Simplify and future proof NOP counting in the peepholer.

No longer assumes that the input is NOP free.

diff --git a/Python/compile.c b/Python/compile.c
index f8083074070bbf8fa2494fe24fdddf17d27110f2..d47f8d53fe4519c8af68b853dab5fde7ef568094 100644 (file)
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -536,8 +536,7 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                goto exitUnchanged;
        assert(PyList_Check(consts));
 
-       for (i=0, nops=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
-               addrmap[i] = i - nops;
+       for (i=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
                opcode = codestr[i];
 
                lastlc = cumlc;
@@ -560,7 +559,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                        SETARG(codestr, i, j);
                        codestr[i+3] = POP_TOP;
                        codestr[i+4] = NOP;
-                       nops++;
                        break;
 
                /* not a is b -->  a is not b
@@ -575,7 +573,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                                continue;
                        SETARG(codestr, i, (j^1));
                        codestr[i+3] = NOP;
-                       nops++;
                        break;
 
                /* Replace LOAD_GLOBAL/LOAD_NAME None with LOAD_CONST None */
@@ -604,7 +601,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                            !PyObject_IsTrue(PyList_GET_ITEM(consts, j)))
                                continue;
                        memset(codestr+i, NOP, 7);
-                       nops += 7;
                        break;
 
                /* Try to fold tuples of constants.
@@ -619,7 +615,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                            codestr[h] == LOAD_CONST  && 
                            ISBASICBLOCK(blocks, h, 3*(j+1))  &&
                            tuple_of_constants(&codestr[h], j, consts)) {
-                               nops += 3 * j;
                                break;
                        }
                        /* Intentional fallthrough */
@@ -631,16 +626,13 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                                continue;
                        if (j == 1) {
                                memset(codestr+i, NOP, 6);
-                               nops += 6;
                        } else if (j == 2) {
                                codestr[i] = ROT_TWO;
                                memset(codestr+i+1, NOP, 5);
-                               nops += 5;
                        } else if (j == 3) {
                                codestr[i] = ROT_THREE;
                                codestr[i+1] = ROT_TWO;
                                memset(codestr+i+2, NOP, 4);
-                               nops += 4;
                        }
                        break;
 
@@ -704,12 +696,16 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                           !ISBASICBLOCK(blocks,i,5))
                               continue;
                        memset(codestr+i+1, NOP, 4);
-                       nops += 4;
                        break;
                }
        }
 
        /* Fixup linenotab */
+       for (i=0, nops=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
+               addrmap[i] = i - nops;
+               if (codestr[i] == NOP)
+                       nops++;
+       }
        cum_orig_line = 0;
        last_line = 0;
        for (i=0 ; i < tabsiz ; i+=2) {
@@ -749,9 +745,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
                while (adj--)
                        codestr[h++] = codestr[i++];
        }
-       /* The following assertion detects the presence of NOPs in the input
-          bytecode.  The compiler never produces NOPs so far; if one day it
-          does, the way 'nops' is counted above must be changed. */
        assert(h + nops == codelen);
 
        code = PyString_FromStringAndSize((char *)codestr, h);