mirror of
https://github.com/tinygo-org/tinygo.git
synced 2026-08-03 02:27:48 +00:00
Nia Waldvogel
a40586d092
The compiler now implements the copy builtin directly instead of calling sliceCopy. The length is calculated with the llvm.umax.* intrinsics, and the move is performed by llvm.memmove.*. Both of these operations are easily understood by LLVM's optimization passes. The type's alignment is also provided to llvm.memmove.*, which is useful when rewriting the move. Interp no longer needs to reimplement sliceCopy. Some edge case handling was implemented by sliceCopy but not llvm.memmove.*/llvm.memcpy.*. I copied this over, so copies of external slices should work now. Volatile moves/copies are now run at runtime by interp. There is a 4-byte size increase due to some confusing length logic in sendUSBPacket. I will look at sendUSBPacket in a future PR.
47 lines
1.6 KiB
Go
47 lines
1.6 KiB
Go
package runtime
|
|
|
|
// This file implements compiler builtins for slices: append() and copy().
|
|
|
|
import (
|
|
"math/bits"
|
|
"unsafe"
|
|
)
|
|
|
|
// Builtin append(src, elements...) function: append elements to src and return
|
|
// the modified (possibly expanded) slice.
|
|
func sliceAppend(srcBuf, elemsBuf unsafe.Pointer, srcLen, srcCap, elemsLen, elemSize uintptr, layout unsafe.Pointer) (unsafe.Pointer, uintptr, uintptr) {
|
|
newLen := srcLen + elemsLen
|
|
if elemsLen > 0 {
|
|
// Allocate a new slice with capacity for elemsLen more elements, if necessary;
|
|
// otherwise, reuse the passed slice.
|
|
srcBuf, _, srcCap = sliceGrow(srcBuf, srcLen, srcCap, newLen, elemSize, layout)
|
|
|
|
// Append the new elements in-place.
|
|
memmove(unsafe.Add(srcBuf, srcLen*elemSize), elemsBuf, elemsLen*elemSize)
|
|
}
|
|
|
|
return srcBuf, newLen, srcCap
|
|
}
|
|
|
|
// sliceGrow returns a new slice with space for at least newCap elements
|
|
func sliceGrow(oldBuf unsafe.Pointer, oldLen, oldCap, newCap, elemSize uintptr, layout unsafe.Pointer) (unsafe.Pointer, uintptr, uintptr) {
|
|
if oldCap >= newCap {
|
|
// No need to grow, return the input slice.
|
|
return oldBuf, oldLen, oldCap
|
|
}
|
|
|
|
// This can be made more memory-efficient by multiplying by some other constant, such as 1.5,
|
|
// which seems to be allowed by the Go language specification (but this can be observed by
|
|
// programs); however, due to memory fragmentation and the current state of the TinyGo
|
|
// memory allocators, this causes some difficult to debug issues.
|
|
newCap = 1 << bits.Len(uint(newCap))
|
|
|
|
buf := alloc(newCap*elemSize, layout)
|
|
if oldLen > 0 {
|
|
// copy any data to new slice
|
|
memmove(buf, oldBuf, oldLen*elemSize)
|
|
}
|
|
|
|
return buf, oldLen, newCap
|
|
}
|