Corrected call interference bug
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@916 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp b/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp
index 4b6a0f9..9830049 100644
--- a/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp
+++ b/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp
@@ -125,25 +125,84 @@
}
- //the live range of this var interferes with this call
- if( isCallInst ) {
- LROfVar->addCallInterference( (const Instruction *const) Def );
- if( DEBUG_RA) {
- cout << "\n ++Added Call Interf to set:";
- LROfVar->printSet();
- }
- }
- }
else if(DEBUG_RA > 1) {
// we will not have LRs for values not explicitly allocated in the
// instruction stream (e.g., constants)
cout << " warning: no live range for " ;
printValue( *LIt); cout << endl; }
- }
+ }
+ }
+
}
+
+//----------------------------------------------------------------------------
+// For a call instruction, this method sets the CallInterference flag in
+// the LR of each variable live int the Live Variable Set live after the
+// call instruction (except the return value of the call instruction - since
+// the return value does not interfere with that call itself).
+//----------------------------------------------------------------------------
+
+void PhyRegAlloc::setCallInterferences(const MachineInstr *MInst,
+ const LiveVarSet *const LVSetAft )
+{
+ // Now find the LR of the return value of the call
+ // The last *implicit operand* is the return value of a call
+
+ // We do this because, we look at the LV set *after* the instruction
+ // to determine, which LRs must be saved across calls. The return value
+ // of the call is live in this set - but it does not interfere with call
+ // (i.e., we can allocate a volatile register to the return value)
+
+ LiveRange *RetValLR = NULL;
+
+ unsigned NumOfImpRefs = MInst->getNumImplicitRefs();
+ if( NumOfImpRefs > 0 ) {
+
+ if( MInst->implicitRefIsDefined(NumOfImpRefs-1) ) {
+
+ const Value *RetVal = MInst->getImplicitRef(NumOfImpRefs-1);
+ RetValLR = LRI.getLiveRangeForValue( RetVal );
+ assert( RetValLR && "No LR for RetValue of call");
+ }
+
+ }
+
+
+ if( DEBUG_RA)
+ cout << "\n For call inst: " << *MInst;
+
+ LiveVarSet::const_iterator LIt = LVSetAft->begin();
+
+ // for each live var in live variable set after machine inst
+ for( ; LIt != LVSetAft->end(); ++LIt) {
+
+ // get the live range corresponding to live var
+ LiveRange *const LR = LRI.getLiveRangeForValue(*LIt );
+
+ if( LR && DEBUG_RA) {
+ cout << "\n\tLR Aft Call: ";
+ LR->printSet();
+ }
+
+
+ // LR can be null if it is a const since a const
+ // doesn't have a dominating def - see Assumptions above
+ if( LR && (LR != RetValLR) ) {
+ LR->setCallInterference();
+ if( DEBUG_RA) {
+ cout << "\n ++Added call interf for LR: " ;
+ LR->printSet();
+ }
+ }
+
+ }
+
+}
+
+
//----------------------------------------------------------------------------
// This method will walk thru code and create interferences in the IG of
// each RegClass.
@@ -174,7 +233,16 @@
const bool isCallInst = TM.getInstrInfo().isCall(MInst->getOpCode());
- // if( isCallInst) cout << "\n%%% Found call Inst:\n";
+ if( isCallInst ) {
+ //cout << "\nFor call inst: " << *MInst;
+
+ // set the isCallInterference flag of each live range wich extends
+ // accross this call instruction. This information is used by graph
+ // coloring algo to avoid allocating volatile colors to live ranges
+ // that span across calls (since they have to be saved/restored)
+ setCallInterferences( MInst, LVSetAI);
+ }
+
// iterate over MI operands to find defs
for( MachineInstr::val_op_const_iterator OpI(MInst);!OpI.done(); ++OpI) {
@@ -275,7 +343,7 @@
void PhyRegAlloc::insertCallerSavingCode(const MachineInstr *MInst,
const BasicBlock *BB )
{
- assert( (TM.getInstrInfo()).isCall( MInst->getOpCode() ) );
+ // assert( (TM.getInstrInfo()).isCall( MInst->getOpCode() ) );
int StackOff = -8; // ****TODO : Change
hash_set<unsigned> PushedRegSet;
@@ -315,7 +383,7 @@
// get the live range corresponding to live var
LiveRange *const LR = LRI.getLiveRangeForValue(*LIt );
- // LROfVar can be null if it is a const since a const
+ // LR can be null if it is a const since a const
// doesn't have a dominating def - see Assumptions above
if( LR ) {
@@ -354,7 +422,7 @@
StackOff -= 8; // ****TODO: Correct ??????
if(DEBUG_RA) {
- cout << "For callee save call inst:" << *MInst << endl;
+ cerr << "\nFor callee save call inst:" << *MInst;
cerr << "\n -inserted caller saving instrs:\n\t ";
cerr << *AdIBef << "\n\t" << *AdIAft ;
}