On Wed, Aug 9, 2023 at 11:17 AM Jakub Jelinek via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi!
>
> I've ran into ICE on gcc.dg/torture/bitint-42.c with -O1 or -Os
> when enabling expensive tests, and unfortunately I can't reproduce without
> _BitInt. The IL before phiopt3 has:
> <bb 87> [local count: 203190070]:
> # .MEM_428 = VDEF <.MEM_367>
> bitint.159 = VIEW_CONVERT_EXPR<unsigned long[8]>(*.LC3);
> goto <bb 89>; [100.00%]
>
> <bb 88> [local count: 203190070]:
> # .MEM_427 = VDEF <.MEM_367>
> bitint.159 = VIEW_CONVERT_EXPR<unsigned long[8]>(*.LC4);
>
> <bb 89> [local count: 406380139]:
> # .MEM_368 = PHI <.MEM_428(87), .MEM_427(88)>
> # VUSE <.MEM_368>
> _123 = VIEW_CONVERT_EXPR<unsigned long[8]>(r495[i_107].D.2780)[0];
> and factor_out_conditional_operation is called on the vop PHI, it
> sees it has exactly two operands and defining statements of both
> PHI arguments are converts (VCEs in this case), so it thinks it is
> a good idea to try to optimize that and while doing that it constructs
> void type SSA_NAMEs and the like.
Maybe it is better to punt for VOPS after the call to
single_non_singleton_phi_for_edges since none of functions called
afterwards support VOPs.
That is something like:
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index ff36bb0119b..d0b659042a7 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -4165,6 +4165,10 @@ pass_phiopt::execute (function *)
arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
+ /* Can't do anything with a VOP here. */
+ if (SSA_NAME_IS_VIRTUAL_OPERAND (arg0))
+ continue;
+
/* Something is wrong if we cannot find the arguments in the PHI
node. */
gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE);
Thanks,
Andrew Pinski
>
> 2023-08-09 <ja...@redhat.com>
>
> PR c/102989
> * tree-ssa-phiopt.cc (factor_out_conditional_operation): Punt for
> vops.
>
> --- gcc/tree-ssa-phiopt.cc.jj 2023-08-08 15:55:09.508122417 +0200
> +++ gcc/tree-ssa-phiopt.cc 2023-08-09 15:55:23.762314103 +0200
> @@ -241,6 +241,7 @@ factor_out_conditional_operation (edge e
> }
>
> if (TREE_CODE (arg0) != SSA_NAME
> + || SSA_NAME_IS_VIRTUAL_OPERAND (arg0)
> || (TREE_CODE (arg1) != SSA_NAME
> && TREE_CODE (arg1) != INTEGER_CST))
> return NULL;
>
> Jakub
>
