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JIT: Make overflow add/sub cheaper #23940

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JIT: Make overflow add/sub cheaper #23940

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41 changes: 37 additions & 4 deletions ext/opcache/jit/zend_jit_ir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5114,15 +5114,48 @@ static int zend_jit_math_long_long(zend_jit_ctx *jit,
SET_STACK_REF(stack, EX_VAR_TO_NUM(opline->result.var), ir_CONST_DOUBLE((double)ZEND_LONG_MIN - 1.0));
exit_point = zend_jit_trace_get_exit_point(opline + 1, 0);
SET_STACK_INFO(stack, EX_VAR_TO_NUM(opline->result.var), old_res_info);
} else if ((op == IR_ADD_OV || op == IR_SUB_OV) && !same_ops && Z_MODE(op1_addr) == IS_REG) {
/* Undo the operation on the cold path for deoptimization,
* instead of keeping op1 alive across it.
* This allows reusing its register for the result. */
uint32_t op1_var = EX_VAR_TO_NUM(opline->op1.var);
ir_ref old_ref = STACK_REF(stack, op1_var);

ir_ref if_ov = ir_IF(ir_OVERFLOW(ref));
ir_IF_TRUE_cold(if_ov);

/* undo: opposite operation */
ir_ref old_op1;
if (op == IR_ADD_OV) {
old_op1 = ir_SUB_L(ref, op2);
} else {
old_op1 = ir_ADD_L(ref, op2);
}

SET_STACK_REF_EX(stack, op1_var, old_op1, STACK_FLAGS(stack, op1_var));

exit_point = zend_jit_trace_get_exit_point(opline, 0);
exit_addr = zend_jit_trace_get_exit_addr(exit_point);
if (!exit_addr) {
return 0;
}
jit_SIDE_EXIT(jit, ir_CONST_ADDR(exit_addr));

/* After the snapshot is built. */
SET_STACK_REF_EX(stack, op1_var, old_ref, STACK_FLAGS(stack, op1_var));
ir_IF_FALSE(if_ov);
exit_point = -1;
} else {
exit_point = zend_jit_trace_get_exit_point(opline, 0);
}

exit_addr = zend_jit_trace_get_exit_addr(exit_point);
if (!exit_addr) {
return 0;
if (exit_point >= 0) {
exit_addr = zend_jit_trace_get_exit_addr(exit_point);
if (!exit_addr) {
return 0;
}
ir_GUARD_NOT(ir_OVERFLOW(ref), ir_CONST_ADDR(exit_addr));
}
ir_GUARD_NOT(ir_OVERFLOW(ref), ir_CONST_ADDR(exit_addr));
may_overflow = 0;
} else if ((res_info & MAY_BE_ANY) == MAY_BE_DOUBLE) {
int32_t exit_point = zend_jit_trace_get_exit_point(opline, 0);
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