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Allow the allocation of empty live ranges that have uses.

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Empty ranges may represent undef values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128144 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-03-23 04:32:51 +00:00
parent bf824efcb9
commit 0b5015188e
1 changed files with 8 additions and 1 deletions
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9
lib/CodeGen/RegAllocBasic.cpp
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@ -289,6 +289,8 @@ void RegAllocBase::allocatePhysRegs() {
// Continue assigning vregs one at a time to available physical registers.
while (LiveInterval *VirtReg = dequeue()) {
assert(!VRM->hasPhys(VirtReg->reg) && "Register already assigned");
// Unused registers can appear when the spiller coalesces snippets.
if (MRI->reg_nodbg_empty(VirtReg->reg)) {
DEBUG(dbgs() << "Dropping unused " << *VirtReg << '\n');
@ -315,7 +317,12 @@ void RegAllocBase::allocatePhysRegs() {
for (VirtRegVec::iterator I = SplitVRegs.begin(), E = SplitVRegs.end();
I != E; ++I) {
LiveInterval *SplitVirtReg = *I;
if (SplitVirtReg->empty()) continue;
assert(!VRM->hasPhys(SplitVirtReg->reg) && "Register already assigned");
if (MRI->reg_nodbg_empty(SplitVirtReg->reg)) {
DEBUG(dbgs() << "not queueing unused " << *SplitVirtReg << '\n');
LIS->removeInterval(SplitVirtReg->reg);
continue;
}
DEBUG(dbgs() << "queuing new interval: " << *SplitVirtReg << "\n");
assert(TargetRegisterInfo::isVirtualRegister(SplitVirtReg->reg) &&
"expect split value in virtual register");