gh-119180: Add LOAD_COMMON_CONSTANT opcode (#119321)

The PEP 649 implementation will require a way to load NotImplementedError
from the bytecode. @markshannon suggested implementing this by converting
LOAD_ASSERTION_ERROR into a more general mechanism for loading constants.

This PR adds this new opcode. I will work on the rest of the implementation
of the PEP separately.

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>

6 files changed, 49 insertions, 18 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 434eb80..b48f913 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -1184,8 +1184,18 @@ dummy_func(
             }
         }
 
-        inst(LOAD_ASSERTION_ERROR, ( -- value)) {
-            value = Py_NewRef(PyExc_AssertionError);
+        inst(LOAD_COMMON_CONSTANT, ( -- value)) {
+            // Keep in sync with _common_constants in opcode.py
+            switch(oparg) {
+            case CONSTANT_ASSERTIONERROR:
+                value = PyExc_AssertionError;
+                break;
+            case CONSTANT_NOTIMPLEMENTEDERROR:
+                value = PyExc_NotImplementedError;
+                break;
+            default:
+                Py_FatalError("bad LOAD_COMMON_CONSTANT oparg");
+            }
         }
 
         inst(LOAD_BUILD_CLASS, ( -- bc)) {
diff --git a/Python/compile.c b/Python/compile.c
index 79f3baa..6dacfc7 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -3974,7 +3974,7 @@ compiler_assert(struct compiler *c, stmt_ty s)
     }
     NEW_JUMP_TARGET_LABEL(c, end);
     RETURN_IF_ERROR(compiler_jump_if(c, LOC(s), s->v.Assert.test, end, 1));
-    ADDOP(c, LOC(s), LOAD_ASSERTION_ERROR);
+    ADDOP_I(c, LOC(s), LOAD_COMMON_CONSTANT, CONSTANT_ASSERTIONERROR);
     if (s->v.Assert.msg) {
         VISIT(c, expr, s->v.Assert.msg);
         ADDOP_I(c, LOC(s), CALL, 0);
diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index 347a1e6..a3d7af2 100644
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -1162,9 +1162,20 @@
             break;
         }
 
-        case _LOAD_ASSERTION_ERROR: {
+        case _LOAD_COMMON_CONSTANT: {
             PyObject *value;
-            value = Py_NewRef(PyExc_AssertionError);
+            oparg = CURRENT_OPARG();
+            // Keep in sync with _common_constants in opcode.py
+            switch(oparg) {
+                case CONSTANT_ASSERTIONERROR:
+                value = PyExc_AssertionError;
+                break;
+                case CONSTANT_NOTIMPLEMENTEDERROR:
+                value = PyExc_NotImplementedError;
+                break;
+                default:
+                Py_FatalError("bad LOAD_COMMON_CONSTANT oparg");
+            }
             stack_pointer[0] = value;
             stack_pointer += 1;
             break;
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index 96161c5..07d9965 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -3695,17 +3695,6 @@
             DISPATCH();
         }
 
-        TARGET(LOAD_ASSERTION_ERROR) {
-            frame->instr_ptr = next_instr;
-            next_instr += 1;
-            INSTRUCTION_STATS(LOAD_ASSERTION_ERROR);
-            PyObject *value;
-            value = Py_NewRef(PyExc_AssertionError);
-            stack_pointer[0] = value;
-            stack_pointer += 1;
-            DISPATCH();
-        }
-
         TARGET(LOAD_ATTR) {
             frame->instr_ptr = next_instr;
             next_instr += 10;
@@ -4251,6 +4240,27 @@
             DISPATCH();
         }
 
+        TARGET(LOAD_COMMON_CONSTANT) {
+            frame->instr_ptr = next_instr;
+            next_instr += 1;
+            INSTRUCTION_STATS(LOAD_COMMON_CONSTANT);
+            PyObject *value;
+            // Keep in sync with _common_constants in opcode.py
+            switch(oparg) {
+                case CONSTANT_ASSERTIONERROR:
+                value = PyExc_AssertionError;
+                break;
+                case CONSTANT_NOTIMPLEMENTEDERROR:
+                value = PyExc_NotImplementedError;
+                break;
+                default:
+                Py_FatalError("bad LOAD_COMMON_CONSTANT oparg");
+            }
+            stack_pointer[0] = value;
+            stack_pointer += 1;
+            DISPATCH();
+        }
+
         TARGET(LOAD_CONST) {
             frame->instr_ptr = next_instr;
             next_instr += 1;
diff --git a/Python/opcode_targets.h b/Python/opcode_targets.h
index fa4f1f8..322483f 100644
--- a/Python/opcode_targets.h
+++ b/Python/opcode_targets.h
@@ -22,7 +22,6 @@ static void *opcode_targets[256] = {
     &&TARGET_GET_LEN,
     &&TARGET_GET_YIELD_FROM_ITER,
     &&TARGET_INTERPRETER_EXIT,
-    &&TARGET_LOAD_ASSERTION_ERROR,
     &&TARGET_LOAD_BUILD_CLASS,
     &&TARGET_LOAD_LOCALS,
     &&TARGET_MAKE_FUNCTION,
@@ -82,6 +81,7 @@ static void *opcode_targets[256] = {
     &&TARGET_LIST_APPEND,
     &&TARGET_LIST_EXTEND,
     &&TARGET_LOAD_ATTR,
+    &&TARGET_LOAD_COMMON_CONSTANT,
     &&TARGET_LOAD_CONST,
     &&TARGET_LOAD_DEREF,
     &&TARGET_LOAD_FAST,
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index cd4431d..30ed011 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -628,7 +628,7 @@
             break;
         }
 
-        case _LOAD_ASSERTION_ERROR: {
+        case _LOAD_COMMON_CONSTANT: {
             _Py_UopsSymbol *value;
             value = sym_new_not_null(ctx);
             stack_pointer[0] = value;