From 9253d4138a0cdb76c40345a1e32694968f375a86 Mon Sep 17 00:00:00 2001
From: Richard Henderson <rth@redhat.com>
Date: Wed, 7 Nov 2012 14:36:01 -0800
Subject: [PATCH 2/2] tm: Optimize nested transactions in an uninstrumented
code path
* trans-mem.c (tm_region_init_0): Consider all edges when looking
for the entry_block.
(collect_bb2reg): Handle uninstrumented only transactions.
(generate_tm_state): Likewise.
(expand_transaction): Likewise.
(execute_tm_memopt): Likewise.
(ipa_uninstrument_transaction0): Convert nested transactions in
the uninstrumented code path to uninstrumented only.
---
gcc/ChangeLog | 9 ++++++++
gcc/trans-mem.c | 66 ++++++++++++++++++++++++++++++++++++++++++++-------------
2 files changed, 60 insertions(+), 15 deletions(-)
@@ -1,5 +1,14 @@
2012-11-07 Richard Henderson <rth@redhat.com>
+ * trans-mem.c (tm_region_init_0): Consider all edges when looking
+ for the entry_block.
+ (collect_bb2reg): Handle uninstrumented only transactions.
+ (generate_tm_state): Likewise.
+ (expand_transaction): Likewise.
+ (execute_tm_memopt): Likewise.
+ (ipa_uninstrument_transaction0): Convert nested transactions in
+ the uninstrumented code path to uninstrumented only.
+
* trans-mem.c (ipa_uninstrument_transaction0): Rename from
ipa_uninstrument_transaction.
(ipa_uninstrument_transaction): New function.
@@ -868,10 +868,13 @@ typedef struct tm_log_entry
{
/* Address to save. */
tree addr;
+
/* Entry block for the transaction this address occurs in. */
basic_block entry_block;
+
/* Dominating statements the store occurs in. */
gimple_vec stmts;
+
/* Initially, while we are building the log, we place a nonzero
value here to mean that this address *will* be saved with a
save/restore sequence. Later, when generating the save sequence
@@ -1721,8 +1724,8 @@ struct tm_region
/* Return value from BUILT_IN_TM_START. */
tree tm_state;
- /* The entry block to this region. This will always be the first
- block of the body of the transaction. */
+ /* The entry block to the instrumented code path for this region.
+ This will always be the first block of the body of the transaction. */
basic_block entry_block;
/* The first block after an expanded call to _ITM_beginTransaction. */
@@ -1732,7 +1735,7 @@ struct tm_region
These blocks are still a part of the region (i.e., the border is
inclusive). Note that this set is only complete for paths in the CFG
starting at ENTRY_BLOCK, and that there is no exit block recorded for
- the edge to the "over" label. */
+ the TM_ABORT edge nor for the body of the uninstrumented code path. */
bitmap exit_blocks;
/* The set of all blocks that have an TM_IRREVOCABLE call. */
@@ -1779,11 +1782,19 @@ tm_region_init_0 (struct tm_region *outer, basic_block bb, gimple stmt)
region->original_transaction_was_outer = false;
region->tm_state = NULL;
- /* There are either one or two edges out of the block containing
- the GIMPLE_TRANSACTION, one to the actual region and one to the
- "over" label if the region contains an abort. The former will
- always be the one marked FALLTHRU. */
- region->entry_block = FALLTHRU_EDGE (bb)->dest;
+ // There are three possible edges out of GIMPLE_TRANSACTION.
+ // The "entry_block" always refers to the instrumented code path.
+ region->entry_block = NULL;
+ {
+ edge_iterator ei;
+ edge e;
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (!(e->flags & (EDGE_TM_ABORT | EDGE_TM_UNINSTRUMENTED)))
+ {
+ region->entry_block = e->dest;
+ break;
+ }
+ }
region->exit_blocks = BITMAP_ALLOC (&tm_obstack);
region->irr_blocks = BITMAP_ALLOC (&tm_obstack);
@@ -2453,6 +2464,10 @@ collect_bb2reg (struct tm_region *region, void *data)
unsigned int i;
basic_block bb;
+ // Don't run on transactions with only uninstrumented code paths.
+ if (region->entry_block == NULL)
+ return NULL;
+
queue = get_tm_region_blocks (region->entry_block,
region->exit_blocks,
region->irr_blocks,
@@ -2564,9 +2579,8 @@ expand_transaction (struct tm_region *region, void *data ATTRIBUTE_UNUSED)
uninst_edge = e;
else
inst_edge = e;
- if (e->flags & EDGE_FALLTHRU)
- fallthru_edge = e;
}
+ fallthru_edge = (inst_edge ? inst_edge : uninst_edge);
}
/* ??? There are plenty of bits here we're not computing. */
@@ -2780,7 +2794,7 @@ generate_tm_state (struct tm_region *region, void *data ATTRIBUTE_UNUSED)
// Reset the subcode, post optimizations. We'll fill this in
// again as we process blocks.
- if (region->exit_blocks)
+ if (region->entry_block && region->exit_blocks)
{
unsigned int subcode
= gimple_transaction_subcode (region->transaction_stmt);
@@ -3695,6 +3709,10 @@ execute_tm_memopt (void)
size_t i;
basic_block bb;
+ // Don't run on transactions with only uninstrumented code paths.
+ if (region->entry_block == NULL)
+ continue;
+
bitmap_obstack_initialize (&tm_memopt_obstack);
/* Save all BBs for the current region. */
@@ -3894,15 +3912,33 @@ ipa_uninstrument_transaction0 (struct tm_region *region,
int n = VEC_length (basic_block, queue);
basic_block *new_bbs = XNEWVEC (basic_block, n);
+ // We will have a GIMPLE_ATOMIC with 3 possible edges out of it.
+ // a) EDGE_FALLTHRU to the instrumented blocks,
+ // b) EDGE_TM_UNINSTRUMENTED to the uninstrumented blocks,
+ // c) EDGE_TM_ABORT out of the transaction
+
copy_bbs (VEC_address (basic_block, queue), n, new_bbs,
NULL, 0, NULL, NULL, transaction_bb);
edge e = make_edge (transaction_bb, new_bbs[0], EDGE_TM_UNINSTRUMENTED);
add_phi_args_after_copy (new_bbs, n, e);
- // Now we will have a GIMPLE_ATOMIC with 3 possible edges out of it.
- // a) EDGE_FALLTHRU into the transaction
- // b) EDGE_TM_ABORT out of the transaction
- // c) EDGE_TM_UNINSTRUMENTED into the uninstrumented blocks.
+ // Note that the region that we copied can contain transactions. Given
+ // that these are on a code path that we've just designated uninstrumented,
+ // there's no point in having these nested transactions have instrumented
+ // code paths. Which means that there's no point processing these new
+ // transactions into new tm_regions so that they could be processed by
+ // ipa_tm_scan_calls_transaction. What we would like to do is change the
+ // fallthru (instrumented) edges to uninstrumented.
+ for (int i = 0; i < n; ++i)
+ {
+ gimple_stmt_iterator gsi = gsi_last_bb (new_bbs[i]);
+ if (!gsi_end_p (gsi)
+ && gimple_code (gsi_stmt (gsi)) == GIMPLE_TRANSACTION)
+ {
+ edge e = FALLTHRU_EDGE (new_bbs[i]);
+ e->flags = EDGE_TM_UNINSTRUMENTED;
+ }
+ }
free (new_bbs);
}
--
1.7.11.7
On 11/07/2012 03:01 PM, Richard Henderson wrote: > Thoughts? Now with 100% more patches per mail! r~