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r242497 - in /trunk/gcc: ChangeLog config/rs600...
- From: segher at gcc dot gnu dot org
- To: gcc-cvs at gcc dot gnu dot org
- Date: Wed, 16 Nov 2016 15:23:36 -0000
- Subject: r242497 - in /trunk/gcc: ChangeLog config/rs600...
Date: Wed Nov 16 15:23:36 2016
New Revision: 242497
df: Change defs in entry and uses in exit block during separate shrink-wrapping
So far all target implementations of the separate shrink-wrapping hooks
use the DF LIVE info to figure out around which basic blocks the non-
volatile registers need to be saved. This is done by looking at the
IN+GEN+KILL sets of the basic blocks. However, that doesn't work for
registers that DF says are defined in the entry block, or used in the
This patch introduces a local flag DF_SCAN_EMPTY_ENTRY_EXIT that says
no registers should be defined in the entry block, and none used in the
exit block. It also makes try_shrink_wrapping_separate use it. The
rs6000 port is changed to use IN+GEN+KILL for the LR component.
* config/rs6000/rs6000.c (rs6000_components_for_bb): Mark the LR
component as used also if LR_REGNO is a live input to the bb.
* df-scan.c (df_get_entry_block_def_set): Return immediately after
clearing the set if DF_SCAN_EMPTY_ENTRY_EXIT is set.
* df.h (df_scan_flags): New enum.
* shrink-wrap.c (try_shrink_wrapping_separate): Set
DF_SCAN_EMPTY_ENTRY_EXIT in df_scan->local_flags, and call
df_update_entry_block_defs and df_update_exit_block_uses
at the start; clear the flag and call those functions at the end.