gh-106290: Fix edge cases around uops (#106319)

- Tweak uops debugging output
- Fix the bug from gh-106290
- Rename `SET_IP` to `SAVE_IP` (per faster-cpython/ideas#558)
- Add a `SAVE_IP` uop at the start of the trace (ditto)
- Allow `unbound_local_error`; this gives us uops for `LOAD_FAST_CHECK`, `LOAD_CLOSURE`, and `DELETE_FAST`
- Longer traces
- Support `STORE_FAST_LOAD_FAST`, `STORE_FAST_STORE_FAST`
- Add deps on pycore_uops.h to Makefile(.pre.in)

Author: gvanrossum

Include/internal/pycore_uops.h

@@ -8,7 +8,7 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE define"
 #endif
 
-#define _Py_UOP_MAX_TRACE_LENGTH 16
+#define _Py_UOP_MAX_TRACE_LENGTH 32
 
 typedef struct {
     int opcode;

Makefile.pre.in

@@ -1800,6 +1800,7 @@ PYTHON_HEADERS= \
 		$(srcdir)/Include/internal/pycore_unionobject.h \
 		$(srcdir)/Include/internal/pycore_unicodeobject.h \
 		$(srcdir)/Include/internal/pycore_unicodeobject_generated.h \
+		$(srcdir)/Include/internal/pycore_uops.h \
 		$(srcdir)/Include/internal/pycore_warnings.h \
 		$(srcdir)/Include/internal/pycore_weakref.h \
 		$(DTRACE_HEADERS) \

Python/ceval.c

@@ -2773,24 +2773,26 @@ void Py_LeaveRecursiveCall(void)
 _PyInterpreterFrame *
 _PyUopExecute(_PyExecutorObject *executor, _PyInterpreterFrame *frame, PyObject **stack_pointer)
 {
-#ifdef LLTRACE
+#ifdef Py_DEBUG
     char *uop_debug = Py_GETENV("PYTHONUOPSDEBUG");
     int lltrace = 0;
     if (uop_debug != NULL && *uop_debug >= '0') {
         lltrace = *uop_debug - '0';  // TODO: Parse an int and all that
     }
-    if (lltrace >= 2) {
-        PyCodeObject *code = _PyFrame_GetCode(frame);
-        _Py_CODEUNIT *instr = frame->prev_instr + 1;
-        fprintf(stderr,
-                "Entering _PyUopExecute for %s (%s:%d) at offset %ld\n",
-                PyUnicode_AsUTF8(code->co_qualname),
-                PyUnicode_AsUTF8(code->co_filename),
-                code->co_firstlineno,
-                (long)(instr - (_Py_CODEUNIT *)code->co_code_adaptive));
-    }
+#define DPRINTF(level, ...) \
+    if (lltrace >= (level)) { fprintf(stderr, __VA_ARGS__); }
+#else
+#define DPRINTF(level, ...)
 #endif
 
+    DPRINTF(3,
+            "Entering _PyUopExecute for %s (%s:%d) at offset %ld\n",
+            PyUnicode_AsUTF8(_PyFrame_GetCode(frame)->co_qualname),
+            PyUnicode_AsUTF8(_PyFrame_GetCode(frame)->co_filename),
+            _PyFrame_GetCode(frame)->co_firstlineno,
+            (long)(frame->prev_instr + 1 -
+                   (_Py_CODEUNIT *)_PyFrame_GetCode(frame)->co_code_adaptive));
+
     PyThreadState *tstate = _PyThreadState_GET();
     _PyUOpExecutorObject *self = (_PyUOpExecutorObject *)executor;
 
@@ -2803,7 +2805,7 @@ _PyUopExecute(_PyExecutorObject *executor, _PyInterpreterFrame *frame, PyObject
     }
 
     OBJECT_STAT_INC(optimization_traces_executed);
-    _Py_CODEUNIT *ip_offset = (_Py_CODEUNIT *)_PyFrame_GetCode(frame)->co_code_adaptive - 1;
+    _Py_CODEUNIT *ip_offset = (_Py_CODEUNIT *)_PyFrame_GetCode(frame)->co_code_adaptive;
     int pc = 0;
     int opcode;
     uint64_t operand;
@@ -2812,14 +2814,11 @@ _PyUopExecute(_PyExecutorObject *executor, _PyInterpreterFrame *frame, PyObject
         opcode = self->trace[pc].opcode;
         operand = self->trace[pc].operand;
         oparg = (int)operand;
-#ifdef LLTRACE
-        if (lltrace >= 3) {
-            const char *opname = opcode < 256 ? _PyOpcode_OpName[opcode] : _PyOpcode_uop_name[opcode];
-            int stack_level = (int)(stack_pointer - _PyFrame_Stackbase(frame));
-            fprintf(stderr, "  uop %s, operand %" PRIu64 ", stack_level %d\n",
-                    opname, operand, stack_level);
-        }
-#endif
+        DPRINTF(3,
+                "  uop %s, operand %" PRIu64 ", stack_level %d\n",
+                opcode < 256 ? _PyOpcode_OpName[opcode] : _PyOpcode_uop_name[opcode],
+                operand,
+                (int)(stack_pointer - _PyFrame_Stackbase(frame)));
         pc++;
         OBJECT_STAT_INC(optimization_uops_executed);
         switch (opcode) {
@@ -2828,14 +2827,15 @@ _PyUopExecute(_PyExecutorObject *executor, _PyInterpreterFrame *frame, PyObject
 #define ENABLE_SPECIALIZATION 0
 #include "executor_cases.c.h"
 
-            case SET_IP:
+            case SAVE_IP:
             {
                 frame->prev_instr = ip_offset + oparg;
                 break;
             }
 
             case EXIT_TRACE:
             {
+                frame->prev_instr--;  // Back up to just before destination
                 _PyFrame_SetStackPointer(frame, stack_pointer);
                 Py_DECREF(self);
                 return frame;
@@ -2850,6 +2850,13 @@ _PyUopExecute(_PyExecutorObject *executor, _PyInterpreterFrame *frame, PyObject
         }
     }
 
+unbound_local_error:
+    format_exc_check_arg(tstate, PyExc_UnboundLocalError,
+        UNBOUNDLOCAL_ERROR_MSG,
+        PyTuple_GetItem(_PyFrame_GetCode(frame)->co_localsplusnames, oparg)
+    );
+    goto error;
+
 pop_4_error:
     STACK_SHRINK(1);
 pop_3_error:
@@ -2861,23 +2868,16 @@ _PyUopExecute(_PyExecutorObject *executor, _PyInterpreterFrame *frame, PyObject
 error:
     // On ERROR_IF we return NULL as the frame.
     // The caller recovers the frame from cframe.current_frame.
-#ifdef LLTRACE
-    if (lltrace >= 2) {
-        fprintf(stderr, "Error: [Opcode %d, operand %" PRIu64 "]\n", opcode, operand);
-    }
-#endif
+    DPRINTF(2, "Error: [Opcode %d, operand %" PRIu64 "]\n", opcode, operand);
     _PyFrame_SetStackPointer(frame, stack_pointer);
     Py_DECREF(self);
     return NULL;
 
 deoptimize:
     // On DEOPT_IF we just repeat the last instruction.
     // This presumes nothing was popped from the stack (nor pushed).
-#ifdef LLTRACE
-    if (lltrace >= 2) {
-        fprintf(stderr, "DEOPT: [Opcode %d, operand %" PRIu64 "]\n", opcode, operand);
-    }
-#endif
+    DPRINTF(2, "DEOPT: [Opcode %d, operand %" PRIu64 "]\n", opcode, operand);
+    frame->prev_instr--;  // Back up to just before destination
     _PyFrame_SetStackPointer(frame, stack_pointer);
     Py_DECREF(self);
     return frame;