mirror of https://github.com/golang/go.git
fb184a383e
This patch changes the way the linker emits the DWARF line table prologue, specifically the file table. Previously files were left unmodified, and the directory table was empty. For each compilation unit we now scan the unit file table and build up a common set of directories, emit them into the directory table, and then emit file entries that refer to the dirs. This provides a modest binary size savings. For kubernetes kubelet: $ objdump -h /tmp/kubelet.old | fgrep debug_line 36 .zdebug_line 019a55f5 0000000000000000 0000000000000000 084a5123 2**0 $ objdump -h /tmp/kubelet.new | fgrep debug_line 36 .zdebug_line 01146fd2 0000000000000000 0000000000000000 084a510a 2**0 [where the value following the section name above is the section size in hex, so roughly a 30% decrease in this case.] The actual savings will depend on the length of the pathnames involved, so it's hard to really pin down how much savings we'll see here. In addition, emitting the files this way reduces the "compressibility" of the line table, so there could even be cases where we don't win at all. Updates #6853, #19784, #36495. Change-Id: I298d8561da5ed3ebc9d38aa772874851baa2f4f4 Reviewed-on: https://go-review.googlesource.com/c/go/+/263017 Run-TryBot: Than McIntosh <thanm@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Austin Clements <austin@google.com> Trust: Than McIntosh <thanm@google.com> |
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