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, 18 insertions, 25 deletions

diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 881a607..fb14c4b 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -507,16 +507,6 @@ dummy_func(void) {
         value = sym_new_const(ctx, ptr);
     }
 
-    op(_LOAD_CONST_INLINE_WITH_NULL, (ptr/4 -- value, null)) {
-        value = sym_new_const(ctx, ptr);
-        null = sym_new_null(ctx);
-    }
-
-    op(_LOAD_CONST_INLINE_BORROW_WITH_NULL, (ptr/4 -- value, null)) {
-        value = sym_new_const(ctx, ptr);
-        null = sym_new_null(ctx);
-    }
-
     op(_COPY, (bottom, unused[oparg-1] -- bottom, unused[oparg-1], top)) {
         assert(oparg > 0);
         top = bottom;
@@ -528,9 +518,8 @@ dummy_func(void) {
         top_out = top_in;
     }
 
-    op(_LOAD_ATTR_INSTANCE_VALUE, (offset/1, owner -- attr, null if (oparg & 1))) {
+    op(_LOAD_ATTR_INSTANCE_VALUE, (offset/1, owner -- attr)) {
         attr = sym_new_not_null(ctx);
-        null = sym_new_null(ctx);
         (void)offset;
         (void)owner;
     }
@@ -553,15 +542,22 @@ dummy_func(void) {
         }
     }
 
-    op(_LOAD_ATTR, (owner -- attr, self_or_null if (oparg & 1))) {
+    op (_PUSH_NULL_CONDITIONAL, ( -- null if (oparg & 1))) {
+        int opcode = (oparg & 1) ? _PUSH_NULL : _NOP;
+        REPLACE_OP(this_instr, opcode, 0, 0);
+        null = sym_new_null(ctx);
+    }
+
+    op(_LOAD_ATTR, (owner -- attr, self_or_null[oparg&1])) {
         (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);
+        }
     }
 
-    op(_LOAD_ATTR_MODULE_FROM_KEYS, (index/1, owner, mod_keys -- attr, null if (oparg & 1))) {
+    op(_LOAD_ATTR_MODULE_FROM_KEYS, (index/1, owner, mod_keys -- attr)) {
         (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.
@@ -589,41 +585,38 @@ dummy_func(void) {
         (void)owner;
     }
 
-    op(_LOAD_ATTR_WITH_HINT, (hint/1, owner, dict -- attr, null if (oparg & 1))) {
+    op(_LOAD_ATTR_WITH_HINT, (hint/1, owner, dict -- attr)) {
         attr = sym_new_not_null(ctx);
-        null = sym_new_null(ctx);
         (void)hint;
         (void)owner;
         (void)dict;
     }
 
-    op(_LOAD_ATTR_SLOT, (index/1, owner -- attr, null if (oparg & 1))) {
+    op(_LOAD_ATTR_SLOT, (index/1, owner -- attr)) {
         attr = sym_new_not_null(ctx);
-        null = sym_new_null(ctx);
         (void)index;
         (void)owner;
     }
 
-    op(_LOAD_ATTR_CLASS, (descr/4, owner -- attr, null if (oparg & 1))) {
+    op(_LOAD_ATTR_CLASS, (descr/4, owner -- attr)) {
         attr = sym_new_not_null(ctx);
-        null = sym_new_null(ctx);
         (void)descr;
         (void)owner;
     }
 
-    op(_LOAD_ATTR_METHOD_WITH_VALUES, (descr/4, owner -- attr, self if (1))) {
+    op(_LOAD_ATTR_METHOD_WITH_VALUES, (descr/4, owner -- attr, self)) {
         (void)descr;
         attr = sym_new_not_null(ctx);
         self = owner;
     }
 
-    op(_LOAD_ATTR_METHOD_NO_DICT, (descr/4, owner -- attr, self if (1))) {
+    op(_LOAD_ATTR_METHOD_NO_DICT, (descr/4, owner -- attr, self)) {
         (void)descr;
         attr = sym_new_not_null(ctx);
         self = owner;
     }
 
-    op(_LOAD_ATTR_METHOD_LAZY_DICT, (descr/4, owner -- attr, self if (1))) {
+    op(_LOAD_ATTR_METHOD_LAZY_DICT, (descr/4, owner -- attr, self)) {
         (void)descr;
         attr = sym_new_not_null(ctx);
         self = owner;