Fix PR8612 in the standard spiller, take two.

The live range of a register defined by an early clobber starts at the use slot,
not the def slot.

Except when it is an early clobber tied to a use operand. Then it starts at the
def slot like a standard def.

llvm-svn: 119305

2 files changed, 9 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index aa2f9658874..9b42012979f 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1136,11 +1136,14 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
       rewriteImplicitOps(li, MI, NewVReg, vrm);
 
     // Reuse NewVReg for other reads.
+    bool HasEarlyClobber = false;
     for (unsigned j = 0, e = Ops.size(); j != e; ++j) {
       MachineOperand &mopj = MI->getOperand(Ops[j]);
       mopj.setReg(NewVReg);
       if (mopj.isImplicit())
         rewriteImplicitOps(li, MI, NewVReg, vrm);
+      if (mopj.isEarlyClobber())
+        HasEarlyClobber = true;
     }
 
     if (CreatedNewVReg) {
@@ -1199,7 +1202,11 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
       }
     }
     if (HasDef) {
-      LiveRange LR(index.getDefIndex(), index.getStoreIndex(),
+      // An early clobber starts at the use slot, except for an early clobber
+      // tied to a use operand (yes, that is a thing).
+      LiveRange LR(HasEarlyClobber && !HasUse ?
+                   index.getUseIndex() : index.getDefIndex(),
+                   index.getStoreIndex(),
                    nI.getNextValue(SlotIndex(), 0, VNInfoAllocator));
       DEBUG(dbgs() << " +" << LR);
       nI.addRange(LR);
diff --git a/llvm/test/CodeGen/ARM/2010-11-15-SpillEarlyClobber.ll b/llvm/test/CodeGen/ARM/2010-11-15-SpillEarlyClobber.ll
index 046016aa3f3..04220949027 100644
--- a/llvm/test/CodeGen/ARM/2010-11-15-SpillEarlyClobber.ll
+++ b/llvm/test/CodeGen/ARM/2010-11-15-SpillEarlyClobber.ll
@@ -1,3 +1,4 @@
+; RUN: llc < %s -verify-machineinstrs -spiller=standard
 ; RUN: llc < %s -verify-machineinstrs -spiller=inline
 ; PR8612
 ;