[PATCH 0/4] bb-reorder: Add the "simple" algorithm

[Segher Boessenkool <segher@kernel.crashing.org>]

The current basic block reordering always uses the "software trace cache"
algorithm.  That has a few problems:

1) It increases code size substantially; this makes it not suitable for
-O1 or -Os, and not at all for some architectures;
2) but it is enabled for -Os and all targets;
3) and -O1 gets nothing, resulting in pretty jumpy code.

This patch set adds a new simple greedy basic block reordering algorithm,
adds a flag -freorder-blocks-algorithm=, and sets things up so that -O1
and -Os use the simple algo.

Split into a few pieces for easier review.  Every intermediate step works.

Bootstrapped and tested on powerpc64-linux.  There are two new fails in
guality testresults for -Os.

Is this okay for mainline?


Segher


Segher Boessenkool (4):
  bb-reorder: Split out STC
  bb-reorder: Add the "simple" algorithm
  bb-reorder: Add -freorder-blocks-algorithm= and wire it up
  bb-reorder: Documentation updates

 gcc/bb-reorder.c    | 196 +++++++++++++++++++++++++++++++++++++++++++++++++---
 gcc/common.opt      |  13 ++++
 gcc/doc/invoke.texi |  23 ++++--
 gcc/flag-types.h    |   7 ++
 gcc/opts.c          |   4 +-
 5 files changed, 227 insertions(+), 16 deletions(-)

-- 
1.8.1.4