Re: [PATCH] Fix PR middle-end/80823, ICE: verify_flow_info failed

[Richard Biener <rguenther@suse.de>]

On May 23, 2017 7:46:59 PM GMT+02:00, Peter Bergner <bergner@vnet.ibm.com> wrote:
>The fix for PR80775 included a thinko bug that caused us to skip some
>case label statements.  This leads to problems for test cases where we
>have multiple case labels that point to the same unreachable block, but
>are not mergeable since they don't have consecutive case values.
>This leads to a problem, because we remove the unreachable block when
>handling this first case label, but then we have a dangling reference
>to that block with the skipped case label.  The fix is to remove the
>unwanted increment, so that we handle the next case label and end up
>removing it too.
>
>This passed bootstrap and regtesting on powerpc64le-linux with no
>regressions.  Is this ok for trunk?

OK.

Richard.

>Peter
>
>gcc/
>	PR middle-end/80823
>	* tree-cfg.c (group_case_labels_stmt): Delete increment of "i";
>
>gcc/testsuite/
>	PR middle-end/80823
>	* gcc.dg/pr80823.c: New test.
>
>Index: gcc/tree-cfg.c
>===================================================================
>--- gcc/tree-cfg.c	(revision 248375)
>+++ gcc/tree-cfg.c	(working copy)
>@@ -1726,7 +1726,6 @@ group_case_labels_stmt (gswitch *stmt)
> 	    remove_edge_and_dominated_blocks (base_edge);
> 	  gimple_switch_set_label (stmt, base_index, NULL_TREE);
> 	  new_size--;
>-	  i++;
> 	}
>     }
> 
>Index: gcc/testsuite/gcc.dg/pr80823.c
>===================================================================
>--- gcc/testsuite/gcc.dg/pr80823.c	(nonexistent)
>+++ gcc/testsuite/gcc.dg/pr80823.c	(working copy)
>@@ -0,0 +1,23 @@
>+/* PR middle-end/80823 ICE: verify_flow_info failed  */
>+/* { dg-do compile }  */
>+/* { dg-options "-O3" }  */
>+
>+int a, c;
>+int b[1];
>+static inline int
>+fn1() {
>+  switch (a)
>+  case 0:
>+  case 2:
>+    return 1;
>+  return 0;
>+}
>+void fn2() {
>+  int i;
>+  for (;; ++i) {
>+    c = b[i];
>+    int d = !fn1();
>+    if (d)
>+      __asm__("");
>+  }
>+}