Revert "Properly transfer location info from debug_value into alloc_stack: we need to drop op_deref expression (#42245)"

This reverts commit c4ebb32.

Author: compnerd

lib/SIL/Verifier/SILVerifier.cpp

@@ -1315,9 +1315,9 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
       case SILInstructionKind::DebugValueInst:
         DebugVarTy = inst->getOperand(0)->getType();
         if (DebugVarTy.isAddress()) {
-          // FIXME: op_deref could be applied to address types only.
-          // FIXME: Add this check
-          if (varInfo->DIExpr.startsWithDeref())
+          auto Expr = varInfo->DIExpr.operands();
+          if (!Expr.empty() &&
+              Expr.begin()->getOperator() == SILDIExprOperator::Dereference)
             DebugVarTy = DebugVarTy.getObjectType();
         }
         break;
@@ -1343,16 +1343,9 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
           require(DebugVars[argNum].first == varInfo->Name,
                   "Scope contains conflicting debug variables for one function "
                   "argument");
-          // The source variable might change its location (e.g. due to
-          // optimizations). Check for most common transformations (e.g. loading
-          // to SSA value and vice versa) as well
-          require(DebugVars[argNum].second == DebugVarTy ||
-                  (DebugVars[argNum].second.isAddress() &&
-                   DebugVars[argNum].second.getObjectType() == DebugVarTy) ||
-                  (DebugVarTy.isAddress() &&
-                   DebugVars[argNum].second == DebugVarTy.getObjectType()),
+          // Check for type
+          require(DebugVars[argNum].second == DebugVarTy,
                   "conflicting debug variable type!");
-          DebugVars[argNum].second = DebugVarTy;
         } else {
           // Reserve enough space.
           while (DebugVars.size() <= argNum) {

lib/SILOptimizer/Differentiation/Common.cpp

@@ -257,11 +257,6 @@ findDebugLocationAndVariable(SILValue originalValue) {
   for (auto *use : originalValue->getUses()) {
     if (auto *dvi = dyn_cast<DebugValueInst>(use->getUser()))
       return dvi->getVarInfo().map([&](SILDebugVariable var) {
-        // We need to drop `op_deref` here as we're transferring debug info
-        // location from debug_value instruction (which describes how to get value)
-        // into alloc_stack (which describes the location)
-        if (var.DIExpr.startsWithDeref())
-          var.DIExpr.eraseElement(var.DIExpr.element_begin());
         return std::make_pair(dvi->getDebugLocation(), var);
       });
   }