SF patch #864059: optimize eval_frame

Simplified version of Neal Norwitz's patch which adds gotos for
opcodes that set "why".  This skips a number of tests where the
outcome of the tests are known in advance.

diff --git a/Python/ceval.c b/Python/ceval.c
index f198da1a8f5c09ac00e695c415082b8ca86a26fc..c6e04702443e23e13c042b864aeb7d184a32bfd3 100644 (file)
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1578,12 +1578,12 @@ eval_frame(PyFrameObject *f)
 #endif
                case BREAK_LOOP:
                        why = WHY_BREAK;
-                       break;
+                       goto fast_block_end;
 
                case CONTINUE_LOOP:
                        retval = PyInt_FromLong(oparg);
                        why = WHY_CONTINUE;
-                       break;
+                       goto fast_block_end;
 
                case RAISE_VARARGS:
                        u = v = w = NULL;
@@ -1620,14 +1620,13 @@ eval_frame(PyFrameObject *f)
                case RETURN_VALUE:
                        retval = POP();
                        why = WHY_RETURN;
-                       break;
+                       goto fast_block_end;
 
                case YIELD_VALUE:
                        retval = POP();
                        f->f_stacktop = stack_pointer;
                        why = WHY_YIELD;
-                       break;
-
+                       goto fast_yield;
 
                case EXEC_STMT:
                        w = TOP();
@@ -2327,6 +2326,7 @@ eval_frame(PyFrameObject *f)
 
                /* Unwind stacks if a (pseudo) exception occurred */
 
+fast_block_end:
                while (why != WHY_NOT && why != WHY_YIELD && f->f_iblock > 0) {
                        PyTryBlock *b = PyFrame_BlockPop(f);
 
@@ -2410,6 +2410,7 @@ eval_frame(PyFrameObject *f)
        if (why != WHY_RETURN && why != WHY_YIELD)
                retval = NULL;
 
+fast_yield:
        if (tstate->use_tracing) {
                if (tstate->c_tracefunc
                    && (why == WHY_RETURN || why == WHY_YIELD)) {