Unnecessary comparisons not eliminated for full range checks #70145
Description
Repro:
public static class C
{
public static bool M0(byte b) => b >= 0;
public static bool M1(byte b) => b <= byte.MaxValue;
public static bool M2(int i) => i <= int.MaxValue;
public static bool M3(long l) => l <= long.MaxValue;
}At least according to SharpLab, this produces:
; Core CLR 6.0.322.12309 on amd64
C.M0(Byte)
L0000: test cl, cl
L0002: setae al
L0005: movzx eax, al
L0008: ret
C.M1(Byte)
L0000: cmp cl, 0xff
L0003: setbe al
L0006: movzx eax, al
L0009: ret
C.M2(Int32)
L0000: cmp ecx, 0x7fffffff
L0006: setle al
L0009: movzx eax, al
L000c: ret
C.M3(Int64)
L0000: mov rax, 0x7fffffffffffffff
L000a: cmp rcx, rax
L000d: setle al
L0010: movzx eax, al
L0013: ret
Is there a reason that couldn't instead be:
C.M0(Byte)
L0000: mov eax, 1
L0005: ret
C.M1(Byte)
L0000: mov eax, 1
L0005: ret
C.M2(Int32)
L0000: mov eax, 1
L0005: ret
C.M3(Int64)
L0000: mov eax, 1
L0005: ret
?