• Matthew Dempsky's avatar
    cmd/compile: fix plan9-amd64 build · da19a0cf
    Matthew Dempsky authored
    The previous rules to combine indexed loads produced addresses like:
    
        From: obj.Addr{
            Type:   TYPE_MEM,
            Reg:    REG_CX,
            Name:   NAME_AUTO,
            Offset: 121,
            ...
        }
    
    which are erroneous because NAME_AUTO implies a base register of
    REG_SP, and cmd/internal/obj/x86 makes many assumptions to this
    effect.  Note that previously we were also producing an extra "ADDQ
    SP, CX" instruction, so indexing off of SP was already handled.
    
    The approach taken by this CL to address the problem is to instead
    produce addresses like:
    
        From: obj.Addr{
            Type:   TYPE_MEM,
            Reg:    REG_SP,
            Name:   NAME_AUTO,
            Offset: 121,
            Index:  REG_CX,
            Scale:  1,
        }
    
    and to omit the "ADDQ SP, CX" instruction.
    
    Downside to this approach is it requires adding a lot of new
    MOV[WLQ]loadidx1 instructions that nearly duplicate functionality of
    the existing MOV[WLQ]loadidx[248] instructions, but with a different
    Scale.
    
    Fixes #15001.
    
    Change-Id: Iad9a1a41e5e2552f8d22e3ba975e4ea0862dffd2
    Reviewed-on: https://go-review.googlesource.com/21245
    Run-TryBot: Matthew Dempsky <mdempsky@google.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    Reviewed-by: default avatarKeith Randall <khr@golang.org>
    da19a0cf
AMD64.rules 60.8 KB