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.
The previous versions calculated at init() prevented `interp` from running
in many cases, increasing compile times due to the increased need to revert
the partially interpreted results and also increasing binary runtime because
fewer optimizations had happened during interp.
* reflect: rawFieldByNameFunc: copy index slice to avoid later overwrites
* runtime: Simplify slice growing/appending code
Refactor the slice appending function to rely on the slice growing
function, and remove branches/loops to use a branchfree variant.
Signed-off-by: L. Pereira <l.pereira@fastly.com>
* runtime: Remove one branch in sliceAppend()
Both branches were equivalent, so guard the overall logic in
sliceAppend() with the more general condition.
Signed-off-by: L. Pereira <l.pereira@fastly.com>
* runtime: Simplify slice growing calculation
Use `bits.Len()` rather than `32 - bits.LeadingZeros32()`. They're
equivalent, but the Len version is a bit easier to read.
Signed-off-by: L. Pereira <l.pereira@fastly.com>
* reflect: Always call sliceGrow() in extendSlice()
sliceGrow() will return the old slice if its capacity is large enough.
Signed-off-by: L. Pereira <l.pereira@fastly.com>
---------
Signed-off-by: L. Pereira <l.pereira@fastly.com>
Co-authored-by: Damian Gryski <damian@gryski.com>
We have an optimization for this specific pattern, but it's really just
a hack. With the addition of unsafe.Add in Go 1.17 we can directly
specify the intent instead and eventually remove this special case.
The code is also easier to read.
This layout parameter is currently always nil and ignored, but will
eventually contain a pointer to a memory layout.
This commit also adds module verification to the transform tests, as I
found out that it didn't (and therefore didn't initially catch all
bugs).
The copy builtin is defined as follows by the Go language spec:
copy(dst, src []T) int
copy(dst []byte, src string) int
In other words, it returns an int. The runtime.sliceCopy compiler
intrinsic returned a uintptr instead, which led to a problem while
compiling the strings package for AVR.
No other architecture should be affected by this change as the
conversion from an uintptr to an int is a no-op on most architectures.
* Use 64-bit integers on 64-bit platforms, just like gc and gccgo:
https://golang.org/doc/go1.1#int
* Do not use a separate length type. Instead, use uintptr everywhere a
length is expected.
Nia Waldvogel
Damian Gryski
L. Pereira
Ayke van Laethem