Revert the previous enhancement to the bytecode optimizer.
The additional code complexity and new NOP opcode were not worth it.
diff --git a/Python/compile.c b/Python/compile.c
index 4afd0eb..57f0edb 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -328,43 +328,6 @@
#define ABSOLUTE_JUMP(op) (op==JUMP_ABSOLUTE || op==CONTINUE_LOOP)
#define GETJUMPTGT(arr, i) (GETARG(arr,i) + (ABSOLUTE_JUMP(arr[i]) ? 0 : i+3))
#define SETARG(arr, i, val) arr[i+2] = val>>8; arr[i+1] = val & 255
-#define CODESIZE(op) (HAS_ARG(op) ? 3 : 1)
-#define ISBASICBLOCK(blocks, start, bytes) (blocks[start]==blocks[start+bytes-1])
-
-static unsigned int *
-markblocks(unsigned char *code, int len)
-{
- unsigned int *blocks = PyMem_Malloc(len*sizeof(int));
- int i,j, opcode, oldblock, newblock, blockcnt = 0;
-
- if (blocks == NULL)
- return NULL;
- memset(blocks, 0, len*sizeof(int));
- for (i=0 ; i<len ; i+=CODESIZE(opcode)) {
- opcode = code[i];
- switch (opcode) {
- case FOR_ITER:
- case JUMP_FORWARD:
- case JUMP_IF_FALSE:
- case JUMP_IF_TRUE:
- case JUMP_ABSOLUTE:
- case CONTINUE_LOOP:
- case SETUP_LOOP:
- case SETUP_EXCEPT:
- case SETUP_FINALLY:
- j = GETJUMPTGT(code, i);
- oldblock = blocks[j];
- newblock = ++blockcnt;
- for (; j<len ; j++) {
- if (blocks[j] != (unsigned)oldblock)
- break;
- blocks[j] = newblock;
- }
- break;
- }
- }
- return blocks;
-}
static PyObject *
optimize_code(PyObject *code, PyObject* consts)
@@ -372,24 +335,18 @@
int i, j, codelen;
int tgt, tgttgt, opcode;
unsigned char *codestr;
- unsigned int *blocks;
/* Make a modifiable copy of the code string */
if (!PyString_Check(code))
goto exitUnchanged;
codelen = PyString_Size(code);
codestr = PyMem_Malloc(codelen);
- if (codestr == NULL)
+ if (codestr == NULL)
goto exitUnchanged;
codestr = memcpy(codestr, PyString_AS_STRING(code), codelen);
- blocks = markblocks(codestr, codelen);
- if (blocks == NULL) {
- PyMem_Free(codestr);
- goto exitUnchanged;
- }
assert(PyTuple_Check(consts));
- for (i=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
+ for (i=0 ; i<codelen-7 ; i += HAS_ARG(codestr[i]) ? 3 : 1) {
opcode = codestr[i];
switch (opcode) {
@@ -406,8 +363,8 @@
SETARG(codestr, i, 4);
break;
- /* Replace BUILD_SEQN 2 UNPACK_SEQN 2 with ROT2 JMP+2 NOP NOP.
- Replace BUILD_SEQN 3 UNPACK_SEQN 3 with ROT3 ROT2 JMP+1 NOP.
+ /* Replace BUILD_SEQN 2 UNPACK_SEQN 2 with ROT2 JMP+2.
+ Replace BUILD_SEQN 3 UNPACK_SEQN 3 with ROT3 ROT2 JMP+1.
Note, these opcodes occur together only in assignment
statements. Accordingly, the unpack opcode is never
a jump target. */
@@ -420,8 +377,8 @@
codestr[i] = ROT_TWO;
codestr[i+1] = JUMP_FORWARD;
SETARG(codestr, i+1, 2);
- codestr[i+4] = NOP;
- codestr[i+5] = NOP;
+ codestr[i+4] = DUP_TOP; /* Filler codes used as NOPs */
+ codestr[i+5] = POP_TOP;
continue;
}
if (GETARG(codestr, i) == 3 && \
@@ -429,41 +386,11 @@
codestr[i] = ROT_THREE;
codestr[i+1] = ROT_TWO;
codestr[i+2] = JUMP_FORWARD;
- SETARG(codestr, i+2, 1);
- codestr[i+5] = NOP;
+ SETARG(codestr, i+2, 1);
+ codestr[i+5] = DUP_TOP;
}
break;
- /* Simplify inverted tests.
- Must verify that sequence is a basic block because the jump
- can itself be a jump target. Also, must verify that *both*
- jump alternatives go to a POP_TOP. Otherwise, the code will
- expect the stack value to have been inverted. */
- case UNARY_NOT:
- if (codestr[i+1] != JUMP_IF_FALSE || \
- codestr[i+4] != POP_TOP || \
- !ISBASICBLOCK(blocks,i,5))
- continue;
- tgt = GETJUMPTGT(codestr, (i+1));
- if (codestr[tgt] != POP_TOP)
- continue;
- codestr[i] = NOP;
- codestr[i+1] = JUMP_IF_TRUE;
- break;
-
- /* not a is b --> a is not b
- not a in b --> a not in b
- not a is not b --> a is b
- not a not in b --> a in b */
- case COMPARE_OP:
- j = GETARG(codestr, i);
- if (codestr[i+3] != UNARY_NOT || j < 6 || \
- j > 9 || !ISBASICBLOCK(blocks,i,4))
- continue;
- SETARG(codestr, i, (j^1));
- codestr[i+3] = NOP;
- break;
-
/* Replace jumps to unconditional jumps */
case FOR_ITER:
case JUMP_FORWARD:
@@ -475,7 +402,7 @@
case SETUP_EXCEPT:
case SETUP_FINALLY:
tgt = GETJUMPTGT(codestr, i);
- if (!UNCONDITIONAL_JUMP(codestr[tgt]))
+ if (!UNCONDITIONAL_JUMP(codestr[tgt]))
continue;
tgttgt = GETJUMPTGT(codestr, tgt);
if (opcode == JUMP_FORWARD) /* JMP_ABS can go backwards */
@@ -495,7 +422,6 @@
}
code = PyString_FromStringAndSize(codestr, codelen);
PyMem_Free(codestr);
- PyMem_Free(blocks);
return code;
exitUnchanged: