[TableGen] More efficiency improvements for encode/decode emission. #84647
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DecoderEmitter and CodeEmitterGen perform repeated linear walks over the entire instruction list. This patch eliminates two more such walks. The eliminated traversals visit every instruction merely to determine whether the target has variable length encodings. For a target with variable length encodings, the original any_of will terminate quickly. But all targets other than M68k use fixed length encodings and thus any_of must visit the entire instruction list.
wangpc-pp
approved these changes
Mar 11, 2024
| @@ -17,6 +17,7 @@ | |||
| #include "llvm/ADT/StringMap.h" | |||
| #include "llvm/ADT/StringRef.h" | |||
| #include "llvm/CodeGenTypes/MachineValueType.h" | |||
| #include "llvm/TableGen/Record.h" | |||
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We don't need forward declarations below now.
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Done.
Thank you for the review.
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Or we can move implementation of isVariableLengthEncoding to llvm/utils/TableGen/CodeGenInstruction.cpp so that we don't need to mess includes. :-)
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DecoderEmitter and CodeEmitterGen perform repeated linear walks over the entire instruction list. This patch eliminates two more such walks.
The eliminated traversals visit every instruction merely to determine whether the target has variable length encodings. For a target with variable length encodings, the original any_of will terminate quickly. But all targets other than M68k use fixed length encodings and thus any_of must visit the entire instruction list.