[Metadata] Extend 'count' field of DISubrange to take a metadata node

Summary:
This patch extends the DISubrange 'count' field to take either a
(signed) constant integer value or a reference to a DILocalVariable
or DIGlobalVariable.

This is patch [1/3] in a series to extend LLVM's DISubrange Metadata
node to support debugging of C99 variable length arrays and vectors with
runtime length like the Scalable Vector Extension for AArch64. It is
also a first step towards representing more complex cases like arrays
in Fortran.

Reviewers: echristo, pcc, aprantl, dexonsmith, clayborg, kristof.beyls, dblaikie

Reviewed By: aprantl

Subscribers: rnk, probinson, fhahn, aemerson, rengolin, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D41695

llvm-svn: 323313

1 files changed, 11 insertions, 2 deletions

diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index 75ddd47b259..b6eda6a2921 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -249,8 +249,17 @@ void GenericDINode::recalculateHash() {
 
 DISubrange *DISubrange::getImpl(LLVMContext &Context, int64_t Count, int64_t Lo,
                                 StorageType Storage, bool ShouldCreate) {
-  DEFINE_GETIMPL_LOOKUP(DISubrange, (Count, Lo));
-  DEFINE_GETIMPL_STORE_NO_OPS(DISubrange, (Count, Lo));
+  auto *CountNode = ConstantAsMetadata::get(
+      ConstantInt::getSigned(Type::getInt64Ty(Context), Count));
+  return getImpl(Context, CountNode, Lo, Storage, ShouldCreate);
+}
+
+DISubrange *DISubrange::getImpl(LLVMContext &Context, Metadata *CountNode,
+                                int64_t Lo, StorageType Storage,
+                                bool ShouldCreate) {
+  DEFINE_GETIMPL_LOOKUP(DISubrange, (CountNode, Lo));
+  Metadata *Ops[] = { CountNode };
+  DEFINE_GETIMPL_STORE(DISubrange, (CountNode, Lo), Ops);
 }
 
 DIEnumerator *DIEnumerator::getImpl(LLVMContext &Context, int64_t Value,