Mercurial > cpython-lru_cache-weakref
diff Python/compile.c @ 32395:6bc6abba8659 legacy-trunk
Install two code generation optimizations that depend on NOP.
Reduces the cost of "not" to almost zero.
| author | Raymond Hettinger <python@rcn.com> |
|---|---|
| date | Mon, 21 Jun 2004 16:31:15 +0000 |
| parents | 13656d58d450 |
| children | 1c2baae14828 |
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--- a/Python/compile.c Mon Jun 21 16:15:22 2004 +0000 +++ b/Python/compile.c Mon Jun 21 16:31:15 2004 +0000 @@ -392,6 +392,33 @@ opcode = codestr[i]; switch (opcode) { + /* Replace UNARY_NOT JUMP_IF_FALSE with NOP JUMP_IF_TRUE */ + 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 (j < 6 || j > 9 || + codestr[i+3] != UNARY_NOT || + !ISBASICBLOCK(blocks,i,4)) + continue; + SETARG(codestr, i, (j^1)); + codestr[i+3] = NOP; + break; + /* Skip over LOAD_CONST trueconst JUMP_IF_FALSE xx POP_TOP. Note, only the first opcode is changed, the others still perform normally if they happen to be jump targets. */ @@ -418,8 +445,8 @@ codestr[i] = ROT_TWO; codestr[i+1] = JUMP_FORWARD; SETARG(codestr, i+1, 2); - codestr[i+4] = DUP_TOP; /* Filler codes used as NOPs */ - codestr[i+5] = POP_TOP; + codestr[i+4] = NOP; + codestr[i+5] = NOP; continue; } if (GETARG(codestr, i) == 3 && \ @@ -428,7 +455,7 @@ codestr[i+1] = ROT_TWO; codestr[i+2] = JUMP_FORWARD; SETARG(codestr, i+2, 1); - codestr[i+5] = DUP_TOP; + codestr[i+5] = NOP; } break;