gh-126835: Avoid creating unnecessary tuple when looking for constant sequence during constant folding (#131054)

Author: WolframAlph

Include/internal/pycore_compile.h

@@ -14,6 +14,15 @@ extern "C" {
 #include "pycore_symtable.h"  // _Py_SourceLocation
 #include "pycore_instruction_sequence.h"
 
+/* A soft limit for stack use, to avoid excessive
+ * memory use for large constants, etc.
+ *
+ * The value 30 is plucked out of thin air.
+ * Code that could use more stack than this is
+ * rare, so the exact value is unimportant.
+ */
+#define _PY_STACK_USE_GUIDELINE 30
+
 struct _arena;   // Type defined in pycore_pyarena.h
 struct _mod;     // Type defined in pycore_ast.h
 

Python/codegen.c

@@ -37,15 +37,6 @@
 #define COMP_SETCOMP  2
 #define COMP_DICTCOMP 3
 
-/* A soft limit for stack use, to avoid excessive
- * memory use for large constants, etc.
- *
- * The value 30 is plucked out of thin air.
- * Code that could use more stack than this is
- * rare, so the exact value is unimportant.
- */
-#define STACK_USE_GUIDELINE 30
-
 #undef SUCCESS
 #undef ERROR
 #define SUCCESS 0
@@ -3209,7 +3200,7 @@ starunpack_helper_impl(compiler *c, location loc,
                        int build, int add, int extend, int tuple)
 {
     Py_ssize_t n = asdl_seq_LEN(elts);
-    int big = n + pushed + (injected_arg ? 1 : 0) > STACK_USE_GUIDELINE;
+    int big = n + pushed + (injected_arg ? 1 : 0) > _PY_STACK_USE_GUIDELINE;
     int seen_star = 0;
     for (Py_ssize_t i = 0; i < n; i++) {
         expr_ty elt = asdl_seq_GET(elts, i);
@@ -3364,7 +3355,7 @@ static int
 codegen_subdict(compiler *c, expr_ty e, Py_ssize_t begin, Py_ssize_t end)
 {
     Py_ssize_t i, n = end - begin;
-    int big = n*2 > STACK_USE_GUIDELINE;
+    int big = n*2 > _PY_STACK_USE_GUIDELINE;
     location loc = LOC(e);
     if (big) {
         ADDOP_I(c, loc, BUILD_MAP, 0);
@@ -3411,7 +3402,7 @@ codegen_dict(compiler *c, expr_ty e)
             ADDOP_I(c, loc, DICT_UPDATE, 1);
         }
         else {
-            if (elements*2 > STACK_USE_GUIDELINE) {
+            if (elements*2 > _PY_STACK_USE_GUIDELINE) {
                 RETURN_IF_ERROR(codegen_subdict(c, e, i - elements, i + 1));
                 if (have_dict) {
                     ADDOP_I(c, loc, DICT_UPDATE, 1);
@@ -3752,7 +3743,7 @@ maybe_optimize_method_call(compiler *c, expr_ty e)
     /* Check that there aren't too many arguments */
     argsl = asdl_seq_LEN(args);
     kwdsl = asdl_seq_LEN(kwds);
-    if (argsl + kwdsl + (kwdsl != 0) >= STACK_USE_GUIDELINE) {
+    if (argsl + kwdsl + (kwdsl != 0) >= _PY_STACK_USE_GUIDELINE) {
         return 0;
     }
     /* Check that there are no *varargs types of arguments. */
@@ -3849,7 +3840,7 @@ codegen_joined_str(compiler *c, expr_ty e)
 {
     location loc = LOC(e);
     Py_ssize_t value_count = asdl_seq_LEN(e->v.JoinedStr.values);
-    if (value_count > STACK_USE_GUIDELINE) {
+    if (value_count > _PY_STACK_USE_GUIDELINE) {
         _Py_DECLARE_STR(empty, "");
         ADDOP_LOAD_CONST_NEW(c, loc, Py_NewRef(&_Py_STR(empty)));
         ADDOP_NAME(c, loc, LOAD_METHOD, &_Py_ID(join), names);
@@ -3928,7 +3919,7 @@ codegen_subkwargs(compiler *c, location loc,
     Py_ssize_t i, n = end - begin;
     keyword_ty kw;
     assert(n > 0);
-    int big = n*2 > STACK_USE_GUIDELINE;
+    int big = n*2 > _PY_STACK_USE_GUIDELINE;
     if (big) {
         ADDOP_I(c, NO_LOCATION, BUILD_MAP, 0);
     }
@@ -3981,7 +3972,7 @@ codegen_call_helper_impl(compiler *c, location loc,
     nelts = asdl_seq_LEN(args);
     nkwelts = asdl_seq_LEN(keywords);
 
-    if (nelts + nkwelts*2 > STACK_USE_GUIDELINE) {
+    if (nelts + nkwelts*2 > _PY_STACK_USE_GUIDELINE) {
          goto ex_call;
     }
     for (i = 0; i < nelts; i++) {