[all-commits] [llvm/llvm-project] 816ab1: [NFCI][TableGen][DecoderEmitter] Cull Op handling ...

[Rahul Joshi via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 816ab1af0da1dc833f487933e7d6fb470d844001
      https://github.com/llvm/llvm-project/commit/816ab1af0da1dc833f487933e7d6fb470d844001
  Author: Rahul Joshi <rjoshi at nvidia.com>
  Date:   2025-06-17 (Tue, 17 Jun 2025)

  Changed paths:
    M llvm/utils/TableGen/DecoderEmitter.cpp

  Log Message:
  -----------
  [NFCI][TableGen][DecoderEmitter] Cull Op handling when possible (#142974)

TryDecode/CheckPredicate/SoftFail MCD ops are not used by many targets.
Track the set of opcodes that were emitted and emit code for handling
TryDecode/CheckPredicate/SoftFail ops when decoding only if there were
emitted. This is purely eliminating dead code in the generated
`decodeInstruction` function.

This results in the following reduction in the size of the Disassembler
.so files with a release x86_64 release build on Linux:

```
Target                                                   Old Size        New Size  %  reduction
build/lib/libLLVMAArch64Disassembler.so.21.0git             256656          256656          0.00
build/lib/libLLVMAMDGPUDisassembler.so.21.0git              813000          808168          0.59
build/lib/libLLVMARCDisassembler.so.21.0git                  44816           43536          2.86
build/lib/libLLVMARMDisassembler.so.21.0git                 281744          278808          1.04
build/lib/libLLVMAVRDisassembler.so.21.0git                  36040           34496          4.28
build/lib/libLLVMBPFDisassembler.so.21.0git                  26248           23168         11.73
build/lib/libLLVMCSKYDisassembler.so.21.0git                 55960           53632          4.16
build/lib/libLLVMHexagonDisassembler.so.21.0git             115952          113416          2.19
build/lib/libLLVMLanaiDisassembler.so.21.0git                24360           21008         13.76
build/lib/libLLVMLoongArchDisassembler.so.21.0git            58584           56168          4.12
build/lib/libLLVMM68kDisassembler.so.21.0git                 57264           53880          5.91
build/lib/libLLVMMSP430Disassembler.so.21.0git               28896           28440          1.58
build/lib/libLLVMMipsDisassembler.so.21.0git                123128          120568          2.08
build/lib/libLLVMPowerPCDisassembler.so.21.0git              80656           78096          3.17
build/lib/libLLVMRISCVDisassembler.so.21.0git               154080          150200          2.52
build/lib/libLLVMSparcDisassembler.so.21.0git                42040           39568          5.88
build/lib/libLLVMSystemZDisassembler.so.21.0git              97056           94552          2.58
build/lib/libLLVMVEDisassembler.so.21.0git                   83944           81352          3.09
build/lib/libLLVMWebAssemblyDisassembler.so.21.0git          25280           25280          0.00
build/lib/libLLVMX86Disassembler.so.21.0git                2920624         2920624          0.00
build/lib/libLLVMXCoreDisassembler.so.21.0git                48320           44288          8.34
build/lib/libLLVMXtensaDisassembler.so.21.0git               42248           35840         15.17
```



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