864eba9fb1
debuginfo: Set bitwidth appropriately in enum variant tags Previously, we unconditionally set the bitwidth to 128-bits, the largest an enum would possibly be. Then, LLVM would cut down the constant by chopping off leading zeroes before emitting the DWARF. LLVM only supported 64-bit enumerators, so this would also have occasionally resulted in truncated data. LLVM added support for 128-bit enumerators in llvm/llvm-project#125578 That patchset trusts the constant to describe how wide the variant tag is, so the high 64-bits of zeros are considered potentially load-bearing. As a result, we went from emitting tags that looked like: DW_AT_discr_value (0xfe) (because `dwarf::BestForm` selected `data1`) to emitting tags that looked like: DW_AT_discr_value (<0x10> fe ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ) This makes the `DW_AT_discr_value` encode at the bitwidth of the tag, which: 1. Is probably closer to our intentions in terms of describing the data. 2. Doesn't invoke the 128-bit support which may not be supported by all debuggers / downstream tools. 3. Will result in smaller debug information. |
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This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.
Why Rust?
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