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df-problems.c (df_simulate_initialize_forwards): Set, don't clear, bits for artificial defs at the top of the block. 

* df-problems.c (df_simulate_initialize_forwards): Set, don't clear,
	bits for artificial defs at the top of the block.
	* fwprop.c (single_def_use_enter_block): Don't call it.

From-SVN: r158750
This commit is contained in:
Bernd Schmidt 2010-04-26 21:17:17 +00:00 committed by Bernd Schmidt
parent 1637c2e1ba
commit 823ff7b434
3 changed files with 14 additions and 9 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2010-04-26 Bernd Schmidt <bernds@codesourcery.com>
* df-problems.c (df_simulate_initialize_forwards): Set, don't clear,
bits for artificial defs at the top of the block.
* fwprop.c (single_def_use_enter_block): Don't call it.
2010-04-26 Jack Howarth <howarth@bromo.med.uc.edu>
PR 43715

12
gcc/df-problems.c
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@ -3913,13 +3913,9 @@ df_simulate_finalize_backwards (basic_block bb, bitmap live)
the block, starting with the first one.
----------------------------------------------------------------------------*/
/* Apply the artificial uses and defs at the top of BB in a forwards
direction. ??? This is wrong; defs mark the point where a pseudo
becomes live when scanning forwards (unless a def is unused). Since
there are no REG_UNUSED notes for artificial defs, passes that
require artificial defs probably should not call this function
unless (as is the case for fwprop) they are correct when liveness
bitmaps are *under*estimated. */
/* Initialize the LIVE bitmap, which should be copied from DF_LIVE_IN or
DF_LR_IN for basic block BB, for forward scanning by marking artificial
defs live. */
void
df_simulate_initialize_forwards (basic_block bb, bitmap live)
@ -3931,7 +3927,7 @@ df_simulate_initialize_forwards (basic_block bb, bitmap live)
{
df_ref def = *def_rec;
if (DF_REF_FLAGS (def) & DF_REF_AT_TOP)
bitmap_clear_bit (live, DF_REF_REGNO (def));
bitmap_set_bit (live, DF_REF_REGNO (def));
}
}

5
gcc/fwprop.c
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@ -228,7 +228,10 @@ single_def_use_enter_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
process_uses (df_get_artificial_uses (bb_index), DF_REF_AT_TOP);
process_defs (df_get_artificial_defs (bb_index), DF_REF_AT_TOP);
df_simulate_initialize_forwards (bb, local_lr);
/* We don't call df_simulate_initialize_forwards, as it may overestimate
the live registers if there are unused artificial defs. We prefer
liveness to be underestimated. */
FOR_BB_INSNS (bb, insn)
if (INSN_P (insn))