On Wed, 2019-01-23 at 16:52 +0300, Alexander Monakov wrote:
> On Wed, 23 Jan 2019, Andrey Belevantsev wrote:
>
> > For that, I'm not sure. Your patch will leave the tablejump
> > unscheduled at
> > all, i.e. any fields like INSN_TICK would be unfilled and thus the
> > later
> > passes like bundling on ia64 will not work. Maybe we can just stop
> > tablejumps from moving within its block, Alexander?
>
> On the Bugzilla there's an alternative patch by Segher that adjusts
> the assert
> to accept this situation (there's still a barrier insn after the
> tablejump insn,
> it's just after a jump_table_data insn rather than immediately
> following the
> jump). That should be a better approach, and David said he was
> testing it.
>
> That said, I'm really concerned that on this testcase we should not
> be moving
> the tablejump *at all*: we are moving it up past a 'use ax' insn (the
> use is
> for the function's return value). So after the move the use is in an
> unreachable
> block, which makes no sense.
>
> So my concern is that just fixing the assert changes the issue from
> the ICE to a
> (latent) wrong-code issue.
>
> There should have been an anti-dependence between the use and the
> jump. I'll try
> to investigate.
>
> Alexander
Thanks everyone for their clarifications (this is somewhat outside
my normal comfort zone of diagnostics/frontend stuff...)
Here's Segher's patch to sched-ebb.c, along with a couple of compile-only
testcases I put together (which triggered ICEs on x86_64 and powerpc
without the sched-ebb.c fix).
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu, and this
fixes the ICE in the the powerpc testcase.
That said, I share your concern that this might be papering over a
latent wrong-code issue.
Dave
gcc/ChangeLog:
PR rtl-optimization/88347
PR rtl-optimization/88423
* sched-ebb.c (begin_move_insn): Update assertion to handle table
jumps.
gcc/testsuite/ChangeLog:
PR rtl-optimization/88347
PR rtl-optimization/88423
* gcc.c-torture/compile/pr88347.c: New test.
* gcc.c-torture/compile/pr88423.c: New test.
---
gcc/sched-ebb.c | 6 +++++-
gcc/testsuite/gcc.c-torture/compile/pr88347.c | 4 ++++
gcc/testsuite/gcc.c-torture/compile/pr88423.c | 5 +++++
3 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr88347.c
create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr88423.c
diff --git a/gcc/sched-ebb.c b/gcc/sched-ebb.c
index d459e09..76a72b0 100644
--- a/gcc/sched-ebb.c
+++ b/gcc/sched-ebb.c
@@ -172,7 +172,11 @@ begin_move_insn (rtx_insn *insn, rtx_insn *last)
if (e)
gcc_checking_assert (NOTE_P (x) || LABEL_P (x));
else
- gcc_checking_assert (BARRIER_P (x));
+ {
+ if (LABEL_P (x) && JUMP_TABLE_DATA_P (NEXT_INSN (x)))
+ x = NEXT_INSN (NEXT_INSN (x));
+ gcc_checking_assert (BARRIER_P (x));
+ }
}
if (e)
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr88347.c
b/gcc/testsuite/gcc.c-torture/compile/pr88347.c
new file mode 100644
index 0000000..4e9b438
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr88347.c
@@ -0,0 +1,4 @@
+/* { dg-do compile { target { powerpc-*-* powerpcle-*-* } } } */
+/* { dg-options "-mcpu=603e -fsched-stalled-insns -fsched2-use-superblocks
-fschedule-insns2 -fno-dce -fno-guess-branch-probability --param
max-cse-insns=4" } */
+
+#include "../../gcc.target/powerpc/ppc-switch-2.c"
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr88423.c
b/gcc/testsuite/gcc.c-torture/compile/pr88423.c
new file mode 100644
index 0000000..4948817
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr88423.c
@@ -0,0 +1,5 @@
+/* { dg-do compile { target { i?86-*-* x86_64-*-* } } } */
+/* { dg-options "-march=skylake -fPIC -fsched2-use-superblocks
-fno-if-conversion" } */
+/* { dg-require-effective-target fpic } */
+
+#include "../../gcc.dg/20030309-1.c"
--
1.8.5.3
