chore(bb): debugging helpers (#13584)

Allows for starting a vscode debugging session with whatever the cmake
target currently selected is and with pretty-print helpers for fq, fr,
uint256_t

Author: ludamad

.vscode/launch.json

@@ -19,6 +19,17 @@
       "request": "attach",
       "name": "Attach",
       "port": 9229
+    },
+    {
+      "name": "Debug Current CMake Target",
+      "type": "lldb",
+      "request": "launch",
+      "program": "${command:cmake.launchTargetPath}",
+      "args": [],
+      "cwd": "${workspaceFolder}/barretenberg/cpp/build",
+      "initCommands": [
+        "command script import ${workspaceFolder}/barretenberg/cpp/scripts/lldb_format.py"
+      ],
     }
   ]
 }

barretenberg/cpp/scripts/lldb_format.py

@@ -1,20 +1,31 @@
 import lldb
 
-# Define the bn254 modulus
-N = 21888242871839275222246405745257275088548364400416034343698204186575808495617
+class Fr:
+    # Define the bn254 modulus
+    N = 21888242871839275222246405745257275088548364400416034343698204186575808495617
 
-# Define R as a power of 2 such that R > N (commonly used R for bn254 is 2^256)
-R = 2**256
+    # Define R as a power of 2 such that R > N (commonly used R for bn254 is 2^256)
+    R = 2**256
 
-# Compute R inverse modulo N
-R_inv = pow(R, -1, N)
+    # Compute R inverse modulo N
+    R_inv = pow(R, -1, N)
 
-def montgomery_to_standard(montgomery_value):
+class Fq:
+    # Define the bn254 modulus
+    N = 21888242871839275222246405745257275088696311157297823662689037894645226208759
+
+    # Define R as a power of 2 such that R > N (commonly used R for bn254 is 2^256)
+    R = 2**256
+
+    # Compute R inverse modulo N
+    R_inv = pow(R, -1, N)
+
+def from_montgomery(field_type, montgomery_value):
     # Convert from Montgomery form to standard representation
-    standard_value = (montgomery_value * R_inv) % N
+    standard_value = (montgomery_value * field_type.R_inv) % field_type.N
     return standard_value
 
-def montgomery_summary(valobj, internal_dict):
+def from_montgomery_field(field_type, valobj, internal_dict):
     try:
         data = valobj.GetChildMemberWithName('data')
         data_0 = data.GetChildAtIndex(0).GetValueAsUnsigned()
@@ -29,17 +40,63 @@ def montgomery_summary(valobj, internal_dict):
             (data_3 << 192)
         )
 
-        standard_value = montgomery_to_standard(montgomery_value)
+        standard_value = from_montgomery(field_type, montgomery_value)
         return hex(standard_value)
     except Exception as e:
         return f"Error: {e}"
 
+def from_montgomery_fr(valobj, internal_dict):
+    return from_montgomery_field(Fr, valobj, internal_dict)
 
-def montgomery_summary2(valobj, internal_dict):
-    return montgomery_summary(valobj.EvaluateExpression("get_value()"), internal_dict)
+def from_montgomery_fq(valobj, internal_dict):
+    return from_montgomery_field(Fq, valobj, internal_dict)
 
+def from_montgomery_field_t_fr(valobj, internal_dict):
+    return from_montgomery_fr(Fr, valobj.EvaluateExpression("get_value()"), internal_dict)
+
+def from_uint256(valobj, internal_dict):
+    """Summarize a uint256_t (with a uint64_t[4] named 'data') as hex."""
+    try:
+        data = valobj.GetChildMemberWithName('data')
+        low64  = data.GetChildAtIndex(0).GetValueAsUnsigned()
+        mid64a = data.GetChildAtIndex(1).GetValueAsUnsigned()
+        mid64b = data.GetChildAtIndex(2).GetValueAsUnsigned()
+        high64 = data.GetChildAtIndex(3).GetValueAsUnsigned()
+
+        combined = (
+            low64
+            | (mid64a << 64)
+            | (mid64b << 128)
+            | (high64 << 192)
+        )
+        return hex(combined)
+    except Exception as e:
+        return f"[uint256_t Error: {e}]"
 
 def __lldb_init_module(debugger, internal_dict):
-    debugger.HandleCommand("type summary add --python-function lldb_format.montgomery_summary bb::fr")
-    debugger.HandleCommand("type summary add --python-function lldb_format.montgomery_summary2 -x \"bb::stdlib::field_t.*\"")
-    print('The "formatter" command has been installed!')
+    commands = [
+        # Matches:
+        #   "bb::fr",
+        #   any optional namespace followed by "Fr" (e.g. "foo::Fr"),
+        #   "bb::field<bb::Bn254FrParams>"
+        # with or without "const"
+        (r'^(const\s+)?(bb::fr|(\w+::)?Fr|bb::field<bb::Bn254FrParams>)$', 'lldb_format.from_montgomery_fr'),
+
+        # Matches:
+        #   any optional namespace followed by "Fq" (e.g. "foo::Fq"),
+        #   "bb::field<bb::Bn254FqParams>"
+        # with or without "const"
+        (r'^(const\s+)?((\w+::)?Fq|bb::field<bb::Bn254FqParams>)$', 'lldb_format.from_montgomery_fq'),
+
+        # Matches:
+        #   "bb::stdlib::field_t" with any additional characters
+        # with or without "const"
+        (r'^(const\s+)?(bb::stdlib::field_t.*)$', 'lldb_format.from_montgomery_field_t_fr'),
+        ('bb::numeric::uint256_t', 'lldb_format.from_uint256'),
+    ]
+
+    for pattern, py_func in commands:
+        cmd = f'type summary add -x "{pattern}" --python-function {py_func}'
+        debugger.HandleCommand(cmd)
+
+    print('lldb_format.py commands have been installed!')