As I mention in the PR...
What's happening here is that the ipa_polymorphic_call_context
constructor is calling walk_ssa_copies on a PHI node that has no
arguments. This happens because finalize_jump_threads eventually
removes some PHI arguments as it's redirecting some edges, leaving a PHI
with no arguments:
SR.33_23 = PHI <>
This should get cleaned up later, but the IPA polymorphic code gets
called during the actual CFG clean-up, and walk_ssa_copies cannot handle
an empty PHI.
Approved by Honza.
Fully tested on x86-64 Linux and verified that the patch fixes the ICE
on an x86-64 Linux cross aarch64-linux-gnu cc1plus.
Committed to mainline.
commit cdb5a8f26178f61d6a2fdb2543f6c8b4c7136c94
Author: Aldy Hernandez <al...@redhat.com>
Date: Sun Mar 1 21:21:37 2015 -0800
PR middle-end/65233
* ipa-polymorphic-call.c (walk_ssa_copies): Handle empty PHIs.
diff --git a/gcc/ipa-polymorphic-call.c b/gcc/ipa-polymorphic-call.c
index aaa549e..13cc7f6 100644
--- a/gcc/ipa-polymorphic-call.c
+++ b/gcc/ipa-polymorphic-call.c
@@ -835,7 +835,10 @@ walk_ssa_copies (tree op, hash_set<tree> **global_visited
= NULL)
{
gimple phi = SSA_NAME_DEF_STMT (op);
- if (gimple_phi_num_args (phi) > 2)
+ if (gimple_phi_num_args (phi) > 2
+ /* We can be called while cleaning up the CFG and can
+ have empty PHIs about to be removed. */
+ || gimple_phi_num_args (phi) == 0)
goto done;
if (gimple_phi_num_args (phi) == 1)
op = gimple_phi_arg_def (phi, 0);
