MachineVerifier: On dead-def live segments, check that corresponding machine operand has a dead flag

llvm-svn: 264769

1 files changed, 18 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index b957fd824f8..e2391b49bab 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1743,18 +1743,33 @@ void MachineVerifier::verifyLiveRangeSegment(const LiveRange &LR,
     // use, or a dead flag on a def.
     bool hasRead = false;
     bool hasSubRegDef = false;
+    bool hasDeadDef = false;
     for (ConstMIBundleOperands MOI(*MI); MOI.isValid(); ++MOI) {
       if (!MOI->isReg() || MOI->getReg() != Reg)
         continue;
       if (LaneMask != 0 &&
           (LaneMask & TRI->getSubRegIndexLaneMask(MOI->getSubReg())) == 0)
         continue;
-      if (MOI->isDef() && MOI->getSubReg() != 0)
-        hasSubRegDef = true;
+      if (MOI->isDef()) {
+        if (MOI->getSubReg() != 0)
+          hasSubRegDef = true;
+        if (MOI->isDead())
+          hasDeadDef = true;
+      }
       if (MOI->readsReg())
         hasRead = true;
     }
-    if (!S.end.isDead()) {
+    if (S.end.isDead()) {
+      // Make sure that the corresponding machine operand for a "dead" live
+      // range has the dead flag. We cannot perform this check for subregister
+      // liveranges as partially dead values are allowed.
+      if (LaneMask == 0 && !hasDeadDef) {
+        report("Instruction ending live segment on dead slot has no dead flag",
+               MI);
+        report_context(LR, Reg, LaneMask);
+        report_context(S);
+      }
+    } else {
       if (!hasRead) {
         // When tracking subregister liveness, the main range must start new
         // values on partial register writes, even if there is no read.