What version of Go are you using (go version)?

go version go1.7.1 windows/amd64

What did you do?

https://play.golang.org/p/91drTKDs_m

What did you expect to see?

andl    $-33, %eax
subl    $65, %eax
cmpb    $25, %al
setbe   %al
movzbl  %al, %eax

This is what GCC 5.4.0 produces. I was surprised by this code, since I only expected it to combine the CMP + CMP to a SUB + CMP. But now that I see this, I'd like the Go compiler to produce similar code.

What did you see instead?

   MOVZX 0x8(SP), AX
   CMPL $0x41, AL
   JB L2
   CMPL $0x5a, AL
   JA L2
   MOVL $0x1, AX
L1:
   MOVB AL, 0x10(SP)
   RET
L2:
   CMPL $0x61, AL
   JB L3
   CMPL $0x7a, AL
   SETBE AL
   JMP L1
L3:
   XORL AX, AX
   JMP L1