- Generated by
1.8.1.1
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GCC Middle and Back End API Reference
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Data Structures | |
| struct | sd_region_p |
| struct | scopdet_info |
Typedefs | |
| typedef enum gbb_type | gbb_type |
| typedef struct sd_region_p | sd_region |
Enumerations | |
| enum | gbb_type { GBB_UNKNOWN, GBB_LOOP_SING_EXIT_HEADER, GBB_LOOP_MULT_EXIT_HEADER, GBB_LOOP_EXIT, GBB_COND_HEADER, GBB_SIMPLE, GBB_LAST } |
| typedef struct sd_region_p sd_region |
A SCoP detection region, defined using bbs as borders.
All control flow touching this region, comes in passing basic_block
ENTRY and leaves passing basic_block EXIT. By using bbs instead of
edges for the borders we are able to represent also regions that do
not have a single entry or exit edge.
But as they have a single entry basic_block and a single exit
basic_block, we are able to generate for every sd_region a single
entry and exit edge.
1 2
\ /
3 <- entry
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4
/ \ This region contains: {3, 4, 5, 6, 7, 8}
5 6
| |
7 8
\ /
9 <- exit
| enum gbb_type |
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static |
Checks if a bb is contained in REGION.
Referenced by create_single_exit_edge(), and mark_exit_edges().
Create graphite SCoPs from an array of scop detection REGIONS.
Are there overlapping SCoPs?
References basic_block_def::count.
Referenced by print_graphite_scop_statistics().
| void build_scops | ( | ) |
Find Static Control Parts (SCoP) in the current function and pushes them to SCOPS.
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staticread |
Starting from CURRENT we walk the dominance tree and add new sd_regions to
SCOPS. The analyse if a sd_region can be handled is based on the value
of OUTERMOST_LOOP. Only loops inside OUTERMOST loops may change. LOOP
is the loop in which CURRENT is handled.
TODO: These functions got a little bit big. They definitely should be cleaned
up. Initialize result.
Loop over the dominance tree. If we meet a difficult bb, close
the current SCoP. Loop and condition header start a new layer,
and can only be added if all bbs in deeper layers are simple. Try to close open_scop, if we are still in an open SCoP.
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static |
Transforms LOOP to the canonical loop closed SSA form.
The code above does not properly handle changes in the post dominance
information (yet).
References rewrite_into_loop_closed_ssa(), update_ssa(), and verify_loop_closed_ssa().
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@verbatim
Converts the current loop closed SSA form to a canonical form expected by the Graphite code generation.
The loop closed SSA form has the following invariant: a variable defined in a loop that is used outside the loop appears only in the phi nodes in the destination of the loop exit. These phi nodes are called close phi nodes.
The canonical loop closed SSA form contains the extra invariants:
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Returns true when BB contains only close phi nodes.
References print_graphite_scop_statistics().
Referenced by print_graphite_scop_statistics().
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Create for all scop regions a single entry and a single exit edge.
Don't handle multiple edges exiting the function.
References gsi_end_p(), gsi_next(), gsi_start_bb(), and gsi_stmt().
Referenced by print_graphite_scop_statistics().
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static |
Create a single entry edge for REGION.
There are multiple predecessors for bb_3 | 1 2 | | / | |/ | 3 <- entry | |\ | | | | 4 ^ | | | | |/ | 5 There are two edges (1->3, 2->3), that point from outside into the region, and another one (5->3), a loop latch, lead to bb_3. We split bb_3. | 1 2 | | / | |/ |3.0 | |\ (3.0 -> 3.1) = single entry edge |3.1 | <- entry | | | | | | | 4 ^ | | | | |/ | 5 If the loop is part of the SCoP, we have to redirect the loop latches. | 1 2 | | / | |/ |3.0 | | (3.0 -> 3.1) = entry edge |3.1 <- entry | |\ | | | | 4 ^ | | | | |/ | 5
This case is never executed, as the loop headers seem always to have a
single edge pointing from outside into the loop.
References edge_def::dest, sd_region_p::entry, and split_block_after_labels().
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Create a single exit edge for REGION.
We create a forwarder bb (5) for all edges leaving this region
(3->5, 4->5). All other edges leading to the same bb, are moved
to a new bb (6). If these edges where part of another region (2->5)
we update the region->exit pointer, of this region.
To identify which edge belongs to which region we depend on the e->aux
pointer in every edge. It points to the region of the edge or to NULL,
if the edge is not part of any region.
1 2 3 4 1->5 no region, 2->5 region->exit = 5,
\| |/ 3->5 region->exit = NULL, 4->5 region->exit = NULL
5 <- exit
changes to
1 2 3 4 1->6 no region, 2->6 region->exit = 6,
| | \/ 3->5 no region, 4->5 no region,
| | 5
\| / 5->6 region->exit = 6
6
Now there is only a single exit edge (5->6). Unmark the edges, that are no longer exit edges.
Mark the new exit edge.
Update the exit bb of all regions, where exit edges lead to
forwarder->dest.
References edge_def::aux, bb_in_sd_region(), sd_region_p::exit, basic_block_def::preds, and edge_def::src.
| DEBUG_FUNCTION void dot_all_scops | ( | ) |
Display all SCoPs using dotty.
When debugging, enable the following code. This cannot be used
in production compilers because it calls "system".
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static |
Pretty print to FILE all the SCoPs in DOT format and mark them with
different colors. If there are not enough colors, paint the
remaining SCoPs in gray.
Special nodes:
- "*" after the node number denotes the entry of a SCoP,
- "#" after the node number denotes the exit of a SCoP,
- "()" around the node number denotes the entry or the
exit nodes of the SCOP. These are not part of SCoP. Disable debugging while printing graph.
Use HTML for every bb label. So we are able to print bbs
which are part of two different SCoPs, with two different
background colors. Select color for SCoP.
Enable debugging again.
| DEBUG_FUNCTION void dot_scop | ( | ) |
Display all SCoPs using dotty.
When debugging, enable the following code. This cannot be used
in production compilers because it calls "system".
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Returns the single entry edge of REGION, if it does not exits NULL.
Referenced by unmark_exit_edges().
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Returns the single exit edge of REGION, if it does not exits NULL.
Referenced by unmark_exit_edges().
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Detect the type of BB. Loop headers are only marked, if they are new. This means their loop_father is different to LAST_LOOP. Otherwise they are treated like any other bb and their type can be any other type.
Check, if we entry into a new loop.
References GBB_COND_HEADER, GBB_LOOP_MULT_EXIT_HEADER, GBB_LOOP_SING_EXIT_HEADER, loop::num, and single_exit().
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Return true when EXPR can be represented in the polyhedral model. This means an expression can be represented, if it is linear with respect to the loops and the strides are non parametric. LOOP is the place where the expr will be evaluated. SCOP_ENTRY defines the entry of the region we analyse.
References graphite_find_data_references_in_stmt(), loop_containing_stmt(), loop_outer(), and vNULL.
Referenced by stmt_simple_for_scop_p().
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Something like "n * m" is not allowed.
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Return true if LOOP can be represented in the polyhedral representation. This is evaluated taking SCOP_ENTRY and OUTERMOST_LOOP in mind.
FIXME: For the moment, graphite cannot be used on loops that
iterate using induction variables that wrap.
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Return true when SCEV can be represented in the polyhedral model. An expression can be represented, if it can be expressed as an affine expression. For loops (i, j) and parameters (m, n) all affine expressions are of the form: x1 * i + x2 * j + x3 * m + x4 * n + x5 * 1 where x1..x5 element of Z 1 i + 20 j + (-2) m + 25 Something like "i * n" or "n * m" is not allowed.
Check for constant strides. With a non constant stride of
'n' we would have a value of 'iv * n'. Also check that the
initial value can represented: for example 'n * m' cannot be
represented. Only affine functions can be represented.
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Returns the statement of BB that contains a harmful operation: that can be a function call with side effects, the induction variables are not linear with respect to SCOP_ENTRY, etc. The current open scop should end before this statement. The evaluation is limited using OUTERMOST_LOOP as outermost loop that may change.
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We limit all SCoPs to SCoPs, that are completely surrounded by a loop.
Example:
for (i |
{ |
for (j | SCoP 1
for (k |
} |
* SCoP frontier, as this line is not surrounded by any loop. *
for (l | SCoP 2
This is necessary as scalar evolution and parameter detection need a
outermost loop to initialize parameters correctly.
TODO: FIX scalar evolution and parameter detection to allow more flexible
SCoP frontiers. This is a hack on top of the limit_scops hack. The
limit_scops hack should disappear all together.
References gimple_phi_num_args(), gsi_end_p(), gsi_next(), gsi_start_phis(), gsi_stmt(), remove_duplicate_close_phi(), and same_close_phi_node().
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@verbatim
Detection of Static Control Parts (SCoP) for Graphite. Copyright (C) 2009-2013 Free Software Foundation, Inc. Contributed by Sebastian Pop sebastian.pop@amd.com and Tobias Grosser grosser@fim.uni-passau.de.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see http://www.gnu.org/licenses/.
Forward declarations.
Referenced by same_close_phi_node().
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Removes all the close phi duplicates from BB.
At this point, PHI should be a close phi in normal form.
Iterate over the next phis and remove duplicates.
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Mark the exit edges of all REGIONS. See comment in "create_single_exit_edge".
References bb_in_sd_region(), and sd_region_p::entry.
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Moves the scops from SOURCE to TARGET and clean up SOURCE.
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Print statistics for SCOP to FILE.
References build_graphite_scops(), build_sese_loop_nests(), contains_only_close_phi_nodes(), create_sese_edges(), edge_def::dest, sd_region_p::entry, sd_region_p::exit, free_scops(), loop::header, loop_in_sese_p(), loop_outer(), single_exit(), single_succ_edge(), and single_succ_p().
Referenced by contains_only_close_phi_nodes().
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Print statistics for SCOPS to FILE.
References gimple_phi_arg_def(), and operand_equal_p().
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Remove the close phi node at GSI and replace its rhs with the rhs of PHI.
It is possible that we just created a duplicate close-phi
for an already-processed containing loop. Check for this
case and clean it up.
Referenced by limit_scops().
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inlinestatic |
Returns true when P1 and P2 are close phis with the same argument.
References make_close_phi_nodes_unique(), split_block_after_labels(), and edge_def::src.
Referenced by limit_scops().
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staticread |
Calculates BB infos. If bb is difficult we add valid SCoPs dominated by BB to SCOPS. TYPE is the gbb_type of BB.
XXX: ENTRY_BLOCK_PTR could be optimized in later steps.
Mark bbs terminating a SESE region difficult, if they start
a condition. Try again with another loop level.
If we do not dominate result.next, remove it. It's either
the EXIT_BLOCK_PTR, or another bb dominates it and will
call the scop detection for this bb. XXX: For now we just do not join loops with multiple exits. If the
exits lead to the same bb it may be possible to join the loop. Scan the code dominated by this loop. This means all bbs, that are
are dominated by a bb in this loop, but are not part of this loop.
The easiest case:
- The loop exit destination is dominated by the exit sources.
TODO: We miss here the more complex cases:
- The exit destinations are dominated by another bb inside
the loop.
- The loop dominates bbs, that are not exit destinations. Pass loop_outer to recognize e->dest as loop header in
build_scops_1. First check the successors of BB, and check if it is
possible to join the different branches. Ignore loop exits. They will be handled after the loop
body. Do not follow edges that lead to the end of the
conditions block. For example, in
| 0
| /|\
| 1 2 |
| | | |
| 3 4 |
| \|/
| 6
the edge from 0 => 6. Only check if all paths lead to
the same node 6. Check, if edge leads directly to the end of this
condition. Checks, if all branches end at the same point.
If that is true, the condition stays joinable.
Have a look at the example above. Join the branches of the condition if possible.
Only return a next pointer if we dominate this pointer.
Otherwise it will be handled by the bb dominating it. Scan remaining bbs dominated by BB.
Ignore loop exits: they will be handled after the loop body.
Ignore the bbs processed above.
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Check if the sd_region, mentioned in EDGE, has no exit bb.
Return true if the data references of STMT can be represented by Graphite.
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Return true only when STMT is simple enough for being handled by Graphite. This depends on SCOP_ENTRY, as the parameters are initialized relatively to this basic block, the linear functions are initialized to OUTERMOST_LOOP and BB is the place where we try to evaluate the STMT.
GIMPLE_ASM and GIMPLE_CALL may embed arbitrary side effects.
Calls have side-effects, except those to const or pure
functions. We can handle all binary comparisons. Inequalities are
also supported as they can be represented with union of
polyhedra. We can not handle REAL_TYPE. Failed for pr39260.
These nodes cut a new scope.
References gimple_cond_code(), and graphite_can_represent_expr().
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Unmark the exit edges of all REGIONS. See comment in "create_single_exit_edge".
References find_single_entry_edge(), find_single_exit_edge(), new_scop(), and new_sese().
1.8.1.1