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author | Hans Wennborg <hans@hanshq.net> | 2012-11-16 20:14:40 +0000 |
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committer | Hans Wennborg <hans@hanshq.net> | 2012-11-16 20:14:40 +0000 |
commit | 21863332ca402263c518840742aee2b126d53007 (patch) | |
tree | 2a926d1196874c833de59bbb1edcdee70697d28b /lib/VMCore | |
parent | 3481efbe83bbd775b609ea02ee426fb956b9c43a (diff) | |
download | llvm-21863332ca402263c518840742aee2b126d53007.tar.gz llvm-21863332ca402263c518840742aee2b126d53007.tar.bz2 llvm-21863332ca402263c518840742aee2b126d53007.tar.xz |
Merge r168037 from trunk:
Make GlobalOpt be conservative with TLS variables (PR14309)
For global variables that get the same value stored into them
everywhere, GlobalOpt will replace them with a constant. The problem is
that a thread-local GlobalVariable looks like one value (the address of
the TLS var), but is different between threads.
This patch introduces Constant::isThreadDependent() which returns true
for thread-local variables and constants which depend on them (e.g. a GEP
into a thread-local array), and teaches GlobalOpt not to track such
values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_32@168192 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/VMCore')
-rw-r--r-- | lib/VMCore/Constants.cpp | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp index a4e21e16b3..041fe2eb4f 100644 --- a/lib/VMCore/Constants.cpp +++ b/lib/VMCore/Constants.cpp @@ -245,6 +245,31 @@ bool Constant::canTrap() const { } } +/// isThreadDependent - Return true if the value can vary between threads. +bool Constant::isThreadDependent() const { + SmallPtrSet<const Constant*, 64> Visited; + SmallVector<const Constant*, 64> WorkList; + WorkList.push_back(this); + Visited.insert(this); + + while (!WorkList.empty()) { + const Constant *C = WorkList.pop_back_val(); + + if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) { + if (GV->isThreadLocal()) + return true; + } + + for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) { + const Constant *D = cast<Constant>(C->getOperand(I)); + if (Visited.insert(D)) + WorkList.push_back(D); + } + } + + return false; +} + /// isConstantUsed - Return true if the constant has users other than constant /// exprs and other dangling things. bool Constant::isConstantUsed() const { |