GH-115819: Eliminate Boolean guards when value is known (GH-116355)

Author: markshannon

Include/internal/pycore_optimizer.h

@@ -90,6 +90,7 @@ extern _Py_UopsSymbol *_Py_uop_sym_new_type(
     _Py_UOpsContext *ctx, PyTypeObject *typ);
 extern _Py_UopsSymbol *_Py_uop_sym_new_const(_Py_UOpsContext *ctx, PyObject *const_val);
 extern _Py_UopsSymbol *_Py_uop_sym_new_null(_Py_UOpsContext *ctx);
+extern bool _Py_uop_sym_has_type(_Py_UopsSymbol *sym);
 extern bool _Py_uop_sym_matches_type(_Py_UopsSymbol *sym, PyTypeObject *typ);
 extern bool _Py_uop_sym_set_null(_Py_UopsSymbol *sym);
 extern bool _Py_uop_sym_set_non_null(_Py_UopsSymbol *sym);

Lib/test/test_capi/test_opt.py

@@ -331,7 +331,8 @@ def testfunc(a):
         ex = get_first_executor(testfunc)
         self.assertIsNotNone(ex)
         uops = get_opnames(ex)
-        self.assertIn("_GUARD_IS_NOT_NONE_POP", uops)
+        self.assertNotIn("_GUARD_IS_NONE_POP", uops)
+        self.assertNotIn("_GUARD_IS_NOT_NONE_POP", uops)
 
     def test_pop_jump_if_not_none(self):
         def testfunc(a):
@@ -347,7 +348,8 @@ def testfunc(a):
         ex = get_first_executor(testfunc)
         self.assertIsNotNone(ex)
         uops = get_opnames(ex)
-        self.assertIn("_GUARD_IS_NONE_POP", uops)
+        self.assertNotIn("_GUARD_IS_NONE_POP", uops)
+        self.assertNotIn("_GUARD_IS_NOT_NONE_POP", uops)
 
     def test_pop_jump_if_true(self):
         def testfunc(n):

Python/optimizer_analysis.c

@@ -292,6 +292,7 @@ remove_globals(_PyInterpreterFrame *frame, _PyUOpInstruction *buffer,
 #define sym_is_null _Py_uop_sym_is_null
 #define sym_new_const _Py_uop_sym_new_const
 #define sym_new_null _Py_uop_sym_new_null
+#define sym_has_type _Py_uop_sym_has_type
 #define sym_matches_type _Py_uop_sym_matches_type
 #define sym_set_null _Py_uop_sym_set_null
 #define sym_set_non_null _Py_uop_sym_set_non_null
@@ -324,6 +325,16 @@ optimize_to_bool(
     return 0;
 }
 
+static void
+eliminate_pop_guard(_PyUOpInstruction *this_instr, bool exit)
+{
+    REPLACE_OP(this_instr, _POP_TOP, 0, 0);
+    if (exit) {
+        REPLACE_OP((this_instr+1), _EXIT_TRACE, 0, 0);
+        this_instr[1].target = this_instr->target;
+    }
+}
+
 /* 1 for success, 0 for not ready, cannot error at the moment. */
 static int
 optimize_uops(

Python/optimizer_bytecodes.c

@@ -21,6 +21,7 @@ typedef struct _Py_UOpsAbstractFrame _Py_UOpsAbstractFrame;
 #define sym_new_const _Py_uop_sym_new_const
 #define sym_new_null _Py_uop_sym_new_null
 #define sym_matches_type _Py_uop_sym_matches_type
+#define sym_has_type _Py_uop_sym_has_type
 #define sym_set_null _Py_uop_sym_set_null
 #define sym_set_non_null _Py_uop_sym_set_non_null
 #define sym_set_type _Py_uop_sym_set_type
@@ -36,6 +37,8 @@ optimize_to_bool(
     _Py_UopsSymbol *value,
     _Py_UopsSymbol **result_ptr);
 
+extern void
+eliminate_pop_guard(_PyUOpInstruction *this_instr, bool exit)
 
 static int
 dummy_func(void) {
@@ -557,7 +560,45 @@ dummy_func(void) {
        (void)iter;
     }
 
+    op(_GUARD_IS_TRUE_POP, (flag -- )) {
+        if (sym_is_const(flag)) {
+            PyObject *value = sym_get_const(flag);
+            assert(value != NULL);
+            eliminate_pop_guard(this_instr, value != Py_True);
+        }
+    }
+
+    op(_GUARD_IS_FALSE_POP, (flag -- )) {
+        if (sym_is_const(flag)) {
+            PyObject *value = sym_get_const(flag);
+            assert(value != NULL);
+            eliminate_pop_guard(this_instr, value != Py_False);
+        }
+    }
+
+    op(_GUARD_IS_NONE_POP, (flag -- )) {
+        if (sym_is_const(flag)) {
+            PyObject *value = sym_get_const(flag);
+            assert(value != NULL);
+            eliminate_pop_guard(this_instr, !Py_IsNone(value));
+        }
+        else if (sym_has_type(flag)) {
+            assert(!sym_matches_type(flag, &_PyNone_Type));
+            eliminate_pop_guard(this_instr, true);
+        }
+    }
 
+    op(_GUARD_IS_NOT_NONE_POP, (flag -- )) {
+        if (sym_is_const(flag)) {
+            PyObject *value = sym_get_const(flag);
+            assert(value != NULL);
+            eliminate_pop_guard(this_instr, Py_IsNone(value));
+        }
+        else if (sym_has_type(flag)) {
+            assert(!sym_matches_type(flag, &_PyNone_Type));
+            eliminate_pop_guard(this_instr, false);
+        }
+    }
 
 
 // END BYTECODES //

Python/optimizer_cases.c.h

@@ -231,6 +231,15 @@ _Py_uop_sym_new_null(_Py_UOpsContext *ctx)
     return null_sym;
 }
 
+bool
+_Py_uop_sym_has_type(_Py_UopsSymbol *sym)
+{
+    if (_Py_uop_sym_is_bottom(sym)) {
+        return false;
+    }
+    return sym->typ != NULL;
+}
+
 bool
 _Py_uop_sym_matches_type(_Py_UopsSymbol *sym, PyTypeObject *typ)
 {