Optimize list<u8> lifting and lowering#6971
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alexcrichton merged 1 commit intoSep 6, 2023
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This commit optimizes the lifting and lowering routines for `list<u8>` and other similar primitive integer types. The current lifting/lowering is intended to be general-purpose and correct but doesn't optimize well with LLVM for a number of reasons. I first attempted to reshape the general-purpose code to be easier for LLVM to optimize but in the end was unable to convince LLVM that various pointers here don't alias which meant that the general-purpose lowering/lifting never optimized well. Instead, however, I've added new trait methods which are implemented the same way as the general purpose methods beforehand. The integer/primitive implementations overwrite these implementations with more specialized versions given knowledge of primitives. On a local benchmark this makes lifting/lowering disappear from a profile since memcpy is generally much faster than per-item processing.
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This commit optimizes the lifting and lowering routines for `list<u8>` and other similar primitive integer types. The current lifting/lowering is intended to be general-purpose and correct but doesn't optimize well with LLVM for a number of reasons. I first attempted to reshape the general-purpose code to be easier for LLVM to optimize but in the end was unable to convince LLVM that various pointers here don't alias which meant that the general-purpose lowering/lifting never optimized well. Instead, however, I've added new trait methods which are implemented the same way as the general purpose methods beforehand. The integer/primitive implementations overwrite these implementations with more specialized versions given knowledge of primitives. On a local benchmark this makes lifting/lowering disappear from a profile since memcpy is generally much faster than per-item processing.
alexcrichton
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This commit optimizes the lifting and lowering routines for `list<u8>` and other similar primitive integer types. The current lifting/lowering is intended to be general-purpose and correct but doesn't optimize well with LLVM for a number of reasons. I first attempted to reshape the general-purpose code to be easier for LLVM to optimize but in the end was unable to convince LLVM that various pointers here don't alias which meant that the general-purpose lowering/lifting never optimized well. Instead, however, I've added new trait methods which are implemented the same way as the general purpose methods beforehand. The integer/primitive implementations overwrite these implementations with more specialized versions given knowledge of primitives. On a local benchmark this makes lifting/lowering disappear from a profile since memcpy is generally much faster than per-item processing.
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This commit optimizes the lifting and lowering routines for
list<u8>and other similar primitive integer types. The current lifting/lowering is intended to be general-purpose and correct but doesn't optimize well with LLVM for a number of reasons. I first attempted to reshape the general-purpose code to be easier for LLVM to optimize but in the end was unable to convince LLVM that various pointers here don't alias which meant that the general-purpose lowering/lifting never optimized well.Instead, however, I've added new trait methods which are implemented the same way as the general purpose methods beforehand. The integer/primitive implementations overwrite these implementations with more specialized versions given knowledge of primitives.
On a local benchmark this makes lifting/lowering disappear from a profile since memcpy is generally much faster than per-item processing.