feat: add GPR Information to UDB

spec/schemas/register_file_schema.json

@@ -0,0 +1,130 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+
+  "title": "Register File Schema",
+  "description": "Schema for describing a register file",
+
+  "$defs": {
+    "register_entry": {
+      "type": "object",
+      "required": ["name"],
+      "additionalProperties": false,
+      "properties": {
+        "name": {
+          "$ref": "schema_defs.json#/$defs/register_name"
+        },
+        "abi_mnemonics": {
+          "type": "array",
+          "items": {
+            "$ref": "schema_defs.json#/$defs/register_alias"
+          },
+          "minItems": 1,
+          "uniqueItems": true,
+          "description": "ABI mnemonic names for the register"
+        },
+        "description": {
+          "$ref": "schema_defs.json#/$defs/spec_text"
+        },
+        "when": {
+          "$ref": "schema_defs.json#/$defs/requires_entry"
+        },
+        "sw_read()": {
+          "type": "string",
+          "description": "Function that returns the value of the register when read by software. Use this to define special behavior for registers (e.g., x0 always reads as zero)."
+        },
+        "sw_write(value)": {
+          "type": "string",
+          "description": "Function implementing custom write behavior for the register. Given a 'value', return either the value to be written or a modified value. Use this to define special behavior for registers (e.g., x0 ignores writes)."
+        },
+        "caller_saved": {
+          "type": "boolean",
+          "default": false,
+          "description": "Whether the register is caller-saved"
+        },
+        "callee_saved": {
+          "type": "boolean",
+          "default": false,
+          "description": "Whether the register is callee-saved"
+        },
+        "roles": {
+          "type": "array",
+          "items": {
+            "type": "string",
+            "enum": [
+              "zero",
+              "return_address",
+              "stack_pointer",
+              "global_pointer",
+              "thread_pointer",
+              "frame_pointer",
+              "return_value",
+              "argument",
+              "temporary"
+            ]
+          },
+          "uniqueItems": true
+        },
+        "writable": {
+          "type": "boolean",
+          "default": true,
+          "description": "Whether the register is writable. If false, no sw_write() method is needed."
+        }
+      }
+    },
+    "register_file": {
+      "type": "object",
+      "required": [
+        "$schema",
+        "kind",
+        "name",
+        "long_name",
+        "description",
+        "register_length",
+        "registers"
+      ],
+      "additionalProperties": false,
+      "properties": {
+        "$schema": {
+          "type": "string",
+          "format": "uri-reference",
+          "const": "register_file_schema.json#",
+          "description": "Path to schema, relative to <UDB ROOT>/schemas"
+        },
+        "kind": {
+          "type": "string",
+          "const": "register_file"
+        },
+        "name": {
+          "$ref": "schema_defs.json#/$defs/register_file_name"
+        },
+        "long_name": {
+          "type": "string"
+        },
+        "description": {
+          "$ref": "schema_defs.json#/$defs/spec_text"
+        },
+        "definedBy": {
+          "$ref": "schema_defs.json#/$defs/requires_entry"
+        },
+        "register_class": {
+          "type": "string",
+          "enum": ["general_purpose", "floating_point", "vector"]
+        },
+        "register_length": {
+          "$ref": "schema_defs.json#/$defs/bit_length_value"
+        },
+        "registers": {
+          "type": "array",
+          "minItems": 1,
+          "items": {
+            "$ref": "#/$defs/register_entry"
+          }
+        },
+        "$source": {
+          "type": "string",
+          "format": "uri-reference"
+        }
+      }
+    }
+  }
+}

spec/schemas/schema_defs.json

@@ -43,6 +43,35 @@
       ],
       "description": "Location of a field in a register"
     },
+    "bit_length_value": {
+      "description": "Bit width value for a register or field",
+      "oneOf": [
+        {
+          "type": "integer",
+          "minimum": 1
+        },
+        {
+          "type": "string",
+          "minLength": 1,
+          "enum": ["MXLEN"]
+        }
+      ]
+    },
+    "register_name": {
+      "type": "string",
+      "pattern": "^[A-Za-z][A-Za-z0-9_.-]*$",
+      "description": "Register name"
+    },
+    "register_file_name": {
+      "type": "string",
+      "pattern": "^[A-Za-z]$",
+      "description": "Register file name"
+    },
+    "register_alias": {
+      "type": "string",
+      "pattern": "^[A-Za-z][A-Za-z0-9_.-]*$",
+      "description": "Register alias or ABI mnemonic"
+    },
     "possibly_split_field_location": {
       "description": "Location specifier for a field",
       "oneOf": [

spec/std/isa/README.adoc

@@ -29,8 +29,8 @@ Three standard configs are present:
  * `rv64`: A configuration where only `MXLEN` is known to be 64, i.e., the RV64 ISA.
 
 The architecture is specified in a series of https://en.wikipedia.org/wiki/YAML[YAML]
-files for _Extensions_, _Instructions_, and _Control and Status Registers (CSRs)_.
-Each extension/instruction/CSR has its own file.
+files for _Extensions_, _Instructions_, _RegFiles_, and _Control and Status Registers (CSRs)_.
+Each extension/instruction/regfile/CSR has its own file.
 
 == Flow
 
@@ -142,6 +142,40 @@ H: # <1>
 
 === Instructions
 
+=== Register Files
+
+.Example register file specification
+[source,yaml]
+----
+$schema: register_file_schema.json#
+kind: register_file
+name: X
+long_name: Integer General Purpose Registers
+definedBy: I
+register_class: general_purpose
+register_length: MXLEN # <1>
+registers:
+  - name: x0    # <2>
+    abi_mnemonics: [zero] # <3>
+    roles: [zero]
+    sw_read(): | # <4>
+      return 0;
+    sw_write(value): |
+      # x0 ignores all writes
+  - name: x1
+    abi_mnemonics: [ra]
+    roles: [return_address]
+  - name: x8
+    abi_mnemonics: [s0, fp] # <5>
+    roles: [callee_saved, frame_pointer]
+----
+
+<1> The registers in a register file have identical fixed widths, either an explicit width or from a parameter (e.g. MXLEN or VLEN).
+<2> Each register has a unique name (e.g., x0, x1, x2, etc.). The register's index is inferred from its position in the array (starting from 0).
+<3> Registers can optionally have ABI mnemonics (e.g., ra, sp, fp, etc.).
+<4> Individual registers can define `sw_read()` and `sw_write()` for special behavior (e.g., x0 hardwired to zero).
+<5> A register can have multiple ABI mnemonics (e.g., x8 is known as both s0 and fp).
+
 [source,yaml]
 ----
 add: # <1>