On Sat, Sep 3, 2016 at 1:12 PM, Patrice Kouame via swift-users < swift-users@swift.org> wrote:
Finally Success! I’m seeing my pretty little 3D twirling Metal Renderer
cubes again… Here’s how
Snippet of old sample code which no longer compiles in Xcode 8 beta 6
with stricter Swift3 unsafe type casting restrictions
(in MetalView.swift from # Adopting Metal II: Designing and Implementing
a Real-World Metal Renderer)
let shadowPtr = UnsafeMutablePointer<ShadowPass>(constantBufferForFrame.
contents())
let mainPtr = UnsafeMutablePointer<MainPass>(shadowPtr.advanced(by: 1))
mainPtr.pointee = mainPassFrameData
var ptr = UnsafeMutablePointer<ObjectData>(mainPtr.advanced(by: 1))
My conversion attempt that crashes Swift 3 Xcode 8 beta 6 (see RADAR 28150447
- Swift 3 UnsafeMutablePointer conversion crashes the compiler and IDE)
let shadowPtr = constantBufferForFrame.contents().bindMemory(to:
ShadowPass.self, capacity: MemoryLayout<shadowPassData>.size)
let mainPtr : UnsafeMutablePointer<MainPass> = shadowPtr.advanced(by:
1).withMemoryRebound(to: MainPass.self, capacity: 1) {
$0.pointee = mainPassFrameData
}
var ptr : UnsafeMutablePointer<ObjectData> = mainPtr.advanced(by:
1).withMemoryRebound(to: ObjectData.self, capacity: MemoryLayout<
ObjectData >.size) {$0}
Latest conversion that make Xcode and Swift 3 smile again...
let shadowPtr = constantBufferForFrame.contents().bindMemory(to:
ShadowPass.self, capacity: shadowPassData.count)
let mainPtr : UnsafeMutablePointer<MainPass> = shadowPtr.advanced(by:
1).withMemoryRebound(to: MainPass.self, capacity: 1) {$0}
mainPtr.pointee = mainPassFrameData
var ptr : UnsafeMutablePointer<ObjectData> = mainPtr.advanced(by:
1).withMemoryRebound(to: ObjectData.self, capacity: objectsToRender) {$0}
Yes… Xcode/Swift3 SIL generation definitely did NOT like my "$0.pointee =
mainPassFrameData" statement.
Apparently, reassigning the pointee within the closure makes Swift gag out
of disgust. Sorry ;-(
That’s what I get for trying to be fancy…
And fixed my “capacity” issues thanks to some previous posters.
Hope this helps anyone trying to get the Metal projects to compile again.
At least I got a Radar out of this ;-) Compilers should never burn and
crash out like this...
Regards to all, Patrice
On Sep 3, 2016, at 1:22 PM, Patrice Kouame via swift-users < > swift-users@swift.org> wrote:
Gerard-
Excellent! Looking forward to seeing your fix (hoping you get your book
back soon ;-) )
I think Xcode/Swift gags on the last ptr advance to objectData. I
recently tried another variant using withUnsafeMutablePointer like this:
var ptr : UnsafeMutablePointer<ObjectData> =
withUnsafeMutablePointer(to: &mainPtr) {
$0.withMemoryRebound(to: ObjectData.self, capacity:
objectsToRender) {
$0.pointee = renderables[0].objectData
}
}
..but still crashes with no hints.
My bug report also mentions that the Xcode migration/conversion tool is
incomplete.
It handles the “simpler" UnsafeMutableRawPointer<X> to
UnsafeMutablePonter<Y> with bindMemory cases correctly (one still has to
mind the capacity value though)
In all fairness, migrating/converting automagically in these cases is
always a little bit tricky - the proposed Xcode fixes should always be
reviewed by a human...
Patrice
On Sep 3, 2016, at 1:05 PM, Gerard Iglesias via swift-users < > swift-users@swift.org> wrote:
Ok
For the record I succeeded this transformation phase last week
I remember the tedious stuff to advance pointer from one struct to the
other kind of struct... it worked
But I don't have my MacBook with me, only the phone, the six :)
Gérard
Le 3 sept. 2016 à 18:22, Patrice Kouame <pkouame@me.com> a écrit :
Indeed. There is a difference between stride and size, but I interpreted
capacity incorrectly for my purposes. It should indicate the number of <T>
elements (not their size - right?) and the snippets below should work.
Still, compiler crashes and Xcode IDE is left in inconsistent state. So I
filed this Apple radar against Developer Tools.
28150447 - Swift 3 UnsafeMutablePointer conversion crashes the compiler
and IDE
Should I file a Swift bug too? Would that be helpful?
Regards, Patrice
On Sep 3, 2016, at 11:39 AM, Gerard Iglesias via swift-users < > swift-users@swift.org> wrote:
Hello,
I think that it is more secure to use stride in place of size, sometimes
it is not the same value.
I use it in my own use of raw bindings
Regards
Gérard
Le 3 sept. 2016 à 10:03, Patrice Kouame via swift-users < > swift-users@swift.org> a écrit :
Hi Jacob -
I think you’re right. “capacity” should be the count of type T elements in
my buffer. So in my case that line should read
let shadowPtr = constantBufferForFrame.contents().bindMemory(to:
ShadowPass.self, capacity: shadowPassData.count)
The withMemoryRebound calls need similar adjustments. The pointer to
MainPass is actually a single structure to it should be safe to do this
let mainPtr : UnsafeMutablePointer<MainPass> =
shadowPtr.advanced(by: 1).withMemoryRebound(to: MainPass.self, capacity: 1)
{
$0.pointee = mainPassFrameData
}
Whereas the unsafe pointer to <ObjectData> is actually a buffer of
renderable objects, so this should work:
var ptr : UnsafeMutablePointer<ObjectData> = mainPtr.advanced(by:
1).withMemoryRebound(to: ObjectData.self, capacity: objectsToRender) {_ in
}
There are surely ways to refactor and simplify this, but I’m trying to
retain as much of the original sample code approach as possible.
However, the compiler still segs badly.
Xcode also borks an internal error often. Only cleaning or restarting the
project can clear up that state.
Compilers (or Playgrounds for that matter) should never crash, and I’m not
sure where to file this bug : Swift or Apple radar against Xcode or both? I
now Xcode 8 is beta but…it’s been doing this for quite a while now...
In both our “close to the metal” (no pun intended) cases, it seems like a
lot of churning for very little gain. Don’t you think? The easier, but
“unsafe” casting afforded previously did the trick with the normal caveats.
Don’t get me wrong, I love Swift and “get" all the neat type safety
features. Guess we can’t have our cake and eat it too, especially when
interfacing with “unsafe” C APIs.
Anyway, back to rtfm … maybe some of the Swift Gods can chime in? ;-)
I must be doing something stupid...Patrice
On Sep 3, 2016, at 2:32 AM, Jacob Bandes-Storch <jtbandes@gmail.com> > wrote:
Hi Patrice,
I don't have a solution for you, but I just wanted to point out what I
think may be an error with your use of the new UnsafeRawPointer APIs:
constantBufferForFrame.contents().bindMemory(to: ShadowPass.self,
capacity: MemoryLayout<ShadowPass>.size)
I believe the `capacity` should actually be the number of ShadowPass
elements in the buffer, not the size of each element. Using `bindMemory(to:
ShadowPass.self` already implies that MemoryLayout<ShadowPass>.size is the
size of each element.
More info at Swift | Apple Developer Documentation
unsaferawpointer/2428875-bindmemory
I just updated a small Metal project of mine to Swift 3. I ran into some
compiler (playground) crashes, but it does seem to work most of the time.
Although I only have 1 buffer :-) jtbandes (Jacob Bandes-Storch) · GitHub
Metalbrot.playground
Jacob
On Fri, Sep 2, 2016 at 11:00 AM, Patrice Kouame via swift-users < > swift-users@swift.org> wrote:
Hi all -
I’m converting Apple’s Swift Sample "Adopting Metal II: Designing and
Implementing a Real-World Metal Renderer” in Xcode 8 beta6 to the latest
UnsafeMutablePointer API for untyped memory access.
Changes are necessary in MetalView.swift (Apple hasn’t updated their
sample code for the latest beta yet…)
The Swift Compiler crashes (Segmentation Fault: 11) on the attempt:
// Grab a pointer to the constant buffer's data store
// Since we are using Swift, it is easier to cast the pointer to
the ShadowPass type to fill the constant buffer
// We need to make a copy of these so the block captures the
correct data
// let shadowPtr = UnsafeMutablePointer<ShadowPas
>(constantBufferForFrame.contents())
let shadowPtr = constantBufferForFrame.contents().bindMemory(to:
ShadowPass.self, capacity: MemoryLayout<ShadowPass>.size)
shadowPtr.pointee = shadowPassData[0]
//More Swift specific stuff - advance pointer and cast to
MainPass
// let mainPtr = UnsafeMutablePointer<MainPass>(shadowPtr.advanced(by:
1))
// mainPtr.pointee = mainPassFrameData
let mainPtr : UnsafeMutablePointer<MainPass> =
shadowPtr.advanced(by: 1).withMemoryRebound(to: MainPass.self, capacity:
MemoryLayout<MainPass>.size) {
$0.pointee = mainPassFrameData
}
//Advance and cast to ObjectData
// var ptr = UnsafeMutablePointer<ObjectData>(mainPtr.advanced(by:
1))
var ptr : UnsafeMutablePointer<ObjectData> =
mainPtr.advanced(by: 1).withMemoryRebound(to: ObjectData.self, capacity:
MemoryLayout<ObjectData>.size) {_ in
}
let shadowOffset = 0
let mainPassOffset = MemoryLayout<ShadowPass>.size + shadowOffset
let objectDataOffset = MemoryLayout<MainPass>.size +
mainPassOffset
// Update position of all the objects
if multithreadedUpdate {
DispatchQueue.concurrentPerform(iterations: objectsToRender)
{ i in
let thisPtr = ptr.advanced(by: i)
_ = self.renderables[i].UpdateData(ptr, deltaTime: 1.0/
60.0)
}
}
else {
for index in 0..<objectsToRender {
ptr = renderables[index].UpdateData(ptr, deltaTime: 1.0/
60.0)
}
}
ptr = ptr.advanced(by: objectsToRender)
_ = groundPlane!.UpdateData(ptr, deltaTime: 1.0/60.0)
Any help is appreciated. I have the latest Xcode log handy if
necessary. Here’s a clip of the stack trace.
0 swift 0x000000010714a99d
PrintStackTraceSignalHandler(void*) + 45
1 swift 0x000000010714a3e6 SignalHandler(int) + 470
2 libsystem_platform.dylib 0x00007fff91461bba _sigtramp + 26
3 libsystem_platform.dylib 000000000000000000 _sigtramp + 1857676384
4 swift 0x00000001047207b3 (anonymous
namespace)::SILGenApply::visitExpr(swift::Expr*) + 51
5 swift 0x0000000104723ace (anonymous
namespace)::SILGenApply::visitApplyExpr(swift::ApplyExpr*) + 5182
6 swift 0x0000000104711cc1
prepareApplyExpr(swift::Lowering::SILGenFunction&, swift::Expr*) + 273
7 swift 0x00000001047624e7
swift::ASTVisitor<(anonymous namespace)::RValueEmitter,
swift::Lowering::RValue, void, void, void, void, void,
swift::Lowering::SGFContext>::visit(swift::Expr*,
swift::Lowering::SGFContext) + 103
8 swift 0x0000000104762313
swift::Lowering::SILGenFunction::emitExprInto(swift::Expr*,
swift::Lowering::Initialization*) + 195
9 swift 0x000000010474fbc3
swift::Lowering::SILGenFunction::emitPatternBinding(swift::PatternBindingDecl*,
unsigned int) + 195
10 swift 0x00000001047077bd
swift::ASTVisitor<swift::Lowering::SILGenFunction, void, void, void,
void, void, void>::visit(swift::Decl*) + 125
11 swift 0x00000001047c0019
swift::ASTVisitor<(anonymous namespace)::StmtEmitter, void, void, void,
void, void, void>::visit(swift::Stmt*) + 4169
12 swift 0x00000001047809ba
swift::Lowering::SILGenFunction::emitFunction(swift::FuncDecl*) + 314
13 swift 0x00000001046fd775
swift::Lowering::SILGenModule::emitFunction(swift::FuncDecl*
)::$_1::operator()(swift::SILFunction*) const + 1877
14 swift 0x00000001046fc322
swift::Lowering::SILGenModule::emitFunction(swift::FuncDecl*) + 626
15 swift 0x00000001047c7007 (anonymous
namespace)::SILGenType::emitType() + 1271
16 swift 0x00000001047c6a9e
swift::Lowering::SILGenModule::visitNominalTypeDecl(swift::NominalTypeDecl*)
+ 30
17 swift 0x0000000104709093
swift::Lowering::SILGenModule::emitSourceFile(swift::SourceFile*,
unsigned int) + 1795
18 swift 0x000000010470ad4d
swift::SILModule::constructSIL(swift::ModuleDecl*, swift::SILOptions&,
swift::FileUnit*, llvm::Optional<unsigned int>, bool, bool) + 1629
19 swift 0x00000001045621bf
performCompile(swift::CompilerInstance&, swift::CompilerInvocation&,
llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*) + 19487
20 swift 0x000000010455b2c5
swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*,
swift::FrontendObserver*) + 17029
21 swift 0x000000010451888d main + 8685
22 libdyld.dylib 0x00007fff91255255 start + 1
Patrice
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