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8743680541
If a string([]byte) conversion is used immediately as a key for a
map read, we don't need to copy the backing store of the byte
slice, as mapaccess does not keep a reference to it.
The gc compiler does more than this: it also avoids the copy if
the map key is a composite literal that contains the conversion
as a field, like, T{ ... { ..., string(b), ... }, ... }. For now,
we just optimize the simple case, which is probably most common.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/176197
* go.dg/mapstring.go: New test.
From-SVN: r271044
12 lines
293 B
Go
12 lines
293 B
Go
// { dg-do compile }
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// { dg-options "-fgo-debug-optimization" }
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package p
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func F(m map[string]int, a, b []byte) int {
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x := m[string(a)] // { dg-error "no copy string\\(\\\[\\\]byte\\)" }
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y, ok := m[string(b)] // { dg-error "no copy string\\(\\\[\\\]byte\\)" }
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_ = ok
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return x + y
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}
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