On May 12, 2017 6:46:29 PM GMT+02:00, Peter Bergner <berg...@vnet.ibm.com>
wrote:
>My fix for PR51513 modified group_case_labels_stmt() to remove
>unreachable
>case statements labels. Being a middle-end newbie, I incorrectly
>thought
>group_case_labels_stmt() was only called very early, before we have a
>cfg.
>With -O3, we can generate extra copies of the switch statement, well
>after
>the cfg exists, and we end up calling group_case_labels_stmt() to
>optimize
>them. In those cases, we need to remove their edges from the cfg.
>
>This passes my bootstrap and regtesting on powerpc64le-linux and
>x86_64-linux
>with no regressions. In addition, both David and HJ confirm this fixes
>the
>bootstrap issues they ran into.
>
>Is this ok for trunk?
OK.
Richard.
>Peter
>
>gcc/
> PR middle-end/80707
> * tree-cfg.c: Remove cfg edges of unreachable case statements.
>
>gcc/testsuite/
> * g++.dg/pr80707.C: New test.
>
>Index: gcc/tree-cfg.c
>===================================================================
>--- gcc/tree-cfg.c (revision 247845)
>+++ gcc/tree-cfg.c (working copy)
>@@ -1684,6 +1684,10 @@ group_case_labels_stmt (gswitch *stmt)
> || (EDGE_COUNT (base_bb->succs) == 0
> && gimple_seq_unreachable_p (bb_seq (base_bb))))
> {
>+ edge e;
>+ if (base_bb != default_bb
>+ && (e = find_edge (gimple_bb (stmt), base_bb)) != NULL)
>+ remove_edge_and_dominated_blocks (e);
> gimple_switch_set_label (stmt, i, NULL_TREE);
> i++;
> new_size--;
>Index: gcc/testsuite/g++.dg/pr80707.C
>===================================================================
>--- gcc/testsuite/g++.dg/pr80707.C (nonexistent)
>+++ gcc/testsuite/g++.dg/pr80707.C (working copy)
>@@ -0,0 +1,29 @@
>+// PR middle-end/80707 ICE: extra outgoing edge causes
>verify_flow_info error.
>+// { dg-do compile }
>+// { dg-options "-O3" } */
>+
>+struct A {
>+ int m_fn1(int &) const;
>+};
>+int A::m_fn1(int &p1) const {
>+ int a[6];
>+ int b = 0;
>+ for (int i;; i++) {
>+ if (a[i])
>+ break;
>+ b++;
>+ }
>+ while (b) {
>+ int c;
>+ switch (b) {
>+ case 1:
>+ c = 0;
>+ break;
>+ case 5:
>+ c = a[0];
>+ }
>+ if (c)
>+ p1 = 0;
>+ b--;
>+ }
>+}
