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Fix some nondeterministic behavior when forwarding

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from a switch table.  Multiple table entries that
branch to the same place were being sorted by the
pointer value of the ConstantInt*; changed to sort
by the actual value of the ConstantInt.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66749 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2009-03-12 01:00:26 +00:00
parent fd82995823
commit a9537cf3fc
1 changed files with 13 additions and 3 deletions
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16
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -719,6 +719,16 @@ static bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
return false; return false;
} }
/// A sorting function for the std::set's in the following function which track
/// the values in switches. This forces deterministic behavior by comparing
/// the values rather than the pointers.
class Sorter {
public:
bool operator() (ConstantInt * const &p, ConstantInt * const &q) const {
return p->getSExtValue() < q->getSExtValue();
}
};
/// FoldValueComparisonIntoPredecessors - The specified terminator is a value /// FoldValueComparisonIntoPredecessors - The specified terminator is a value
/// equality comparison instruction (either a switch or a branch on "X == c"). /// equality comparison instruction (either a switch or a branch on "X == c").
/// See if any of the predecessors of the terminator block are value comparisons /// See if any of the predecessors of the terminator block are value comparisons
@ -754,7 +764,7 @@ static bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI) {
if (PredDefault == BB) { if (PredDefault == BB) {
// If this is the default destination from PTI, only the edges in TI // If this is the default destination from PTI, only the edges in TI
// that don't occur in PTI, or that branch to BB will be activated. // that don't occur in PTI, or that branch to BB will be activated.
std::set<ConstantInt*> PTIHandled; std::set<ConstantInt*, Sorter> PTIHandled;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i) for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].second != BB) if (PredCases[i].second != BB)
PTIHandled.insert(PredCases[i].first); PTIHandled.insert(PredCases[i].first);
@ -782,7 +792,7 @@ static bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI) {
// If this is not the default destination from PSI, only the edges // If this is not the default destination from PSI, only the edges
// in SI that occur in PSI with a destination of BB will be // in SI that occur in PSI with a destination of BB will be
// activated. // activated.
std::set<ConstantInt*> PTIHandled; std::set<ConstantInt*, Sorter> PTIHandled;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i) for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].second == BB) { if (PredCases[i].second == BB) {
PTIHandled.insert(PredCases[i].first); PTIHandled.insert(PredCases[i].first);
@ -803,7 +813,7 @@ static bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI) {
// If there are any constants vectored to BB that TI doesn't handle, // If there are any constants vectored to BB that TI doesn't handle,
// they must go to the default destination of TI. // they must go to the default destination of TI.
for (std::set<ConstantInt*>::iterator I = PTIHandled.begin(), for (std::set<ConstantInt*, Sorter>::iterator I = PTIHandled.begin(),
E = PTIHandled.end(); I != E; ++I) { E = PTIHandled.end(); I != E; ++I) {
PredCases.push_back(std::make_pair(*I, BBDefault)); PredCases.push_back(std::make_pair(*I, BBDefault));
NewSuccessors.push_back(BBDefault); NewSuccessors.push_back(BBDefault);