Recommit "[CodeView] Emit static data members as S_CONSTANTs."

We used to only emit static const data members in CodeView as
S_CONSTANTS when they were used; this patch makes it so they are always emitted.

This changes CodeViewDebug.cpp to find the static const members from the
class debug info instead of creating DIGlobalVariables in the IR
whenever a static const data member is used.

Bug: https://bugs.llvm.org/show_bug.cgi?id=47580

Differential Revision: https://reviews.llvm.org/D89072

This reverts commit 504615353f31136dd6bf7a971b6c236fd70582be.

1 files changed, 48 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
index 826c507..9d963a3 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
@@ -158,6 +158,54 @@ uint64_t DebugHandlerBase::getBaseTypeSize(const DIType *Ty) {
   return getBaseTypeSize(BaseType);
 }
 
+bool DebugHandlerBase::isUnsignedDIType(const DIType *Ty) {
+  if (auto *CTy = dyn_cast<DICompositeType>(Ty)) {
+    // FIXME: Enums without a fixed underlying type have unknown signedness
+    // here, leading to incorrectly emitted constants.
+    if (CTy->getTag() == dwarf::DW_TAG_enumeration_type)
+      return false;
+
+    // (Pieces of) aggregate types that get hacked apart by SROA may be
+    // represented by a constant. Encode them as unsigned bytes.
+    return true;
+  }
+
+  if (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
+    dwarf::Tag T = (dwarf::Tag)Ty->getTag();
+    // Encode pointer constants as unsigned bytes. This is used at least for
+    // null pointer constant emission.
+    // FIXME: reference and rvalue_reference /probably/ shouldn't be allowed
+    // here, but accept them for now due to a bug in SROA producing bogus
+    // dbg.values.
+    if (T == dwarf::DW_TAG_pointer_type ||
+        T == dwarf::DW_TAG_ptr_to_member_type ||
+        T == dwarf::DW_TAG_reference_type ||
+        T == dwarf::DW_TAG_rvalue_reference_type)
+      return true;
+    assert(T == dwarf::DW_TAG_typedef || T == dwarf::DW_TAG_const_type ||
+           T == dwarf::DW_TAG_volatile_type ||
+           T == dwarf::DW_TAG_restrict_type || T == dwarf::DW_TAG_atomic_type);
+    assert(DTy->getBaseType() && "Expected valid base type");
+    return isUnsignedDIType(DTy->getBaseType());
+  }
+
+  auto *BTy = cast<DIBasicType>(Ty);
+  unsigned Encoding = BTy->getEncoding();
+  assert((Encoding == dwarf::DW_ATE_unsigned ||
+          Encoding == dwarf::DW_ATE_unsigned_char ||
+          Encoding == dwarf::DW_ATE_signed ||
+          Encoding == dwarf::DW_ATE_signed_char ||
+          Encoding == dwarf::DW_ATE_float || Encoding == dwarf::DW_ATE_UTF ||
+          Encoding == dwarf::DW_ATE_boolean ||
+          (Ty->getTag() == dwarf::DW_TAG_unspecified_type &&
+           Ty->getName() == "decltype(nullptr)")) &&
+         "Unsupported encoding");
+  return Encoding == dwarf::DW_ATE_unsigned ||
+         Encoding == dwarf::DW_ATE_unsigned_char ||
+         Encoding == dwarf::DW_ATE_UTF || Encoding == dwarf::DW_ATE_boolean ||
+         Ty->getTag() == dwarf::DW_TAG_unspecified_type;
+}
+
 static bool hasDebugInfo(const MachineModuleInfo *MMI,
                          const MachineFunction *MF) {
   if (!MMI->hasDebugInfo())