[PATCH] Fix force_nonfallthru_and_redirect with asm goto (PR rtl-optimization/54127)

[Jakub Jelinek]

Hi!

The following testcase was ICEing on powerpc64-linux.
While force_nonfallthru_and_redirect properly adjusted the LABEL_REFs
in asm goto from the old fallthru block to a new one, it didn't adjust
LABEL_NUSES and didn't adjust JUMP_LABEL resp. REG_LABEL_TARGET.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk (and 4.7 after say a week)?

2012-11-12  Jakub Jelinek  <ja...@redhat.com>

        PR rtl-optimization/54127
        * cfgrtl.c (force_nonfallthru_and_redirect): When redirecting
        asm goto labels from BB_HEAD (e->dest) to target bb, decrement
        LABEL_NUSES of BB_HEAD (e->dest) and increment LABEL_NUSES of
        BB_HEAD (target) appropriately and adjust JUMP_LABEL and/or
        REG_LABEL_TARGET and REG_LABEL_OPERAND.

        * gcc.dg/torture/pr54127.c: New test.

--- gcc/cfgrtl.c.jj     2012-11-05 08:55:21.000000000 +0100
+++ gcc/cfgrtl.c        2012-11-12 11:06:32.254919581 +0100
@@ -1424,14 +1424,46 @@ force_nonfallthru_and_redirect (edge e,
       && (note = extract_asm_operands (PATTERN (BB_END (e->src)))))
     {
       int i, n = ASM_OPERANDS_LABEL_LENGTH (note);
+      bool adjust_jump_target = false;
 
       for (i = 0; i < n; ++i)
        {
          if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (e->dest))
-           XEXP (ASM_OPERANDS_LABEL (note, i), 0) = block_label (target);
+           {
+             LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note, i), 0))--;
+             XEXP (ASM_OPERANDS_LABEL (note, i), 0) = block_label (target);
+             LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note, i), 0))++;
+             adjust_jump_target = true;
+           }
          if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target))
            asm_goto_edge = true;
        }
+      if (adjust_jump_target)
+       {
+         rtx insn = BB_END (e->src), note;
+         rtx old_label = BB_HEAD (e->dest);
+         rtx new_label = BB_HEAD (target);
+
+         if (JUMP_LABEL (insn) == old_label)
+           {
+             JUMP_LABEL (insn) = new_label;
+             note = find_reg_note (insn, REG_LABEL_TARGET, new_label);
+             if (note)
+               remove_note (insn, note);
+           }
+         else
+           {
+             note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
+             if (note)
+               remove_note (insn, note);
+             if (JUMP_LABEL (insn) != new_label
+                 && !find_reg_note (insn, REG_LABEL_TARGET, new_label))
+               add_reg_note (insn, REG_LABEL_TARGET, new_label);
+           }
+         while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label))
+                != NULL_RTX)
+           XEXP (note, 0) = new_label;
+       }
     }
 
   if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge)
--- gcc/testsuite/gcc.dg/torture/pr54127.c.jj   2012-11-12 11:13:45.422433593 
+0100
+++ gcc/testsuite/gcc.dg/torture/pr54127.c      2012-11-12 11:09:07.000000000 
+0100
@@ -0,0 +1,16 @@
+/* PR rtl-optimization/54127 */
+/* { dg-do compile } */
+
+extern void foo (void) __attribute__ ((__noreturn__));
+
+void
+bar (int x)
+{
+  if (x < 0)
+    foo ();
+  if (x == 0)
+    return;
+  __asm goto ("# %l[lab] %l[lab2]" : : : : lab, lab2);
+lab:;
+lab2:;
+}

        Jakub