Add a utility function for conservatively clearing kill flags, and make
use of it in MachineCSE.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103726 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineCSE.cpp b/lib/CodeGen/MachineCSE.cpp
index 84c3d71..cfe5040 100644
--- a/lib/CodeGen/MachineCSE.cpp
+++ b/lib/CodeGen/MachineCSE.cpp
@@ -112,6 +112,7 @@
DEBUG(dbgs() << "Coalescing: " << *DefMI);
DEBUG(dbgs() << "*** to: " << *MI);
MO.setReg(SrcReg);
+ MRI->clearKillFlags(SrcReg);
if (NewRC != SRC)
MRI->setRegClass(SrcReg, NewRC);
DefMI->eraseFromParent();
@@ -365,8 +366,10 @@
// Actually perform the elimination.
if (DoCSE) {
- for (unsigned i = 0, e = CSEPairs.size(); i != e; ++i)
+ for (unsigned i = 0, e = CSEPairs.size(); i != e; ++i) {
MRI->replaceRegWith(CSEPairs[i].first, CSEPairs[i].second);
+ MRI->clearKillFlags(CSEPairs[i].second);
+ }
MI->eraseFromParent();
++NumCSEs;
} else {
diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp
index 5465fca..402be47 100644
--- a/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/lib/CodeGen/MachineRegisterInfo.cpp
@@ -133,6 +133,15 @@
return ++UI == use_nodbg_end();
}
+/// clearKillFlags - Iterate over all the uses of the given register and
+/// clear the kill flag from the MachineOperand. This function is used by
+/// optimization passes which extend register lifetimes and need only
+/// preserve conservative kill flag information.
+void MachineRegisterInfo::clearKillFlags(unsigned Reg) const {
+ for (use_iterator UI = use_begin(Reg), UE = use_end(); UI != UE; ++UI)
+ UI.getOperand().setIsKill(false);
+}
+
bool MachineRegisterInfo::isLiveIn(unsigned Reg) const {
for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
if (I->first == Reg || I->second == Reg)