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author | David Crawshaw <crawshaw@golang.org> | 2016-02-20 22:54:15 -0500 |
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committer | David Crawshaw <crawshaw@golang.org> | 2016-03-08 23:23:13 +0000 |
commit | a24b3ed7538dd2eb013005fb1e153468f486857a (patch) | |
tree | 1984c416b16989a003a8adbdd2356fde7cffb7f2 /src/runtime/type.go | |
parent | 0321cabdfacc5472d2bc650de3e36ca10131b60a (diff) | |
download | go-a24b3ed7538dd2eb013005fb1e153468f486857a.tar.gz go-a24b3ed7538dd2eb013005fb1e153468f486857a.zip |
cmd/compile: remove rtype *uncommonType field
Instead of a pointer on every rtype, use a bit flag to indicate that
the contents of uncommonType directly follows the rtype value when it
is needed.
This requires a bit of juggling in the compiler's rtype encoder. The
backing arrays for fields in the rtype are presently encoded directly
after the slice header. This packing requires separating the encoding
of the uncommonType slice headers from their backing arrays.
Reduces binary size of godoc by ~180KB (1.5%).
No measurable change in all.bash time.
For #6853.
Change-Id: I60205948ceb5c0abba76fdf619652da9c465a597
Reviewed-on: https://go-review.googlesource.com/19790
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'src/runtime/type.go')
-rw-r--r-- | src/runtime/type.go | 70 |
1 files changed, 68 insertions, 2 deletions
diff --git a/src/runtime/type.go b/src/runtime/type.go index 2312f819ea..9c9b5fb8cc 100644 --- a/src/runtime/type.go +++ b/src/runtime/type.go @@ -8,6 +8,11 @@ package runtime import "unsafe" +// tflag is documented in ../reflect/type.go. +type tflag uint8 + +const tflagUncommon tflag = 1 + // Needs to be in sync with ../cmd/compile/internal/ld/decodesym.go:/^func.commonsize, // ../cmd/compile/internal/gc/reflect.go:/^func.dcommontype and // ../reflect/type.go:/^type.rtype. @@ -15,7 +20,7 @@ type _type struct { size uintptr ptrdata uintptr // size of memory prefix holding all pointers hash uint32 - _unused uint8 + tflag tflag align uint8 fieldalign uint8 kind uint8 @@ -25,7 +30,68 @@ type _type struct { // Otherwise it is a ptrmask bitmap. See mbitmap.go for details. gcdata *byte _string string - x *uncommontype +} + +func (t *_type) uncommon() *uncommontype { + if t.tflag&tflagUncommon == 0 { + return nil + } + switch t.kind & kindMask { + case kindStruct: + type u struct { + structtype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + case kindPtr: + type u struct { + ptrtype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + case kindFunc: + type u struct { + functype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + case kindSlice: + type u struct { + slicetype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + case kindArray: + type u struct { + arraytype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + case kindChan: + type u struct { + chantype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + case kindMap: + type u struct { + maptype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + case kindInterface: + type u struct { + interfacetype + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + default: + type u struct { + _type + u uncommontype + } + return &(*u)(unsafe.Pointer(t)).u + } } func hasPrefix(s, prefix string) bool { |