[PATCH] D42574: [ARM] Lower lower saturate to 0 and lower saturate to -1 using bit-operations

[Marten Svanfeldt via Phabricator via llvm-commits]

thebolt added a comment.

I'm looking into it right now.

I found one direct error (which caused the armv7-linux-android misscompile) and also "pessimised" it a bit to only do the optimization on i32 variables. This still covers the majority of cases as clang for 16/8 bit variables creates signextend->select->truncate sequences, but avoids a few corner cases.

Will try to post a new patch during the day, but I don't know how to runtime test it or do any more testing than "ninja check" (I runtime-test it on our Cortex-M4 ARM based boards).


Repository:
  rL LLVM

https://reviews.llvm.org/D42574