STATISTIC(numAborts , "Number of times interval joining aborted");
char SimpleRegisterCoalescing::ID = 0;
-namespace {
- static cl::opt<bool>
- EnableJoining("join-liveintervals",
- cl::desc("Coalesce copies (default=true)"),
- cl::init(true));
+static cl::opt<bool>
+EnableJoining("join-liveintervals",
+ cl::desc("Coalesce copies (default=true)"),
+ cl::init(true));
- static cl::opt<bool>
- NewHeuristic("new-coalescer-heuristic",
- cl::desc("Use new coalescer heuristic"),
- cl::init(false));
+static cl::opt<bool>
+NewHeuristic("new-coalescer-heuristic",
+ cl::desc("Use new coalescer heuristic"),
+ cl::init(false));
- RegisterPass<SimpleRegisterCoalescing>
- X("simple-register-coalescing", "Simple Register Coalescing");
+static RegisterPass<SimpleRegisterCoalescing>
+X("simple-register-coalescing", "Simple Register Coalescing");
- // Declare that we implement the RegisterCoalescer interface
- RegisterAnalysisGroup<RegisterCoalescer, true/*The Default*/> V(X);
-}
+// Declare that we implement the RegisterCoalescer interface
+static RegisterAnalysisGroup<RegisterCoalescer, true/*The Default*/> V(X);
-const PassInfo *llvm::SimpleRegisterCoalescingID = X.getPassInfo();
+const PassInfo *const llvm::SimpleRegisterCoalescingID = &X;
void SimpleRegisterCoalescing::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<LiveIntervals>();
// Copy from the RHS?
if (!RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg))
return false; // Nope, bail out.
-
+
+ if (LHSIt->contains(RHSIt->valno->def))
+ // Here is an interesting situation:
+ // BB1:
+ // vr1025 = copy vr1024
+ // ..
+ // BB2:
+ // vr1024 = op
+ // = vr1025
+ // Even though vr1025 is copied from vr1024, it's not safe to
+ // coalesced them since live range of vr1025 intersects the
+ // def of vr1024. This happens because vr1025 is assigned the
+ // value of the previous iteration of vr1024.
+ return false;
EliminatedLHSVals.push_back(LHSIt->valno);
}
// Otherwise, if this is a copy from the RHS, mark it as being merged
// in.
if (RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg)) {
+ if (LHSIt->contains(RHSIt->valno->def))
+ // Here is an interesting situation:
+ // BB1:
+ // vr1025 = copy vr1024
+ // ..
+ // BB2:
+ // vr1024 = op
+ // = vr1025
+ // Even though vr1025 is copied from vr1024, it's not safe to
+ // coalesced them since live range of vr1025 intersects the
+ // def of vr1024. This happens because vr1025 is assigned the
+ // value of the previous iteration of vr1024.
+ return false;
EliminatedLHSVals.push_back(LHSIt->valno);
// We know this entire LHS live range is okay, so skip it now.