While sinking machine instructions, sink matching DBG_VALUEs also otherwise live debug variable pass will drop DBG_VALUEs on the floor.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139208 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index 916dff7..29cfb49 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -382,6 +382,25 @@
return MI->isInsertSubreg() || MI->isSubregToReg() || MI->isRegSequence();
}
+/// collectDebgValues - Scan instructions following MI and collect any
+/// matching DBG_VALUEs.
+static void collectDebugValues(MachineInstr *MI,
+ SmallVector<MachineInstr *, 2> & DbgValues) {
+ DbgValues.clear();
+ if (!MI->getOperand(0).isReg())
+ return;
+
+ MachineBasicBlock::iterator DI = MI; ++DI;
+ for (MachineBasicBlock::iterator DE = MI->getParent()->end();
+ DI != DE; ++DI) {
+ if (!DI->isDebugValue())
+ return;
+ if (DI->getOperand(0).isReg() &&
+ DI->getOperand(0).getReg() == MI->getOperand(0).getReg())
+ DbgValues.push_back(DI);
+ }
+}
+
/// SinkInstruction - Determine whether it is safe to sink the specified machine
/// instruction out of its current block into a successor.
bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
@@ -598,10 +617,22 @@
while (InsertPos != SuccToSinkTo->end() && InsertPos->isPHI())
++InsertPos;
+ // collect matching debug values.
+ SmallVector<MachineInstr *, 2> DbgValuesToSink;
+ collectDebugValues(MI, DbgValuesToSink);
+
// Move the instruction.
SuccToSinkTo->splice(InsertPos, ParentBlock, MI,
++MachineBasicBlock::iterator(MI));
+ // Move debug values.
+ for (SmallVector<MachineInstr *, 2>::iterator DBI = DbgValuesToSink.begin(),
+ DBE = DbgValuesToSink.end(); DBI != DBE; ++DBI) {
+ MachineInstr *DbgMI = *DBI;
+ SuccToSinkTo->splice(InsertPos, ParentBlock, DbgMI,
+ ++MachineBasicBlock::iterator(DbgMI));
+ }
+
// Conservatively, clear any kill flags, since it's possible that they are no
// longer correct.
MI->clearKillInfo();