Am 02/24/2015 um 06:06 PM schrieb Eric Botcazou:
Could you give me some advice on correct usage of df or even more preferred
point me to a comprehensible documentation of df which is more complete than
in df-core.c?
Take a look at the c6x and mep ports.
Thanks for the hint. I changed the execute method to:
unsigned int execute ()
{
compute_bb_for_insn ();
//df_clear_flags (DF_LR_RUN_DCE);
df_note_add_problem ();
df_analyze ();
df_finish_pass (false);
return 0;
}
bit it keeps aborting. Actually I am just copy pasting code from some other
passes / BEs, but these places also don't have explanation for why they must
use, may use, must not use specific functions.
Compiling the mentioned test case from libgcc with -Os (so that less insns are
left over) and patching df-scan.c:df_refs_verify to print the refs just before
it does gcc_assert (0):
new_ref = { u-1(18){ }}
*old_rec = { u-1(18){ }u-1(19){ }u-1(24){ }u-1(25){ }}
libgcc2-addvsi3.c: In function '__addvhi3':
libgcc2-addvsi3.c:1514:1: internal compiler error: in df_refs_verify, at
df-scan.c:4338
In df_insn_refs_verify which is in the call chain of df_refs_verify, insn reads:
(insn 21 19 22 5 (parallel [
(set (cc0)
(compare (reg/v:HI 18 r18 [orig:48 a ] [48])
(reg/v:HI 24 r24 [orig:46 w ] [46])))
(clobber (scratch:QI))
]) libgcc2-addvsi3.c:1511 408 {*cmphi}
(expr_list:REG_DEAD (reg/v:HI 18 r18 [orig:48 a ] [48])
(nil)))
r18 and r24 are ordinary general-purpose hard registers.
The latest pass which runs before the crash is .split5, i.e.
recog.c::pass_split_for_shorten_branches which executes split_all_insns_noflow
which in turn reads:
/* Same as split_all_insns, but do not expect CFG to be available.
Used by machine dependent reorg passes. */
unsigned int
split_all_insns_noflow (void)
{ ...
Does this mean CFG is (or might be) messed up after this pass and this is the
reason for why df crashes because df needs correct CFG?
Johann
