Fewer jumps in ERROR_IF expansion

Author: gvanrossum

Python/bytecodes.c

@@ -260,7 +260,7 @@ dummy_func(
             JUMPBY(INLINE_CACHE_ENTRIES_BINARY_OP);
         }
 
-        // This is a weird one. It's a super-instruction for
+        // This is a subtle one. It's a super-instruction for
         // BINARY_OP_ADD_UNICODE followed by STORE_FAST
         // where the store goes into the left argument.
         // So the inputs are the same as for all BINARY_OP

Python/ceval.c

@@ -1275,6 +1275,14 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             goto error;
         }
 
+pop_4_error:
+    STACK_SHRINK(1);
+pop_3_error:
+    STACK_SHRINK(1);
+pop_2_error:
+    STACK_SHRINK(1);
+pop_1_error:
+    STACK_SHRINK(1);
 error:
         call_shape.kwnames = NULL;
         /* Double-check exception status. */

Python/generated_cases.c.h

@@ -100,9 +100,9 @@ def write_instr(instr: InstDef, predictions: set[str], indent: str, f: TextIO, d
             # ERROR_IF() must remove the inputs from the stack.
             # The code block is responsible for DECREF()ing them.
             if ninputs:
-                f.write(f"{space}if ({cond}) {{ STACK_SHRINK({ninputs}); goto {label}; }}\n")
+                f.write(f"{space}if ({cond}) goto pop_{ninputs}_{label};\n")
             else:
-                f.write(f"{space}if ({cond}) {{ goto {label}; }}\n")
+                f.write(f"{space}if ({cond}) goto {label};\n")
         else:
             f.write(line)
     noutputs = len(instr.outputs or ())