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cmd/compile,runtime: pass elem type to {make,grow}slice

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No point in passing the slice type to these functions.
All they need is the element type.  One less indirection,
maybe a few less []T type descriptors in the binary.

Change-Id: Ib0b83b5f14ca21d995ecc199ce8ac00c4eb375e6
Reviewed-on: https://go-review.googlesource.com/22275
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit is contained in:
Keith Randall 2016-04-19 15:38:59 -07:00
parent 0150f15a92
commit bfe0cbdc50
4 changed files with 13 additions and 15 deletions
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16
src/runtime/slice.go
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@ -37,14 +37,14 @@ func maxSliceCap(elemsize uintptr) uintptr {
}
// TODO: take uintptrs instead of int64s?
func makeslice(t *slicetype, len64, cap64 int64) slice {
func makeslice(et *_type, len64, cap64 int64) slice {
// NOTE: The len > maxElements check here is not strictly necessary,
// but it produces a 'len out of range' error instead of a 'cap out of range' error
// when someone does make([]T, bignumber). 'cap out of range' is true too,
// but since the cap is only being supplied implicitly, saying len is clearer.
// See issue 4085.
maxElements := maxSliceCap(t.elem.size)
maxElements := maxSliceCap(et.size)
len := int(len64)
if len64 < 0 || int64(len) != len64 || uintptr(len) > maxElements {
panic(errorString("makeslice: len out of range"))
@ -55,7 +55,6 @@ func makeslice(t *slicetype, len64, cap64 int64) slice {
panic(errorString("makeslice: cap out of range"))
}
et := t.elem
var flags uint32
if et.kind&kindNoPointers != 0 {
flags = flagNoScan
@ -65,7 +64,7 @@ func makeslice(t *slicetype, len64, cap64 int64) slice {
}
// growslice handles slice growth during append.
// It is passed the slice type, the old slice, and the desired new minimum capacity,
// It is passed the slice element type, the old slice, and the desired new minimum capacity,
// and it returns a new slice with at least that capacity, with the old data
// copied into it.
// The new slice's length is set to the old slice's length,
@ -74,16 +73,15 @@ func makeslice(t *slicetype, len64, cap64 int64) slice {
// to calculate where to write new values during an append.
// TODO: When the old backend is gone, reconsider this decision.
// The SSA backend might prefer the new length or to return only ptr/cap and save stack space.
func growslice(t *slicetype, old slice, cap int) slice {
func growslice(et *_type, old slice, cap int) slice {
if raceenabled {
callerpc := getcallerpc(unsafe.Pointer(&t))
racereadrangepc(old.array, uintptr(old.len*int(t.elem.size)), callerpc, funcPC(growslice))
callerpc := getcallerpc(unsafe.Pointer(&et))
racereadrangepc(old.array, uintptr(old.len*int(et.size)), callerpc, funcPC(growslice))
}
if msanenabled {
msanread(old.array, uintptr(old.len*int(t.elem.size)))
msanread(old.array, uintptr(old.len*int(et.size)))
}
et := t.elem
if et.size == 0 {
if cap < old.cap {
panic(errorString("growslice: cap out of range"))