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Re: [PR69634] fix debug_insn-inconsistent REG_N_CALLS_CROSSED

On 02/06/2016 03:06 AM, Alexandre Oliva wrote:

The testcase has a debug insn referencing a pseudo right before an
insn that modifies the pseudo.

Without debug insns, REG_N_CALLS_CROSSED was zero for that pseudo, so
sched_analyze_reg added a dep between the pseudo setter and an earlier
(lib)call.

With debug insns, we miscomputed REG_N_CALLS_CROSSED as nonzero
because of the debug insn, and then no dep was added between the two
insns.  This was enough to change sched1's decisions about where to
place the pseudo setter.

REG_N_CALLS_CROSSED is computed by both regstat_bb_compute_ri and
regstat_bb_compute_calls_crossed, but although the former skipped
debug insns, the latter didn't.

Fixing this inconsistency was enough to fix the -fcompare-debug error.

Regstrapped on x86_64-linux-gnu and i686-linux-gnu.  Ok to install?


for  gcc/ChangeLog

	PR target/69634
	* regstat.c (regstat_bb_compute_calls_crossed): Disregard
	debug insns.

for  gcc/testsuite/ChangeLog

	PR target/69634
	* gcc.dg/pr69634.c: New.
I removed the explicit -m32. It was there merely to try and exercise the test, even on an x86-64 configured toolchain. As Uros noted, a standard multilib of x86-64 will test -m32, so the explicit -m32 isn't needed and it is in fact harmful.
Committed to the trunk with that change. I'm going to add 4.9/5 regression markers to the BZ since this affects those releases as well. 

Jeff
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