[PATCH] D67686: Fix compile-time regression caused by rL371928

[Daniel Sanders via Phabricator via llvm-commits]

dsanders created this revision.
dsanders added a reviewer: jmolloy.
Herald added subscribers: dexonsmith, hiraditya.
Herald added a project: LLVM.

Also fixup rL371928 <https://reviews.llvm.org/rL371928> for cases that occur on our out-of-tree backend

There were still quite a few intermediate APInts and this caused the
compile time of MCCodeEmitter for our target to jump from 16s up to
~5m40s. This patch, brings it back down to ~17s by eliminating pretty
much all of them using two new APInt functions (extractBitsAsZExtValue(),
insertBits() but with a uint64_t). The exact conditions for eliminating
them is that the field extracted/inserted must be <=64-bit which is
almost always true.

Note: The two new APInt API's assume that APInt::WordSize is at least
64-bit because that means they touch at most 2 APInt words. They
statically assert that's true. It seems very unlikely that someone
is patching it to be smaller so this should be fine.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D67686

Files:
  llvm/include/llvm/ADT/APInt.h
  llvm/lib/Support/APInt.cpp
  llvm/test/TableGen/BigEncoder.td
  llvm/unittests/ADT/APIntTest.cpp
  llvm/utils/TableGen/CodeEmitterGen.cpp

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