Hi Eric,
this patch fixes an inefficiency problem I observed while working on PR50764.
For the test-case of PR50764, a dead label is introduced by fixup_reorder_chain
in cfg_layout_finalize, called from pass_reorder_blocks.
The dead label is removed by a cleanup_cfg in pass_duplicate_computed_gotos, but
is still present during pass_sched2.
When constructing ebbs in schedule_ebbs, the dead label ends an ebb. If we
remove the label before pass_sched2, the ebb is allowed to grow larger.
The patch tries to get rid of the dead label immediately after it's introduced,
in cfg_layout_finalized.
The new test gcc.dg/superblock.c uses -fno-asynchronous-unwind-tables to work
around PR50764.
bootstrapped and reg-tested on x86_64.
OK for next stage 1?
Thanks,
- Tom
2011-11-18 Tom de Vries <t...@codesourcery.com>
* rtl.h (delete_dead_labels): Declare.
* cfgcleanup.c (delete_dead_labels): New function.
* cfglayout.c (cfg_layout_finalize): Use delete_dead_labels.
* gcc.dg/superblock.c: New test.
