shift jump mask for backwards jumps

python · markshannon · Apr 11, 2022 · Apr 6, 2022 · Apr 6, 2022 · Apr 6, 2022
commit 3f5626c00ef0e27a7a7310bda1f199f4c7cdb8e4
@@ -3697,22 +3697,22 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
                   opcode == POP_JUMP_BACKWARD_IF_FALSE ||
                   opcode == POP_JUMP_FORWARD_IF_TRUE ||
                   opcode == POP_JUMP_BACKWARD_IF_TRUE);
-            int jump = (1 << (sign + 1)) & when_to_jump_mask;
+            int jump = (9 << (sign + 1)) & when_to_jump_mask;
            if (!jump) {
                next_instr++;
-                NOTRACE_DISPATCH();
            }
-            else {
-                if (opcode == POP_JUMP_BACKWARD_IF_FALSE ||
-                    opcode == POP_JUMP_BACKWARD_IF_TRUE) {
-                    JUMPBY(1 - oparg);
-                }
-                else {
-                    JUMPBY(1 + oparg);
-                }
+            else if (jump >= 8) {
+                assert(opcode == POP_JUMP_BACKWARD_IF_TRUE ||
+                       opcode == POP_JUMP_BACKWARD_IF_FALSE);
+                JUMPBY(1 - oparg);
                CHECK_EVAL_BREAKER();
-                NOTRACE_DISPATCH();
            }
+            else {
+                assert(opcode == POP_JUMP_FORWARD_IF_TRUE ||
+                       opcode == POP_JUMP_FORWARD_IF_FALSE);
+                JUMPBY(1 + oparg);
+            }
+            NOTRACE_DISPATCH();
        }

        TARGET(COMPARE_OP_INT_JUMP) {
@@ -3740,29 +3740,29 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
                   opcode == POP_JUMP_BACKWARD_IF_FALSE ||
                   opcode == POP_JUMP_FORWARD_IF_TRUE ||
                   opcode == POP_JUMP_BACKWARD_IF_TRUE);
-            int jump = (1 << (sign + 1)) & when_to_jump_mask;
+            int jump = (9 << (sign + 1)) & when_to_jump_mask;
            if (!jump) {
                next_instr++;
-                NOTRACE_DISPATCH();
            }
-            else {
-                if (opcode == POP_JUMP_BACKWARD_IF_FALSE ||
-                    opcode == POP_JUMP_BACKWARD_IF_TRUE) {
-                    JUMPBY(1 - oparg);
-                }
-                else {
-                    JUMPBY(1 + oparg);
-                }
+            else if (jump >= 8) {
+                assert(opcode == POP_JUMP_BACKWARD_IF_TRUE ||
+                       opcode == POP_JUMP_BACKWARD_IF_FALSE);
+                JUMPBY(1 - oparg);
                CHECK_EVAL_BREAKER();
-                NOTRACE_DISPATCH();
            }
+            else {
+                assert(opcode == POP_JUMP_FORWARD_IF_TRUE ||
+                       opcode == POP_JUMP_FORWARD_IF_FALSE);
+                JUMPBY(1 + oparg);
+            }
+            NOTRACE_DISPATCH();
        }

        TARGET(COMPARE_OP_STR_JUMP) {
            assert(cframe.use_tracing == 0);
            // Combined: COMPARE_OP (str == str or str != str) + POP_JUMP_(direction)_IF_(true/false)
            _PyCompareOpCache *cache = (_PyCompareOpCache *)next_instr;
-            int invert = cache->mask;
+            int when_to_jump_mask = cache->mask;
            PyObject *right = TOP();
            PyObject *left = SECOND();
            DEOPT_IF(!PyUnicode_CheckExact(left), COMPARE_OP);
@@ -3783,23 +3783,23 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
            Py_DECREF(left);
            Py_DECREF(right);
            assert(res == 0 || res == 1);
-            assert(invert == 0 || invert == 1);
-            int jump = res ^ invert;
+            int sign = 1 - res;
+            int jump = (9 << (sign + 1)) & when_to_jump_mask;
            if (!jump) {
                next_instr++;
-                NOTRACE_DISPATCH();
            }
-            else {
-                if (opcode == POP_JUMP_BACKWARD_IF_FALSE ||
-                    opcode == POP_JUMP_BACKWARD_IF_TRUE) {
-                    JUMPBY(1 - oparg);
-                }
-                else {
-                    JUMPBY(1 + oparg);
-                }
+            else if (jump >= 8) {
+                assert(opcode == POP_JUMP_BACKWARD_IF_TRUE ||
+                       opcode == POP_JUMP_BACKWARD_IF_FALSE);
+                JUMPBY(1 - oparg);
                CHECK_EVAL_BREAKER();
-                NOTRACE_DISPATCH();
            }
+            else {
+                assert(opcode == POP_JUMP_FORWARD_IF_TRUE ||
+                       opcode == POP_JUMP_FORWARD_IF_FALSE);
+                JUMPBY(1 + oparg);
+            }
+            NOTRACE_DISPATCH();
        }

        TARGET(IS_OP) {

diff --git a/Python/specialize.c b/Python/specialize.c
@@ -1908,6 +1908,10 @@ _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
        next_opcode == POP_JUMP_BACKWARD_IF_FALSE) {
        when_to_jump_mask = (1 | 2 | 4) & ~when_to_jump_mask;
    }
+    if (next_opcode == POP_JUMP_BACKWARD_IF_TRUE ||
+        next_opcode == POP_JUMP_BACKWARD_IF_FALSE) {
+        when_to_jump_mask <<= 3;
+    }
    if (Py_TYPE(lhs) != Py_TYPE(rhs)) {
        SPECIALIZATION_FAIL(COMPARE_OP, compare_op_fail_kind(lhs, rhs));
        goto failure;
@@ -1935,7 +1939,7 @@ _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
        }
        else {
            _Py_SET_OPCODE(*instr, COMPARE_OP_STR_JUMP);
-            cache->mask = (when_to_jump_mask & 2) == 0;
+            cache->mask = when_to_jump_mask;
            goto success;
        }
    }