Re: combine.c

[Ian Lance Taylor <ian at airs dot com>]

Rajkishore Barik <rajbarik@in.ibm.com> writes:

> Can someone tell me why are the "REG_VALUE_PROFILE" notes
> dropped in "combine.c"? I am using these notes to carry some values to 
> back-end (reg-alloc)
> and it seems to get lost somewhere. "combine.c" looked to me as the 
> potential place.

When combining instructions, REG_VALUE_PROFILE notes are dropped by
distribute_notes, here:

	case REG_VALUE_PROFILE:
	  /* Just get rid of this note, as it is unused later anyway.  */
	  break;

The comment explains why: the notes are only used in the value
profiling pass, which occurs before the combine pass.

It would probably do no harm to change that code to set PLACE to
whereever you want the note to wind up.  In the long run you should
probably implement your own specific kind of register note, and handle
it appropriately.

Ian