GH-128914: Remove all but one conditional stack effects (GH-129226)

* Remove all 'if (0)' and 'if (1)' conditional stack effects

* Use array instead of conditional for BUILD_SLICE args

* Refactor LOAD_GLOBAL to use a common conditional uop

* Remove conditional stack effects from LOAD_ATTR specializations

* Replace conditional stack effects in LOAD_ATTR with a 0 or 1 sized array.

* Remove conditional stack effects from CALL_FUNCTION_EX

1 files changed, 31 insertions, 90 deletions

diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index fa0b4ed4345..2497754745c 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -928,12 +928,20 @@
 
         case _LOAD_GLOBAL: {
             JitOptSymbol **res;
-            JitOptSymbol *null = NULL;
             res = &stack_pointer[0];
             res[0] = sym_new_not_null(ctx);
+            stack_pointer += 1;
+            assert(WITHIN_STACK_BOUNDS());
+            break;
+        }
+
+        case _PUSH_NULL_CONDITIONAL: {
+            JitOptSymbol *null = NULL;
+            int opcode = (oparg & 1) ? _PUSH_NULL : _NOP;
+            REPLACE_OP(this_instr, opcode, 0, 0);
             null = sym_new_null(ctx);
-            if (oparg & 1) stack_pointer[1] = null;
-            stack_pointer += 1 + (oparg & 1);
+            if (oparg & 1) stack_pointer[0] = null;
+            stack_pointer += (oparg & 1);
             assert(WITHIN_STACK_BOUNDS());
             break;
         }
@@ -966,25 +974,15 @@
 
         case _LOAD_GLOBAL_MODULE_FROM_KEYS: {
             JitOptSymbol *res;
-            JitOptSymbol *null = NULL;
             res = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             stack_pointer[-1] = res;
-            if (oparg & 1) stack_pointer[0] = null;
-            stack_pointer += (oparg & 1);
-            assert(WITHIN_STACK_BOUNDS());
             break;
         }
 
         case _LOAD_GLOBAL_BUILTINS_FROM_KEYS: {
             JitOptSymbol *res;
-            JitOptSymbol *null = NULL;
             res = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             stack_pointer[-1] = res;
-            if (oparg & 1) stack_pointer[0] = null;
-            stack_pointer += (oparg & 1);
-            assert(WITHIN_STACK_BOUNDS());
             break;
         }
 
@@ -1133,14 +1131,16 @@
         case _LOAD_ATTR: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *self_or_null = NULL;
+            JitOptSymbol **self_or_null;
             owner = stack_pointer[-1];
+            self_or_null = &stack_pointer[0];
             (void)owner;
             attr = sym_new_not_null(ctx);
-            self_or_null = sym_new_unknown(ctx);
+            if (oparg &1) {
+                self_or_null[0] = sym_new_unknown(ctx);
+            }
             stack_pointer[-1] = attr;
-            if (oparg & 1) stack_pointer[0] = self_or_null;
-            stack_pointer += (oparg & 1);
+            stack_pointer += (oparg&1);
             assert(WITHIN_STACK_BOUNDS());
             break;
         }
@@ -1182,17 +1182,12 @@
         case _LOAD_ATTR_INSTANCE_VALUE: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *null = NULL;
             owner = stack_pointer[-1];
             uint16_t offset = (uint16_t)this_instr->operand0;
             attr = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             (void)offset;
             (void)owner;
             stack_pointer[-1] = attr;
-            if (oparg & 1) stack_pointer[0] = null;
-            stack_pointer += (oparg & 1);
-            assert(WITHIN_STACK_BOUNDS());
             break;
         }
 
@@ -1230,11 +1225,9 @@
         case _LOAD_ATTR_MODULE_FROM_KEYS: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *null = NULL;
             owner = stack_pointer[-2];
             uint16_t index = (uint16_t)this_instr->operand0;
             (void)index;
-            null = sym_new_null(ctx);
             attr = NULL;
             if (this_instr[-1].opcode == _NOP) {
                 // Preceding _CHECK_ATTR_MODULE_PUSH_KEYS was removed: mod is const and dict is watched.
@@ -1243,8 +1236,7 @@
                 assert(PyModule_CheckExact(mod));
                 PyObject *dict = mod->md_dict;
                 stack_pointer[-2] = attr;
-                if (oparg & 1) stack_pointer[-1] = null;
-                stack_pointer += -1 + (oparg & 1);
+                stack_pointer += -1;
                 assert(WITHIN_STACK_BOUNDS());
                 PyObject *res = convert_global_to_const(this_instr, dict);
                 if (res != NULL) {
@@ -1254,7 +1246,7 @@
                 else {
                     this_instr->opcode = _LOAD_ATTR_MODULE;
                 }
-                stack_pointer += 1 - (oparg & 1);
+                stack_pointer += 1;
                 assert(WITHIN_STACK_BOUNDS());
             }
             if (attr == NULL) {
@@ -1262,8 +1254,7 @@
                 attr = sym_new_not_null(ctx);
             }
             stack_pointer[-2] = attr;
-            if (oparg & 1) stack_pointer[-1] = null;
-            stack_pointer += -1 + (oparg & 1);
+            stack_pointer += -1;
             assert(WITHIN_STACK_BOUNDS());
             break;
         }
@@ -1284,18 +1275,15 @@
             JitOptSymbol *dict;
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *null = NULL;
             dict = stack_pointer[-1];
             owner = stack_pointer[-2];
             uint16_t hint = (uint16_t)this_instr->operand0;
             attr = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             (void)hint;
             (void)owner;
             (void)dict;
             stack_pointer[-2] = attr;
-            if (oparg & 1) stack_pointer[-1] = null;
-            stack_pointer += -1 + (oparg & 1);
+            stack_pointer += -1;
             assert(WITHIN_STACK_BOUNDS());
             break;
         }
@@ -1303,17 +1291,12 @@
         case _LOAD_ATTR_SLOT: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *null = NULL;
             owner = stack_pointer[-1];
             uint16_t index = (uint16_t)this_instr->operand0;
             attr = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             (void)index;
             (void)owner;
             stack_pointer[-1] = attr;
-            if (oparg & 1) stack_pointer[0] = null;
-            stack_pointer += (oparg & 1);
-            assert(WITHIN_STACK_BOUNDS());
             break;
         }
 
@@ -1324,17 +1307,12 @@
         case _LOAD_ATTR_CLASS: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *null = NULL;
             owner = stack_pointer[-1];
             PyObject *descr = (PyObject *)this_instr->operand0;
             attr = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             (void)descr;
             (void)owner;
             stack_pointer[-1] = attr;
-            if (oparg & 1) stack_pointer[0] = null;
-            stack_pointer += (oparg & 1);
-            assert(WITHIN_STACK_BOUNDS());
             break;
         }
 
@@ -1723,7 +1701,7 @@
         case _LOAD_ATTR_METHOD_WITH_VALUES: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *self = NULL;
+            JitOptSymbol *self;
             owner = stack_pointer[-1];
             PyObject *descr = (PyObject *)this_instr->operand0;
             (void)descr;
@@ -1739,7 +1717,7 @@
         case _LOAD_ATTR_METHOD_NO_DICT: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *self = NULL;
+            JitOptSymbol *self;
             owner = stack_pointer[-1];
             PyObject *descr = (PyObject *)this_instr->operand0;
             (void)descr;
@@ -1773,7 +1751,7 @@
         case _LOAD_ATTR_METHOD_LAZY_DICT: {
             JitOptSymbol *owner;
             JitOptSymbol *attr;
-            JitOptSymbol *self = NULL;
+            JitOptSymbol *self;
             owner = stack_pointer[-1];
             PyObject *descr = (PyObject *)this_instr->operand0;
             (void)descr;
@@ -2262,11 +2240,11 @@
 
         case _MAKE_CALLARGS_A_TUPLE: {
             JitOptSymbol *tuple;
-            JitOptSymbol *kwargs_out = NULL;
+            JitOptSymbol *kwargs_out;
             tuple = sym_new_not_null(ctx);
             kwargs_out = sym_new_not_null(ctx);
-            stack_pointer[-1 - (oparg & 1)] = tuple;
-            if (oparg & 1) stack_pointer[-(oparg & 1)] = kwargs_out;
+            stack_pointer[-2] = tuple;
+            stack_pointer[-1] = kwargs_out;
             break;
         }
 
@@ -2315,8 +2293,8 @@
         case _BUILD_SLICE: {
             JitOptSymbol *slice;
             slice = sym_new_not_null(ctx);
-            stack_pointer[-2 - ((oparg == 3) ? 1 : 0)] = slice;
-            stack_pointer += -1 - ((oparg == 3) ? 1 : 0);
+            stack_pointer[-oparg] = slice;
+            stack_pointer += 1 - oparg;
             assert(WITHIN_STACK_BOUNDS());
             break;
         }
@@ -2607,69 +2585,32 @@
             break;
         }
 
-        case _LOAD_CONST_INLINE_WITH_NULL: {
-            JitOptSymbol *value;
-            JitOptSymbol *null;
-            PyObject *ptr = (PyObject *)this_instr->operand0;
-            value = sym_new_const(ctx, ptr);
-            null = sym_new_null(ctx);
-            stack_pointer[0] = value;
-            stack_pointer[1] = null;
-            stack_pointer += 2;
-            assert(WITHIN_STACK_BOUNDS());
-            break;
-        }
-
-        case _LOAD_CONST_INLINE_BORROW_WITH_NULL: {
-            JitOptSymbol *value;
-            JitOptSymbol *null;
-            PyObject *ptr = (PyObject *)this_instr->operand0;
-            value = sym_new_const(ctx, ptr);
-            null = sym_new_null(ctx);
-            stack_pointer[0] = value;
-            stack_pointer[1] = null;
-            stack_pointer += 2;
-            assert(WITHIN_STACK_BOUNDS());
-            break;
-        }
-
         case _CHECK_FUNCTION: {
             break;
         }
 
         case _LOAD_GLOBAL_MODULE: {
             JitOptSymbol *res;
-            JitOptSymbol *null = NULL;
             res = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             stack_pointer[0] = res;
-            if (oparg & 1) stack_pointer[1] = null;
-            stack_pointer += 1 + (oparg & 1);
+            stack_pointer += 1;
             assert(WITHIN_STACK_BOUNDS());
             break;
         }
 
         case _LOAD_GLOBAL_BUILTINS: {
             JitOptSymbol *res;
-            JitOptSymbol *null = NULL;
             res = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             stack_pointer[0] = res;
-            if (oparg & 1) stack_pointer[1] = null;
-            stack_pointer += 1 + (oparg & 1);
+            stack_pointer += 1;
             assert(WITHIN_STACK_BOUNDS());
             break;
         }
 
         case _LOAD_ATTR_MODULE: {
             JitOptSymbol *attr;
-            JitOptSymbol *null = NULL;
             attr = sym_new_not_null(ctx);
-            null = sym_new_null(ctx);
             stack_pointer[-1] = attr;
-            if (oparg & 1) stack_pointer[0] = null;
-            stack_pointer += (oparg & 1);
-            assert(WITHIN_STACK_BOUNDS());
             break;
         }