Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

runtime: use 1-bit pointer bitmaps in type representation

Browse source 
The type information in reflect.Type and the GC programs is now
1 bit per word, down from 2 bits.

The in-memory unrolled type bitmap representation are now
1 bit per word, down from 4 bits.

The conversion from the unrolled (now 1-bit) bitmap to the
heap bitmap (still 4-bit) is not optimized. A followup CL will
work on that, after the heap bitmap has been converted to 2-bit.

The typeDead optimization, in which a special value denotes
that there are no more pointers anywhere in the object, is lost
in this CL. A followup CL will bring it back in the final form of
heapBitsSetType.

Change-Id: If61e67950c16a293b0b516a6fd9a1c755b6d5549
Reviewed-on: https://go-review.googlesource.com/9702
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Russ Cox 2015-04-28 00:28:47 -04:00
parent 7d9e16abc6
commit 6d8a147bef
10 changed files with 204 additions and 301 deletions
Download patch file Download diff file Expand all files Collapse all files

36
src/reflect/all_test.go
View file

@ -4388,7 +4388,7 @@ func TestCallGC(t *testing.T) {
type funcLayoutTest struct {
rcvr, t Type
size, argsize, retOffset uintptr
stack []byte
stack []byte // pointer bitmap: 1 is pointer, 0 is scalar (or uninitialized)
gc []byte
}
@ -4399,7 +4399,7 @@ func init() {
var naclExtra []byte
if runtime.GOARCH == "amd64p32" {
argAlign = 2 * PtrSize
naclExtra = append(naclExtra, BitsScalar)
naclExtra = append(naclExtra, 0)
}
roundup := func(x uintptr, a uintptr) uintptr {
return (x + a - 1) / a * a
@ -4412,17 +4412,17 @@ func init() {
6 * PtrSize,
4 * PtrSize,
4 * PtrSize,
[]byte{BitsPointer, BitsScalar, BitsPointer},
[]byte{BitsPointer, BitsScalar, BitsPointer, BitsScalar, BitsPointer, BitsScalar},
[]byte{1, 0, 1},
[]byte{1, 0, 1, 0, 1, 0},
})
var r, s []byte
if PtrSize == 4 {
r = []byte{BitsScalar, BitsScalar, BitsScalar, BitsPointer}
s = append([]byte{BitsScalar, BitsScalar, BitsScalar, BitsPointer, BitsScalar}, naclExtra...)
r = []byte{0, 0, 0, 1}
s = append([]byte{0, 0, 0, 1, 0}, naclExtra...)
} else {
r = []byte{BitsScalar, BitsScalar, BitsPointer}
s = []byte{BitsScalar, BitsScalar, BitsPointer, BitsScalar}
r = []byte{0, 0, 1}
s = []byte{0, 0, 1, 0}
}
funcLayoutTests = append(funcLayoutTests,
funcLayoutTest{
@ -4442,8 +4442,8 @@ func init() {
4 * PtrSize,
4 * PtrSize,
4 * PtrSize,
[]byte{BitsPointer, BitsScalar, BitsPointer, BitsPointer},
[]byte{BitsPointer, BitsScalar, BitsPointer, BitsPointer},
[]byte{1, 0, 1, 1},
[]byte{1, 0, 1, 1},
})
type S struct {
@ -4457,8 +4457,8 @@ func init() {
4 * PtrSize,
4 * PtrSize,
4 * PtrSize,
[]byte{BitsScalar, BitsScalar, BitsPointer, BitsPointer},
[]byte{BitsScalar, BitsScalar, BitsPointer, BitsPointer},
[]byte{0, 0, 1, 1},
[]byte{0, 0, 1, 1},
})
funcLayoutTests = append(funcLayoutTests,
@ -4468,8 +4468,8 @@ func init() {
roundup(3*PtrSize, argAlign),
3 * PtrSize,
roundup(3*PtrSize, argAlign),
[]byte{BitsPointer, BitsScalar, BitsPointer},
append([]byte{BitsPointer, BitsScalar, BitsPointer}, naclExtra...),
[]byte{1, 0, 1},
append([]byte{1, 0, 1}, naclExtra...),
})
funcLayoutTests = append(funcLayoutTests,
@ -4480,7 +4480,7 @@ func init() {
PtrSize,
roundup(PtrSize, argAlign),
[]byte{},
append([]byte{BitsScalar}, naclExtra...),
append([]byte{0}, naclExtra...),
})
funcLayoutTests = append(funcLayoutTests,
@ -4491,7 +4491,7 @@ func init() {
0,
0,
[]byte{},
[]byte{BitsScalar},
[]byte{0},
})
funcLayoutTests = append(funcLayoutTests,
@ -4501,8 +4501,8 @@ func init() {
2 * PtrSize,
2 * PtrSize,
2 * PtrSize,
[]byte{BitsPointer},
[]byte{BitsPointer, BitsScalar},
[]byte{1},
[]byte{1, 0},
// Note: this one is tricky, as the receiver is not a pointer. But we
// pass the receiver by reference to the autogenerated pointer-receiver
// version of the function.