Move unpredictable jump detection to the cases generator

Author: Fidget-Spinner

Include/internal/pycore_interp_structs.h

@@ -759,7 +759,6 @@ typedef _Py_CODEUNIT *(*_PyJitEntryFuncPtr)(struct _PyExecutorObject *exec, _PyI
 
 typedef struct _PyJitTracerState {
     bool dependencies_still_valid;
-    bool dynamic_jump_taken;
     bool prev_instr_is_super;
     int code_max_size;
     int code_curr_size;

Include/internal/pycore_opcode_metadata.h

@@ -333,12 +333,6 @@ GETITEM(PyObject *v, Py_ssize_t i) {
 #define RECORD_BRANCH_TAKEN(bitset, flag)
 #endif
 
-#if _Py_TIER2
-#   define RECORD_DYNAMIC_JUMP_TAKEN() tstate->interp->jit_state.dynamic_jump_taken = true;
-#else
-#   define RECORD_DYNAMIC_JUMP_TAKEN()
-#endif
-
 #define UNBOUNDLOCAL_ERROR_MSG \
     "cannot access local variable '%s' where it is not associated with a value"
 #define UNBOUNDFREE_ERROR_MSG \

Python/ceval_macros.h

@@ -632,8 +632,10 @@ _PyJit_translate_single_bytecode_to_trace(
         goto done;
     }
 
-    // Strange control-flow, unsupported opcode, etc.
-    if (tstate->interp->jit_state.dynamic_jump_taken) {
+    // Strange control-flow
+    bool has_dynamic_jump_taken = OPCODE_HAS_UNPREDICTABLE_JUMP(opcode) &&
+        (next_instr != this_instr + 1 + _PyOpcode_Caches[_PyOpcode_Deopt[opcode]]);
+    if (has_dynamic_jump_taken) {
         DPRINTF(2, "Unsupported: dynamic jump taken\n");
         goto unsupported;
     }
@@ -974,7 +976,6 @@ _PyJit_TryInitializeTracing(PyThreadState *tstate, _PyInterpreterFrame *frame, _
     tstate->interp->jit_state.prev_instr_frame = frame;
     tstate->interp->jit_state.prev_instr_oparg = oparg;
     tstate->interp->jit_state.prev_instr_stacklevel = curr_stackdepth;
-    tstate->interp->jit_state.dynamic_jump_taken = false;
     tstate->interp->jit_state.prev_instr_is_super = false;
     _Py_BloomFilter_Init(&tstate->interp->jit_state.dependencies);
     return 1;

Python/generated_cases.c.h

@@ -910,7 +910,11 @@ def stmt_has_jump_on_unpredictable_path(stmt: Stmt, branches_seen: int) -> tuple
                 return True, branches_seen
         return False, branches_seen
     elif isinstance(stmt, IfStmt):
-        return True, branches_seen + 1
+        predict, seen = stmt_has_jump_on_unpredictable_path(stmt.body, branches_seen)
+        if stmt.else_body:
+            predict_else, seen_else = stmt_has_jump_on_unpredictable_path(stmt.else_body, branches_seen)
+            return predict != predict_else, seen + seen_else + 1
+        return predict, seen + 1
     elif isinstance(stmt, MacroIfStmt):
         predict, seen = stmt_has_jump_on_unpredictable_path_body(stmt.body, branches_seen)
         if stmt.else_body:

Python/optimizer.c

@@ -129,7 +129,6 @@ def __init__(self, out: CWriter, labels: dict[str, Label], cannot_escape: bool =
             "DISPATCH": self.dispatch,
             "INSTRUCTION_SIZE": self.instruction_size,
             "stack_pointer": self.stack_pointer,
-            "JUMPBY": self.jumpby,
             "DISPATCH_SAME_OPARG": self.dispatch_same_oparg,
         }
         self.out = out
@@ -422,30 +421,6 @@ def sync_sp(
         storage.stack.clear(self.out)
         return True
 
-    def jumpby(
-        self,
-        tkn: Token,
-        tkn_iter: TokenIterator,
-        uop: CodeSection,
-        storage: Storage,
-        inst: Instruction | None,
-    ) -> bool:
-        self.out.start_line()
-        self.emit(tkn)
-        lparen = next(tkn_iter)
-        self.emit(lparen)
-        jump = next(tkn_iter)
-        self.emit(jump)
-        emit_to(self.out, tkn_iter, "RPAREN")
-        next(tkn_iter)
-        self.emit(");\n")
-
-
-        if uop.properties.unpredictable_jump and jump.text != "0":
-            self.out.start_line()
-            self.emit("RECORD_DYNAMIC_JUMP_TAKEN();\n")
-        return True
-
     def stack_pointer(
         self,
         tkn: Token,
@@ -780,6 +755,8 @@ def cflags(p: Properties) -> str:
         flags.append("HAS_PURE_FLAG")
     if p.no_save_ip:
         flags.append("HAS_NO_SAVE_IP_FLAG")
+    if p.unpredictable_jump:
+        flags.append("HAS_UNPREDICTABLE_JUMP_FLAG")
     if flags:
         return " | ".join(flags)
     else:

Tools/cases_generator/analyzer.py

@@ -56,6 +56,7 @@
     "ERROR_NO_POP",
     "NO_SAVE_IP",
     "PERIODIC",
+    "UNPREDICTABLE_JUMP",
 ]