[PATCH, haifa-sched]: Fix PR56023, -fcompare-debug failure due to sched1 pass on 4.6 branch

[Uros Bizjak]

Hello!

We should not update ticks of instructions, dependent on debug
instruction. Without the patch, the scheduling order depends on the
presence of debug instructions and leads to -fcompare-debug failures.

2012-01-19  Uros Bizjak  <ubiz...@gmail.com>

        PR rtl-optimization/56023
        * haifa-sched.c (fix_inter_tick): Do not update ticks of instructions,
        dependent on debug instruction.

testsuite/ChangeLog:

2012-01-19  Uros Bizjak  <ubiz...@gmail.com>

        PR rtl-optimization/56023
        * gcc.dg/pr56023.c: New test.

Tested on 4.6 branch on alpha-linux-gnu, where it fixes the bootstrap
failure and x86_64-pc-linux-gnu {,-m32}.

The patch should be applied to 4.7 and 4.8 branches as well. Patch was
also tested on mainline x86_64-pc-linux-gnu {,-m32}.

OK for 4.6, 4.7 and mainline?

Uros.

Index: haifa-sched.c
===================================================================
--- haifa-sched.c       (revision 195276)
+++ haifa-sched.c       (working copy)
@@ -3684,6 +3684,9 @@ fix_inter_tick (rtx head, rtx tail)
              INSN_TICK (head) = tick;
            }
 
+         if (DEBUG_INSN_P (head))
+           continue;
+
          FOR_EACH_DEP (head, SD_LIST_RES_FORW, sd_it, dep)
            {
              rtx next;
Index: testsuite/gcc.dg/pr56023.c
===================================================================
--- testsuite/gcc.dg/pr56023.c  (revision 0)
+++ testsuite/gcc.dg/pr56023.c  (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fcompare-debug" } */
+
+void
+foo (char *c)
+{
+  unsigned int x = 0;
+  unsigned int i;
+
+  for (i = 0; c[i]; i++)
+    {
+      if (i >= 5 && x != 1)
+       break;
+      else if (c[i] == ' ')
+       x = i;
+      else if (c[i] == '/' && c[i + 1] != ' ' && i)
+       x = i + 1;
+    }
+}