[commit, spu] Fix ICEs with -fvar-tracking -O0

["Ulrich Weigand" <uweigand at de dot ibm dot com>]

Hello,

when using -fvar-tracking with optimization disabled, the compiler
crashed on SPU.  This is because the back-end disables the call to
the regular var-tracking pass (before machine-dependent reorg), and
manually calls it at the end of machine-dependent reorg instead.

However, if optimization is off, machine-dependent reorg is short-
circuited, and actually does *not* call var-tracking.  This means
the pass is *never* called, and thus we get DEBUG_INSNs remaining
in the instruction stream, which crashes in final.

Fixed by just letting the regular var-tracking pass be invoked in
those cases where we don't call it in machine-dependent reorg.

Tested on spu-elf.
Committed to mainline.

Bye,
Ulrich

ChangeLog:

	* config/spu/spu.c (asm_file_start): Only reset flag_var_tracking
	if branch-hint optimization will be performed.


Index: gcc/config/spu/spu.c
===================================================================
*** gcc/config/spu/spu.c	(revision 168294)
--- gcc/config/spu/spu.c	(working copy)
*************** static void
*** 7014,7022 ****
  asm_file_start (void)
  {
    /* Variable tracking should be run after all optimizations which
!      change order of insns.  It also needs a valid CFG. */
!   spu_flag_var_tracking = flag_var_tracking;
!   flag_var_tracking = 0;
  
    default_file_start ();
  }
--- 7014,7030 ----
  asm_file_start (void)
  {
    /* Variable tracking should be run after all optimizations which
!      change order of insns.  It also needs a valid CFG.  Therefore,
!      *if* we make nontrivial changes in machine-dependent reorg,
!      run variable tracking after those.  However, if we do not run
!      our machine-dependent reorg pass, we must still run the normal
!      variable tracking pass (or else we will ICE in final since
!      debug insns have not been removed).  */
!   if (TARGET_BRANCH_HINTS && optimize)
!     {
!       spu_flag_var_tracking = flag_var_tracking;
!       flag_var_tracking = 0;
!     }
  
    default_file_start ();
  }
-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com