc/gdb.py
index 038ebfc069..6f26fc1111 100644
--- a/misc/gdb.py
+++ b/misc/gdb.py
@@ -2,6 +2,34 @@
 #   cfp: Dump the current cfp
 #   cfp + 1: Dump the caller cfp
 class CFP(gdb.Command):
+    FRAME_MAGICS = [
+        # frame types
+        'VM_FRAME_MAGIC_METHOD',
+        'VM_FRAME_MAGIC_BLOCK',
+        'VM_FRAME_MAGIC_CLASS',
+        'VM_FRAME_MAGIC_TOP',
+        'VM_FRAME_MAGIC_CFUNC',
+        'VM_FRAME_MAGIC_IFUNC',
+        'VM_FRAME_MAGIC_EVAL',
+        'VM_FRAME_MAGIC_RESCUE',
+        'VM_FRAME_MAGIC_DUMMY',
+    ]
+    FRAME_FLAGS = [
+        # frame flag
+        'VM_FRAME_FLAG_FINISH',
+        'VM_FRAME_FLAG_BMETHOD',
+        'VM_FRAME_FLAG_CFRAME',
+        'VM_FRAME_FLAG_LAMBDA',
+        'VM_FRAME_FLAG_MODIFIED_BLOCK_PARAM',
+        'VM_FRAME_FLAG_CFRAME_KW',
+        'VM_FRAME_FLAG_PASSED',
+        # env flag
+        'VM_ENV_FLAG_LOCAL',
+        'VM_ENV_FLAG_ESCAPED',
+        'VM_ENV_FLAG_WB_REQUIRED',
+        'VM_ENV_FLAG_ISOLATED',
+    ]
+
     def __init__(self):
         super(CFP, self).__init__('cfp', gdb.COMMAND_USER)
 
@@ -17,12 +45,53 @@ class CFP(gdb.Command):
         gdb.execute(f'p *({cfp})')
         print()
 
+        print('Env:')
+        self.print_stack(cfp, -3, self.rp(cfp, -3))
+        self.print_stack(cfp, -2, self.specval(cfp, -2))
+        self.print_stack(cfp, -1, self.frame_types(cfp, -1))
+        print()
+
         stack_size = int((self.get_int(f'{cfp}->sp') - self.get_int(f'{cfp}->__bp__')) / 8)
         print(f'Stack (size={stack_size}):')
         for i in range(0, stack_size):
-            obj = self.get_int(f'{cfp}->__bp__[{i}]')
-            rp = self.get_string(f'rp {obj}')
-            print(f'[{i}] {rp}', end='')
+            self.print_stack(cfp, i, self.rp(cfp, i))
+
+    def print_stack(self, cfp, bp_index, content):
+        address = self.get_int(f'{cfp}->__bp__ + {bp_index}')
+        print('0x{:x} [{}] {}'.format(address, bp_index, content))
+
+    def rp(self, cfp, bp_index):
+        value = self.get_value(cfp, bp_index)
+        return self.get_string(f'rp {value}').rstrip()
+
+    # specval: block_handler or previous EP
+    def specval(self, cfp, bp_index):
+        value = self.get_value(cfp, bp_index)
+        specval = '0x{:x}'.format(value)
+        for block_handler in ['VM_BLOCK_HANDLER_NONE', 'rb_block_param_proxy']:
+            if value == self.get_int(block_handler):
+                return f'{specval} ({block_handler})'
+        return specval
+
+    def frame_types(self, cfp, bp_index):
+        types = []
+        value = self.get_value(cfp, bp_index)
+
+        magic_mask = self.get_int('VM_FRAME_MAGIC_MASK')
+        for magic in self.FRAME_MAGICS:
+            magic_value = self.get_int(magic)
+            if value & magic_mask == magic_value:
+                types.append(magic)
+
+        for flag in self.FRAME_FLAGS:
+            flag_value = self.get_int(flag)
+            if value & flag_value:
+                types.append(flag)
+
+        return '0x{:x} ({})'.format(self.get_value(cfp, bp_index), ' | '.join(types))
+
+    def get_value(self, cfp, bp_index):
+        return self.get_int(f'{cfp}->__bp__[{bp_index}]')
 
     def get_int(self, expr):
         return int(self.get_string(f'printf "%ld", ({expr})'))
-- 
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