With the fix to PR51513 and follow on fixes for PR80707, PR80775 and PR80823,
we can now end up with switch statements that contain nothing but a default
case statement. The expand_case() function contains code that assumes we
have at least one non-default case statement, leading to the ICE reported
in the PR81194.
This patch fixes the bug by expanding switch statements that contain only
a default case statement, as a GOTO to the default case's label.
This passed bootstrap and regtesting on x86_64-linux with no regressions.
Ok for trunk?
Peter
gcc/
PR middle-end/81194
* cfgexpand.c (expand_gimple_stmt_1): Handle switch statements
with only one label.
* stmt.c (expand_case): Assert NCASES is greater than one.
gcc/testsuite/
PR middle-end/81194
* g++.dg/pr81194.C: New test.
Index: gcc/cfgexpand.c
===================================================================
--- gcc/cfgexpand.c (revision 249747)
+++ gcc/cfgexpand.c (working copy)
@@ -3566,7 +3566,13 @@
case GIMPLE_PREDICT:
break;
case GIMPLE_SWITCH:
- expand_case (as_a <gswitch *> (stmt));
+ {
+ gswitch *swtch = as_a <gswitch *> (stmt);
+ if (gimple_switch_num_labels (swtch) == 1)
+ expand_goto (CASE_LABEL (gimple_switch_default_label (swtch)));
+ else
+ expand_case (swtch);
+ }
break;
case GIMPLE_ASM:
expand_asm_stmt (as_a <gasm *> (stmt));
Index: gcc/stmt.c
===================================================================
--- gcc/stmt.c (revision 249747)
+++ gcc/stmt.c (working copy)
@@ -1142,8 +1142,11 @@
/* cleanup_tree_cfg removes all SWITCH_EXPR with their index
expressions being INTEGER_CST. */
gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);
-
+ /* Optimization of switch statements with only one label has already
+ occurred, so we should never see them at this point. */
+ gcc_assert (ncases > 1);
+
do_pending_stack_adjust ();
/* Find the default case target label. */
Index: gcc/testsuite/g++.dg/pr81194.C
===================================================================
--- gcc/testsuite/g++.dg/pr81194.C (nonexistent)
+++ gcc/testsuite/g++.dg/pr81194.C (working copy)
@@ -0,0 +1,60 @@
+// { dg-do compile }
+// { dg-options "-O2 -std=c++17 -fno-exceptions" }
+
+template <class a> struct b { typedef a *c; };
+class e {};
+template <typename a> class d {
+public:
+ typedef typename b<a>::c c;
+ c begin();
+ c end();
+};
+struct f {
+ enum { g } h;
+};
+struct i {
+ d<f *> j();
+};
+struct l {
+ d<i *> k();
+};
+class ac;
+class o {
+public:
+ o(int *, int *, int *, ac *);
+};
+class ac {
+public:
+ ac(e);
+ virtual o *ae(int *, int *, int *, int *);
+};
+class p {
+ void af(f *m) {
+ switch (m->h)
+ case f::g:
+ ag();
+ }
+
+public:
+ void n() {
+ l ah;
+ for (i *ai : ah.k())
+ for (f *m : ai->j())
+ af(m);
+ }
+ virtual void ag() { __builtin_unreachable(); }
+};
+template <typename = int> class an : o {
+public:
+ an(int *, int *, int *, int *, ac *);
+};
+class q : ac {
+public:
+ q() : ac([]() -> e {}()) {}
+ o *ae(int *ap, int *aq, int *ar, int *as) { an(ap, aq, ar, as, this); }
+};
+template <typename at>
+an<at>::an(int *, int *aq, int *ar, int *as, ac *au) : o(aq, ar, as, au) {
+ p().n();
+}
+void av() { new q; }
