Local spiller kills a store if the folded restore is turned into a copy.
But this is incorrect if the spilled value live range extends beyond the
current BB.
It is currently controlled by a temporary option -spiller-check-liveout.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28024 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index f0dd40d..6122dc1 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -50,6 +50,10 @@
clEnumVal(local, " local spiller"),
clEnumValEnd),
cl::init(local));
+
+ // TEMPORARY option to test a fix.
+ cl::opt<bool>
+ SpillerCheckLiveOut("spiller-check-liveout", cl::Hidden);
}
//===----------------------------------------------------------------------===//
@@ -81,7 +85,8 @@
}
void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
- unsigned OpNo, MachineInstr *NewMI) {
+ unsigned OpNo, MachineInstr *NewMI,
+ bool LiveOut) {
// Move previous memory references folded to new instruction.
MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(NewMI);
for (MI2VirtMapTy::iterator I = MI2VirtMap.lower_bound(OldMI),
@@ -96,6 +101,7 @@
MRInfo = isRef;
} else {
MRInfo = OldMI->getOperand(OpNo).isUse() ? isModRef : isMod;
+ if (LiveOut) MRInfo = (ModRef)(MRInfo | isLiveOut);
}
// add new memory reference
@@ -727,10 +733,14 @@
MaybeDeadStores.erase(MDSI);
else {
// If we get here, the store is dead, nuke it now.
- assert(MR == VirtRegMap::isMod && "Can't be modref!");
- MBB.erase(MDSI->second);
- MaybeDeadStores.erase(MDSI);
- ++NumDSE;
+ assert(!(MR & VirtRegMap::isRef) && "Can't be modref!");
+ // Don't nuke it if the value is needed in another block.
+ if (!SpillerCheckLiveOut || !(MR & VirtRegMap::isLiveOut)) {
+ DEBUG(std::cerr << " Killed store:\t" << *MDSI->second);
+ MBB.erase(MDSI->second);
+ MaybeDeadStores.erase(MDSI);
+ ++NumDSE;
+ }
}
}