Parse and print DIExpressions inline to ease IR and MIR testing

Summary:
Most DIExpressions are empty or very simple. When they are complex, they
tend to be unique, so checking them inline is reasonable.

This also avoids the need for CodeGen passes to append to the
llvm.dbg.mir named md node.

See also PR22780, for making DIExpression not be an MDNode.

Reviewers: aprantl, dexonsmith, dblaikie

Subscribers: qcolombet, javed.absar, eraman, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D37075

llvm-svn: 311594

1 files changed, 21 insertions, 1 deletions

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 170bc544d53..1cd6dd0ddff 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -1046,6 +1046,10 @@ void SlotTracker::CreateFunctionSlot(const Value *V) {
 void SlotTracker::CreateMetadataSlot(const MDNode *N) {
   assert(N && "Can't insert a null Value into SlotTracker!");
 
+  // Don't make slots for DIExpressions. We just print them inline everywhere.
+  if (isa<DIExpression>(N))
+    return;
+
   unsigned DestSlot = mdnNext;
   if (!mdnMap.insert(std::make_pair(N, DestSlot)).second)
     return;
@@ -2073,6 +2077,13 @@ static void WriteAsOperandInternal(raw_ostream &Out, const Metadata *MD,
                                    TypePrinting *TypePrinter,
                                    SlotTracker *Machine, const Module *Context,
                                    bool FromValue) {
+  // Write DIExpressions inline when used as a value. Improves readability of
+  // debug info intrinsics.
+  if (const DIExpression *Expr = dyn_cast<DIExpression>(MD)) {
+    writeDIExpression(Out, Expr, TypePrinter, Machine, Context);
+    return;
+  }
+
   if (const MDNode *N = dyn_cast<MDNode>(MD)) {
     std::unique_ptr<SlotTracker> MachineStorage;
     if (!Machine) {
@@ -2424,7 +2435,16 @@ void AssemblyWriter::printNamedMDNode(const NamedMDNode *NMD) {
   for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
     if (i)
       Out << ", ";
-    int Slot = Machine.getMetadataSlot(NMD->getOperand(i));
+
+    // Write DIExpressions inline.
+    // FIXME: Ban DIExpressions in NamedMDNodes, they will serve no purpose.
+    MDNode *Op = NMD->getOperand(i);
+    if (auto *Expr = dyn_cast<DIExpression>(Op)) {
+      writeDIExpression(Out, Expr, nullptr, nullptr, nullptr);
+      continue;
+    }
+
+    int Slot = Machine.getMetadataSlot(Op);
     if (Slot == -1)
       Out << "<badref>";
     else