Stream: git-cranelift

Topic: cranelift / Issue #815 iconst + icmp -> icmp_imm incorrec...

view this post on Zulip GitHub (Feb 28 2020 at 23:26):

alexcrichton transferred Issue #815:

Eg

ebb0(v0: i8):
    v1 = iconst.i8 255 ; -1i8 as u8
    v2 = icmp sge v0, v1; true for v0 s> -1

gets converted to

ebb0(v0: i8):
    v2 = icmp_imm sge v0, 255 ; never true, as an i8 is never bigger than 127

The optimization should be prevented for out of bound integers, or it should convert the 255 to -1.

cc https://github.com/bjorn3/rustc_codegen_cranelift/commit/b0ecbf14a23a301183ff194ca97a62e23e2cc6f7

Last updated: Nov 22 2024 at 16:03 UTC