Place the lowered phi instruction(s) before the DEBUG_VALUE entry

When a phi node is finally lowered to a machine instruction it is
important that the lowered "load" instruction is placed before the
associated DEBUG_VALUE entry describing the value loaded.

Renamed the existing SkipPHIsAndLabels to SkipPHIsLabelsAndDebug to
more fully describe that it also skips debug entries. Then used the
"new" function SkipPHIsAndLabels when the debug information should not
be skipped when placing the lowered "load" instructions so that it is
placed before the debug entries.

Differential Revision: https://reviews.llvm.org/D23760 

llvm-svn: 281727

6 files changed, 20 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/InlineSpiller.cpp b/llvm/lib/CodeGen/InlineSpiller.cpp
index 15f77c620c7..3ccc18d120f 100644
--- a/llvm/lib/CodeGen/InlineSpiller.cpp
+++ b/llvm/lib/CodeGen/InlineSpiller.cpp
@@ -377,7 +377,7 @@ bool InlineSpiller::hoistSpillInsideBB(LiveInterval &SpillLI,
   MachineBasicBlock *MBB = LIS.getMBBFromIndex(SrcVNI->def);
   MachineBasicBlock::iterator MII;
   if (SrcVNI->isPHIDef())
-    MII = MBB->SkipPHIsAndLabels(MBB->begin());
+    MII = MBB->SkipPHIsLabelsAndDebug(MBB->begin());
   else {
     MachineInstr *DefMI = LIS.getInstructionFromIndex(SrcVNI->def);
     assert(DefMI && "Defining instruction disappeared");
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index 966b4f1f4e4..97531971c9d 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -951,7 +951,7 @@ findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
   while (!(MI = LIS.getInstructionFromIndex(Idx))) {
     // We've reached the beginning of MBB.
     if (Idx == Start) {
-      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
+      MachineBasicBlock::iterator I = MBB->SkipPHIsLabelsAndDebug(MBB->begin());
       return I;
     }
     Idx = Idx.getPrevIndex();
diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index b43a253e2df..55138f64198 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -149,12 +149,25 @@ MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
 MachineBasicBlock::iterator
 MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
   iterator E = end();
+  while (I != E && (I->isPHI() || I->isPosition()))
+    ++I;
+  // FIXME: This needs to change if we wish to bundle labels
+  // inside the bundle.
+  assert((I == E || !I->isInsideBundle()) &&
+         "First non-phi / non-label instruction is inside a bundle!");
+  return I;
+}
+
+MachineBasicBlock::iterator
+MachineBasicBlock::SkipPHIsLabelsAndDebug(MachineBasicBlock::iterator I) {
+  iterator E = end();
   while (I != E && (I->isPHI() || I->isPosition() || I->isDebugValue()))
     ++I;
   // FIXME: This needs to change if we wish to bundle labels / dbg_values
   // inside the bundle.
   assert((I == E || !I->isInsideBundle()) &&
-         "First non-phi / non-label instruction is inside a bundle!");
+         "First non-phi / non-label / non-debug "
+         "instruction is inside a bundle!");
   return I;
 }
 
diff --git a/llvm/lib/CodeGen/PHIEliminationUtils.cpp b/llvm/lib/CodeGen/PHIEliminationUtils.cpp
index 4cabc3a8c1f..4e67ff2e508 100644
--- a/llvm/lib/CodeGen/PHIEliminationUtils.cpp
+++ b/llvm/lib/CodeGen/PHIEliminationUtils.cpp
@@ -54,6 +54,7 @@ llvm::findPHICopyInsertPoint(MachineBasicBlock* MBB, MachineBasicBlock* SuccMBB,
     ++InsertPoint;
   }
 
-  // Make sure the copy goes after any phi nodes however.
+  // Make sure the copy goes after any phi nodes but before
+  // any debug nodes.
   return MBB->SkipPHIsAndLabels(InsertPoint);
 }
diff --git a/llvm/lib/CodeGen/SplitKit.cpp b/llvm/lib/CodeGen/SplitKit.cpp
index e06bc4a3614..2d5a9d6a92c 100644
--- a/llvm/lib/CodeGen/SplitKit.cpp
+++ b/llvm/lib/CodeGen/SplitKit.cpp
@@ -675,7 +675,7 @@ SlotIndex SplitEditor::leaveIntvAtTop(MachineBasicBlock &MBB) {
   }
 
   VNInfo *VNI = defFromParent(0, ParentVNI, Start, MBB,
-                              MBB.SkipPHIsAndLabels(MBB.begin()));
+                              MBB.SkipPHIsLabelsAndDebug(MBB.begin()));
   RegAssign.insert(Start, VNI->def, OpenIdx);
   DEBUG(dump());
   return VNI->def;
diff --git a/llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp b/llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp
index cad4f4f2289..6bd229625fc 100644
--- a/llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp
+++ b/llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp
@@ -58,7 +58,7 @@ protected:
       bool Changed = false;
 
       MachineBasicBlock::iterator I = ReturnMBB.begin();
-      I = ReturnMBB.SkipPHIsAndLabels(I);
+      I = ReturnMBB.SkipPHIsLabelsAndDebug(I);
 
       // The block must be essentially empty except for the blr.
       if (I == ReturnMBB.end() ||