[llvm] [DebugInfo][RemoveDIs] Handle dbg.declares in SelectionDAGISel (PR #73496)

[Matt Arsenault via llvm-commits]

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@@ -1148,6 +1148,60 @@ SDValue SelectionDAGBuilder::getControlRoot() {
   return updateRoot(PendingExports);
 }
 
+void SelectionDAGBuilder::handleDebugDeclare(Value *Address,
+                                             DILocalVariable *Variable,
+                                             DIExpression *Expression,
+                                             DebugLoc DL) {
+  assert(Variable && "Missing variable");
+
+  // Check if address has undef value.
+  if (!Address || isa<UndefValue>(Address) ||
+      (Address->use_empty() && !isa<Argument>(Address))) {
+    LLVM_DEBUG(
+        dbgs()
+        << "dbg_declare: Dropping debug info (bad/undef/unused-arg address)\n");
+    return;
+  }
+
+  bool IsParameter = Variable->isParameter() || isa<Argument>(Address);
+
+  SDValue &N = NodeMap[Address];
+  if (!N.getNode() && isa<Argument>(Address))
+    // Check unused arguments map.
+    N = UnusedArgNodeMap[Address];
+  SDDbgValue *SDV;
+  if (N.getNode()) {
+    if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
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arsenm wrote:

Do you really need this with opaque pointers? stripPointerCasts?

https://github.com/llvm/llvm-project/pull/73496