• David Crawshaw's avatar
    cmd/link: deduplicate read-only string data · afd83543
    David Crawshaw authored
    Many read-only strings in Go binaries are substrings of other read-only
    strings. A common source is the text form of type information, which
    will include both "struct { X int }" and "*struct { X int }" or
    "*bytes.Reader" and "func(*bytes.Reader)" in the same binary.
    
    Because this character data is referred to by separate string headers,
    we can skip writing the smaller string and modify the pointer
    relocation to point to the larger string. This CL does this
    deduplication in the linker after the reachable set of strings has
    been determined.
    
    This removes 765KB from juju (1.4% without DWARF).
    
    Link time goes at tip goes form 4.6s to 6.3s, but note that this CL
    is part of a series that recently reduced link time from 9.6s.
    
    For #6853.
    
    Change-Id: Ib2087cf627c9f1e9a1181f9b4c8f81d1a3f42191
    Reviewed-on: https://go-review.googlesource.com/19987Reviewed-by: 's avatarIan Lance Taylor <iant@golang.org>
    Run-TryBot: David Crawshaw <crawshaw@golang.org>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    afd83543
mergestrings.go 4.26 KB