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Also eliminate redundant spills downstream of inserted reloads.

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This can happen when multiple sibling registers are spilled after live range
splitting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127965 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-03-20 05:44:58 +00:00
parent 01a46c82e0
commit 682eed0da8
1 changed files with 17 additions and 9 deletions
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26
lib/CodeGen/InlineSpiller.cpp
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@ -466,6 +466,7 @@ bool InlineSpiller::hoistSpill(LiveInterval &SpillLI, MachineInstr *CopyMI) {
/// eliminateRedundantSpills - SLI:VNI is known to be on the stack. Remove any /// eliminateRedundantSpills - SLI:VNI is known to be on the stack. Remove any
/// redundant spills of this value in SLI.reg and sibling copies. /// redundant spills of this value in SLI.reg and sibling copies.
void InlineSpiller::eliminateRedundantSpills(LiveInterval &SLI, VNInfo *VNI) { void InlineSpiller::eliminateRedundantSpills(LiveInterval &SLI, VNInfo *VNI) {
assert(VNI && "Missing value");
SmallVector<std::pair<LiveInterval*, VNInfo*>, 8> WorkList; SmallVector<std::pair<LiveInterval*, VNInfo*>, 8> WorkList;
WorkList.push_back(std::make_pair(&SLI, VNI)); WorkList.push_back(std::make_pair(&SLI, VNI));
LiveInterval &StackInt = LSS.getInterval(StackSlot); LiveInterval &StackInt = LSS.getInterval(StackSlot);
@ -793,15 +794,22 @@ void InlineSpiller::spillAroundUses(unsigned Reg) {
// Check for a sibling copy. // Check for a sibling copy.
unsigned SibReg = isFullCopyOf(MI, Reg); unsigned SibReg = isFullCopyOf(MI, Reg);
if (!isSibling(SibReg)) if (SibReg && isSibling(SibReg)) {
SibReg = 0; if (Writes) {
// Hoist the spill of a sib-reg copy.
// Hoist the spill of a sib-reg copy. if (hoistSpill(OldLI, MI)) {
if (SibReg && Writes && !Reads && hoistSpill(OldLI, MI)) { // This COPY is now dead, the value is already in the stack slot.
// This COPY is now dead, the value is already in the stack slot. MI->getOperand(0).setIsDead();
MI->getOperand(0).setIsDead(); DeadDefs.push_back(MI);
DeadDefs.push_back(MI); continue;
continue; }
} else {
// This is a reload for a sib-reg copy. Drop spills downstream.
SlotIndex Idx = LIS.getInstructionIndex(MI).getDefIndex();
LiveInterval &SibLI = LIS.getInterval(SibReg);
eliminateRedundantSpills(SibLI, SibLI.getVNInfoAt(Idx));
// The COPY will fold to a reload below.
}
} }
// Attempt to fold memory ops. // Attempt to fold memory ops.