1 files changed, 49 insertions, 21 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
index d855f3f0e42..34741850f82 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -6269,47 +6269,75 @@ MachineInstr *llvm::getVRegSubRegDef(const TargetInstrInfo::RegSubRegPair &P,
 }
 
 bool llvm::execMayBeModifiedBeforeUse(const MachineRegisterInfo &MRI,
-                                      unsigned VReg,
+                                      Register VReg,
                                       const MachineInstr &DefMI,
-                                      const MachineInstr *UseMI) {
+                                      const MachineInstr &UseMI) {
   assert(MRI.isSSA() && "Must be run on SSA");
 
   auto *TRI = MRI.getTargetRegisterInfo();
   auto *DefBB = DefMI.getParent();
 
-  if (UseMI) {
+  // Don't bother searching between blocks, although it is possible this block
+  // doesn't modify exec.
+  if (UseMI.getParent() != DefBB)
+    return true;
+
+  const int MaxInstScan = 20;
+  int NumInst = 0;
+
+  // Stop scan at the use.
+  auto E = UseMI.getIterator();
+  for (auto I = std::next(DefMI.getIterator()); I != E; ++I) {
+    if (I->isDebugInstr())
+      continue;
+
+    if (++NumInst > MaxInstScan)
+      return true;
+
+    if (I->modifiesRegister(AMDGPU::EXEC, TRI))
+      return true;
+  }
+
+  return false;
+}
+
+bool llvm::execMayBeModifiedBeforeAnyUse(const MachineRegisterInfo &MRI,
+                                         Register VReg,
+                                         const MachineInstr &DefMI) {
+  assert(MRI.isSSA() && "Must be run on SSA");
+
+  auto *TRI = MRI.getTargetRegisterInfo();
+  auto *DefBB = DefMI.getParent();
+
+  const int MaxUseInstScan = 10;
+  int NumUseInst = 0;
+
+  for (auto &UseInst : MRI.use_nodbg_instructions(VReg)) {
     // Don't bother searching between blocks, although it is possible this block
     // doesn't modify exec.
-    if (UseMI->getParent() != DefBB)
+    if (UseInst.getParent() != DefBB)
       return true;
-  } else {
-    int NumUse = 0;
-    const int MaxUseScan = 10;
-
-    for (auto &UseInst : MRI.use_nodbg_instructions(VReg)) {
-      if (UseInst.getParent() != DefBB)
-        return true;
 
-      if (NumUse++ > MaxUseScan)
-        return true;
-    }
+    if (++NumUseInst > MaxUseInstScan)
+      return true;
   }
 
   const int MaxInstScan = 20;
-  int NumScan = 0;
+  int NumInst = 0;
 
-  // Stop scan at the use if known.
-  auto E = UseMI ? UseMI->getIterator() : DefBB->end();
-  for (auto I = std::next(DefMI.getIterator()); I != E; ++I) {
+  // Stop scan when we have seen all the uses.
+  for (auto I = std::next(DefMI.getIterator()); ; ++I) {
     if (I->isDebugInstr())
       continue;
 
-    if (NumScan++ > MaxInstScan)
+    if (++NumInst > MaxInstScan)
       return true;
 
+    if (I->readsRegister(VReg))
+      if (--NumUseInst == 0)
+        return false;
+
     if (I->modifiesRegister(AMDGPU::EXEC, TRI))
       return true;
   }
-
-  return false;
 }