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cmd/compile: remove overflow pointer padding for nacl

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CL 200077 removed nacl bits in the toolchain, but it misses the code to
add pointer overflow padding, which is specific for nacl.

This CL removes that part.

Passes toolstash-check.

Updates #30439

Change-Id: I1e77cade9f31690e16cd13d3445a98b500671252
Reviewed-on: https://go-review.googlesource.com/c/go/+/202159
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Cuong Manh Le 2019-10-19 23:31:52 +07:00 committed by Keith Randall
parent 3b2eb699a0
commit ba97d0d84d
1 changed files with 1 additions and 22 deletions
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23
src/cmd/compile/internal/gc/reflect.go
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@ -112,27 +112,6 @@ func bmap(t *types.Type) *types.Type {
elems := makefield("elems", arr)
field = append(field, elems)
// Make sure the overflow pointer is the last memory in the struct,
// because the runtime assumes it can use size-ptrSize as the
// offset of the overflow pointer. We double-check that property
// below once the offsets and size are computed.
//
// BUCKETSIZE is 8, so the struct is aligned to 64 bits to this point.
// On 32-bit systems, the max alignment is 32-bit, and the
// overflow pointer will add another 32-bit field, and the struct
// will end with no padding.
// On 64-bit systems, the max alignment is 64-bit, and the
// overflow pointer will add another 64-bit field, and the struct
// will end with no padding.
// On nacl/amd64p32, however, the max alignment is 64-bit,
// but the overflow pointer will add only a 32-bit field,
// so if the struct needs 64-bit padding (because a key or elem does)
// then it would end with an extra 32-bit padding field.
// Preempt that by emitting the padding here.
if int(elemtype.Align) > Widthptr || int(keytype.Align) > Widthptr {
field = append(field, makefield("pad", types.Types[TUINTPTR]))
}
// If keys and elems have no pointers, the map implementation
// can keep a list of overflow pointers on the side so that
// buckets can be marked as having no pointers.
@ -196,7 +175,7 @@ func bmap(t *types.Type) *types.Type {
}
// Double-check that overflow field is final memory in struct,
// with no padding at end. See comment above.
// with no padding at end.
if overflow.Offset != bucket.Width-int64(Widthptr) {
Fatalf("bad offset of overflow in bmap for %v", t)
}