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Only eliminate jumps to successor block if jump is unconditional. (GH-24417)

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* Prevents elimination of the sole test of a value in statements like:
   if x or True: ...
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Mark Shannon 2021-02-02 14:59:15 +00:00 • committed by GitHub
parent 9eb11a139f
commit 802b645e81
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 20 additions and 17 deletions
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21
Python/compile.c
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@ -6586,27 +6586,14 @@ optimize_cfg(struct assembler *a, PyObject *consts)
for (basicblock *b = a->a_entry; b != NULL; b = b->b_next) {
if (b->b_iused > 0) {
struct instr *b_last_instr = &b->b_instr[b->b_iused - 1];
if (b_last_instr->i_opcode == POP_JUMP_IF_FALSE ||
b_last_instr->i_opcode == POP_JUMP_IF_TRUE ||
b_last_instr->i_opcode == JUMP_ABSOLUTE ||
if (b_last_instr->i_opcode == JUMP_ABSOLUTE ||
b_last_instr->i_opcode == JUMP_FORWARD) {
if (b_last_instr->i_target == b->b_next) {
assert(b->b_next->b_iused);
b->b_nofallthrough = 0;
switch(b_last_instr->i_opcode) {
case POP_JUMP_IF_FALSE:
case POP_JUMP_IF_TRUE:
b_last_instr->i_opcode = POP_TOP;
b_last_instr->i_target = NULL;
b_last_instr->i_oparg = 0;
break;
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
b_last_instr->i_opcode = NOP;
clean_basic_block(b, -1);
maybe_empty_blocks = 1;
break;
}
b_last_instr->i_opcode = NOP;
clean_basic_block(b, -1);
maybe_empty_blocks = 1;
}
}
}