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ICE on ARM due to recent patch

With the following change:

2005-07-27 Steven Bosscher <>

PR rtl-optimization/17808
* sched-deps.c (sched_get_condition): Enable #if 0'ed code.
(sched_insns_conditions_mutex_p): Split out from...
(add_dependence): But don't call it from here.
(add_dependence_list): Check sched_insns_conditions_mutex_p
before calling add_dependence.
(add_dependence_list_and_free): Likewise.
(fixup_sched_groups): Likewise.
(sched_analyze_1): Likewise.
(sched_analyze_2): Likewise (and replace a "0" with REG_DEP_TRUE).
(sched_analyze): Likewise.
(sched_analyze_insn): Likewise.
* sched-ebb.c (add_deps_for_risky_insns): Likewise.
* sched-rgn.c (add_branch_dependences): Likewise. Also, add
dependencies on all COND_EXEC insns to jumps ending basic blocks
when doing intrablock scheduling.
* sched-int.h (sched_insns_conditions_mutex_p): Add prototype.

I see an ICE during scheduling when trying to build for arm-none- elf. I tracked the failures back to two issues in the following code (from add_branch_dependences):

  insn = PREV_INSN (tail);
  while (insn != head)
      /* Note that we want to add this dependency even when
         sched_insns_conditions_mutex_p returns true.  The whole point
         is that we _want_ this dependency, even if these insns really
         are independent.  */
      if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == COND_EXEC)
        add_dependence (tail, insn, REG_DEP_ANTI);

      insn = PREV_INSN (insn);

First, if head == tail, this code walks back into other bb's.
Second, it never generates a dependency for the head instruction, since the loop exits as soon as head is reached -- without head ever being processed.

To address these issues, I propose the replacement code in the attached patch. I have verified that it gets past the build failures I was seeing before, and I will do a full set of tests on arm-none- elf and report the results. Might someone be willing to test it on ia64?

- Josh

Attachment: cond-exe.patch
Description: Binary data

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