[PATCH] D134684: [LegalizeTypes][Mips][RISCV][SystemZ] Mask shift amounts in ExpandShiftWithUnknownAmountBit.

[Amanieu d'Antras via Phabricator via llvm-commits]

Amanieu added a comment.

Note that the case in PR57988 doesn't involve any out-of-range shifts in the source program. The current codegen means that with (1i128 << 0) you end up calling __ashldi with a shift amount of -64. If that's something we're happy with then the documentation should be fixed and I can go update Rust's compiler-builtins to wrap instead of panicking on out-of-range shifts in debug builds (which is how this bug was discovered).


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https://reviews.llvm.org/D134684