On Fri, Nov 16, 2018 at 9:55 AM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> On this testcase on aarch64-linux, we have a bb end like:
> (insn 119 80 120 5 (set (reg:DI 110)
> (high:DI (label_ref:DI 19))) -1
> (insn_list:REG_LABEL_OPERAND 19 (nil)))
> (insn 120 119 121 5 (set (reg:DI 109)
> (lo_sum:DI (reg:DI 110)
> (label_ref:DI 19))) -1
> (insn_list:REG_LABEL_OPERAND 19 (expr_list:REG_EQUAL (label_ref:DI 19)
> (nil))))
> (jump_insn/j 121 120 19 5 (set (pc)
> (reg:DI 109)) -1
> (nil)
> -> 19)
> and try to redirect that CROSSING_JUMP_P to another label. As it is not
> considered a computed jump (as it has a JUMP_LABEL), but it is hard to
> adjust it (we'd need to generate new insns to compute that label into a
> register and replace the old ones with it (and find them)), redirect_jump
> fails, but patch_jump_insn assumes it must not fail.
>
> I think it is best to allow it to fail, at least until somebody writes code
> to redirect_jump even this kind of calls.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux + tested with
> aarch64-linux cross on the testcase. Ok for trunk?
LGTM.
Richard.
> 2018-11-16 Jakub Jelinek <ja...@redhat.com>
>
> PR rtl-optimization/87475
> * cfgrtl.c (patch_jump_insn): Allow redirection failure for
> CROSSING_JUMP_P insns.
> (cfg_layout_redirect_edge_and_branch): Don't ICE if ret is NULL.
>
> * g++.dg/opt/pr87475.C: New test.
>
> --- gcc/cfgrtl.c.jj 2018-11-15 09:46:46.383739915 +0100
> +++ gcc/cfgrtl.c 2018-11-15 16:58:08.972980656 +0100
> @@ -1268,11 +1268,13 @@ patch_jump_insn (rtx_insn *insn, rtx_ins
>
> /* If the substitution doesn't succeed, die. This can happen
> if the back end emitted unrecognizable instructions or if
> - target is exit block on some arches. */
> + target is exit block on some arches. Or for crossing
> + jumps. */
> if (!redirect_jump (as_a <rtx_jump_insn *> (insn),
> block_label (new_bb), 0))
> {
> - gcc_assert (new_bb == EXIT_BLOCK_PTR_FOR_FN (cfun));
> + gcc_assert (new_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)
> + || CROSSING_JUMP_P (insn));
> return false;
> }
> }
> @@ -4460,6 +4462,9 @@ cfg_layout_redirect_edge_and_branch (edg
> else
> ret = redirect_branch_edge (e, dest);
>
> + if (!ret)
> + return NULL;
> +
> fixup_partition_crossing (ret);
> /* We don't want simplejumps in the insn stream during cfglayout. */
> gcc_assert (!simplejump_p (BB_END (src)) || CROSSING_JUMP_P (BB_END
> (src)));
> --- gcc/testsuite/g++.dg/opt/pr87475.C.jj 2018-11-15 17:05:51.793393450
> +0100
> +++ gcc/testsuite/g++.dg/opt/pr87475.C 2018-11-15 17:05:34.713673436 +0100
> @@ -0,0 +1,7 @@
> +// PR rtl-optimization/87475
> +// { dg-do compile { target freorder } }
> +// { dg-options "-O2 -freorder-blocks-and-partition -fmodulo-sched" }
> +
> +struct A { A (); ~A (); };
> +int foo (A, A);
> +void bar (bool x) { x ? foo (A (), A ()) : 0; }
>
> Jakub
