invoke.texi (sink-frequency-threshold): Document.
* doc/invoke.texi (sink-frequency-threshold): Document. * tree-ssa-sink.c: Include params.h. (select_best_block): New function. (statement_sink_location): Use it. * params.def (SINK_FREQUENCY_THRESHOLD): New PARAM. From-SVN: r180524
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Jeff Law
Jeff Law
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@ -1,3 +1,11 @@
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2011-10-26 Jeff Law <law@redhat.com>
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* doc/invoke.texi (sink-frequency-threshold): Document.
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* tree-ssa-sink.c: Include params.h.
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(select_best_block): New function.
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(statement_sink_location): Use it.
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* params.def (SINK_FREQUENCY_THRESHOLD): New PARAM.
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2011-10-14 Iain Sandoe <iains@gcc.gnu.org>
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PR target/48108
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@ -880,6 +880,7 @@ See RS/6000 and PowerPC Options.
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-mfaster-structs -mno-faster-structs -mflat -mno-flat @gol
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-mfpu -mno-fpu -mhard-float -msoft-float @gol
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-mhard-quad-float -msoft-quad-float @gol
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-mlittle-endian @gol
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-mstack-bias -mno-stack-bias @gol
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-munaligned-doubles -mno-unaligned-doubles @gol
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-mv8plus -mno-v8plus -mvis -mno-vis @gol
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@ -9132,6 +9133,13 @@ partitions.
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The maximum number of namespaces to consult for suggestions when C++
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name lookup fails for an identifier. The default is 1000.
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@item sink-frequency-threshold
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The maximum relative execution frequency (in percents) of the target block
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relative to a statement's original block to allow statement sinking of a
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statement. Larger numbers result in more aggressive statement sinking.
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The default value is 75. A small positive adjustment is applied for
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statements with memory operands as those are even more profitable so sink.
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@item max-stores-to-sink
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The maximum number of conditional stores paires that can be sunk. Set to 0
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if either vectorization (@option{-ftree-vectorize}) or if-conversion
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@ -17708,6 +17716,11 @@ These @samp{-m} options are supported in addition to the above
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on SPARC-V9 processors in 64-bit environments:
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@table @gcctabopt
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@item -mlittle-endian
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@opindex mlittle-endian
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Generate code for a processor running in little-endian mode. It is only
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available for a few configurations and most notably not on Solaris and Linux.
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@item -m32
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@itemx -m64
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@opindex m32
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@ -566,6 +566,11 @@ DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
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"The maximum number of instructions to search backward when looking for equivalent reload",
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100, 0, 0)
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DEFPARAM(PARAM_SINK_FREQUENCY_THRESHOLD,
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"sink-frequency-threshold",
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"Target block's relative execution frequency (as a percentage) required to sink a statement",
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75, 0, 100)
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DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
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"max-sched-region-blocks",
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"The maximum number of blocks in a region to be considered for interblock scheduling",
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@ -40,6 +40,7 @@ along with GCC; see the file COPYING3. If not see
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#include "bitmap.h"
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#include "langhooks.h"
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#include "cfgloop.h"
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#include "params.h"
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/* TODO:
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1. Sinking store only using scalar promotion (IE without moving the RHS):
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@ -258,6 +259,71 @@ nearest_common_dominator_of_uses (gimple stmt, bool *debug_stmts)
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return commondom;
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}
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/* Given EARLY_BB and LATE_BB, two blocks in a path through the dominator
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tree, return the best basic block between them (inclusive) to place
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statements.
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We want the most control dependent block in the shallowest loop nest.
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If the resulting block is in a shallower loop nest, then use it. Else
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only use the resulting block if it has significantly lower execution
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frequency than EARLY_BB to avoid gratutious statement movement. We
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consider statements with VOPS more desirable to move.
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This pass would obviously benefit from PDO as it utilizes block
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frequencies. It would also benefit from recomputing frequencies
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if profile data is not available since frequencies often get out
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of sync with reality. */
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static basic_block
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select_best_block (basic_block early_bb,
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basic_block late_bb,
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gimple stmt)
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{
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basic_block best_bb = late_bb;
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basic_block temp_bb = late_bb;
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int threshold;
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while (temp_bb != early_bb)
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{
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/* If we've moved into a lower loop nest, then that becomes
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our best block. */
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if (temp_bb->loop_depth < best_bb->loop_depth)
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best_bb = temp_bb;
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/* Walk up the dominator tree, hopefully we'll find a shallower
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loop nest. */
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temp_bb = get_immediate_dominator (CDI_DOMINATORS, temp_bb);
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}
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/* If we found a shallower loop nest, then we always consider that
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a win. This will always give us the most control dependent block
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within that loop nest. */
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if (best_bb->loop_depth < early_bb->loop_depth)
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return best_bb;
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/* Get the sinking threshold. If the statement to be moved has memory
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operands, then increase the threshold by 7% as those are even more
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profitable to avoid, clamping at 100%. */
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threshold = PARAM_VALUE (PARAM_SINK_FREQUENCY_THRESHOLD);
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if (gimple_vuse (stmt) || gimple_vdef (stmt))
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{
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threshold += 7;
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if (threshold > 100)
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threshold = 100;
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}
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/* If BEST_BB is at the same nesting level, then require it to have
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significantly lower execution frequency to avoid gratutious movement. */
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if (best_bb->loop_depth == early_bb->loop_depth
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&& best_bb->frequency < (early_bb->frequency * threshold / 100.0))
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return best_bb;
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/* No better block found, so return EARLY_BB, which happens to be the
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statement's original block. */
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return early_bb;
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}
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/* Given a statement (STMT) and the basic block it is currently in (FROMBB),
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determine the location to sink the statement to, if any.
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Returns true if there is such location; in that case, TOGSI points to the
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@ -379,24 +445,10 @@ statement_sink_location (gimple stmt, basic_block frombb,
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if (!dominated_by_p (CDI_DOMINATORS, commondom, frombb))
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return false;
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/* It doesn't make sense to move to a dominator that post-dominates
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frombb, because it means we've just moved it into a path that always
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executes if frombb executes, instead of reducing the number of
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executions . */
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if (dominated_by_p (CDI_POST_DOMINATORS, frombb, commondom))
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{
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if (dump_file && (dump_flags & TDF_DETAILS))
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fprintf (dump_file, "Not moving store, common dominator post-dominates from block.\n");
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return false;
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}
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commondom = select_best_block (frombb, commondom, stmt);
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if (commondom == frombb || commondom->loop_depth > frombb->loop_depth)
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return false;
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if (dump_file && (dump_flags & TDF_DETAILS))
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{
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fprintf (dump_file, "Common dominator of all uses is %d\n",
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commondom->index);
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}
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if (commondom == frombb)
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return false;
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*togsi = gsi_after_labels (commondom);
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@ -415,13 +467,9 @@ statement_sink_location (gimple stmt, basic_block frombb,
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if (gimple_code (use) != GIMPLE_PHI)
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{
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sinkbb = gimple_bb (use);
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if (sinkbb == frombb || sinkbb->loop_depth > frombb->loop_depth
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|| sinkbb->loop_father != frombb->loop_father)
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return false;
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sinkbb = select_best_block (frombb, gimple_bb (use), stmt);
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/* Move the expression to a post dominator can't reduce the number of
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executions. */
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if (dominated_by_p (CDI_POST_DOMINATORS, frombb, sinkbb))
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if (sinkbb == frombb)
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return false;
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*togsi = gsi_for_stmt (use);
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@ -431,21 +479,13 @@ statement_sink_location (gimple stmt, basic_block frombb,
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}
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sinkbb = find_bb_for_arg (use, DEF_FROM_PTR (def_p));
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/* This can happen if there are multiple uses in a PHI. */
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if (!sinkbb)
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return false;
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/* This will happen when you have
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a_3 = PHI <a_13, a_26>
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a_26 = VDEF <a_3>
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If the use is a phi, and is in the same bb as the def,
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we can't sink it. */
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if (gimple_bb (use) == frombb)
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return false;
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if (sinkbb == frombb || sinkbb->loop_depth > frombb->loop_depth
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|| sinkbb->loop_father != frombb->loop_father)
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sinkbb = select_best_block (frombb, sinkbb, stmt);
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if (!sinkbb || sinkbb == frombb)
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return false;
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/* If the latch block is empty, don't make it non-empty by sinking
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@ -454,11 +494,6 @@ statement_sink_location (gimple stmt, basic_block frombb,
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&& empty_block_p (sinkbb))
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return false;
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/* Move the expression to a post dominator can't reduce the number of
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executions. */
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if (dominated_by_p (CDI_POST_DOMINATORS, frombb, sinkbb))
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return false;
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*togsi = gsi_after_labels (sinkbb);
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return true;
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