1 files changed, 31 insertions, 4 deletions
diff --git a/lib/Target/AMDGPU/SIFixSGPRCopies.cpp b/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
index 6a422e70fe1f..f9d258f44a62 100644
--- a/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
+++ b/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
@@ -65,6 +65,7 @@
 /// ultimately led to the creation of an illegal COPY.
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/DenseSet.h"
 #include "AMDGPU.h"
 #include "AMDGPUSubtarget.h"
 #include "SIInstrInfo.h"
@@ -198,6 +199,10 @@ static bool foldVGPRCopyIntoRegSequence(MachineInstr &MI,
   if (!CopyUse.isCopy())
     return false;
 
+  // It is illegal to have vreg inputs to a physreg defining reg_sequence.
+  if (TargetRegisterInfo::isPhysicalRegister(CopyUse.getOperand(0).getReg()))
+    return false;
+
   const TargetRegisterClass *SrcRC, *DstRC;
   std::tie(SrcRC, DstRC) = getCopyRegClasses(CopyUse, *TRI, MRI);
 
@@ -234,8 +239,9 @@ static bool foldVGPRCopyIntoRegSequence(MachineInstr &MI,
 
     unsigned TmpReg = MRI.createVirtualRegister(NewSrcRC);
 
-    BuildMI(*MI.getParent(), &MI, MI.getDebugLoc(), TII->get(AMDGPU::COPY), TmpReg)
-      .addOperand(MI.getOperand(I));
+    BuildMI(*MI.getParent(), &MI, MI.getDebugLoc(), TII->get(AMDGPU::COPY),
+            TmpReg)
+        .add(MI.getOperand(I));
 
     MI.getOperand(I).setReg(TmpReg);
   }
@@ -326,6 +332,27 @@ static bool isSafeToFoldImmIntoCopy(const MachineInstr *Copy,
   return true;
 }
 
+static bool predsHasDivergentTerminator(MachineBasicBlock *MBB,
+                               const TargetRegisterInfo *TRI) {
+  DenseSet<MachineBasicBlock*> Visited;
+  SmallVector<MachineBasicBlock*, 4> Worklist(MBB->pred_begin(), 
+                                              MBB->pred_end());
+
+  while (!Worklist.empty()) {
+    MachineBasicBlock *mbb = Worklist.back();
+    Worklist.pop_back();
+
+    if (!Visited.insert(mbb).second)
+      continue;
+    if (hasTerminatorThatModifiesExec(*mbb, *TRI))
+      return true;
+
+    Worklist.insert(Worklist.end(), mbb->pred_begin(), mbb->pred_end());
+  }
+
+  return false;
+}
+
 bool SIFixSGPRCopies::runOnMachineFunction(MachineFunction &MF) {
   const SISubtarget &ST = MF.getSubtarget<SISubtarget>();
   MachineRegisterInfo &MRI = MF.getRegInfo();
@@ -382,8 +409,8 @@ bool SIFixSGPRCopies::runOnMachineFunction(MachineFunction &MF) {
           MachineBasicBlock *MBB0 = MI.getOperand(2).getMBB();
           MachineBasicBlock *MBB1 = MI.getOperand(4).getMBB();
 
-          MachineBasicBlock *NCD = MDT->findNearestCommonDominator(MBB0, MBB1);
-          if (NCD && !hasTerminatorThatModifiesExec(*NCD, *TRI)) {
+          if (!predsHasDivergentTerminator(MBB0, TRI) &&
+              !predsHasDivergentTerminator(MBB1, TRI)) {
             DEBUG(dbgs() << "Not fixing PHI for uniform branch: " << MI << '\n');
             break;
           }