Patch for PR 28574 (tablejump label disappears)

[Steve Ellcey <sje at cup dot hp dot com>]

PR 28574 on IA64 occurs when we have a then-clause basic block with a
tablejump in it.  If we can predicate the tablejump and move it up to
the if-block then we remove the then-block.  But when the then-block
gets removed, the jump table, still in use by the predicated tablejump
gets removed too.

It might be possible to move the jumptable up from the then-block to the
if-block in this situation but I don't know how to do it so I just turn
off the predication conversion when the then-block contains a tablejump.

Tested on IA64 HP-UX and Linux with no regressions.  I also attached a
test case which only really fails on IA64 (other targets with
predication might be affected) but since it doesn't contain any IA64
specifics I put it in gcc.dg instead of gcc.target.

OK to check in?


2006-09-19  Steve Ellcey  <sje@cup.hp.com>

	PR 28574
	* ifcvt.c (dead_or_predicable): Don't predicate then blocks
	with tablejumps in them.

Index: ifcvt.c
===================================================================
--- ifcvt.c	(revision 117048)
+++ ifcvt.c	(working copy)
@@ -3560,6 +3560,13 @@ dead_or_predicable (basic_block test_bb,
   head = BB_HEAD (merge_bb);
   end = BB_END (merge_bb);
 
+  /* If merge_bb ends with a tablejump, predicating/moving insn's
+     into test_bb and then deleting merge_bb will result in the jumptable
+     that follows merge_bb being removed along with merge_bb and then we
+     get an unresolved reference to the jumptable.  */
+  if (tablejump_p (end, NULL, NULL))
+    return FALSE;
+
   if (LABEL_P (head))
     head = NEXT_INSN (head);
   if (NOTE_P (head))




2006-09-19  Steve Ellcey  <sje@cup.hp.com>

	PR 28574
	* gcc.dg/pr28574.c: New test.


Index: gcc.dg/pr28574.c
===================================================================
--- gcc.dg/pr28574.c	(revision 0)
+++ gcc.dg/pr28574.c	(revision 0)
@@ -0,0 +1,74 @@
+/* On IA64 This test resulted in a missing jumptable and an undefined
+   reference    to a label.  Make sure we can compile and link it with
+   no undefs at -O2.  */
+
+/* { dg-do link } */
+/* { dg-options "-O2" } */
+
+typedef enum yasm_module_type {
+    YASM_MODULE_ARCH = 0,
+    YASM_MODULE_DBGFMT,
+    YASM_MODULE_OBJFMT,
+    YASM_MODULE_LISTFMT,
+    YASM_MODULE_OPTIMIZER
+} yasm_module_type;
+
+struct yasm_module {
+    const char *name;
+};
+
+typedef struct yasm_module yasm_arch_module;
+typedef struct yasm_module yasm_dbgfmt_module;
+typedef struct yasm_module yasm_objfmt_module;
+typedef struct yasm_module yasm_listfmt_module;
+typedef struct yasm_module yasm_optimizer_module;
+
+typedef struct module {
+    void *data;
+} module;
+
+static struct {
+    module *m;
+    int n;
+} module_types[] = {
+ {},
+};
+
+void
+yasm_list_modules(yasm_module_type type,
+                  void (*printfunc) (const char *name))
+{
+    int i;
+    module *modules = module_types[type].m;
+    yasm_arch_module *arch;
+    yasm_dbgfmt_module *dbgfmt;
+    yasm_objfmt_module *objfmt;
+    yasm_listfmt_module *listfmt;
+    yasm_optimizer_module *optimizer;
+
+    for (i=0; i<2; i++) {
+        switch (type) {
+            case YASM_MODULE_ARCH:
+                arch = modules[i].data;
+                printfunc(arch->name);
+                break;
+            case YASM_MODULE_DBGFMT:
+                dbgfmt = modules[i].data;
+                printfunc(dbgfmt->name);
+                break;
+            case YASM_MODULE_OBJFMT:
+                objfmt = modules[i].data;
+                printfunc(objfmt->name);
+                break;
+            case YASM_MODULE_LISTFMT:
+                listfmt = modules[i].data;
+                printfunc(listfmt->name);
+                break;
+            case YASM_MODULE_OPTIMIZER:
+                optimizer = modules[i].data;
+                printfunc(optimizer->name);
+        }
+    }
+}
+
+main() {}