[Assignment Tracking][6/*] Add trackAssignments function

The Assignment Tracking debug-info feature is outlined in this RFC:

https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir

Add trackAssignments which adds assignment tracking metadata to a function for
a specified set of variables. The intended callers are the inliner and the
front end - those calls will be added in separate patches.

I've added a pass called declare-to-assign (AssignmentTrackingPass) that
converts dbg.declare intrinsics to dbg.assigns using trackAssignments so that
the function can be easily tested (see
llvm/test/DebugInfo/Generic/track-assignments.ll). The pass could also be used
by front ends to easily test out enabling assignment tracking.

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D132225

1 files changed, 31 insertions, 1 deletions

diff --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp
index 76d7ade..989b554 100644
--- a/llvm/lib/IR/DIBuilder.cpp
+++ b/llvm/lib/IR/DIBuilder.cpp
@@ -30,7 +30,7 @@ static cl::opt<bool>
 
 DIBuilder::DIBuilder(Module &m, bool AllowUnresolvedNodes, DICompileUnit *CU)
     : M(m), VMContext(M.getContext()), CUNode(CU), DeclareFn(nullptr),
-      ValueFn(nullptr), LabelFn(nullptr), AddrFn(nullptr),
+      ValueFn(nullptr), LabelFn(nullptr), AddrFn(nullptr), AssignFn(nullptr),
       AllowUnresolvedNodes(AllowUnresolvedNodes) {
   if (CUNode) {
     if (const auto &ETs = CUNode->getEnumTypes())
@@ -960,6 +960,36 @@ Instruction *DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
   return insertDeclare(Storage, VarInfo, Expr, DL, InsertAtEnd, InsertBefore);
 }
 
+DbgAssignIntrinsic *
+DIBuilder::insertDbgAssign(Instruction *LinkedInstr, Value *Val,
+                           DILocalVariable *SrcVar, DIExpression *ValExpr,
+                           Value *Addr, DIExpression *AddrExpr,
+                           const DILocation *DL) {
+  LLVMContext &Ctx = LinkedInstr->getContext();
+  Module *M = LinkedInstr->getModule();
+  if (!AssignFn)
+    AssignFn = Intrinsic::getDeclaration(M, Intrinsic::dbg_assign);
+
+  auto *Link = LinkedInstr->getMetadata(LLVMContext::MD_DIAssignID);
+  assert(Link && "Linked instruction must have DIAssign metadata attached");
+
+  std::array<Value *, 6> Args = {
+      MetadataAsValue::get(Ctx, ValueAsMetadata::get(Val)),
+      MetadataAsValue::get(Ctx, SrcVar),
+      MetadataAsValue::get(Ctx, ValExpr),
+      MetadataAsValue::get(Ctx, Link),
+      MetadataAsValue::get(Ctx, ValueAsMetadata::get(Addr)),
+      MetadataAsValue::get(Ctx, AddrExpr),
+  };
+
+  IRBuilder<> B(Ctx);
+  B.SetCurrentDebugLocation(DL);
+
+  auto *DVI = cast<DbgAssignIntrinsic>(B.CreateCall(AssignFn, Args));
+  DVI->insertAfter(LinkedInstr);
+  return DVI;
+}
+
 Instruction *DIBuilder::insertLabel(DILabel *LabelInfo, const DILocation *DL,
                                     Instruction *InsertBefore) {
   return insertLabel(LabelInfo, DL,