The description of the REG_NOALIAS note in reg-notes.def isn't quite
right. It describes it as being attached to call insns, but it is
instead attached to a move insn receiving the return value from a call.
This can be seen by looking at the code in calls.cc:expand_call which
attaches the note:
emit_move_insn (temp, valreg);
/* The return value from a malloc-like function cannot alias
anything else. */
last = get_last_insn ();
add_reg_note (last, REG_NOALIAS, temp);
gcc/ChangeLog:
* reg-notes.def (NOALIAS): Correct comment.
to extract the actual value. */
REG_NOTE (BR_PROB)
-/* Attached to a call insn; indicates that the call is malloc-like and
- that the pointer returned cannot alias anything else. */
+/* Attached to a move insn which receives the result of a call; indicates that
+ the call is malloc-like and that the pointer returned cannot alias anything
+ else. */
REG_NOTE (NOALIAS)
/* REG_BR_PRED is attached to JUMP_INSNs. It contains