Revert "Revert "DI: Fold constant arguments into a single MDString""

This reverts commit r218918, effectively reapplying r218914 after fixing
an Ocaml bindings test and an Asan crash.  The root cause of the latter
was a tightened-up check in `DILexicalBlock::Verify()`, so I'll file a
PR to investigate who requires the loose check (and why).

Original commit message follows.

--

This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString.  Integers are stringified and
a `\0` character is used as a separator.

Part of PR17891.

Note: I've attached my testcases upgrade scripts to the PR.  If I've
just broken your out-of-tree testcases, they might help.

llvm-svn: 219010

2 files changed, 69 insertions, 0 deletions

diff --git a/llvm/unittests/IR/CMakeLists.txt b/llvm/unittests/IR/CMakeLists.txt
index 824e7fc099b..a0462091a31 100644
--- a/llvm/unittests/IR/CMakeLists.txt
+++ b/llvm/unittests/IR/CMakeLists.txt
@@ -10,6 +10,7 @@ set(IRSources
   AttributesTest.cpp
   ConstantRangeTest.cpp
   ConstantsTest.cpp
+  DebugInfoTest.cpp
   DominatorTreeTest.cpp
   IRBuilderTest.cpp
   InstructionsTest.cpp
diff --git a/llvm/unittests/IR/DebugInfoTest.cpp b/llvm/unittests/IR/DebugInfoTest.cpp
new file mode 100644
index 00000000000..e8bbe61d45f
--- /dev/null
+++ b/llvm/unittests/IR/DebugInfoTest.cpp
@@ -0,0 +1,68 @@
+//===- llvm/unittest/IR/DebugInfo.cpp - DebugInfo tests -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/DebugInfo.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace llvm {
+
+static void PrintTo(const StringRef &S, ::std::ostream *os) {
+  *os << "(" << (void *)S.data() << "," << S.size() << ") = '";
+  for (auto C : S)
+    if (C)
+      *os << C;
+    else
+      *os << "\\00";
+  *os << "'";
+}
+static void PrintTo(const DIHeaderFieldIterator &I, ::std::ostream *os) {
+  PrintTo(I.getCurrent(), os);
+  *os << " in ";
+  PrintTo(I.getHeader(), os);
+}
+
+} // end namespace llvm
+
+namespace {
+
+#define MAKE_FIELD_ITERATOR(S)                                                 \
+  DIHeaderFieldIterator(StringRef(S, sizeof(S) - 1))
+TEST(DebugInfoTest, DIHeaderFieldIterator) {
+  ASSERT_EQ(DIHeaderFieldIterator(), DIHeaderFieldIterator());
+
+  ASSERT_NE(DIHeaderFieldIterator(), MAKE_FIELD_ITERATOR(""));
+  ASSERT_EQ(DIHeaderFieldIterator(), ++MAKE_FIELD_ITERATOR(""));
+  ASSERT_EQ("", *DIHeaderFieldIterator(""));
+
+  ASSERT_NE(DIHeaderFieldIterator(), MAKE_FIELD_ITERATOR("stuff"));
+  ASSERT_EQ(DIHeaderFieldIterator(), ++MAKE_FIELD_ITERATOR("stuff"));
+  ASSERT_EQ("stuff", *DIHeaderFieldIterator("stuff"));
+
+  ASSERT_NE(DIHeaderFieldIterator(), MAKE_FIELD_ITERATOR("st\0uff"));
+  ASSERT_NE(DIHeaderFieldIterator(), ++MAKE_FIELD_ITERATOR("st\0uff"));
+  ASSERT_EQ(DIHeaderFieldIterator(), ++++MAKE_FIELD_ITERATOR("st\0uff"));
+  ASSERT_EQ("st", *MAKE_FIELD_ITERATOR("st\0uff"));
+  ASSERT_EQ("uff", *++MAKE_FIELD_ITERATOR("st\0uff"));
+
+  ASSERT_NE(DIHeaderFieldIterator(), MAKE_FIELD_ITERATOR("stuff\0"));
+  ASSERT_NE(DIHeaderFieldIterator(), ++MAKE_FIELD_ITERATOR("stuff\0"));
+  ASSERT_EQ(DIHeaderFieldIterator(), ++++MAKE_FIELD_ITERATOR("stuff\0"));
+  ASSERT_EQ("stuff", *MAKE_FIELD_ITERATOR("stuff\0"));
+  ASSERT_EQ("", *++MAKE_FIELD_ITERATOR("stuff\0"));
+
+  ASSERT_NE(DIHeaderFieldIterator(), MAKE_FIELD_ITERATOR("\0stuff"));
+  ASSERT_NE(DIHeaderFieldIterator(), ++MAKE_FIELD_ITERATOR("\0stuff"));
+  ASSERT_EQ(DIHeaderFieldIterator(), ++++MAKE_FIELD_ITERATOR("\0stuff"));
+  ASSERT_EQ("", *MAKE_FIELD_ITERATOR("\0stuff"));
+  ASSERT_EQ("stuff", *++MAKE_FIELD_ITERATOR("\0stuff"));
+}
+
+} // end namespace