Magic-Mirror/llvm-capstone
1
0
Fork 0
mirror of https://github.com/capstone-engine/llvm-capstone.git synced 2025-01-09 17:43:57 +00:00
Code Issues Actions 2 Packages Projects Releases Wiki Activity

[sanitizer] partially implement racy fast path in bitset-based deadlock detector

Browse Source 
llvm-svn: 203904
This commit is contained in:
Kostya Serebryany 2014-03-14 08:06:15 +00:00
parent 39aa6af23f
commit 61a0f1c564
4 changed files with 30 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
compiler-rt/lib/sanitizer_common/sanitizer_bvgraph.h
View File

@ -60,6 +60,20 @@ class BVGraph {
return res;
}
// *EXPERIMENTAL*
// Returns true if all edges from=>to exist.
// This function does not use any global state except for 'this' itself,
// and thus can be called from different threads w/o locking.
// This would be racy.
// FIXME: investigate how much we can prove about this race being "benign".
bool hasAllEdges(const BV &from, uptr to) {
for (typename BV::Iterator it(from); it.hasNext(); ) {
uptr idx = it.next();
if (!v[idx].getBit(to)) return false;
}
return true;
}
// Returns true if the edge from=>to was removed.
bool removeEdge(uptr from, uptr to) {
return v[from].clearBit(to);

10
compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector.h
View File

@ -172,6 +172,16 @@ class DeadlockDetector {
dtls->addLock(cur_idx, current_epoch_);
}
// Experimental *racy* fast path function.
// Returns true if all edges from the currently held locks to cur_node exist.
bool hasAllEdges(DeadlockDetectorTLS<BV> *dtls, uptr cur_node) {
if (dtls->getEpoch() == nodeToEpoch(cur_node)) {
uptr cur_idx = nodeToIndexUnchecked(cur_node);
return g_.hasAllEdges(dtls->getLocks(current_epoch_), cur_idx);
}
return false;
}
// Adds edges from currently held locks to cur_node,
// returns the number of added edges, and puts the sources of added edges
// into added_edges[].

2
compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector1.cc
View File

@ -100,6 +100,7 @@ void DD::MutexBeforeLock(DDCallback *cb,
DDMutex *m, bool wlock) {
DDLogicalThread *lt = cb->lt;
if (lt->dd.empty()) return; // This will be the first lock held by lt.
if (dd.hasAllEdges(&lt->dd, m->id)) return; // We already have all edges.
SpinMutexLock lk(&mtx);
MutexEnsureID(lt, m);
if (dd.isHeld(&lt->dd, m->id))
@ -131,6 +132,7 @@ void DD::MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock, bool trylock) {
// Printf("T%p MutexLock: %zx\n", lt, m->id);
if (dd.onFirstLock(&lt->dd, m->id))
return;
// if (dd.hasAllEdges(&lt->dd, m->id)) return;
SpinMutexLock lk(&mtx);
MutexEnsureID(lt, m);
if (wlock) // Only a recursive rlock may be held.

4
compiler-rt/lib/sanitizer_common/tests/sanitizer_bvgraph_test.cc
View File

@ -320,10 +320,14 @@ void RunAddEdgesTest() {
from.clear();
from.setBit(1);
EXPECT_EQ(1U, g.addEdges(from, 4, added_edges, kMaxEdges));
EXPECT_TRUE(g.hasAllEdges(from, 4));
EXPECT_FALSE(g.hasAllEdges(from, 5));
EXPECT_EQ(1U, added_edges[0]);
from.setBit(2);
from.setBit(3);
EXPECT_FALSE(g.hasAllEdges(from, 4));
EXPECT_EQ(2U, g.addEdges(from, 4, added_edges, kMaxEdges));
EXPECT_TRUE(g.hasAllEdges(from, 4));
EXPECT_EQ(2U, added_edges[0]);
EXPECT_EQ(3U, added_edges[1]);
}