Allow the allocation of empty live ranges that have uses.
Empty ranges may represent undef values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128144 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocBasic.cpp b/lib/CodeGen/RegAllocBasic.cpp
index ce92f3d..ad33473 100644
--- a/lib/CodeGen/RegAllocBasic.cpp
+++ b/lib/CodeGen/RegAllocBasic.cpp
@@ -289,6 +289,8 @@
// 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 @@
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");