[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, 27 insertions, 2 deletions

diff --git a/llvm/unittests/IR/MetadataTest.cpp b/llvm/unittests/IR/MetadataTest.cpp
index 51ca8408f1a..af58657d5f1 100644
--- a/llvm/unittests/IR/MetadataTest.cpp
+++ b/llvm/unittests/IR/MetadataTest.cpp
@@ -932,8 +932,11 @@ typedef MetadataTest DISubrangeTest;
 
 TEST_F(DISubrangeTest, get) {
   auto *N = DISubrange::get(Context, 5, 7);
+  auto Count = N->getCount();
   EXPECT_EQ(dwarf::DW_TAG_subrange_type, N->getTag());
-  EXPECT_EQ(5, N->getCount());
+  ASSERT_TRUE(Count);
+  ASSERT_TRUE(Count.is<ConstantInt*>());
+  EXPECT_EQ(5, Count.get<ConstantInt*>()->getSExtValue());
   EXPECT_EQ(7, N->getLowerBound());
   EXPECT_EQ(N, DISubrange::get(Context, 5, 7));
   EXPECT_EQ(DISubrange::get(Context, 5, 0), DISubrange::get(Context, 5));
@@ -944,12 +947,34 @@ TEST_F(DISubrangeTest, get) {
 
 TEST_F(DISubrangeTest, getEmptyArray) {
   auto *N = DISubrange::get(Context, -1, 0);
+  auto Count = N->getCount();
   EXPECT_EQ(dwarf::DW_TAG_subrange_type, N->getTag());
-  EXPECT_EQ(-1, N->getCount());
+  ASSERT_TRUE(Count);
+  ASSERT_TRUE(Count.is<ConstantInt*>());
+  EXPECT_EQ(-1, Count.get<ConstantInt*>()->getSExtValue());
   EXPECT_EQ(0, N->getLowerBound());
   EXPECT_EQ(N, DISubrange::get(Context, -1, 0));
 }
 
+TEST_F(DISubrangeTest, getVariableCount) {
+  DILocalScope *Scope = getSubprogram();
+  DIFile *File = getFile();
+  DIType *Type = getDerivedType();
+  DINode::DIFlags Flags = static_cast<DINode::DIFlags>(7);
+  auto *VlaExpr = DILocalVariable::get(Context, Scope, "vla_expr", File, 8,
+                                       Type, 2, Flags, 8);
+
+  auto *N = DISubrange::get(Context, VlaExpr, 0);
+  auto Count = N->getCount();
+  ASSERT_TRUE(Count);
+  ASSERT_TRUE(Count.is<DIVariable*>());
+  EXPECT_EQ(VlaExpr, Count.get<DIVariable*>());
+  ASSERT_TRUE(isa<DIVariable>(N->getRawCountNode()));
+  EXPECT_EQ(0, N->getLowerBound());
+  EXPECT_EQ("vla_expr", Count.get<DIVariable*>()->getName());
+  EXPECT_EQ(N, DISubrange::get(Context, VlaExpr, 0));
+}
+
 typedef MetadataTest DIEnumeratorTest;
 
 TEST_F(DIEnumeratorTest, get) {