Emit comment for gc.relocate's showing base and derived pointers in human readable form

[igor-laevsky]

Summary

In AsmWriter emit comment for gc.relocate showing base and derived pointer in human readable form. This is a lot more convenient than looking just at the indexes in this call.

Example: %67 = call float addrspace(1)* @llvm.experimental.gc.relocate.p1f32(i32 %sp, i32 40, i32 31) ; (%base, %derived)

[reames]

The idea seems helpful and reasonable, but I am not familiar enough with this code to review. I'd suggest checking git blame for the functions in question.

p.s. I suspect that this should be inside the annotation writer mechanism, but I haven't really checked to confirm.

[igor-laevsky]

Duncan, could you please take a look at this changes? I am asking you because I am seeing a lot of submits from you to AsmParser lately. Please correct me if you are the wrong person to ask.

Philip, by using AnnotationWriter I can achieve same thing only for calls to which we explicitly pass AnnotationWriter. And there is no default AnnotationWriter. Because of this, for example, calls to Value->dump() will not emit intended comments. Also -print-after-all will not emit them. This will reduce usability of this feature.

[igor-laevsky]

Move comment generation into separate function.

llvm/trunk/lib/IR/AsmWriter.cpp

 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/IR/Statepoint.h"
 #include "llvm/IR/TypeFinder.h"
 #include "llvm/IR/UseListOrder.h"
 #include "llvm/IR/ValueSymbolTable.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/MathExtras.h"
private:
   /// \brief Print out metadata attachments.
   void printMetadataAttachments(
       const SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs,
       StringRef Separator);
 
   // printInfoComment - Print a little comment after the instruction indicating
   // which slot it occupies.
   void printInfoComment(const Value &V);
+
+  // printGCRelocateComment - print comment after call to the gc.relocate
+  // intrinsic indicating base and derived pointer names.
+  void printGCRelocateComment(const Value &V);
 };
 } // namespace
 
 void AssemblyWriter::init() {
   if (!TheModule)
     return;
   TypePrinter.incorporateTypes(*TheModule);
   for (const Function &F : *TheModule)

 }
 
 /// printInstructionLine - Print an instruction and a newline character.
 void AssemblyWriter::printInstructionLine(const Instruction &I) {
   printInstruction(I);
   Out << '\n';
 }
 
+/// printGCRelocateComment - print comment after call to the gc.relocate
+/// intrinsic indicating base and derived pointer names.
+void AssemblyWriter::printGCRelocateComment(const Value &V) {
+  assert(isGCRelocate(&V));
+  GCRelocateOperands GCOps(cast<Instruction>(&V));
+
+  Out << " ; (";
+  writeOperand(GCOps.basePtr(), false);
+  Out << ", ";
+  writeOperand(GCOps.derivedPtr(), false);
+  Out << ")";
+}
+
 /// printInfoComment - Print a little comment after the instruction indicating
 /// which slot it occupies.
 ///
 void AssemblyWriter::printInfoComment(const Value &V) {
+  if (isGCRelocate(&V))
+    printGCRelocateComment(V);
+
   if (AnnotationWriter)
     AnnotationWriter->printInfoComment(V, Out);
 }
 
 // This member is called for each Instruction in a function..
 void AssemblyWriter::printInstruction(const Instruction &I) {
   if (AnnotationWriter) AnnotationWriter->emitInstructionAnnot(&I, Out);