<div dir="ltr"><div>FYI I see the following CHECK-failure in GCC build of LLVM:</div><div><br></div><div>[ RUN ] SanitizerCommon.TwoLevelBitVector</div><div>==11875==Sanitizer CHECK failed: /llvm/projects/compiler-rt/lib/sanitizer_common/sanitizer_bitvector.h:325 ((idx)) <= ((size())) (67, 64)</div>
<div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Mar 31, 2014 at 11:23 AM, Kostya Serebryany <span dir="ltr"><<a href="mailto:kcc@google.com" target="_blank">kcc@google.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: kcc<br>
Date: Mon Mar 31 02:23:50 2014<br>
New Revision: 205168<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=205168&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=205168&view=rev</a><br>
Log:<br>
[sanitizer] speed up the bitvector-based deadlock detector by ~15% (iterate over the currently held locks using the array, not the bitvector. Bitvector is not the best data structure to iterate over)<br>
<br>
Modified:<br>
compiler-rt/trunk/lib/sanitizer_common/sanitizer_bvgraph.h<br>
compiler-rt/trunk/lib/sanitizer_common/sanitizer_deadlock_detector.h<br>
compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_bvgraph_test.cc<br>
<br>
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_bvgraph.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_bvgraph.h?rev=205168&r1=205167&r2=205168&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_bvgraph.h?rev=205168&r1=205167&r2=205168&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_bvgraph.h (original)<br>
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_bvgraph.h Mon Mar 31 02:23:50 2014<br>
@@ -61,18 +61,12 @@ class BVGraph {<br>
}<br>
<br>
// *EXPERIMENTAL*<br>
- // Returns true if all edges from=>to exist.<br>
+ // Returns true if an edge from=>to exist.<br>
// This function does not use any global state except for 'this' itself,<br>
// and thus can be called from different threads w/o locking.<br>
// This would be racy.<br>
// FIXME: investigate how much we can prove about this race being "benign".<br>
- bool hasAllEdges(const BV &from, uptr to) {<br>
- for (typename BV::Iterator it(from); it.hasNext(); ) {<br>
- uptr idx = it.next();<br>
- if (!v[idx].getBit(to)) return false;<br>
- }<br>
- return true;<br>
- }<br>
+ bool hasEdge(uptr from, uptr to) { return v[from].getBit(to); }<br>
<br>
// Returns true if the edge from=>to was removed.<br>
bool removeEdge(uptr from, uptr to) {<br>
<br>
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_deadlock_detector.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_deadlock_detector.h?rev=205168&r1=205167&r2=205168&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_deadlock_detector.h?rev=205168&r1=205167&r2=205168&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_deadlock_detector.h (original)<br>
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_deadlock_detector.h Mon Mar 31 02:23:50 2014<br>
@@ -64,12 +64,10 @@ class DeadlockDetectorTLS {<br>
recursive_locks[n_recursive_locks++] = lock_id;<br>
return false;<br>
}<br>
- if (stk) {<br>
- CHECK_LT(n_all_locks_, ARRAY_SIZE(all_locks_with_contexts_));<br>
- // lock_id < BV::kSize, can cast to a smaller int.<br>
- u32 lock_id_short = static_cast<u32>(lock_id);<br>
- all_locks_with_contexts_[n_all_locks_++] = {lock_id_short, stk};<br>
- }<br>
+ CHECK_LT(n_all_locks_, ARRAY_SIZE(all_locks_with_contexts_));<br>
+ // lock_id < BV::kSize, can cast to a smaller int.<br>
+ u32 lock_id_short = static_cast<u32>(lock_id);<br>
+ all_locks_with_contexts_[n_all_locks_++] = {lock_id_short, stk};<br>
return true;<br>
}<br>
<br>
@@ -109,6 +107,9 @@ class DeadlockDetectorTLS {<br>
return bv_;<br>
}<br>
<br>
+ uptr getNumLocks() const { return n_all_locks_; }<br>
+ uptr getLock(uptr idx) const { return all_locks_with_contexts_[idx].lock; }<br>
+<br>
private:<br>
BV bv_;<br>
uptr epoch_;<br>
@@ -222,7 +223,11 @@ class DeadlockDetector {<br>
if (cur_node && local_epoch == current_epoch_ &&<br>
local_epoch == nodeToEpoch(cur_node)) {<br>
uptr cur_idx = nodeToIndexUnchecked(cur_node);<br>
- return g_.hasAllEdges(dtls->getLocks(local_epoch), cur_idx);<br>
+ for (uptr i = 0, n = dtls->getNumLocks(); i < n; i++) {<br>
+ if (!g_.hasEdge(dtls->getLock(i), cur_idx))<br>
+ return false;<br>
+ }<br>
+ return true;<br>
}<br>
return false;<br>
}<br>
<br>
Modified: compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_bvgraph_test.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_bvgraph_test.cc?rev=205168&r1=205167&r2=205168&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_bvgraph_test.cc?rev=205168&r1=205167&r2=205168&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_bvgraph_test.cc (original)<br>
+++ compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_bvgraph_test.cc Mon Mar 31 02:23:50 2014<br>
@@ -320,14 +320,16 @@ void RunAddEdgesTest() {<br>
from.clear();<br>
from.setBit(1);<br>
EXPECT_EQ(1U, g.addEdges(from, 4, added_edges, kMaxEdges));<br>
- EXPECT_TRUE(g.hasAllEdges(from, 4));<br>
- EXPECT_FALSE(g.hasAllEdges(from, 5));<br>
+ EXPECT_TRUE(g.hasEdge(1, 4));<br>
+ EXPECT_FALSE(g.hasEdge(1, 5));<br>
EXPECT_EQ(1U, added_edges[0]);<br>
from.setBit(2);<br>
from.setBit(3);<br>
- EXPECT_FALSE(g.hasAllEdges(from, 4));<br>
EXPECT_EQ(2U, g.addEdges(from, 4, added_edges, kMaxEdges));<br>
- EXPECT_TRUE(g.hasAllEdges(from, 4));<br>
+ EXPECT_TRUE(g.hasEdge(2, 4));<br>
+ EXPECT_FALSE(g.hasEdge(2, 5));<br>
+ EXPECT_TRUE(g.hasEdge(3, 4));<br>
+ EXPECT_FALSE(g.hasEdge(3, 5));<br>
EXPECT_EQ(2U, added_edges[0]);<br>
EXPECT_EQ(3U, added_edges[1]);<br>
}<br>
<br>
<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><div>Alexey Samsonov, MSK</div>
</div>