2 files changed, 18 insertions, 3 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 518121e..751d373 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -1793,9 +1793,13 @@ void DwarfCompileUnit::createBaseTypeDIEs() {
                     "_" + Twine(Btr.BitSize)).toStringRef(Str));
     addUInt(Die, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1, Btr.Encoding);
     // Round up to smallest number of bytes that contains this number of bits.
+    // ExprRefedBaseTypes is populated with types referenced by
+    // DW_OP_LLVM_convert operations in location expressions. These are often
+    // byte-sized, but one common counter-example is 1-bit sized conversions
+    // from `i1` types. TODO: Should these use DW_AT_bit_size? See
+    // DwarfUnit::constructTypeDIE.
     addUInt(Die, dwarf::DW_AT_byte_size, std::nullopt,
             divideCeil(Btr.BitSize, 8));
-
     Btr.Die = &Die;
   }
 }
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index e40fb76..555c56f 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -766,8 +766,19 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DIBasicType *BTy) {
     addUInt(Buffer, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1,
             BTy->getEncoding());
 
-  uint64_t Size = BTy->getSizeInBits() >> 3;
-  addUInt(Buffer, dwarf::DW_AT_byte_size, std::nullopt, Size);
+  uint64_t SizeInBytes = divideCeil(BTy->getSizeInBits(), 8);
+  addUInt(Buffer, dwarf::DW_AT_byte_size, std::nullopt, SizeInBytes);
+  if (BTy->getTag() == dwarf::Tag::DW_TAG_base_type) {
+    // DW_TAG_base_type:
+    // If the value of an object of the given type does not fully occupy the
+    // storage described by a byte size attribute, the base type entry may also
+    // have a DW_AT_bit_size [...] attribute.
+    // TODO: Do big endian targets need DW_AT_data_bit_offset? See discussion in
+    // pull request #164372.
+    if (uint64_t DataSizeInBits = BTy->getDataSizeInBits();
+        DataSizeInBits && DataSizeInBits != SizeInBytes * 8)
+      addUInt(Buffer, dwarf::DW_AT_bit_size, std::nullopt, DataSizeInBits);
+  }
 
   if (BTy->isBigEndian())
     addUInt(Buffer, dwarf::DW_AT_endianity, std::nullopt, dwarf::DW_END_big);