[DebugInfo] Add dataSize to DIBasicType to add DW_AT_bit_size to _BitInt types (#164372)

DW_TAG_base_type DIEs are permitted to have both byte_size and bit_size
attributes "If the value of an object of the given type does not fully
occupy the storage described by a byte size attribute"

* Add DataSizeInBits to DIBasicType (`DIBasicType(... dataSize: n ...)` in IR).
* Change Clang to add DataSizeInBits to _BitInt type metadata.
* Change LLVM to add DW_AT_bit_size to base_type DIEs that have non-zero
  DataSizeInBits.

TODO: Do we need to emit DW_AT_data_bit_offset for big endian targets?
See discussion on the PR.

Fixes [#61952](https://github.com/llvm/llvm-project/issues/61952)

---------

Co-authored-by: David Stenberg <david.stenberg@ericsson.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 61aa7c2f5..f17656c 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1925,6 +1925,7 @@ void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
   Record.push_back(N->getEncoding());
   Record.push_back(N->getFlags());
   Record.push_back(N->getNumExtraInhabitants());
+  Record.push_back(N->getDataSizeInBits());
 
   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
   Record.clear();