Handle llvm.dbg.values in SROA.

This patch properly handles llvm.dbg.values in SROA by making sure that
any llvm.dbg.values get moved to before a storejust like
llvm.dbg.declares do, or the llvm.dbg.value is correctly updated with
the right alloca after an aggregate alloca is broken up.

Author: rastogishubham

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -5045,10 +5045,20 @@ static void insertNewDbgInst(DIBuilder &DIB, DbgVariableRecord *Orig,
                                                    BeforeInst->getIterator());
     return;
   }
+
+  if (Orig->isDbgValue()) {
+    DbgVariableRecord *DVR = DbgVariableRecord::createDbgVariableRecord(
+        NewAddr, Orig->getVariable(), NewFragmentExpr, Orig->getDebugLoc());
+    BeforeInst->getParent()->insertDbgRecordBefore(DVR,
+                                                   BeforeInst->getIterator());
+    return;
+  }
+
   if (!NewAddr->hasMetadata(LLVMContext::MD_DIAssignID)) {
     NewAddr->setMetadata(LLVMContext::MD_DIAssignID,
                          DIAssignID::getDistinct(NewAddr->getContext()));
   }
+
   DbgVariableRecord *NewAssign = DbgVariableRecord::createLinkedDVRAssign(
       NewAddr, Orig->getValue(), Orig->getVariable(), NewFragmentExpr, NewAddr,
       Orig->getAddressExpression(), Orig->getDebugLoc());
@@ -5221,6 +5231,7 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
       };
       for_each(findDbgDeclares(Fragment.Alloca), RemoveOne);
       for_each(findDVRDeclares(Fragment.Alloca), RemoveOne);
+      for_each(findDVRValues(Fragment.Alloca), RemoveOne);
 
       insertNewDbgInst(DIB, DbgVariable, Fragment.Alloca, FragmentExpr, &AI);
     }
@@ -5230,6 +5241,7 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
   // and the individual partitions.
   for_each(findDbgDeclares(&AI), MigrateOne);
   for_each(findDVRDeclares(&AI), MigrateOne);
+  for_each(findDVRValues(&AI), MigrateOne);
   for_each(at::getAssignmentMarkers(&AI), MigrateOne);
   for_each(at::getDVRAssignmentMarkers(&AI), MigrateOne);
 
@@ -5357,6 +5369,8 @@ bool SROA::deleteDeadInstructions(
         OldDII->eraseFromParent();
       for (DbgVariableRecord *OldDII : findDVRDeclares(AI))
         OldDII->eraseFromParent();
+      for (DbgVariableRecord *OldDII : findDVRValues(AI))
+        OldDII->eraseFromParent();
     }
 
     at::deleteAssignmentMarkers(I);

llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp

@@ -582,6 +582,9 @@ rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info, LargeBlockInfo &LBI,
         DbgItem->eraseFromParent();
       } else if (DbgItem->getExpression()->startsWithDeref()) {
         DbgItem->eraseFromParent();
+      } else if (DbgItem->isValueOfVariable()) {
+        MoveDebugValueToStoreLoc(DbgItem, Info.OnlyStore, DIB);
+        DbgItem->eraseFromParent();
       }
     }
   };

llvm/test/DebugInfo/X86/sroa-after-inlining.ll

@@ -35,9 +35,11 @@
 ; CHECK: _Z3barv
 ; CHECK: %[[RESULT:.*]] = call i32 @_Z3foov
 ; CHECK: llvm.dbg.value(metadata i32 %[[RESULT]], metadata [[METADATA_IDX1:![0-9]+]]
+; CHECK: llvm.dbg.value(metadata i32 %[[RESULT]], metadata [[METADATA_IDX2:![0-9]+]]
 ; CHECK: ret
 ; CHECK: DICompileUnit
-; CHECK: [[METADATA_IDX1]] = !DILocalVariable(name: "result"
+; CHECK: [[METADATA_IDX2]] = !DILocalVariable(name: "result"
+; CHECK: [[METADATA_IDX1]] = !DILocalVariable(name: "this"
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"