Golang cmd/compile: inlining blocks integer range optimization

Consider the following code:

func gte4(x uint64) bool {
    return 4 <= x
}

func lt20(x uint64) bool {
    return x < 20
}

func example(x uint64, t, f int) int {
    if gte4(x) && lt20(x) {
        return t
    }
    return f
}

When compiled this produces:

00007 CMP $4, R0
00008 BLO 14
00009 NOP
00010 CMP $20, R0
00011 BHS 14
00012 MOVD R1, R0
00013 RET
00014 MOVD R2, R0
00015 RET

If, however, I manually inline the gte4 and lt20 functions the result is more optimal:

00006 SUB $4, R0, R3
00007 CMP $16, R3
00008 BHS 11
00009 MOVD R1, R0
00010 RET
00011 MOVD R2, R0
00012 RET

After a bit of investigation it turns out this is because the InlMark op has a memory argument which currently prevents speculative execution of any block containing it. That in turn blocks the integer range check optimisation. I will send a fix.

Comment From: gopherbot

Change https://go.dev/cl/693795 mentions this issue: cmd/compile: allow InlMark operations to be speculatively executed