diff options
| -rw-r--r-- | lib/CodeGen/RegisterCoalescer.cpp | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp index 7dd070ca1d..bb5e65e8aa 100644 --- a/lib/CodeGen/RegisterCoalescer.cpp +++ b/lib/CodeGen/RegisterCoalescer.cpp @@ -1431,6 +1431,31 @@ bool RegisterCoalescer::JoinIntervals(CoalescerPair &CP) { // than the full interfeence check below. We allow overlapping live ranges // only when one is a copy of the other. if (CP.isPhys()) { + // Optimization for reserved registers like ESP. + // We can only merge with a reserved physreg if RHS has a single value that + // is a copy of CP.DstReg(). The live range of the reserved register will + // look like a set of dead defs - we don't properly track the live range of + // reserved registers. + if (RegClassInfo.isReserved(CP.getDstReg())) { + assert(CP.isFlipped() && RHS.containsOneValue() && + "Invalid join with reserved register"); + // Deny any overlapping intervals. This depends on all the reserved + // register live ranges to look like dead defs. + for (const unsigned *AS = TRI->getOverlaps(CP.getDstReg()); *AS; ++AS) { + if (!LIS->hasInterval(*AS)) + continue; + if (RHS.overlaps(LIS->getInterval(*AS))) { + DEBUG(dbgs() << "\t\tInterference: " << PrintReg(*AS, TRI) << '\n'); + return false; + } + } + // Skip any value computations, we are not adding new values to the + // reserved register. Also skip merging the live ranges, the reserved + // register live range doesn't need to be accurate as long as all the + // defs are there. + return true; + } + for (const unsigned *AS = TRI->getAliasSet(CP.getDstReg()); *AS; ++AS){ if (!LIS->hasInterval(*AS)) continue; |