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Re: [RFA] Fix Ada bootstrap (was: 16: EH redirection)
> If CSE introduces unreachable basic blocks and cse_main does *not*
> return non-zero, then cse_main is broken.
It's actually intra-CSE this time, at least for c41401a.adb:
int
cse_main (rtx f ATTRIBUTE_UNUSED, int nregs)
{
struct cse_basic_block_data ebb_data;
basic_block bb;
int *rc_order = XNEWVEC (int, last_basic_block);
int i, n_blocks;
df_set_flags (DF_LR_RUN_DCE);
df_analyze ();
[...]
n_blocks = pre_and_rev_post_order_compute (NULL, rc_order, false);
Before the call to df_analyze ():
(gdb) p debug_bb_n(27)
;; basic block 27, loop depth 0, count 0
;; prev block 26, next block 28
;; pred: 8 (ab,eh)
;; succ: 32 [100.0%] (fallthru)
After:
(gdb) p debug_bb_n(27)
;; basic block 27, loop depth 0, count 0
;; prev block 26, next block 29
;; pred:
;; succ: 32 [100.0%] (fallthru)
so pre_and_rev_post_order_compute aborts.
It's a known underlying problem with DCE and -fnon-call-exceptions, the simple
solution is to avoid deleting CFG-changing insns when DF is being run, like
already done for calls:
if (CALL_P (insn)
/* We cannot delete calls inside of the recursive dce because
this may cause basic blocks to be deleted and this messes up
the rest of the stack of optimization passes. */
&& (!df_in_progress)
--
Eric Botcazou