Revert "[SelectionDAG] Salvage debuginfo when combining load and sext… (#171745)

… instrs. (#169779)"

This reverts commit 2b958b9.

I might have broken the sanitizer-x86_64-linux bot


/home/b/sanitizer-x86_64-linux/build/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_linux.cpp
clang++:
/home/b/sanitizer-x86_64-linux/build/llvm-project/llvm/include/llvm/ADT/ArrayRef.h:248:
const T &llvm::ArrayRef<llvm::DbgValueLocEntry>::operator[](size_t)
const [T = llvm::DbgValueLocEntry]: Assertion `Index < Length &&
"Invalid index!"' failed.

Author: rastogishubham

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -51,7 +51,6 @@
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/DataLayout.h"
-#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Metadata.h"
@@ -79,7 +78,6 @@
 #include <variant>
 
 #include "MatchContext.h"
-#include "SDNodeDbgValue.h"
 
 using namespace llvm;
 using namespace llvm::SDPatternMatch;
@@ -14467,52 +14465,17 @@ static SDValue tryToFoldExtOfLoad(SelectionDAG &DAG, DAGCombiner &Combiner,
                                    LN0->getBasePtr(), N0.getValueType(),
                                    LN0->getMemOperand());
   Combiner.ExtendSetCCUses(SetCCs, N0, ExtLoad, ExtOpc);
-  unsigned Opcode = N->getOpcode();
-  bool IsSigned = Opcode == ISD::SIGN_EXTEND;
   // If the load value is used only by N, replace it via CombineTo N.
-  SDValue OldLoadVal(LN0, 0);
-  SDValue OldExtValue(N, 0);
-  bool NoReplaceTrunc = OldLoadVal.hasOneUse();
-
-  // Because we are replacing a load and a s|z ext with a load-s|z ext
-  // instruction, the dbg_value attached to the load will be of a smaller bit
-  // width, and we have to add a DW_OP_LLVM_convert expression to get the
-  // correct size.
-  auto SalvageToOldLoadSize = [&](SDValue From, SDValue To, bool IsSigned) {
-    for (SDDbgValue *Dbg : DAG.GetDbgValues(From.getNode())) {
-      unsigned VarBitsFrom = From->getValueSizeInBits(0);
-      unsigned VarBitsTo = To->getValueSizeInBits(0);
-
-      // Build a convert expression for the s|z extend.
-      const DIExpression *OldE = Dbg->getExpression();
-      auto *NewE =
-          DIExpression::appendExt(OldE, VarBitsFrom, VarBitsTo, IsSigned);
-
-      // Create a new SDDbgValue that points at the widened node with the
-      // fragment.
-      Dbg->setIsInvalidated();
-      Dbg->setIsEmitted();
-      SDDbgValue *NewDV = DAG.getDbgValue(
-          Dbg->getVariable(), NewE, To.getNode(), To.getResNo(),
-          Dbg->isIndirect(), Dbg->getDebugLoc(), Dbg->getOrder());
-      DAG.AddDbgValue(NewDV, /*isParametet*/ false);
-    }
-  };
-
+  bool NoReplaceTrunc = SDValue(LN0, 0).hasOneUse();
+  Combiner.CombineTo(N, ExtLoad);
   if (NoReplaceTrunc) {
-    if (LN0->getHasDebugValue())
-      SalvageToOldLoadSize(OldLoadVal, ExtLoad, IsSigned);
-
-    if (N->getHasDebugValue())
-      DAG.transferDbgValues(OldExtValue, ExtLoad);
     DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
     Combiner.recursivelyDeleteUnusedNodes(LN0);
   } else {
     SDValue Trunc =
         DAG.getNode(ISD::TRUNCATE, SDLoc(N0), N0.getValueType(), ExtLoad);
     Combiner.CombineTo(LN0, Trunc, ExtLoad.getValue(1));
   }
-  Combiner.CombineTo(N, ExtLoad);
   return SDValue(N, 0); // Return N so it doesn't get rechecked!
 }