diff options
Diffstat (limited to 'Python/flowgraph.c')
| -rw-r--r-- | Python/flowgraph.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/Python/flowgraph.c b/Python/flowgraph.c index 7f790b7..f8039a4 100644 --- a/Python/flowgraph.c +++ b/Python/flowgraph.c @@ -1293,6 +1293,11 @@ swaptimize(basicblock *block, int *ix) (opcode) == STORE_FAST_MAYBE_NULL || \ (opcode) == POP_TOP) +#define STORES_TO(instr) \ + (((instr).i_opcode == STORE_FAST || \ + (instr).i_opcode == STORE_FAST_MAYBE_NULL) \ + ? (instr).i_oparg : -1) + static int next_swappable_instruction(basicblock *block, int i, int lineno) { @@ -1344,6 +1349,23 @@ apply_static_swaps(basicblock *block, int i) return; } } + // The reordering is not safe if the two instructions to be swapped + // store to the same location, or if any intervening instruction stores + // to the same location as either of them. + int store_j = STORES_TO(block->b_instr[j]); + int store_k = STORES_TO(block->b_instr[k]); + if (store_j >= 0 || store_k >= 0) { + if (store_j == store_k) { + return; + } + for (int idx = j + 1; idx < k; idx++) { + int store_idx = STORES_TO(block->b_instr[idx]); + if (store_idx >= 0 && (store_idx == store_j || store_idx == store_k)) { + return; + } + } + } + // Success! INSTR_SET_OP0(swap, NOP); cfg_instr temp = block->b_instr[j]; |