gh-144145: Track nullness of properties in the Tier 2 JIT optimizer

Include/internal/pycore_optimizer.h

@@ -37,10 +37,15 @@ typedef struct _JitOptContext {
     // Arena for the symbolic types.
     ty_arena t_arena;
 
+    // Arena for the descriptor mappings.
+    descr_arena d_arena;
+
     JitOptRef *n_consumed;
     JitOptRef *limit;
     JitOptRef locals_and_stack[MAX_ABSTRACT_INTERP_SIZE];
     _PyJitUopBuffer out_buffer;
+    // Index of the last escaped uop in out_buffer.
+    int last_escape_index;
 } JitOptContext;
 
 
@@ -295,6 +300,9 @@ extern JitOptRef _Py_uop_sym_new_truthiness(JitOptContext *ctx, JitOptRef value,
 extern bool _Py_uop_sym_is_compact_int(JitOptRef sym);
 extern JitOptRef _Py_uop_sym_new_compact_int(JitOptContext *ctx);
 extern void _Py_uop_sym_set_compact_int(JitOptContext *ctx,  JitOptRef sym);
+extern JitOptRef _Py_uop_sym_new_descr_object(JitOptContext *ctx, unsigned int type_version);
+extern JitOptRef _Py_uop_sym_get_attr(JitOptContext *ctx, JitOptRef ref, uint16_t slot_index);
+extern JitOptRef _Py_uop_sym_set_attr(JitOptContext *ctx, JitOptRef ref, uint16_t slot_index, JitOptRef value);
 extern JitOptRef _Py_uop_sym_new_predicate(JitOptContext *ctx, JitOptRef lhs_ref, JitOptRef rhs_ref, JitOptPredicateKind kind);
 extern void _Py_uop_sym_apply_predicate_narrowing(JitOptContext *ctx, JitOptRef sym, bool branch_is_true);
 

Include/internal/pycore_optimizer_types.h

@@ -16,6 +16,10 @@ extern "C" {
 
 #define TY_ARENA_SIZE (UOP_MAX_TRACE_LENGTH * 5)
 
+// Maximum descriptor mappings per object tracked symbolically
+#define MAX_SYMBOLIC_DESCR_SIZE 16
+#define DESCR_ARENA_SIZE (MAX_SYMBOLIC_DESCR_SIZE * 100)
+
 // Need extras for root frame and for overflow frame (see TRACE_STACK_PUSH())
 #define MAX_ABSTRACT_FRAME_DEPTH (16)
 
@@ -41,6 +45,7 @@ typedef enum _JitSymType {
     JIT_SYM_TRUTHINESS_TAG = 9,
     JIT_SYM_COMPACT_INT = 10,
     JIT_SYM_PREDICATE_TAG = 11,
+    JIT_SYM_DESCR_TAG = 12,
 } JitSymType;
 
 typedef struct _jit_opt_known_class {
@@ -91,6 +96,31 @@ typedef struct {
     uint8_t tag;
 } JitOptCompactInt;
 
+/*
+Mapping from slot index or attribute offset to its symbolic value.
+SAFETY:
+This structure is used for both STORE_ATTR_SLOT and STORE_ATTR_INSTANCE_VALUE.
+These two never appear on the same object type because:
+__slots__ classes don't have Py_TPFLAGS_INLINE_VALUES
+Therefore, there is no index collision between slot offsets and inline value offsets.
+Note:
+STORE_ATTR_WITH_HINT is NOT currently tracked.
+If we want to track it in the future, we need to be careful about
+potential index collisions with STORE_ATTR_INSTANCE_VALUE.
+*/
+typedef struct {
+    uint16_t slot_index;
+    uint16_t symbol;
+} JitOptDescrMapping;
+
+typedef struct _jit_opt_descr {
+    uint8_t tag;
+    uint8_t num_descrs;
+    uint16_t last_modified_index;  // Index in out_buffer when this object was last modified
+    uint32_t type_version;
+    JitOptDescrMapping *descrs;
+} JitOptDescrObject;
+
 typedef union _jit_opt_symbol {
     uint8_t tag;
     JitOptKnownClass cls;
@@ -99,6 +129,7 @@ typedef union _jit_opt_symbol {
     JitOptTuple tuple;
     JitOptTruthiness truthiness;
     JitOptCompactInt compact;
+    JitOptDescrObject descr;
     JitOptPredicate predicate;
 } JitOptSymbol;
 
@@ -128,6 +159,11 @@ typedef struct ty_arena {
     JitOptSymbol arena[TY_ARENA_SIZE];
 } ty_arena;
 
+typedef struct descr_arena {
+    int descr_curr_number;
+    int descr_max_number;
+    JitOptDescrMapping arena[DESCR_ARENA_SIZE];
+} descr_arena;
 
 #ifdef __cplusplus
 }