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bb-reorder: Add -freorder-blocks-algorithm= and wire it up

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This adds an -freorder-blocks-algorithm=[simple|stc] flag, with "simple"
as default.  For -O2 and up (except -Os) it is switched to "stc" instead.
Targets that never want STC can override this.  This changes -freorder-blocks
to be on at -O1 and up (was -O2 and up).

In effect, the changes are for -O1 (which now gets "simple" instead of
nothing), -Os (which now gets "simple" instead of "stc", since STC results
in much bigger code), and for targets that wish to never use STC (not in
this patch though).


2015-09-23   Segher Boessenkool  <segher@kernel.crashing.org>

	* bb-reorder.c (reorder_basic_blocks): Use the algorithm selected
	with flag_reorder_blocks_algorithm.
	* common.opt (freorder-blocks-algorithm=): New flag.
	(reorder_blocks_algorithm): New enum.
	* flag-types.h (reorder_blocks_algorithm): New enum.
	* opts.c (default_options_table): Use -freorder-blocks at -O1 and up,
	and -freorder-blocks-algorithm=stc at -O2 and up (not at -Os).

From-SVN: r228318
This commit is contained in:
Segher Boessenkool 2015-10-01 08:38:24 +02:00 committed by Segher Boessenkool
parent 248c16c49a
commit 59faab7cc4
5 changed files with 46 additions and 5 deletions
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10
gcc/ChangeLog
View File

@ -1,3 +1,13 @@
2015-10-01 Segher Boessenkool <segher@kernel.crashing.org>
* bb-reorder.c (reorder_basic_blocks): Use the algorithm selected
with flag_reorder_blocks_algorithm.
* common.opt (freorder-blocks-algorithm=): New flag.
(reorder_blocks_algorithm): New enum.
* flag-types.h (reorder_blocks_algorithm): New enum.
* opts.c (default_options_table): Use -freorder-blocks at -O1 and up,
and -freorder-blocks-algorithm=stc at -O2 and up (not at -Os).
2015-10-01 Segher Boessenkool <segher@kernel.crashing.org>
* bb-reorder.c: Add intro comment.

17
gcc/bb-reorder.c
View File

@ -2444,10 +2444,19 @@ reorder_basic_blocks (void)
set_edge_can_fallthru_flag ();
mark_dfs_back_edges ();
if (1)
reorder_basic_blocks_software_trace_cache ();
else
reorder_basic_blocks_simple ();
switch (flag_reorder_blocks_algorithm)
{
case REORDER_BLOCKS_ALGORITHM_SIMPLE:
reorder_basic_blocks_simple ();
break;
case REORDER_BLOCKS_ALGORITHM_STC:
reorder_basic_blocks_software_trace_cache ();
break;
default:
gcc_unreachable ();
}
relink_block_chain (/*stay_in_cfglayout_mode=*/true);

13
gcc/common.opt
View File

@ -1910,6 +1910,19 @@ freorder-blocks
Common Report Var(flag_reorder_blocks) Optimization
Reorder basic blocks to improve code placement
freorder-blocks-algorithm=
Common Joined RejectNegative Enum(reorder_blocks_algorithm) Var(flag_reorder_blocks_algorithm) Init(REORDER_BLOCKS_ALGORITHM_SIMPLE) Optimization
-freorder-blocks-algorithm=[simple|stc] Set the used basic block reordering algorithm
Enum
Name(reorder_blocks_algorithm) Type(enum reorder_blocks_algorithm) UnknownError(unknown basic block reordering algorithm %qs)
EnumValue
Enum(reorder_blocks_algorithm) String(simple) Value(REORDER_BLOCKS_ALGORITHM_SIMPLE)
EnumValue
Enum(reorder_blocks_algorithm) String(stc) Value(REORDER_BLOCKS_ALGORITHM_STC)
freorder-blocks-and-partition
Common Report Var(flag_reorder_blocks_and_partition) Optimization
Reorder basic blocks and partition into hot and cold sections

7
gcc/flag-types.h
View File

@ -109,6 +109,13 @@ enum stack_reuse_level
SR_ALL
};
/* The algorithm used for basic block reordering. */
enum reorder_blocks_algorithm
{
REORDER_BLOCKS_ALGORITHM_SIMPLE,
REORDER_BLOCKS_ALGORITHM_STC
};
/* The algorithm used for the integrated register allocator (IRA). */
enum ira_algorithm
{

4
gcc/opts.c
View File

@ -441,6 +441,7 @@ static const struct default_options default_options_table[] =
{ OPT_LEVELS_1_PLUS, OPT_fipa_reference, NULL, 1 },
{ OPT_LEVELS_1_PLUS, OPT_fipa_profile, NULL, 1 },
{ OPT_LEVELS_1_PLUS, OPT_fmerge_constants, NULL, 1 },
{ OPT_LEVELS_1_PLUS, OPT_freorder_blocks, NULL, 1 },
{ OPT_LEVELS_1_PLUS, OPT_fshrink_wrap, NULL, 1 },
{ OPT_LEVELS_1_PLUS, OPT_fsplit_wide_types, NULL, 1 },
{ OPT_LEVELS_1_PLUS, OPT_ftree_ccp, NULL, 1 },
@ -483,7 +484,8 @@ static const struct default_options default_options_table[] =
#endif
{ OPT_LEVELS_2_PLUS, OPT_fstrict_aliasing, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_fstrict_overflow, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_freorder_blocks, NULL, 1 },
{ OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_freorder_blocks_algorithm_, NULL,
REORDER_BLOCKS_ALGORITHM_STC },
{ OPT_LEVELS_2_PLUS, OPT_freorder_functions, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_ftree_vrp, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_ftree_builtin_call_dce, NULL, 1 },