Add abbreviations for icmp/fcmp, store and br, which are the most common instructions that don't have abbreviations yet. This requires increasing the abbreviation size to 5 bits. This gives about 3-5% bitcode size reductions for the clang build.
PR #141106 changed the debuginfo metdata to allow dynamic bit offsets and sizes. This caused a crash in lld when using LTO. The problem is that lazyLoadOneMetadata assumes that the metadata in question can be cast to MDNode; but in the typical case where the offset is a constant, this is not true. This patch changes this spot to allow non-MDNodes through. The included test case comes from the report in #141106.
We always use the same abbreviations for type and for value references, so avoid repeating them.
Add `dead_on_return` attribute, which is meant to be taken advantage by the frontend, and states that the memory pointed to by the argument is dead upon function return. As with `byval`, it is supposed to be used for passing aggregates by value. The difference lies in the ABI: `byval` implies that the pointer is explicitly passed as argument to the callee (during codegen the copy is emitted as per byval contract), whereas a `dead_on_return`-marked argument implies that the copy already exists in the IR, is located at a specific stack offset within the caller, and this memory will not be read further by the caller upon callee return – or otherwise poison, if read before being written. RFC: https://discourse.llvm.org/t/rfc-add-dead-on-return-attribute/86871.
In Ada, a record type can have a non-constant size, and a field can appear at a non-constant bit offset in a record. To support this, this patch changes DIType to record the size and offset using metadata, rather than plain integers. In addition to a constant offset, both DIVariable and DIExpression are now supported here. One thing of note in this patch is the choice of how exactly to represent a non-constant bit offset, with the difficulty being that DWARF 5 does not support this. DWARF 3 did have a way to support a non-constant byte offset, combined with a constant bit offset within the byte, but this was deprecated in DWARF 4 and removed from DWARF 5. This patch takes a simple approach: a DWARF extension allowing the use of an expression with DW_AT_data_bit_offset. There is a corresponding DWARF issue, see https://dwarfstd.org/issues/250501.1.html. The main reason for this approach is that it keeps API simplicity: just a single value is needed, rather than having separate data describing the byte offset and the bit within the byte.
This flag was used to let us incrementally introduce debug records into LLVM, however everything is now using records. It serves no purpose now, so delete it.
This was a utility for flipping between intrinsic and debug record mode -- we don't need it any more. The "IsNewDbgInfoFormat" should be true everywhere.
Start removing debug intrinsics support -- starting with the flag that controls production of their replacement, debug records. This patch removes the command-line-flag and with it the ability to switch back to intrinsics. The module / function / block level "IsNewDbgInfoFormat" flags get hardcoded to true, I'll to incrementally remove things that depend on those flags.