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author | Matthew Dempsky <mdempsky@google.com> | 2019-10-03 10:49:28 -0700 |
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committer | Matthew Dempsky <mdempsky@google.com> | 2019-10-03 18:08:32 +0000 |
commit | c33d45a898ab1d966faba33d18acdffefb0fae0d (patch) | |
tree | 425b1208dde73aa82fb5e1adf8f9f382a50e46ee /test/linkx.go | |
parent | 6b85fa80519615ae5fd58154277b47d77e5cf08b (diff) | |
download | go-c33d45a898ab1d966faba33d18acdffefb0fae0d.tar.gz go-c33d45a898ab1d966faba33d18acdffefb0fae0d.zip |
cmd/compile: don't statically copy string-typed variables
During package initialization, the compiler tries to optimize:
var A = "foo"
var B = A
into
var A = "foo"
var B = "foo"
so that we can statically initialize both A and B and skip emitting
dynamic initialization code to assign "B = A".
However, this isn't safe in the presence of cmd/link's -X flag, which
might overwrite an initialized string-typed variable at link time. In
particular, if cmd/link changes A's static initialization, it won't
know it also needs to change B's static initialization.
To address this, this CL disables this optimization for string-typed
variables.
Fixes #34675.
Change-Id: I1c18f3b855f6d7114aeb39f96aaaf1b452b88236
Reviewed-on: https://go-review.googlesource.com/c/go/+/198657
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'test/linkx.go')
-rw-r--r-- | test/linkx.go | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/test/linkx.go b/test/linkx.go index 20b8c773d8..520a065182 100644 --- a/test/linkx.go +++ b/test/linkx.go @@ -14,10 +14,19 @@ import "fmt" var tbd string var overwrite string = "dibs" +var tbdcopy = tbd +var overwritecopy = overwrite +var arraycopy = [2]string{tbd, overwrite} + var b bool var x int func main() { fmt.Println(tbd) + fmt.Println(tbdcopy) + fmt.Println(arraycopy[0]) + fmt.Println(overwrite) + fmt.Println(overwritecopy) + fmt.Println(arraycopy[1]) } |